2024-03-28T20:17:13Z
https://eprints.whiterose.ac.uk/cgi/oai2
oai:eprints.whiterose.ac.uk:609
2016-10-24T16:40:08Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D42494F4C:4C656564732E52432D494D4342
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/609/
Unfolding dynamics of proteins under applied force
Smith, D.A.
Brockwell, D.J.
Zinober, R.C.
Blake, A.W.
Beddard, G.S.
Olmsted, P.D.
Radford, S.E.
Understanding the mechanisms of protein folding is a major challenge that is being addressed effectively by collaboration between researchers in the physical and life sciences. Recently, it has become possible to mechanically unfold proteins by pulling on their two termini using local force probes such as the atomic force microscope. Here, we present data from experiments in which synthetic protein polymers designed to mimic naturally occurring polyproteins have been mechanically unfolded. For many years protein folding dynamics have been studied using chemical denaturation, and we therefore firstly discuss our mechanical unfolding data in the context of such experiments and show that the two unfolding mechanisms are not the same, at least for the proteins studied here. We also report unexpected observations that indicate a history effect in the observed unfolding forces of polymeric proteins and explain this in terms of the changing number of domains remaining to unfold and the increasing compliance of the lengthening unstructured polypeptide chain produced each time a domain unfolds.
2003-04-15
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/609/1/radfordse4.pdf
Smith, D.A., Brockwell, D.J., Zinober, R.C. et al. (4 more authors) (2003) Unfolding dynamics of proteins under applied force. Philosophical Transactions Of The Royal Society Of London Series A - Mathematical Physical and Engineering Sciences, 361 (1805). 713 -730. ISSN 1471-2962
http://www.journals.royalsoc.ac.uk/link.asp?id=b62ebuhdgxnacyep
doi:10.1098/rsta.2002.1160
oai:eprints.whiterose.ac.uk:919
2016-10-25T16:19:01Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/919/
Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives
Kennedy, A.
Nelson, A.
Perry, A.
Background: Many polyhydroxylated piperidines are inhibitors of the oligosaccharide processing
enzymes, glycosidases and glycosyltransferases. Aza-C-linked disaccharide mimetics are compounds
in which saturated polyhydroxylated nitrogen and oxygen heterocycles are linked by an all-carbon
tether. The saturated oxygen heterocycle has the potential to mimic the departing sugar in a
glycosidase-catalysed reaction and aza-C-linked disaccharide mimetics may, therefore, be more
potent inhibitors of these enzymes.
Results: The scope, limitations and diastereoselectivity of the dihydroxylation of stereoisomeric
2-butyl-1-(toluene-4-sulfonyl)-1,2,3,6-tetrahydro-pyridin-3-ols is discussed. In the absence of a 6-
substituent on the piperidine ring, the Upjohn (cat. OsO4, NMO, acetone-water) and Donohoe
(OsO4, TMEDA, CH2Cl2) conditions allow complementary diastereoselective functionalisation of
the alkene of the (2R*,3R*) diastereoisomer. However, in the presence of a 6-substituent, the
reaction is largely controlled by steric effects with both reagents. The most synthetically useful
protocols were exploited in the two-directional synthesis of aza-C-linked disaccharide analogues.
A two-directional oxidative ring expansion was used to prepare bis-enones such as (2R,6S,2'S)-6-
methoxy-2-(6-methoxy-3-oxo-3,6-dihydro-2H-pyran-2-ylmethyl)-1-(toluene-4-sulfonyl)-1,6-
dihydro-2H-pyridin-3-one from the corresponding difuran. Selective substitution of its N,O acetal
was possible. The stereochemical outcome of a two-directional Luche reduction step was different
in the two heterocyclic rings, and depended on the conformation of the ring. Finally, twodirectional
diastereoselective dihydroxylation yielded seven different aza-C-linked disaccharide
analogues.
Conclusion: A two-directional approach may be exploited in the synthesis of aza-C-linked
disaccharide mimetics. Unlike previous approaches to similar molecules, neither of the heterocyclic
rings is directly derived from a sugar, allowing mimetics with unusual configurations to be prepared.
The work demonstrates that highly unsymmetrical molecules may be prepared using a two
directional approach. The deprotected compounds may have potential as inhibitors of
oligosaccharide-processing enzymes and as tools in chemical genetic investigations.
2005-08-26
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/919/1/Nelsona.1.pdf
Kennedy, A., Nelson, A. and Perry, A. (2005) Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives. Beilstein Journal of Organic Chemistry, 1 (2). ISSN 1860-5397
http://bjoc.beilstein-journals.org/content/1/1/2
doi:10.1186/1860-5397-1-2
oai:eprints.whiterose.ac.uk:924
2016-10-26T03:00:22Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/924/
Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes
Marsden, S.P.
Ducept, P.C.
BACKGROUND:
Allenylsilanes are useful intermediates in organic synthesis. An attractive, convergent but little used approach for their synthesis is the alkylidenation of stable silylketenes. Reactions thus far have been limited to the use of unsubstituted silylketenes (or equivalents) with stabilised or semi-stabilised ylides only. The current study explores the reactions of substituted ketenes prepared through rhodium(II)-mediated rearrangement of silylated diazoketones.
RESULTS:
A range of novel 1,3-disubstituted and 1,3,3-trisubstituted allenylsilanes were prepared using stabilised and semi-stabilised ylides. Alkylidenation with non-stabilised phosphorus ylides was not viable, but the use of titanium-based methylenating reagents was successful, allowing access to 1-substituted allenylsilanes.
CONCLUSION:
Many novel allenylsilanes may be accessed by alkylidenation of substituted silylketenes. Importantly, for the first time, simple methylenation of silylketenes has been achieved using titanium carbenoid-based reagents.
2005-08-26
Article
PeerReviewed
text
en
cc_by_2
https://eprints.whiterose.ac.uk/924/1/marsdensp1.pdf
Marsden, S.P. and Ducept, P.C. (2005) Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes. Beilstein Journal of Organic Chemistry, 1 (5). ISSN 1860-5397
http://bjoc.beilstein-journals.org/content/1/1/5
doi:10.1186/1860-5397-1-5
oai:eprints.whiterose.ac.uk:925
2016-10-24T22:11:02Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/925/
Inter- and intramolecular Diels-Alder/retro-Diels-Alder
reactions of 4-silylated oxazoles
Ducept, P.C.
Marsden, S.P.
4-Silylated oxazoles have been shown to undergo inter- and intramolecular Diels-Alder/retro-Diels-Alder reactions with electron-poor alkynes to generate polysubstituted furans. The ease of synthesis of the requisite oxazoles by the rhodium-catalysed condensation of nitriles with silylated diazoacetate greatly increases the scope of this reaction.
2002-07-12
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/925/1/marsdensp2.pdf
Ducept, P.C. and Marsden, S.P. (2002) Inter- and intramolecular Diels-Alder/retro-Diels-Alder reactions of 4-silylated oxazoles. Arkivoc, 2002 (6). pp. 22-34. ISSN 1424-6376
http://www.arkat-usa.org/ark/journal/2002/I06_Rees/CF-510B/510B.asp
oai:eprints.whiterose.ac.uk:1311
2014-06-06T05:52:25Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D536865666669656C64:536865666669656C642E464345:536865666669656C642E434F4D
696E737469747574696F6E3D4C65656473
696E737469747574696F6E3D536865666669656C64
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1311/
Acidosis in models of cardiac ventricular myocytes
Crampin, E.J.
Smith, N.P.
Langham, A.E.
Clayton, R.H.
Orchard, C.H.
The effects of acidosis on cardiac electrophysiology and excitation–contraction coupling have been studied extensively. Acidosis decreases the strength of contraction and leads to altered calcium transients as a net result of complex interactions between protons and a variety of intracellular processes. The relative contributions of each of the changes under acidosis are difficult to establish experimentally, however, and significant uncertainties remain about the key mechanisms of impaired cardiac function.
In this paper, we review the experimental findings concerning the effects of acidosis on the action potential and calcium handling in the cardiac ventricular myocyte, and we present a modelling study that establishes the contribution of the different effects to altered Ca2+ transients during acidosis. These interactions are incorporated into a dynamical model of pH regulation in the myocyte to simulate respiratory acidosis in the heart.
The Royal Society
2006-05-15
Article
PeerReviewed
text
en
https://eprints.whiterose.ac.uk/1311/1/claytonrh2.pdf
Crampin, E.J., Smith, N.P., Langham, A.E. et al. (2 more authors) (2006) Acidosis in models of cardiac ventricular myocytes. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364 (1842). pp. 1171-1186. ISSN 1471-2962
http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&id=doi:10.1098/rsta.2006.1763
doi:10.1098/rsta.2006.1763
oai:eprints.whiterose.ac.uk:1328
2016-10-26T14:47:26Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D43495645
756E69743D4C65656473:4C656564732E46412D4541454E:4C656564732E52432D534F4545:4C656564732E52432D454152535F31
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D43495645:4C656564732E53522D49504345
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1328/
Performance of Three Resin Based Materials for Treating Uranium Contaminated Groundwater within a PRB.
Barton, C.S.
Stewart, D.I.
Morris, K.
Bryant, D.E.
Three materials that are designed to treat uranium-contaminated water were investigated. These are a cation exchange resin, IRN 77; an anion exchange resin, Varion AP; and a recently developed material called PANSIL (quartz sand coated with 2% amidoxime resin by weight). The reaction rate, capacity, and effective pH range of the three materials are reported. The capacity and conditional distribution coefficient in neutral, uranyl-contaminated synthetic groundwater containing carbonate are also reported. The suitability of each material for treating uranium-contaminated groundwater using a permeable reactive barrier (PRB) approach is then discussed.
All three materials react rapidly in the pH range 5–7, reaching equilibrium in less than 4 h at ~23◦C. The unconditioned cation exchange resin removed 8 g UO22+ per kg of resin from neutral synthetic groundwater containing 30 mg/l of UO22+, but a lower capacity is anticipated in groundwater with either higher ionic strength or lower UO22+ concentrations. It operates by first acidifying the solution, then sorbing UO22+, and can release UO22+ when its buffering capacity has been exhausted. The anion exchange resin is very effective at removing anionic uranyl carbonate species from solutions with a pH above 5, with good specificity. Up to 50 g/kg of uranium is removed from contaminated groundwater at neutral pH. PANSIL is effective at sequestering cationic and neutral uranyl species from solutions in the pH range 4.5–7.5, with very good specificity. The capacity of PANSIL is pH-dependent, increasing from about 0.4 g/kg at pH 4.5, to about 1 g/kg at pH 6, and 1.5 g/kg around pH 7.5. In neutral groundwater containing carbonate, both the anion exchange resin and PANSIL exhibit conditional distribution coefficients exceeding 1470 ml/g, which is about an order of magnitude higher than comparable reactive barrier materials reported in the literature.
Elsevier
2004-12-31
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1328/2/stewartdi3_Three_resin_based_materials_%28final%29.pdf
Barton, C.S., Stewart, D.I., Morris, K. et al. (1 more author) (2004) Performance of Three Resin Based Materials for Treating Uranium Contaminated Groundwater within a PRB. Journal of Hazardous Materials, 116 (3). pp. 191-204. ISSN 0304-3894
http://dx.doi.org/10.1016/j.jhazmat.2004.08.028
doi:10.1016/j.jhazmat.2004.08.028
oai:eprints.whiterose.ac.uk:1818
2016-10-26T03:00:28Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1818/
Collaborative e-science architecture for Reaction Kinetics research community
Pham, T.V.
Lau, L.M.S.
Dew, P.M.
Pilling, M.J.
This paper presents a novel collaborative e-science architecture (CeSA) to address two challenging issues in e-science that arise from the management of heterogeneous distributed environments: (i) how to provide individual scientists an integrated environment to collaborate with each other in distributed, loosely coupled research communities where each member might be using a disparate range of tools; and (ii) how to provide easy access to a range of computationally intensive resources from a desktop. The Reaction Kinetics research community was used to capture the requirements and in the evaluation of the proposed architecture. The result demonstrated the feasibility of the approach and the potential benefits of the CeSA.
IEEE
2005-07-24
Book Section
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1818/1/laul3.pdf
Pham, T.V., Lau, L.M.S., Dew, P.M. et al. (1 more author) (2005) Collaborative e-science architecture for Reaction Kinetics research community. In: Challenges of Large Applications in Distributed Environments, 2005. CLADE 2005. Proceedings. IEEE , pp. 13-22. ISBN 0780390431
http://dx.doi.org/10.1109/CLADE.2005.1520893
doi:10.1109/CLADE.2005.1520893
oai:eprints.whiterose.ac.uk:1819
2016-10-25T06:30:23Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1819/
A collaborative e-Science architecture towards a virtual research environment
Pham, T.V.
Lau, L.M.S.
Dew, P.M.
Pilling, M.J.
This paper presents a novel Collaborative e-Science Architecture (CeSA) to address two challenging issues in e-Science that have arisen from the management of heterogeneous distributed environments. By combining the capabilities of peer-to-peer and Grid computing, the architecture provides an environment for scientific collaborations within distributed, loosely coupled research communities and brings computation and data intensive resources to the desktops of the scientists in these communities. The Reaction Kinetics research community had been used as a case study to capture realistic requirements. A prototype based on the architecture was developed for user experiment and evaluation. The results of these experiments were promising. It has provided further motivation to evolve CeSA towards a Virtual Research Environment.
EPSRC
Cox, S.J.
Walker, D.W.
2005-09
Book Section
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1819/1/laul4.pdf
Pham, T.V., Lau, L.M.S., Dew, P.M. et al. (1 more author) (2005) A collaborative e-Science architecture towards a virtual research environment. In: Cox, S.J. and Walker, D.W., (eds.) Challenges of Large Applications in Distributed Environments, 2005. CLADE 2005. Proceedings. EPSRC , pp. 13-22. ISBN ISBN 1-904425-53-4
http://www.allhands.org.uk/2005/proceedings/papers/427.pdf
oai:eprints.whiterose.ac.uk:1898
2016-10-25T21:21:02Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1898/
Enabling e-Research in combustion research community
Pham, T.V.
Dew, P.M.
Lau, L.M.S.
Pilling, M.J.
Abstract
This paper proposes an application of the Collaborative e-Science Architecture (CeSA) to enable e-Research in combustion research community. A major problem of the community is that data required for constructing modelling might already exist but scattered and improperly evaluated. That makes the collection of data for constructing models difficult and time-consuming. The decentralised P2P collaborative environment of the CeSA is well suited to solve this distributed problem. It opens up access to scattered data and turns them to valuable resources. Other issues of the community addressed here are the needs for computational resources, storages and interoperability amongst different data formats can also be addressed by the use of Grid environment in the CeSA.
IEEE
2006-12
Book Section
NonPeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1898/1/laul7.pdf
Pham, T.V., Dew, P.M., Lau, L.M.S. et al. (1 more author) (2006) Enabling e-Research in combustion research community. In: Second IEEE International Conference on e-Science and Grid Computing, 2006, 4-6 December 2006. IEEE , p. 130. ISBN 0-7695-2734-5
http://dx.doi.org/10.1109/E-SCIENCE.2006.261063
doi:10.1109/E-SCIENCE.2006.261063
oai:eprints.whiterose.ac.uk:1939
2016-09-16T13:16:28Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1939/
Enantioselective synthesis of non-proteinogenic 2-arylallyl-α-amino acids via Pd/In catalytic cascades
Grigg, R.
McCaffrey, S.
Sridharan, V.
Fishwick, C.W.G.
Kilner, C.
Korn, S.
Bailey, K.
Blacker, J.
An efficient synthesis of both R- and S-enantiomers of 2-arylallyl-α-amino acids via a diastereoselective Pd/In mediated catalytic allylation of chiral N-sulfinyl-α-imino esters is described. The potential for further enhancement of molecular complexity and creating contiguous chiral centres by interfacing these processes with catalytic cyclisation–anion capture methodology is demonstrated.
Elsevier
2006-12-25
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1939/1/griggr1_tetrahedronshaun.doc_1.2doc.pdf
Grigg, R., McCaffrey, S., Sridharan, V. et al. (5 more authors) (2006) Enantioselective synthesis of non-proteinogenic 2-arylallyl-α-amino acids via Pd/In catalytic cascades. Tetrahedron, 62 (52). pp. 12159-12171. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2006.09.098
doi:10.1016/j.tet.2006.09.098
oai:eprints.whiterose.ac.uk:1940
2016-10-24T17:51:48Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1940/
Catch and release’ cascades: a resin-mediated three-component cascade approach to small molecules
Grigg, R.
Cook, A.
The application of a ‘catch and release’ approach to palladium-catalysed multi-component cascade reactions leads to diverse libraries of pharmacologically interesting small molecules in high yield and with excellent purity.
Elsevier
2006-12-25
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1940/1/griggr2_Tetrahedron_Final_DraftCatch_and_Release.pdf
Grigg, R. and Cook, A. (2006) Catch and release’ cascades: a resin-mediated three-component cascade approach to small molecules. Tetrahedron, 62 (52). pp. 12172-12181. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2006.09.101
doi:10.1016/j.tet.2006.09.101
oai:eprints.whiterose.ac.uk:1950
2016-10-25T01:30:18Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
756E69743D4C65656473:4C656564732E5243:4C656564732E52432D504F4C59
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1950/
Lifshitz points in blends of AB and BC diblock copolymers
Olmsted, P.D.
Hamley, I.W.
We consider micro- and macro-phase separation in blends of AB and BC flexible diblock copolymers. We show that, depending on architecture, a number of phase diagram topologies are possible. Microphase separation or macrophase separation can occur, and there are a variety of possible Lifshitz points. Because of the rich parameter space, Lifshitz points of multiple order are possible. We demonstrate Lifshitz points of first and second order, and argue that, in principle, up to 5th-order Lifshitz points are possible.
EDP Sciences
1999-01-01
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1950/1/olmstedpd1.pdf
Olmsted, P.D. and Hamley, I.W. (1999) Lifshitz points in blends of AB and BC diblock copolymers. Europhysics Letters, 45 (1). pp. 83-89. ISSN 1286-4854
http://dx.doi.org/10.1209/epl/i1999-00135-4
doi:10.1209/epl/i1999-00135-4
oai:eprints.whiterose.ac.uk:1952
2016-10-24T17:46:20Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
756E69743D536865666669656C64:536865666669656C642E464350:536865666669656C642E43484D
756E69743D4C65656473:4C656564732E5243:4C656564732E52432D504F4C59
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D536865666669656C64
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/1952/
Micro- vs. macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers
Frielinghaus, H.
Hermsdorf, N.
Almdal, K.
Mortensen, K.
Messe, L.
Corvazier, L.
Fairclough, J.P.A.
Ryan, A.J.
Olmsted, P.D.
Hamley, I.W.
In this paper we present an experimentally determined phase diagram of binary blends of the diblock copolymers poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide). At high temperatures, the blends form an isotropic mixture. Upon lowering the temperature, the blend macro-phase separates before micro-phase separation occurs. The observed phase diagram is compared to theoretical predictions based on experimental parameters. In the low-temperature phase the crystallisation of the poly(ethylene oxide) block influences the spacing of the ordered phase.
EDP Sciences
2001-03-01
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/1952/1/olmstedpd3.pdf
Frielinghaus, H., Hermsdorf, N., Almdal, K. et al. (7 more authors) (2001) Micro- vs. macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers. Europhysics Letters, 53 (5). pp. 680-686. ISSN 1286-4854
http://dx.doi.org/10.1209/epl/i2001-00205-7
doi:10.1209/epl/i2001-00205-7
oai:eprints.whiterose.ac.uk:3723
2016-09-16T13:35:24Z
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https://eprints.whiterose.ac.uk/3723/
Pulsed Laval nozzle study of the kinetics of OH with unsaturated hydrocarbons at very low temperatures
Taylor, S.E.
Goddard, A.
Blitz, M.A.
Cleary, P.A.
Heard, D.E.
The kinetics of reactions of the OH radical with ethene, ethyne (acetylene), propyne (methyl acetylene) and t-butyl-hydroperoxide were studied at temperatures of 69 and 86 K using laser flash-photolysis combined with laser-induced fluorescence spectroscopy. A new pulsed Laval nozzle apparatus is used to provide the low-temperature thermalised environment at a single density of similar to 4 x 10(16) molecule cm(-3) in N-2. The density and temperature within the flow are determined using measurements of impact pressure and rotational populations from laser-induced fluorescence spectroscopy of NO and OH. For ethene, rate coefficients were determined to be k(2) = (3.22 +/- 0.46) x 10(-11) and (2.12 +/- 0.12) x 10(-11) cm(3) molecule(-1) s(-1) at T = 69 and 86 K, respectively, in good agreement with a master-equation calculation utilising an ab initio surface recently calculated for this reaction by Cleary et al. (P. A. Cleary, M. T. Baeza Romero, M. A. Blitz, D. E. Heard, M. J. Pilling, P. W. Seakins and L. Wang, Phys. Chem. Chem. Phys., 2006, 8, 5633-5642) For ethyne, no previous data exist below 210 K and a single measurement at 69 K was only able to provide an approximate upper limit for the rate coefficient of k(3) < 1 x 10(-12) cm(3) molecule(-1) s (-1), consistent with the presence of a small activation barrier of similar to 5 kJ mol (-1) between the reagents and the OH-C2H2 adduct. For propyne, there are no previous measurements below 253 K, and rate coefficients of k(4) = (5.08 +/- 0.65), (5.02 +/- 1.11) and (3.11 +/- 0.09) x 10(-12) cm(3) molecule(-1) s(-1) were obtained at T = 69, 86 and 299 K, indicating a much weaker temperature dependence than for ethene. The rate coefficient k(1) = (7.8 +/- 2.5) x 10(-11) cm(3) molecule(-1) s (-1) was obtained for the reaction of OH with t-butyl-hydroperoxide at T = 86 K. Studies of the reaction of OH with benzene and toluene yielded complex kinetic profiles of OH which did not allow the extraction of rate coefficients. Uncertainties are quoted at the 95% confidence limit and include systematic errors.
Royal Society of Chemistry
2008
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3723/1/Heard-PCCP-25-7-07-Laval-revised.pdf
Taylor, S.E., Goddard, A., Blitz, M.A. et al. (2 more authors) (2008) Pulsed Laval nozzle study of the kinetics of OH with unsaturated hydrocarbons at very low temperatures. Physical Chemistry Chemical Physics, 10 (3). pp. 422-437. ISSN 1463-9076
http://dx.doi.org/10.1039/b711411g
doi:10.1039/b711411g
oai:eprints.whiterose.ac.uk:3751
2016-09-16T13:35:36Z
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696E737469747574696F6E3D4C65656473
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https://eprints.whiterose.ac.uk/3751/
Macropolyhedral boron-containing cluster chemistry. Cluster assembly about a molybdenum centre. Formation of the 19-vertex [(CO)(2)MoB16H15C2Ph2](-) anion
Carr, M.J.
Franken, A.
Kennedy, J.D.
Fusion of nine-vertex [1-Ph-nido-1-CB8H11] with [Mo(CH3CN)3(CO)3] in the presence of tetramethylnaphthalenediamine gives the nineteen-vertex macropolyhedral metallaborane anion [(CO)2MoB16H15C2Ph]− with a molybdenum(VI) twelve-atom coordination sphere.
Royal Society of Chemistry
2004
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3751/1/kennedyjd1_Macropolyhedral__3751.pdf
Carr, M.J., Franken, A. and Kennedy, J.D. (2004) Macropolyhedral boron-containing cluster chemistry. Cluster assembly about a molybdenum centre. Formation of the 19-vertex [(CO)(2)MoB16H15C2Ph2](-) anion. Dalton Transactions, 17. pp. 2612-2613. ISSN 1477-9226
http://dx.doi.org/10.1039/b410873f
doi:10.1039/b410873f
oai:eprints.whiterose.ac.uk:3752
2016-09-16T13:35:39Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3752/
Macropolyhedral boron-containing cluster chemistry: two-electron variations in intercluster bonding intimacy. Contrasting structures of 19-vertex [(eta(5)-C5Me5)HIrB18H19(PHPh2)] and [(eta(5) -C5Me5)IrB18H18(PH2Ph)]
Shea, S.L.
Jelínek, T.
Perera, S.D.
Stibr, B.
Thornton-Pett, M.
Kennedy, J.D.
Fused double-cluster [(5-C5Me5)IrB18H18(PH2Ph)]8, from syn-[(5-C5Me5)IrB18H20] 1 and PH2Ph, retains the three-atoms-in-common cluster fusion intimacy of 1, in contrast to [(5-C5Me5)HIrB18H19(PHPh2)]6, from PHPh2 with 1, which exhibits an opening to a two atoms-in-common cluster fusion intimacy. Compound 8 forms via spontaneous dihydrogen loss from its precursor [(5-C5Me5)HIrB18H19(PH2Ph)]7, which has two-atoms-in-common cluster-fusion intimacy and is structurally analogous to 6.
Elsevier Science B.V., Amsterdam
2004-07
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3752/1/Macropolyhedral_3752.pdf
Shea, S.L., Jelínek, T., Perera, S.D. et al. (3 more authors) (2004) Macropolyhedral boron-containing cluster chemistry: two-electron variations in intercluster bonding intimacy. Contrasting structures of 19-vertex [(eta(5)-C5Me5)HIrB18H19(PHPh2)] and [(eta(5) -C5Me5)IrB18H18(PH2Ph)]. Inorganica Chimica Acta, 357 (10). pp. 3119-3123. ISSN 0020-1693
http://dx.doi.org/10.1016/j.ica.2004.03.041
doi:10.1016/j.ica.2004.03.041
oai:eprints.whiterose.ac.uk:3931
2016-09-16T13:36:03Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3931/
Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states
Blanchet, V.
Raffael, K.
Turri, G.
Chatel, B.
Girard, B.
Garcia, I.A.
Wilkinson, I.
Whitaker, B.J.
Pump-probe photoionization has been used to map the relaxation processes taking place from highly vibrationally excited levels of the S2 state of azulene, populated directly or via internal conversion from the S4 state. Photoelectron spectra obtained by 1+2’ two-color time-resolved photoelectron imaging are invariant (apart from in intensity) to the pump-probe time delay and to pump wavelength. This reveals a photoionization process which is driven by an unstable electronic state (e.g. doubly excited state) lying below the ionization potential. This state is postulated to be populated by a probe transition from S2 and to rapidly relax via an Auger like process onto highly
vibrationally excited Rydberg states. This accounts for the time invariance of the photoelectron spectrum. The intensity of the photoelectron spectrum is proportional to the population in S2. An exponential energy gap law is used to describe the internal conversion rate from S2 to S0. The
vibronic coupling strength is found to be larger than 60±5 μeV.
American Institute of Physics
2008-04
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3931/1/whitakerb1.pdf
Blanchet, V., Raffael, K., Turri, G. et al. (5 more authors) (2008) Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states. Journal of Chemical Physics, 128 (16). p. 164318.
http://dx.doi.org/10.1063/1.2913167
doi:10.1063/1.2913167
oai:eprints.whiterose.ac.uk:3932
2016-09-16T13:36:06Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3932/
Polyhedral monocarbaborane chemistry. Carboxylic acid derivatives of the [closo-2-CB9H10](-) anion
Franken, A.
Kilner, C.A.
Kennedy, J.D.
Reaction of B10H14 with para-(OHC)C6H4(COOH) in aqueous KOH gives the [nido-6-CB9H11-6-(C6H4-para-COOH)](-) anion I which upon cluster closure with iodine in alkali solution gives the [closo-2-CB9H9-2-(C6H4-para-COOH)](-) anion 2; an analogous procedure with B10H14 and glyoxalic acid OHCCOOH gives the [closo-2-CB9H9-2-(COOH)](-) anion 4 via the [arachno-6-CB9H13-6-(COOH)](-) anion 3.
Royal Society of Chemistry
2004-02-07
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3932/1/B311853N_paper.pdf
Franken, A., Kilner, C.A. and Kennedy, J.D. (2004) Polyhedral monocarbaborane chemistry. Carboxylic acid derivatives of the [closo-2-CB9H10](-) anion. Chemical Communications, 3. pp. 328-329. ISSN 1359-7345
http://dx.doi.org/10.1039/b311853n
doi:10.1039/b311853n
oai:eprints.whiterose.ac.uk:3934
2016-09-16T13:36:10Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3934/
Macropolyhedral boron-containing cluster chemistry. Ligand-induced two-electron variations of intercluster bonding intimacy. Structures of nineteen-vertex[(eta(5)-C5Me5) HIrB18H19(PMe2Ph)] and the related carbene complex [(eta(5)-C5Me5)HIrB18H19{C(NHMe)(2)}]
Shea, S.L.
Jelinek, T.
Perera, S.D.
Stibr, B.
Thornton-Pett, M.
Kennedy, J.D.
Addition of PMe2Ph to fused-cluster syn-[(η5-C5Me5)IrB18H20] 1 to give [(η5-C5Me5)HIrB18H19(PMe2Ph)] 3 entails a diminution in the degree of intimacy of the intercluster fusion, rather than retention of inter-subcluster binding intimacy and a nido → arachno conversion of the character of either of the subclusters. Reaction with MeNC gives [(η5-C5Me5)HIrB18H19{C(NHMe)2}] 4 which has a similar structure, but with the ligand now being the carbene {:C(NHMe)2}, resulting from a reductive assembly reaction involving two MeNC residues and the loss of a carbon atom.
Royal Society of Chemistry
2004
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3934/1/B404322G_amended_%282%29.pdf
Shea, S.L., Jelinek, T., Perera, S.D. et al. (3 more authors) (2004) Macropolyhedral boron-containing cluster chemistry. Ligand-induced two-electron variations of intercluster bonding intimacy. Structures of nineteen-vertex[(eta(5)-C5Me5) HIrB18H19(PMe2Ph)] and the related carbene complex [(eta(5)-C5Me5)HIrB18H19{C(NHMe)(2)}]. Dalton Transactions, 10. pp. 1521-1523. ISSN 1477-9226
http://dx.doi.org/10.1039/b404322g
doi:10.1039/b404322g
oai:eprints.whiterose.ac.uk:3935
2016-09-16T13:36:13Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3935/
Metallaborane reaction chemistry. A facile and reversible dioxygen capture by a B-frame-supported bimetallic: structure of [(PMe2Ph)(4)(O-2)Pt2B10H10]
Bould, J.
McInnes, Y.M.
Carr, M.J.
Kennedy, J.D.
[(PMe2Ph)(4)Pt2B10H10] 1 reversibly takes up atmospheric dioxygen to give the fluxional dioxygen-dimetallaborane complex [(PMe2Ph)(4)(O-2)Pt2B10H10] 2, which has Pt-Pt 2.7143(3), Pt-O 2.141(4) and 2.151(4) and O-O 1.434(6) Angstrom.
Royal Society of Chemistry
2004
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3935/1/B406974A_after_refs_%282%29.pdf
Bould, J., McInnes, Y.M., Carr, M.J. et al. (1 more author) (2004) Metallaborane reaction chemistry. A facile and reversible dioxygen capture by a B-frame-supported bimetallic: structure of [(PMe2Ph)(4)(O-2)Pt2B10H10]. ChemicalL Communications (21). pp. 2380-2381. ISSN 1359-7345
http://dx.doi.org/10.1039/b406974a
doi:10.1039/b406974a
oai:eprints.whiterose.ac.uk:3936
2016-09-16T13:36:14Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/3936/
Antiferromagnetic spin-coupling between MnII and amminium radical cation ligands: models for coordination polymer magnets
Bushby, R.J.
Kilner, C.
Taylor, N.
Williams, R.A.
One and two electron oxidation of the manganese(II) complex [L2Mn(hfac)2] {L = 4'',4'''-di-tert-butyl-2',2'',2'''trimethoxy-{4-(4'-diphenylaminophenyl)pyridine} were studied by ultra violet/ visible/ near infra red spectroscopy, cyclic voltammetry and magnetometry. A one-electron oxidation converts the triarylamine ligand to its radical cation and gives a complex in which the antiferromagnetic coupling between the spin on the ligand and that on the metal J/kb is -1.5 K. In a dilute frozen matrix and at low temperature this behaves as an S = 2 system. A two electron oxidation gives [L2Mn(hfac)2]2.+ which at low enough temperatures behaves as an S = 3/2 system but the spin-coupling between the metal and the ligand is weaker (J/kb = -0.3 K). The weakness of these spin-couplings mean that MnII/amminium radical cation complexes are not promising systems on which to base coordination polymer magnets. The equivalent copper(II) complex [L2Cu(hfac)2] was also investigated but this decomposes when an attempt is made to oxidise the ligand to its amminium radical cation.
PERGAMON-ELSEVIER SCIENCE LTD
2008-01-08
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/3936/1/Rhidssecondpaperrevised.pdf
Bushby, R.J., Kilner, C., Taylor, N. et al. (1 more author) (2008) Antiferromagnetic spin-coupling between MnII and amminium radical cation ligands: models for coordination polymer magnets. POLYHEDRON, 27 (1). pp. 383-392. ISSN 0277-5387
http://dx.doi.org/10.1016/j.poly.2007.09.020
10.1016/j.poly.2007.09.020
oai:eprints.whiterose.ac.uk:4731
2016-09-16T13:37:47Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/4731/
Gaussian-based techniques for quantum propagation from the time-dependent variational principle: Formulation in terms of trajectories of coupled classical and quantum variables
Shalashilin, D.V.
Burghardt, I.
In this article, two coherent-state based methods of quantum propagation, namely, coupled coherent states (CCS) and Gaussian-based multiconfiguration time-dependent Hartree (G-MCTDH), are put on the same formal footing, using a derivation from a variational principle in Lagrangian form. By this approach, oscillations of the classical-like Gaussian parameters and oscillations of the quantum amplitudes are formally treated in an identical fashion. We also suggest a new approach denoted here as coupled coherent states trajectories (CCST), which completes the family of Gaussian-based methods. Using the same formalism for all related techniques allows their systematization and a straightforward comparison of their mathematical structure and cost.
American Institute of Physics
2008-08
Article
NonPeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/4731/1/shalashilindv1.pdf
Shalashilin, D.V. and Burghardt, I. (2008) Gaussian-based techniques for quantum propagation from the time-dependent variational principle: Formulation in terms of trajectories of coupled classical and quantum variables. Journal of Chemical Physics, 129 (8). 084104.
http://dx.doi.org/10.1063/1.2969101
doi:10.1063/1.2969101
oai:eprints.whiterose.ac.uk:4734
2013-02-08T16:56:48Z
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696E737469747574696F6E3D4C65656473
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https://eprints.whiterose.ac.uk/4734/
Reactive organoallyl species generated from aryl halides and allene: allylation of alpha,beta-unsaturated aldehydes and cyclic ketones employing Pd/In transmetallation processes
Cleghorn, L.A.T.
Grigg, R.
Savic, V.
Simic, M.
Allylation of α,β-unsaturated aldehydes and cyclic ketones promoted by Pd/In transmetallation processes has been studied. The unsaturated aldehydes underwent regioselective 1,2-addition to afford secondary homoally alcohols. The reactions have been performed using Pd(OAc)2/PPh3 as catalytic system and metallic indium affording the products in good yields. The same transformation with unsaturated ketones proved to be less efficient, while saturated cyclic ketones delivered generally excellent yields in the presence of CuI. In these latter processes the presence of a distal heteroatom influences the reaction rate.
Elsevier B.V.
2008-09
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/4734/1/griggsr1.pdf
Cleghorn, L.A.T., Grigg, R., Savic, V. et al. (1 more author) (2008) Reactive organoallyl species generated from aryl halides and allene: allylation of alpha,beta-unsaturated aldehydes and cyclic ketones employing Pd/In transmetallation processes. Tetrahedron, 64 (37). pp. 8731-8738. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2008.06.100
doi:10.1016/j.tet.2008.06.100
oai:eprints.whiterose.ac.uk:4739
2016-09-16T13:37:50Z
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696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/4739/
Stereoselective synthesis of chiral β2,3-disubstituted-β-amino acid derivatives using Pd/In transmetallation cascade processes
Grigg, R.
Blacker, J.
Kilner, C.
McCaffrey, S.
Savic, V.
Sridharan, V.
A new, highly efficient synthesis of chiral β2,3-disubstituted-β-amino acid derivatives has been developed, based on an allylation procedure employing allene and a catalytic Pd/In bimetallic process.
Elsevier B.V.
2008-08
Article
NonPeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/4739/1/griggs3..pdf
Grigg, R., Blacker, J., Kilner, C. et al. (3 more authors) (2008) Stereoselective synthesis of chiral β2,3-disubstituted-β-amino acid derivatives using Pd/In transmetallation cascade processes. Tetrahedron, 64 (35). pp. 8177-8181. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2008.06.037
doi:10.1016/j.tet.2008.06.037
oai:eprints.whiterose.ac.uk:4740
2013-02-08T16:56:50Z
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756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/4740/
X=Y–ZH compounds as potential 1,3-dipoles. Part 64: Synthesis of highly substituted conformationally restricted and spiro nitropyrrolidines via Ag(I) catalysed azomethine ylide cycloadditions
Grigg, R.
Kilner, C.
Sarker, M.A.B.
Orgaz de la Cierva, C.
Dondas, H.A.
1,3-Dipolar reactions of imines of both acyclic and cyclic α-amino esters with a range of nitroolefins using a combination of AgOAc or Ag2O with NEt3 are described. In most cases the reactions were highly regio- and stereospecific and endo-cycloadducts were obtained in good yield. However, in a few cases the initially formed cycloadducts underwent base catalysed epimerisation. The stereochemistry of the cycloadducts was assigned from NOE data and established unequivocally in several cases by X-ray crystallography.
Elsevier B.V.
2008-09
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/4740/1/griggsr2.pdf
Grigg, R., Kilner, C., Sarker, M.A.B. et al. (2 more authors) (2008) X=Y–ZH compounds as potential 1,3-dipoles. Part 64: Synthesis of highly substituted conformationally restricted and spiro nitropyrrolidines via Ag(I) catalysed azomethine ylide cycloadditions. Tetrahedron, 64 (37). pp. 8974-8991. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2008.05.132
doi:10.1016/j.tet.2008.05.132
oai:eprints.whiterose.ac.uk:4752
2016-09-16T13:37:51Z
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756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/4752/
Sonogashira/N-acyliminium ion aromatic π-cyclisation processes: access to tetra- and pentacyclic lactams
Grigg, R.
Sridharan, V.
Sykes, D.A.
Application of the Sonogashira reaction of N-alkynylimides with 2-iodophenol or 2-iodo-N-tosylaniline affords 2-(N-alkylimino)-benzofurans and indoles in good yield. Selective partial reduction of the latter followed by treatment with TsOH generates N-acyliminium ions, which cyclise to afford tetra- and pentacyclic lactams in good yield. The latter are reduced to the analogous cyclic amines by BH3.
Elsevier B.V.
2008-09
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/4752/1/griggsr4.pdf
Grigg, R., Sridharan, V. and Sykes, D.A. (2008) Sonogashira/N-acyliminium ion aromatic π-cyclisation processes: access to tetra- and pentacyclic lactams. Tetrahedron, 64 (37). pp. 8952-8962. ISSN 0040-4020
http://dx.doi.org/10.1016/j.tet.2008.06.044
doi:10.1016/j.tet.2008.06.044
oai:eprints.whiterose.ac.uk:4923
2024-02-20T15:35:25Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/4923/
Semantically-Enhanced Model-Experiment-Evaluation
Processes (SeMEEPs) within the Atmospheric Chemistry
Community
Dew, P.M.
Haji, M.H.
Jimack, P.K.
Martin, C.
Pilling, M.
The scientific model development process is often documented in an ad-hoc unstructured manner leading to difficulty in attributing provenance to data products. This can cause issues when the data owner or other interested stakeholder seeks to interpret the data at a later date. In this paper we discuss the design, development and evaluation of a Semantically-enhanced Electronic Lab-Notebook to facilitate the capture of provenance for the model development
process, within the atmospheric chemistry community. We then proceed to consider the value of semantically enhanced provenance within the wider community processes, Semantically-enhanced Model-Experiment Evaluation
Processes (SeMEEPs), that leverage data generated by experiments and computational
models to conduct evaluations.
Springer-Verlag
Freire, J.
Koop, D.
Moreau, L.
2008
Book Section
PeerReviewed
Dew, P.M., Haji, M.H., Jimack, P.K. et al. (2 more authors) (2008) Semantically-Enhanced Model-Experiment-Evaluation Processes (SeMEEPs) within the Atmospheric Chemistry Community. In: Freire, J., Koop, D. and Moreau, L., (eds.) Proceedings of Second International Provenance and Annotation Workshop (IPAW 2008). Lecture Notes in Computer Science (5272). Springer-Verlag , pp. 293-308.
10.1007/978-3-540-89965-5
oai:eprints.whiterose.ac.uk:4931
2013-02-08T16:57:05Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/4931/
Photodissociation of NO2 in the (2)B-2(2) state: A slice imaging study and reinterpretation of previous results
Wilkinson, I.
Whitaker, B.J.
The photodissociation dynamics of nitrogen dioxide have been probed above the second dissociation limit at photolysis wavelengths close to 226 nm. The O(3PJ)+NO(2) product channel has been examined using direct current slice velocity map imaging of the O(3PJ) and NO(2) fragments. Mass-resolved resonantly enhanced multiphoton ionization spectroscopy and velocity map imaging have been used to probe directly the rovibrational population distributions of the NO fragments. We also examine possible interference from the dissociation of N2O4 by investigating the effect of the sample temperature on the O(3PJ) fragment energy distributions. The O(3PJ)+NO(2) dissociation channel has been found to favor the production of vibrationally cold, highly rotationally excited NO(2) products with all three oxygen spin-orbit components. Other minor dissociation channels which produce O(3PJ) atoms have also been identified. We discuss the significance of these dissociation channels and present a reinterpretation of previous studies of NO2 dissociation on excitation to the (2)2B2 state.
American Institute of Physics
2008-10
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/4931/1/Whitakerb2.pdf
Wilkinson, I. and Whitaker, B.J. (2008) Photodissociation of NO2 in the (2)B-2(2) state: A slice imaging study and reinterpretation of previous results. Journal of Chemical Physics, 129 (15). p. 154312.
http://dx.doi.org/10.1063/1.2994735
doi:10.1063/1.2994735
oai:eprints.whiterose.ac.uk:6538
2015-06-18T17:28:02Z
7374617475733D707562
74797065733D61727469636C65
756E69743D596F726B:596F726B2E46414332:596F726B2E594F5233
756E69743D596F726B:596F726B2E46414332:596F726B2E594F523130
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D596F726B
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/6538/
Urban atmospheric chemistry during the PUMA campaign 1: Comparison of modelled OH and HO2 concentrations with measurements
Emmerson, K.M.
Carslaw, N.
Carpenter, L.J.
Heard, D.E.
Lee, J.D.
Pilling, M.J.
Photochemical box modelling was undertaken to investigate OH and HO2 radical chemistry during summer and winter field campaigns in the urban city-centre of Birmingham in the UK. The model employed the most recent version of the Master Chemical Mechanism (v3.1) and was constrained to 15-minute average measurements of long-lived species determined in situ at the site. The model was used to predict OH and HO2 concentrations for comparison with measurements made by the fluorescence assay by gas expansion technique. Whilst there was generally good agreement between the modelled and measured OH concentrations, particularly during summer, there was sometimes a significant model under-prediction during daylight hours, which significantly skews the overall model: measured agreement. There were less measured data available for HO2, but the agreement between model and measurement for the days where measurements existed were less good than for OH, with one or two exceptions. The modelled:measured ratios between the hours of 11:00–15:00 h for OH were 0.58 and 0.50 for summer and winter respectively. For HO2, the same ratios were 0.56 in the summer and 0.49 in the winter. Sensitivity studies were conducted to attempt to understand the model-measurement discrepancy. The predicted radical concentrations were particularly sensitive to changes in NOX concentrations. Constraining the model to the observed HO2 concentrations made the OH predictions worse. These results highlight the fact that there are many complexities in urban areas and that more highly-instrumented campaigns are required in the future to further our understanding.
Springer Science + Business Media
2005-10
Article
NonPeerReviewed
Emmerson, K.M., Carslaw, N., Carpenter, L.J. et al. (3 more authors) (2005) Urban atmospheric chemistry during the PUMA campaign 1: Comparison of modelled OH and HO2 concentrations with measurements. Journal of Atmospheric Chemistry, 52 (2). pp. 143-164. ISSN 0167-7764
http://dx.doi.org/10.1007/s10874-005-1322-3
10.1007/s10874-005-1322-3
oai:eprints.whiterose.ac.uk:6678
2016-09-16T13:54:08Z
oai:eprints.whiterose.ac.uk:7946
2016-10-24T17:07:50Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/7946/
Semantically enhanced provenance capture
for chamber model development with
a master chemical mechanism
Martin, C.J.
Haji, M.H.
Dew, P.M.
Pilling, M.J.
Jimack, P.K.
The development and maintenance of benchmark databases within scientific communities is reliant on interactions with database users.We explore the role of semantically enhanced provenance for computational modelling processes that make use of one such database: the master chemical mechanism, a key resource within the atmospheric chemistry community.
Royal Society
2009-03-13
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/7946/1/Peter_Jimack_5.pdf
Martin, C.J., Haji, M.H., Dew, P.M. et al. (2 more authors) (2009) Semantically enhanced provenance capture for chamber model development with a master chemical mechanism. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 367 (1890). pp. 987-990. ISSN 1471-2962
http://dx.doi.org/10.1098/rsta.2008.0168
doi:10.1098/rsta.2008.0168
oai:eprints.whiterose.ac.uk:7972
2016-09-16T13:46:01Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/7972/
Photoelectric emission from the alkali metal doped vacuum-ice interface
Vondrak, T.
Meech, S.R.
Plane, J.M.C.
The photoelectron photoemission spectra and thresholds for low coverages of Li and K adsorbed on water-ice have been measured, compared with photoionization spectra of the gas-phase atoms, and modeled by quantum chemical calculations. For both alkali metals the threshold for photoemission is dramatically decreased and the cross section increased on adsorption to the water-ice surface. Quantum chemical calculations suggest that the initial state is formed by the metal atoms adsorbed into the water-ice surface, forming a state with a delocalized electron distribution. This state is metastable and decays on the hundreds of seconds time scale at 92 K. The decay is markedly faster for Li than for K, probably due to diffusion into the ice film.
American Institute of Physics
2009-02
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/7972/1/planrjmc.pdf
Vondrak, T., Meech, S.R. and Plane, J.M.C. (2009) Photoelectric emission from the alkali metal doped vacuum-ice interface. The Journal of Chemical Physics, 130 (5). 054702. ISSN 0021-9606
http://dx.doi.org/10.1063/1.3063658
doi:10.1063/1.3063658
oai:eprints.whiterose.ac.uk:43165
2016-11-04T03:16:30Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/43165/
The photodissociation of NO2 by visible and ultraviolet light
Wikinson, I
Gacia, IA
Whitaker, BJ
Hamard, JB
Blanchet, V
We present velocity map images of the NO, O(P-3(J)) and O(S-1(0)) photofragments from NO2 excited in the range 7.6 to 9.0 eV. The molecule was initially pumped with a visible photon between 2.82-2.95 eV (440-420 nm), below the first dissociation threshold. A second ultraviolet laser with photon energies between 4.77 and 6.05 eV (260-205 nm) was used to pump high-lying excited states of neutral NO2 and/or probe neutral photoproducts. Analysis of the kinetic energy release spectra revealed that the NO photofragments were predominantly formed in their ground electronic state with little kinetic energy. The O(P-3(J)) and O(S-1(0)) kinetic energy distributions were also dominated by kinetically 'cold' fragments. We discuss the possible excitation schemes and conclude that the unstable photoexcited states probed in the experiment were Rydberg states coupled to dissociative valence states. We compare our results with recent time-resolved studies using similar excitation and probe photon energies.
Royal Society of Chemistry
2010-11
Article
NonPeerReviewed
Wikinson, I, Gacia, IA, Whitaker, BJ et al. (2 more authors) (2010) The photodissociation of NO2 by visible and ultraviolet light. Physical Chemistry Chemical Physics, 12 (48). 15766 - 15779 . ISSN 1463-9076
http://dx.doi.org/10.1039/C0CP01551B
10.1039/C0CP01551B
oai:eprints.whiterose.ac.uk:43177
2016-09-16T14:06:42Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/43177/
Reaction-diffusion waves; homogeneous and inhomogeneous effects
Johnson, BR
Scott, SK
Taylor, AF
Experimental evidence for the spontaneous formation of spiral waves and crossing wave patterns for the Belousov–Zhabotinsky reaction in solution are presented. Also observed are so-called ‘lateral instabilities’ with the spontaneous deformation of circular fronts in systems of low excitability. Lateral instabilities in resin-based systems, with the redox catalyst immobilised on ion-exchange beads, and the effect of the ageing of solutions, are also reported.
1997
Article
NonPeerReviewed
Johnson, BR, Scott, SK and Taylor, AF (1997) Reaction-diffusion waves; homogeneous and inhomogeneous effects. Faraday Transactions, 93 (20). 3733 - 3736 . ISSN 0956-5000
http://dx.doi.org/10.1039/A704616B
10.1039/A704616B
oai:eprints.whiterose.ac.uk:43317
2016-10-26T03:00:09Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D4541454E:4C656564732E52432D534F4545
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/43317/
Potential climatic effects of meteoric smoke in the Earth's paleo-atmosphere
Saunders, RW
Forster, PM
Plane, JMC
Modelling of the growth of meteoric smoke in the Earth's atmosphere, by assuming the formation of either simple spherical ( compact) particles or, more realistically, fractal ( porous) aggregates, highlights important differences in the predicted atmospheric size distributions as a function of altitude. The calculated UV extinction and direct radiative forcing ( DRF) of these types of particles is also quite different. It is shown that, with regard to ( a), forming a UV barrier before the presence of significant ozone levels in the atmosphere and ( b), triggering 'snowball Earth' glaciations by negative DRF, fractal smoke particles are unlikely to have been important even if the flux of interplanetary dust into the atmosphere was 3 orders of magnitude higher than the present day. However, if these particles are effective ice nuclei, then subsequent indirect forcing through ice cloud formation could have made a more significant contribution to the onset of ancient glaciation episodes.
American Geophysical Union
2007-08-16
Article
NonPeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/43317/2/GRL_2007GL029648%5B1%5D.pdf
Saunders, RW, Forster, PM and Plane, JMC (2007) Potential climatic effects of meteoric smoke in the Earth's paleo-atmosphere. Geophysical Research Letters, 34 (16). ISSN 0094-8276
http://dx.doi.org/10.1029/2007GL029648
10.1029/2007GL029648
oai:eprints.whiterose.ac.uk:43750
2022-12-19T13:24:29Z
7374617475733D707562
74797065733D7075626C69736865645F636F6E666572656E63655F70726F63656564696E6773
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D5052454E
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/43750/
Semantically-Enhanced Model-Experiment-Evaluation Processes (SeMEEPs) within the Atmospheric Chemistry Community
Martin, C
Haji, MH
Dew, P
Pilling, M
Jimack, P
The scientific model development process is often documented in an ad-hoc unstructured manner leading to difficulty in attributing provenance to data products. This can cause issues when the data owner or other interested stakeholder seeks to interpret the data at a later date. In this paper we discuss the design, development and evaluation of a Semantically-enhanced Electronic Lab-Notebook to facilitate the capture of provenance for the model development process, within the atmospheric chemistry community. We then proceed to consider the value of semantically enhanced provenance within the wider community processes, Semantically-enhanced Model-Experiment Evaluation Processes (SeMEEPs), that leverage data generated by experiments and computational models to conduct evaluations.
Springer
Freire, J
Koop, D
Moreau, L
2008
Proceedings Paper
NonPeerReviewed
Martin, C, Haji, MH, Dew, P et al. (2 more authors) (2008) Semantically-Enhanced Model-Experiment-Evaluation Processes (SeMEEPs) within the Atmospheric Chemistry Community. In: Freire, J, Koop, D and Moreau, L, (eds.) Provenance and Annotation of Data and Processes. Second International Provenance and Annotation Workshop, 17-18 Jun 2008, Salt Lake City,UT, USA. Springer , 293 - 308 . ISBN 978-3-540-89964-8
oai:eprints.whiterose.ac.uk:43752
2016-10-27T16:24:02Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D434F4D50
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D5052454E
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/43752/
Semantically enhanced provenance capture for chamber model development with a master chemical mechanism
Martin, CJ
Haji, MH
Dew, PM
Pilling, MJ
Jimack, PK
The development and maintenance of benchmark databases within scientific communities is reliant on interactions with database users. We explore the role of semantically enhanced provenance for computational modelling processes that make use of one such database: the master chemical mechanism, a key resource within the atmospheric chemistry community.
The Royal Society
2009-06-01
Article
PeerReviewed
text
en
https://eprints.whiterose.ac.uk/43752/6/martinCJ2pdf.pdf
Martin, CJ, Haji, MH, Dew, PM et al. (2 more authors) (2009) Semantically enhanced provenance capture for chamber model development with a master chemical mechanism. Philosophical Transactions of the Royal Society A. Mathematical, Physical and Engineering Sciences, 367. 987 - 990 . ISSN 1364-503X
http://dx.doi.org/10.1098/rsta.2008.0168
10.1098/rsta.2008.0168
oai:eprints.whiterose.ac.uk:43835
2016-09-16T14:16:24Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/43835/
Acid-catalyzed aromatization of benzene CIS-1,2-dihydrodiols - a carbocation transition-state poorly stabilized by resonance
Boyd, DR
Blacker, J
Byrne, B
Dalton, H
Hand, MV
Kelly, SC
Oferrall, RAM
Rao, SN
Sharma, ND
Sheldrake, GN
Acid-catalysed dehydration of 3-substituted benzene cis-1,2-dihydrodiols exhibits a Hammett plot with ρ=–8.2, consistent with reaction via a benzenonium ion-like intermediate; however, correlation of +M resonance substituents such as Me and MeO by σp rather than σ+ constants indicates a marked imbalance between resonance and inductive stabilisation of the transition state.
Royal Society of Chemistry
1994-02-07
Article
NonPeerReviewed
Boyd, DR, Blacker, J, Byrne, B et al. (7 more authors) (1994) Acid-catalyzed aromatization of benzene CIS-1,2-dihydrodiols - a carbocation transition-state poorly stabilized by resonance. Journal of the Chemical Society, Chemical Communications (3). 313 - 314 . ISSN 0022-4936
http://dx.doi.org/10.1039/C39940000313
10.1039/C39940000313
oai:eprints.whiterose.ac.uk:74467
2016-09-16T14:19:09Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74467/
Triazole phosphohistidine analogues compatible with the Fmoc-strategy.
McAllister, TE
Webb, ME
Phosphorylation of histidine is essential for bacterial two-component signalling; its importance to modulation of eukaryotic protein function remains undefined. Until recently, no immunochemical probes of this post-translational modification existed, however triazole phosphonate analogues of this modified amino acid have now been applied to the generation of site-specific antibodies. The protecting group strategy used in the original report is incompatible with standard protocols for Fmoc-solid phase peptide synthesis. In this paper, we report the application of P(III) chemistry to generate the complementary dibenzyl and di-tert-butyl phosphonate esters. These forms of the triazole analogue are fully compatible with standard Fmoc-SPPS and are therefore ideal for wider application by the chemical and biochemical community.
Royal Society of Chemistry
2012-05-28
Article
NonPeerReviewed
McAllister, TE and Webb, ME (2012) Triazole phosphohistidine analogues compatible with the Fmoc-strategy. Organic and Biomolecular Chemistry, 10 (20). 4043 - 4049 . ISSN 1477-0520
http://dx.doi.org/10.1039/c2ob25517k
10.1039/c2ob25517k
oai:eprints.whiterose.ac.uk:74468
2016-09-16T14:19:10Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74468/
Structure of Escherichia coli aspartate α-decarboxylase Asn72Ala: probing the role of Asn72 in pyruvoyl cofactor formation
Webb, ME
Lobley, CM
Soliman, F
Kilkenny, ML
Smith, AG
Blundell, TL
Abell, C
The crystal structure of the Asn72Ala site-directed mutant of Escherichia coli aspartate α-decarboxylase (ADC) has been determined at 1.7 Å resolution. The refined structure is consistent with the presence of a hydrolysis product serine in the active site in place of the pyruvoyl group required for catalysis, which suggests that the role of Asn72 is to protect the ester formed during ADC activation from hydrolysis. In previously determined structures of activated ADC, including the wild type and other site-directed mutants, the C-terminal region of the protein is disordered, but in the Asn72Ala mutant these residues are ordered owing to an interaction with the active site of the neighbouring symmetry-related multimer.
International Union of Crystallography
2012-04-01
Article
NonPeerReviewed
Webb, ME, Lobley, CM, Soliman, F et al. (4 more authors) (2012) Structure of Escherichia coli aspartate α-decarboxylase Asn72Ala: probing the role of Asn72 in pyruvoyl cofactor formation. Acta CrystallographicaSection F: Structural Biology and Crystallization Communications Online, 68 (4). 414 - 417 . ISSN 1744-3091
http://dx.doi.org/10.1107/S1744309112009487
10.1107/S1744309112009487
oai:eprints.whiterose.ac.uk:74913
2016-11-04T03:18:49Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74913/
Towards a structural basis for the relationship between blood group and the severity of El Tor cholera
Mandal, PK
Branson, TR
Hayes, ED
Ross, JF
Gavín, JA
Daranas, AH
Turnbull, WB
It has long been known that people with blood group O are more severely affected by El Tor cholera than those with blood groups A or B. Microcalorimetry and NMR spectroscopy are used to evaluate the ability of the B-subunits of cholera toxin and E. coli heat-labile toxin to bind to selected blood group oligosaccharides.
Wiley Verlag
2012-05-21
Article
NonPeerReviewed
Mandal, PK, Branson, TR, Hayes, ED et al. (4 more authors) (2012) Towards a structural basis for the relationship between blood group and the severity of El Tor cholera. Angewandte Chemie International Edition, 51 (21). 5143 - 5146 . ISSN 1433-7851
http://dx.doi.org/10.1002/anie.201109068
10.1002/anie.201109068
oai:eprints.whiterose.ac.uk:74914
2016-11-04T03:18:58Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74914/
Methylthioxylose--a jewel in the mycobacterial crown?
Turnbull, WB
Stalford, SA
Ten years ago an unusual sugar was discovered in a cell wall polysaccharide of Mycobacterium tuberculosis. Structural elucidation revealed the presence of the first thiosugar in a bacterial polysaccharide. Synthetic studies have helped to define its relative and absolute configuration as α-D-methylthioxylofuranosyl. While its biosynthetic origins remain the subject of speculation, work has begun to define its possible biological roles.
Royal Society of Chemistry
2012-08-14
Article
NonPeerReviewed
Turnbull, WB and Stalford, SA (2012) Methylthioxylose--a jewel in the mycobacterial crown? Organic and Biomolecular Chemistry, 10 (30). 5698 - 5706 . ISSN 1477-0520
http://dx.doi.org/10.1039/c2ob25630d
10.1039/c2ob25630d
oai:eprints.whiterose.ac.uk:74915
2024-02-20T15:42:46Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/74915/
Stereoselective glycosylations using oxathiane spiroketal glycosyl donors
Fascione, MA
Webb, NJ
Kilner, CA
Warriner, SL
Turnbull, WB
Novel oxathiane spiroketal donors have been synthesised and activated via an umpolung S-arylation strategy using 1,3,5-trimethoxybenzene and 1,3-dimethoxybenzene. The comparative reactivity of the resulting 2,4,6-trimethoxyphenyl (TMP)- and 2,4-dimethoxyphenyl (DMP)-oxathiane spiroketal sulfonium ions is discussed, and their α-stereoselectivity in glycosylation reactions is compared to the analogous TMP- and DMP-sulfonium ions derived from an oxathiane glycosyl donor bearing a methyl ketal group. The results show that the stereoselectivity of the oxathiane glycosyl donors is dependent on the structure of the ketal group and reactivity can be tuned by varying the substituent on the sulfonium ion.
Elsevier
2012-02-01
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/74915/2/CarbohydrRes%202012%20348%206%20accepted%20version%20for%20WhiteRose.pdf
Fascione, MA, Webb, NJ, Kilner, CA et al. (2 more authors) (2012) Stereoselective glycosylations using oxathiane spiroketal glycosyl donors. Carbohydrate Research, 348. 6 - 13 . ISSN 0008-6215
http://dx.doi.org/10.1016/j.carres.2011.07.020
10.1016/j.carres.2011.07.020
oai:eprints.whiterose.ac.uk:74917
2016-10-26T02:58:56Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/74917/
Benzyne arylation of oxathiane glycosyl donors
Fascione, MA
Turnbull, WB
The arylation of bicyclic oxathiane glycosyl donors has been achieved using benzyne generated in situ from 1-aminobenzotriazole (1-ABT) and lead tetraacetate. Following sulfur arylation, glycosylation of acetate ions proceeded with high levels of stereoselectivity to afford α-glycosyl acetates in a ‘one-pot’ reaction, even in the presence of alternative acceptor alcohols.
Beilstein Institute
2010-02-22
Article
PeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/74917/2/BeilsteinJOrgChem%202010%206%2019.pdf
Fascione, MA and Turnbull, WB (2010) Benzyne arylation of oxathiane glycosyl donors. Beilstein Journal of Organic Chemistry, 6. ISSN 1860-5397
http://dx.doi.org/10.3762/bjoc.6.19
10.3762/bjoc.6.19
oai:eprints.whiterose.ac.uk:74918
2016-11-04T03:19:05Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74918/
Neighbouring group participation vs. addition to oxacarbenium ions: studies on the synthesis of mycobacterial oligosaccharides
Stalford, SA
Kilner, CA
Leach, AG
Turnbull, WB
Neighbouring group participation is frequently used to control the stereoselectivity of chemical reactions. Herein, we investigate the use of neighbouring group participation for the synthesis of disaccharides incorporating the mycobacterial sugar methylthioxylose. A bicyclic thioglycoside was activated by methylation to generate a methylsulfonium group that would act both as the anomeric leaving group, and also provide the methylsulfide group in the product. Model reactions indicated that the bicyclic intermediate would also act as a participating group to direct the acceptor alcohol to the lower alpha-face of the sugar. While the key sulfonium intermediate could be detected in the reaction mixture, the glycosylation reaction proceeded with moderate stereoselectivity, apparently via an S(N)1-type mechanism. Density functional theory calculations were used to compare our methylthioxylose sulfonium ion with a trans-decalin-like sulfonium ion described by Boons and co-workers to be an alpha-directing participating group (J. Am. Chem. Soc. 2005, 127, 12090). Our studies show that even where a bicyclic sulfonium ion can be detected in the reaction mixture, caution should be applied before invoking it as an intermediate on the reaction pathway.
Royal Society of Chemistry
2009-12-07
Article
NonPeerReviewed
Stalford, SA, Kilner, CA, Leach, AG et al. (1 more author) (2009) Neighbouring group participation vs. addition to oxacarbenium ions: studies on the synthesis of mycobacterial oligosaccharides. Organic and Biomolecular Chemistry, 7 (23). 4842 - 4852 . ISSN 1477-0520
http://dx.doi.org/10.1039/b914417j
10.1039/b914417j
oai:eprints.whiterose.ac.uk:74919
2016-11-04T03:19:08Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74919/
Stereoselective glycosylation using oxathiane glycosyl donors
Fascione, MA
Adshead, SJ
Stalford, SA
Kilner, CA
Leach, AG
Turnbull, WB
A bicyclic glycosyl donor is activated as an arylsulfonium ion and used to synthesise alpha-glycosides with high stereoselectivity.
Royal Society of Chemistry
2009-10-21
Article
NonPeerReviewed
Fascione, MA, Adshead, SJ, Stalford, SA et al. (3 more authors) (2009) Stereoselective glycosylation using oxathiane glycosyl donors. Chemical Communications (39). 5841 - 5843 . ISSN 1359-7345
http://dx.doi.org/10.1039/b913308a
10.1039/b913308a
oai:eprints.whiterose.ac.uk:74920
2016-11-08T18:27:16Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74920/
A natural carbohydrate substrate for Mycobacterium tuberculosis methionine sulfoxide reductase A
Stalford, SA
Fascione, MA
Sasindran, SJ
Chatterjee, D
Dhandayuthapani, S
Turnbull, WB
Enzymatic reduction of the methylsulfinylxylofuranosyl (MSX) groups in lipoarabinomannan provides proof of the absolute configuration of MSX and a possible biochemical mechanism for oxidative protection in Mycobacterium tuberculosis.
Royal Society of Chemistry
2009
Article
NonPeerReviewed
Stalford, SA, Fascione, MA, Sasindran, SJ et al. (3 more authors) (2009) A natural carbohydrate substrate for Mycobacterium tuberculosis methionine sulfoxide reductase A. Chemical Communications. 110 - 112 . ISSN 1359-7345
http://dx.doi.org/10.1039/b817483k
10.1039/b817483k
oai:eprints.whiterose.ac.uk:74921
2016-11-04T03:20:06Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74921/
Thio-oligosaccharides of sialic acid – synthesis of an alpha(2-3)sialyl galactoside via a gulofuranose/galactopyranose approach
Turnbull, WB
Field, RA
A new approach to the synthesis of thio-oligosaccharides containing the N-acetylneuraminic acid-α(2→3)-galactopyranose linkage is described. 3-O-(Trifluoromethylsulfonyl)gulofuranose derivative 5 can be converted into the α-2,3-sialyl-3-thiogalactofuranose derivative 8 in good yield. Partial deprotection of the thiodisaccharide provides an α/β mixture of both galactofuranose and galactopyranose isomers, but this mixture can be transformed efficiently into the desired pyranose-ring form to allow further elaboration into other glycosides via trichloroacetimidate donor 21. This strategy avoids introducing sulfur into 3-O-(trifluoromethylsulfonyl)gulopyranose derivatives, which can be prone to elimination side reactions.
Royal Society of Chemistry
2000-05
Article
PeerReviewed
Turnbull, WB and Field, RA (2000) Thio-oligosaccharides of sialic acid – synthesis of an alpha(2-3)sialyl galactoside via a gulofuranose/galactopyranose approach. Journal of the Chemical Society, Perkin Transactions 1, 12. 1859 - 1866 . ISSN 1472-7781
http://dx.doi.org/10.1039/B002319L
10.1039/B002319L
oai:eprints.whiterose.ac.uk:74922
2018-03-29T17:51:24Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74922/
Biophysical Studies on the Interactions of Bacterial Toxins
Turnbull, WB
Many diarrhoeal diseases such as cholera are caused by protein toxins that have an AB5 hetero-oligomeric structure. The proteins comprise a single toxic A-subunit and a pentameric B-subunit that interacts with specific cell surface glycolipids. Inhibitors of such protein-carbohydrate interactions could provide prophylactic treatments for these debilitating diseases. In our work we aim to understand the binding interactions of multivalent inhibitors for bacterial toxins. Often a single biophysical technique is limited in the information it can provide, whereas a more complete picture can be constructed through an integrated approach using a broad range of biophysical methods. For example, the importance of protein and ligand dynamics in multivalent interactions is revealed when combinations of NMR spectroscopy, isothermal titration calorimetry, analytical ultracentrifugation and dynamic light scattering are used to study to different multivalent systems.
Beilstein Institute
Hicks, MG
Kettner, C
2012
Book Section
NonPeerReviewed
Turnbull, WB (2012) Biophysical Studies on the Interactions of Bacterial Toxins. In: Hicks, MG and Kettner, C, (eds.) Proceedings of the International Beilstein Symposium on Glyco-Bioinformatics: Cracking the Sugar Code by Navigating the Glycospace. Beilstein Institute , Frankfurt/Main , 55 - 68 . ISBN 3 832 532 056
oai:eprints.whiterose.ac.uk:74923
2018-03-29T17:51:37Z
7374617475733D707562
74797065733D626F6F6B5F73656374696F6E
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74923/
Monovalent and multivalent inhibitors of bacterial toxins
Turnbull, WB
Hayes, ED
Cholera and travellers’ diarrhoea are caused by AB5 protein toxins that bind to ganglioside GM1 at the surface of the cells lining the intestine. Inhibition of this protein-carbohydrate interaction would prevent the toxin from entering the cells, and thus prevents toxin-induced diarrhoea. In this review we will describe the structures of the cholera and E. coli heat-labile toxins, and summarize the main strategies that have led to the development of monovalent and multivalent inhibitors of these toxins. A number of key design concepts emerge from these studies including the importance of pre-organization of the sugar residues within the monovalent ligands, and also the pre-organization of monovalent ligand groups within larger multivalent ligands. The importance of chelation and protein aggregation as mechanisms of multivalent inhibition is also discussed.
Bentham Science Publishers
Renaudet, O
Spinelli, N
2011
Book Section
NonPeerReviewed
Turnbull, WB and Hayes, ED (2011) Monovalent and multivalent inhibitors of bacterial toxins. In: Renaudet, O and Spinelli, N, (eds.) Synthesis and Biological Applications of Multivalent Glycoconjugates. Bentham Science Publishers , 78 - 91 .
http://www.benthamscience.com/ebooks/openaccessplus.php?JCode=9781608052776
10.2174/978160805277611101010078
oai:eprints.whiterose.ac.uk:74932
2018-03-29T02:35:10Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/74932/
Mechanistic studies on a sulfoxide transfer reaction mediated by diphenyl sulfoxide/triflic anhydride
Fascione, MA
Adshead, SJ
Mandal, PK
Kilner, CA
Leach, AG
Turnbull, WB
Sulfoxides are frequently used in organic synthesis as chiral auxiliaries and reagents to mediate a wide variety of chemical transformations. For example, diphenyl sulfoxide and triflic anhydride can be used to activate a wide range of glycosyl donors including hemiacetals, glycals and thioglycosides. In this way, an alcohol, enol or sulfide is converted into a good leaving group for subsequent reaction with an acceptor alcohol. However, reaction of diphenyl sulfoxide and triflic anhydride with oxathiane-based thioglycosides, and other oxathianes, leads to a different process in which the thioglycoside is oxidised to a sulfoxide. This unexpected oxidation reaction is very stereoselective and proceeds under anhydrous conditions in which the diphenyl sulfoxide acts both as oxidant and as the source of the oxygen atom. Isotopic labelling experiments support a reaction mechanism that involves the formation of oxodisulfonium (S-O-S) dication intermediates. These intermediates undergo oxygen-exchange reactions with other sulfoxides and also allow interconversion of axial and equatorial sulfoxides in oxathiane rings. The reversibility of the oxygen-exchange reaction suggests that the stereochemical outcome of the oxidation reaction may be under thermodynamic control, which potentially presents a novel strategy for the stereoselective synthesis of sulfoxides.
Wiley-VCH Verlag
2012-03-05
Article
NonPeerReviewed
Fascione, MA, Adshead, SJ, Mandal, PK et al. (3 more authors) (2012) Mechanistic studies on a sulfoxide transfer reaction mediated by diphenyl sulfoxide/triflic anhydride. Chemistry: A European Journal, 18 (10). 2987 - 2997. ISSN 0947-6539
http://dx.doi.org/10.1002/chem.201102861
10.1002/chem.201102861
oai:eprints.whiterose.ac.uk:75279
2023-06-23T21:32:30Z
7374617475733D707562
74797065733D61727469636C65
756E69743D596F726B:596F726B2E46414332:596F726B2E594F5233
756E69743D4C65656473:4C656564732E46412D4541454E:4C656564732E52432D534F4545:4C656564732E52432D454E56495F31
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D4541454E:4C656564732E52432D534F4545
696E737469747574696F6E3D596F726B
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/75279/
OH reactivity in a South East Asian Tropical rainforest during the Oxidant and Particle Photochemical Processes (OP3) project
Edwards, PM
Evans, MJ
Furneaux, KL
Hopkins, J
Ingham, T
Jones, C
Lee, JD
Lewis, AC
Moller, SJ
Stone, D
Whalley, LK
Heard, DE
OH reactivity, the reciprocal of its lifetime from reaction with its sinks, was measured for 12 days in April 2008 within a tropical rainforest on Borneo as part of the OP3 project. The maximum observed value was 83.8 ± 26.0 s−1 with the campaign averaged noon-time maximum being 29.1 ± 8.5 s−1. The maximum OH reactivity calculated using the campaign averaged noon-time concentrations of observed sinks was ~18 s−1, significantly less than the observations, consistent with other studies in similar environments. OH reactivity was dominated by reaction with isoprene. Numerical simulations of isoprene oxidation using the Master Chemical Mechanism (v3.2) in a highly simplified physical and chemical environment show that the steady state OH reactivity is a linear function of the OH reactivity due to isoprene alone, with a maximum multiplier being equal to the number of isoprene OH attackable bonds (10). Thus the emission of isoprene constitutes a significantly larger emission of reactivity than is offered by the primary reaction with isoprene alone, with significant scope for the secondary oxidation products of isoprene to constitute the missing reactivity. A physically and chemically more sophisticated simulation (including physical loss, photolysis, and other oxidants) showed that the calculated OH reactivity is reduced by the removal of the OH attackable bonds by other oxidants and photolysis, and by physical loss (mixing and deposition). The calculated OH reactivity is increased by peroxide cycling, and by the OH concentration itself. Notable in these calculations is that the lifetime of OH reactivity is significantly longer than the lifetime of isoprene and critically depends on the chemical and physical lifetime of intermediate species. When constrained to the observed campaign averaged diurnal concentrations of primary volatile organic compounds (VOCs), O3, nitrogen oxides (NOx) and other parameters, the model underestimated the observed mean OH reactivity by 30%. However, it was found that: (1) the short lifetimes of isoprene and OH lead to a large variability in their concentrations and so significant variation in the calculated OH reactivity, (2) uncertainties in the OH chemistry in these high isoprene environments can lead to an underestimate of the OH reactivity, and (3) the physical loss of species that react with OH plays a significant role in the calculated OH reactivity, (4) a missing primary source of reactive carbon would have to be emitted at a rate equivalent to 50% that of isoprene to account for the missing OH sink. A clear argument for a significant missing flux of primary emitted VOC compounds to account for the unmeasured reactivity is not found and the development of techniques for the measurement of secondary multifunctional carbon compounds is needed to close the OH reactivity budget.
Copernicus Publications
2013-02-22
Article
PeerReviewed
text
en
https://eprints.whiterose.ac.uk/75279/16/heardd1.pdf
Edwards, PM, Evans, MJ, Furneaux, KL et al. (9 more authors) (2013) OH reactivity in a South East Asian Tropical rainforest during the Oxidant and Particle Photochemical Processes (OP3) project. Atmospheric Chemistry and Physics Discussions, 13 (2). 5233 - 5278 (46). ISSN 1680-7367
http://dx.doi.org/10.5194/acpd-13-5233-2013
10.5194/acpd-13-5233-2013
oai:eprints.whiterose.ac.uk:75684
2023-06-23T21:33:29Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E5243:4C656564732E52435F3331
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75684/
Near-Infrared Fluorescent Ribonuclease-A-Encapsulated Gold Nanoclusters: Preparation, Characterization, Cancer Cell Targeting and Imaging
Kong, Y
Chen, J
Gao, F
Brydson, R
Johnson, B
Heath, G
Zhang, Y
Wu, L
Zhou, DJ
Ultra-small gold nanoclusters (AuNCs) have unique size-dependent optical, electrical and chemical properties. They have emerged as a new nanomaterial with broad applications in optoelectronics, catalysis, biosensing, and bioimaging. Several strategies have been exploited to prepare AuNCs of different “magic number” sizes, using different templates e.g. dendrimers, polyethyleneimines, peptides, and more recently, proteins. Notwithstanding, almost all bio-template-protected AuNCs reported so far exhibit fairly low fluorescence quantum yields (QYs), typically < 5%, which is especially true for AuNCs prepared using the protein templates. In this paper, we report a facile, one-pot aqueous synthesis of highly fluorescent AuNCs using bovine pancreatic ribonuclease A (RNase-A) as the bio-template. The as-prepared AuNCs not only fluoresce strongly at the near-infrared (NIR) region (λEM = 682 nm), but also exhibit an elevated QY of 12.1%. In addition, the RNase-A-encapsulated AuNC (RNase-A-AuNC) displays an exceptionally large Stokes shift of ~210 nm as well as a single dominant fluorescence lifetime of ~1.5 μs, about three orders of magnitudes longer than biological autofluorescence. Furthermore, by coupling vitamin B12 (VB12) to the RNase-A-AuNC, we develop a multifunctional nanoplatform that is suitable for simultaneous targeting and imaging cancer at the cellular level using Caco-2 cell lines as an in vitro model. Since VB12 has effective uptake pathways in the digestion system, this nanoplatform may have potential for targeted oral drug delivery in vivo.
Royal Society of Chemistry
2013-01-21
Article
NonPeerReviewed
Kong, Y, Chen, J, Gao, F et al. (6 more authors) (2013) Near-Infrared Fluorescent Ribonuclease-A-Encapsulated Gold Nanoclusters: Preparation, Characterization, Cancer Cell Targeting and Imaging. Nanoscale, 5 (3). 1009 - 1017 (9). ISSN 2040-3364
http://dx.doi.org/10.1039/C2NR32760K
10.1039/C2NR32760K
oai:eprints.whiterose.ac.uk:75685
2016-09-16T14:35:37Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75685/
Efficient, pH-triggered drug delivery using a pH-responsive DNA conjugated gold nanoparticle
Song, L
Ho, VHB
Chen, C
Yang, Z
Liu, D
Chen, R
Zhou, DJ
A stable, efficient drug nanocarrier that resists non-specific adsorption of serum proteins has been developed using a PEG750-modified pH-responsive DNA-gold nanoparticle conjugate. It provides efficient delivery and pH-triggered release of anticancer drugs into cancer cells, leading to high cytotoxicity.
Wiley-VCH
2013
Article
NonPeerReviewed
Song, L, Ho, VHB, Chen, C et al. (4 more authors) (2013) Efficient, pH-triggered drug delivery using a pH-responsive DNA conjugated gold nanoparticle. Advanced Healthcare Materials, 2 (2). 275 - 280 (6). ISSN 2192-2640
http://dx.doi.org/10.1002/adhm.201200112
10.1002/adhm.201200112
oai:eprints.whiterose.ac.uk:75686
2016-11-04T03:13:19Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75686/
Toggled RNA Aptamers Against Aminoglycosides Allowing Facile Detection of Antibiotics Using Gold Nanoparticle Assays.
Derbyshire, N
White, SJ
Bunka, DH
Song, L
Stead, S
Tarbin, J
Sharman, M
Zhou, DJ
Stockley, PG
We have used systematic evolution of ligands by exponential enrichment (SELEX) to isolate RNA aptamers against aminoglycoside antibiotics. The SELEX rounds were toggled against four pairs of aminoglycosides with the goal of isolating reagents that recognize conserved structural features. The resulting aptamers bind both of their selection targets with nanomolar affinities. They also bind the less structurally related targets, although they show clear specificity for this class of antibiotics. We show that this lack of aminoglycoside specificity is a common property of aptamers previously selected against single compounds and described as "specific". Broad target specificity aptamers would be ideal for sensors detecting the entire class of aminoglycosides. We have used ligand-induced aggregation of gold-nanoparticles coated with our aptamers as a rapid and sensitive assay for these compounds. In contrast to DNA aptamers, unmodified RNA aptamers cannot be used as the recognition ligand in this assay, whereas 2'-fluoro-pyrimidine derivatives work reliably. We discuss the possible application of these reagents as sensors for drug residues and the challenges for understanding the structural basis of aminoglycoside-aptamer recognition highlighted by the SELEX results.
American Chemical Society
2012-07-25
Article
NonPeerReviewed
Derbyshire, N, White, SJ, Bunka, DH et al. (6 more authors) (2012) Toggled RNA Aptamers Against Aminoglycosides Allowing Facile Detection of Antibiotics Using Gold Nanoparticle Assays. Analytical Chemistry, 84 (15). 6595 - 6602 (8).
http://dx.doi.org/10.1021/ac300815c
10.1021/ac300815c
oai:eprints.whiterose.ac.uk:75693
2016-11-08T18:26:52Z
7374617475733D707562
74797065733D7075626C69736865645F636F6E666572656E63655F70726F63656564696E6773
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D454C4543:4C656564732E53522D4D495048
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D:4C656564732E53522D50484348
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75693/
Spectroscopic analysis of powders through diffuse-reflectance imaging using a frequency-switchable terahertz quantum cascade laser
Valavanis, A
Dean, P
Chowdhury, S
Burnett, AD
Khanna, SP
Davies, AG
Linfield, EH
A heterogeneous THz-QCL is used for 4-frequency diffuse-reflectance imaging of powdered sugars and polymers. An effective-optical-path model reproduces features in the Beer–Lambert absorption spectra accurately and discriminates between admixtures of materials with differing concentration.
IEEE
2013-12-01
Proceedings Paper
NonPeerReviewed
Valavanis, A, Dean, P, Chowdhury, S et al. (4 more authors) (2013) Spectroscopic analysis of powders through diffuse-reflectance imaging using a frequency-switchable terahertz quantum cascade laser. In: 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2013. IRMMW-THz 2013: The 38th International Conference on Infrared, Millimeter and Terahertz Waves, 01-06 Sep 2013, Mainz on the Rhine, Germany. IEEE . ISBN 978-1-4673-4717-4
http://dx.doi.org/10.1109/IRMMW-THz.2013.6665598
10.1109/IRMMW-THz.2013.6665598
oai:eprints.whiterose.ac.uk:75705
2016-09-16T14:36:00Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75705/
A pH-trigged, fast-responding DNA hydrogel
Cheng, EJ
Xing, YZ
Chen, P
Yang, Y
Sun, YW
Zhou, DJ
Xu, LJ
Fan, QH
Liu, DS
A fast, pH-responsive DNA hydrogel (see picture; right) was prepared by a three-armed DNA nanostructure (left) assembling together through the formation of intermolecular i-motif structures (middle). The hydrogel can be switched to the non-gel state in minutes by simply using environmental pH changes.
Wiley-VCH Verlag GmbH & Co.
2009-09-28
Article
NonPeerReviewed
Cheng, EJ, Xing, YZ, Chen, P et al. (6 more authors) (2009) A pH-trigged, fast-responding DNA hydrogel. Angewandte Chemie International Edition, 48 (41). 7660 - 7663 . ISSN 1433-7851
http://dx.doi.org/10.1002/anie.200902538
10.1002/anie.200902538
oai:eprints.whiterose.ac.uk:75712
2016-11-04T03:11:59Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75712/
Ultrasensitive single-nucleotide polymorphism detection using target-recycled ligation, strand displacement and enzymatic amplification
Zhang, Y
Guo, Y
Quirke, P
Zhou, DJ
We report herein the development of a highly sensitive and selective approach for label-free DNA detection by combining target-recycled ligation (TRL), magnetic nanoparticle assisted target capture/ separation, and efficient enzymatic amplification. We show our approach can detect as little as 30 amol (600 fM in 50 μL) of unlabelled single-stranded DNA targets and offer exquisitely high discrimination ratio (up to > 380 fold with background correction) between a perfect-match caner mutant and its single-base mismatch (wild-type) DNA target. Furthermore, it can quantitate the rare cancer mutant (KRAS codon 12) in large excesses of coexisting wild-type DNAs down to 0.75%. This sensor appears to be well-suited for sensitive SNP detection and a wide range of DNA mutation based diagnostic applications.
Royal Society of Chemistry
2013-05-16
Article
NonPeerReviewed
Zhang, Y, Guo, Y, Quirke, P et al. (1 more author) (2013) Ultrasensitive single-nucleotide polymorphism detection using target-recycled ligation, strand displacement and enzymatic amplification. Nanoscale, 5 (11). 5027 - 5035 (9).
10.1039/C3NR01010D
oai:eprints.whiterose.ac.uk:75713
2016-09-16T14:36:09Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/75713/
Quantum dot-nucleic acid/aptamer bioconjugate based fluorimetric biosensors
Zhou, DJ
Over the past 10 years, fluorescent semiconductor quantum dot (QD)-biomolecule conjugates have emerged as a powerful new sensing platform showing great potential in a wide range of applications in biosensing, environmental monitoring, and disease diagnosis. This mini-review presents a brief account of the recent development on QD-nucleic acid (NA), particularly NA aptamer, conjugates based biosensors using the Förster resonance energy transfer (FRET) readout mechanism. It starts with a brief introduction to the NA aptamer and QD FRET, followed by example approaches to compact QD-DNA conjugates, target readout strategies and sensing performance, and concluded with challenges and outlook for the QD-NA/aptamer bioconjugate sensors.
Portland Press
2012-07-17
Article
NonPeerReviewed
text
en
attached
https://eprints.whiterose.ac.uk/75713/9/Combine.pdf
Zhou, DJ (2012) Quantum dot-nucleic acid/aptamer bioconjugate based fluorimetric biosensors. Biochemical Society Transactions, 40 (4). 635 - 639 (5). ISSN 0300-5127
http://dx.doi.org/10.1042/BST20120059
10.1042/BST20120059
oai:eprints.whiterose.ac.uk:75714
2023-06-23T21:33:36Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75714/
Magnetic particle based ultrasensitive biosensors for diagnostics
Zhang, Y
Zhou, DJ
The ability of sensitive and accurate detection of small quantities of disease biomarkers is critical for clinical diagnosis of disease. In this regard, magnetic particles (MPs) have been widely used because of their unique magnetic properties allowing for efficient target capture, enrichment and convenient separation. These coupled with great signal amplification, have enabled MP-based biosensors to achieve ultra-sensitivities. Over the past few years, several ultrasensitive MP-based biosensors suitable for early clinical diagnostics have been reported. This article highlights some of the most recent developments, with a focus on MP-based ultrasensitive assays using antibody or aptamer as target-binding agent using efficient signal amplification/readout strategies.
Expert Reviews Ltd
2012-06-22
Article
NonPeerReviewed
Zhang, Y and Zhou, DJ (2012) Magnetic particle based ultrasensitive biosensors for diagnostics. Expert Review of Molecular Diagnostics, 12 (6). 565 - 571 (7). ISSN 1473-7159
http://dx.doi.org/10.1586/ERM.12.54
10.1586/ERM.12.54
oai:eprints.whiterose.ac.uk:75715
2016-11-04T03:12:06Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75715/
A quantum dot-intercalating dye dual-donor FRET based biosensor
Zhang, HY
Zhou, DJ
We report herein the development of a novel quantum dot-intercalating dye dual-donor FRET system that can be used for sensitive detection of pM level DNA and protein targets.
royal society of chemistry
2012-04-30
Article
NonPeerReviewed
Zhang, HY and Zhou, DJ (2012) A quantum dot-intercalating dye dual-donor FRET based biosensor. Chemical Communications, 48 (42). 5097 - 5099 (3). ISSN 1359-7345
http://dx.doi.org/10.1039/C2CC30422H
10.1039/C2CC30422H
oai:eprints.whiterose.ac.uk:75716
2016-11-04T03:12:03Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75716/
Small-molecule ligands strongly affect the Förster resonance energy transfer between quantum dot and fluorescent protein
Zhang, Y
Zhang, HY
Hollins, J
Webb, ME
Zhou, DJ
We report herein the study of the Förster resonance energy transfer (FRET) between a CdSe/ZnS core/shell quantum dot (QD) capped with three different small-molecule ligands, 3-mercaptopropionic acid (MPA), glutathione (GSH), and dihydrolipoic acid (DHLA), and a hexa-histidine (His6)-tagged fluorescent protein, mCherry (FP). The Förster radius (R0) and corresponding donor-acceptor distances (r) for each of the QD-FP FRET systems were evaluated by using the Förster dipole-dipole interaction formula. Interestingly, both the FRET efficiency (E) and r were found to be strongly dependent on the capping small-molecule ligands on the QD surface, where E >80% was obtained at a FP:QD copy number of 2:1 for MPA capped QD, while that for the DHLA capped QD was < 25% under the same condition. A molecular model was proposed to explain the possible reasons behind these observations. The dissociation constants (Kds) and kinetics of the self-assembled QD-FP systems were also evaluated. Results show that the QD-FP self-assembly process is fast (completes in minutes at low nM concentration), strong (with Kd ~ 1 nM) and positively cooperative (with Hill coefficient n >1), suggesting that the QD-His-tagged biomolecule self-assembly is a facile, effective approach for making compact QD-bioconjugates which may have a wide range of sensing and biomedical applications.
Royal Society of Chemistry
2011-10-25
Article
NonPeerReviewed
Zhang, Y, Zhang, HY, Hollins, J et al. (2 more authors) (2011) Small-molecule ligands strongly affect the Förster resonance energy transfer between quantum dot and fluorescent protein. Physical Chemistry Chemical Physics, 13 (43). 19427 - 19436 (10). ISSN 1463-9076
http://dx.doi.org/10.1039/c1cp22024a
10.1039/c1cp22024a
oai:eprints.whiterose.ac.uk:75717
2016-11-04T03:12:14Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75717/
Multilayer enzyme-coupled magnetic nanoparticles as efficient, reusable biocatalysts and biosensors
Garcia, J
Zhang, Y
Taylor, H
Cespedes, O
Webb, WE
Zhou, DJ
Herein we report the development of a highly active, magnetically retrievable and reusable biocatalyst using multilayer enzyme coupled-magnetic nanoparticles (MNPs) prepared by layer-by-layer assembly using two well-studied enzymes, horseradish peroxidise (HRP) and glucose oxidase (GOX), as a model enzyme system. We show that by combining the use of a biocompatible linker as well as biospecific immobilisation, the first layer enzyme in our HRP1-MNP retains the native activity of the enzyme in solution, and the overall catalytic activity of the multilayer enzyme system, HRPx-MNP, increases linearly with the increasing number of enzyme layers. Furthermore, the HRPx-MNP system can be conveniently retrieved by using an external magnitic field and reused for 10 consecutive cycles without apparent reduction of catalytic activity. We also report the development of a novel coupled bienzyme, GOX/HRPx-MNP system that can perform bi-enzymatic reactions to couple the colourless GOX-catalyzed reaction to the chromophoric HRP-catalyzed reaction via H2O2 production. This model bienzyme-MNP system can be used for simple, rapid colourimetric quantification of micromolar glucose.
Royal Society of Chemistry
2011-09-02
Article
NonPeerReviewed
Garcia, J, Zhang, Y, Taylor, H et al. (3 more authors) (2011) Multilayer enzyme-coupled magnetic nanoparticles as efficient, reusable biocatalysts and biosensors. Nanoscale, 3. 3721 - 3730 (10). ISSN 2040-3364
http://dx.doi.org/10.1039/C1NR10411J
10.1039/C1NR10411J
oai:eprints.whiterose.ac.uk:75718
2016-11-08T18:26:45Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75718/
A chelating dendritic ligand capped quantum dot: preparation, surface passivation, bioconjugation and specific DNA detection
Zhou, DJ
Li, Y
Hall, EA
Abell, C
Klenerman, D
Herein we report the synthesis of a new chelating dendritic ligand (CDL) and its use in the preparation a compact, stable and water-soluble quantum dot (QD). The CDL ligand, which contains a chelative dihydrolipoic acid (DHLA) moiety for strong QD surface anchoring and four dendritic carboxylic acid groups, can provide a stable, compact and entangled hydrophilic coating around the QD. We show that a CDL capped CdSe/ZnS core/shell QD (with a relatively thin ZnS shell) can be effectively “annealed” of surface defects by treatments with Zn2+ or S2- ions, leading to a significant fluorescence enhancement of over 250%. Further, by coupling a short DNA target to the QD via the CDL carboxylic acid group, a functional QD-DNA conjugate that can resist the strong, non-specific adsorption of DNA has been prepared. The resulting QD-DNA conjugate hybridizes quickly and specifically to its complementary DNA probe, making it a suitable DNA sensor capable of detecting specific complimentary DNA probe at low DNA probe:QD copy numbers via QD-sensitised dye fluorescence resonance energy transfer (FRET) response with sub-nanomolar detection limit on a conventional fluorimeter.
Royal Society of Chemitry
2011-01-13
Article
NonPeerReviewed
Zhou, DJ, Li, Y, Hall, EA et al. (2 more authors) (2011) A chelating dendritic ligand capped quantum dot: preparation, surface passivation, bioconjugation and specific DNA detection. Nanoscale, 3 (1). 201 - 211 (11). ISSN 2040-3364
http://dx.doi.org/10.1039/C0NR00462F
10.1039/C0NR00462F
oai:eprints.whiterose.ac.uk:75719
2016-11-04T03:08:55Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75719/
Development of smart nanoparticle-aptamer sensing technology
Zhang, HY
Sockley, PG
Zhou, DJ
Quantum dots (QDs) are excellent donors in Förster resonance energy transfer (FRET) based sensors because of their broad absorption and narrow symmetric emission. However, the strict requirement of a short donor-acceptor distance to achieve high FRET (hence sensitivity) has posed a significant challenge for QD- FRET based sensors due to challenges associated with the preparation of QD-conjugates that are both compact and highly stable. Consequently, most robust QD-FRET sensors are often too bulky to produce FRET efficiently, especially at low target to QD copy numbers (e.g. 1:1). They have largely relied on increasing the target:QD ratio to achieve high FRET, making them undesirable and inefficient in situations of low target:QD copy numbers. Here we report our recent work in the preparation of stable, compact and water-soluble QDs via ligand exchange and their subsequent conjugation to DNAs to make compact, functional QD-DNA conjugates based smart nanoparticle sensors for labelled and label-free DNA and protein detection. We have developed two strategies to prepare QD-DNA sensors: 1) via QD-thiolated DNA self-assembly, and 2) via covalent coupling between DNA and a QD surface ligand functional group. We show that a thiolated DNA (labelled with a fluorophore) can self-assemble onto a 3-mercaptopropionic acid-capped, CdSe/ZnS core/shell QD to produce highly efficient FRET (~80%) at a low DNA:QD ratio of 1:1 at single molecule level. However, this system suffers from strong, non-specific DNA adsorption and the self-assembled single-stranded (ss) DNA is unable to hybridise to its target complementary DNA. More recently, we found that a dihydrolipoic acid (DHLA)-capped QD-ssDNA self-assembled system can hybridise to its labelled DNA target to produce very efficient FRET that can be exploited for labelled-DNA quantification. By incorporating an anti-thrombin DNA aptamer to the self-assembled QD-DNA system, the resulting QD-DNA aptamer sensor can detect specifically 10 nM unlabelled protein target (thrombin) in standard aqueous buffer. In strategy 2, we show that the non-specific DNA adsorption can be eliminated by introducing a polyethylene glycol (PEG) linker to the QD capping ligands or by capping the QD with a novel chelating dendritic ligand. The resulting QD-DNA sensors can specifically detect 1 nM unlabelled short DNA targets, or 35 pM of a labelled-DNA target using QD sensitised dye FRET signals on a conventional fluorimeter.
Royal Society of Chemistry
2011-01-06
Article
NonPeerReviewed
Zhang, HY, Sockley, PG and Zhou, DJ (2011) Development of smart nanoparticle-aptamer sensing technology. Faraday Discussions, 149 (1). 319 - 332 (14). ISSN 1359-6640
http://dx.doi.org/10.1039/C005373B
10.1039/C005373B
oai:eprints.whiterose.ac.uk:75720
2016-09-16T14:36:22Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75720/
Controlled Assembly of Well-Defined 3D Bioarchitecture Using Two Active Enzymes
Kim DC
Sohn JI
Zhou, DJ
Duke, TAJ
Kang, DJ
This paper reports that a bioarchitecture with two different active enzymes can be fabricated conveniently on a prepatterned surface by highly selective surface-templated layer-by-layer (LBL) assembly by coupling a bilayer of avidin/biotin-lactate oxidase (biotin-LOD) with a bilayer of avidin/biotin-horseradish peroxidase (biotin-HRP). The two different active enzymes can be utilized as excellent building blocks for the fabrication of well-defined 3D nanostructures with precise control of the position and height on the surface. In addition, the LBL assembled bienzyme structures are highly functional, and bioarchitectures based on LOD and HRP-mediated coupling reaction can be employed in a number of viable biosensing applications.
American Chemical Society
2010-02-24
Article
NonPeerReviewed
Kim DC, Sohn JI, Zhou, DJ et al. (2 more authors) (2010) Controlled Assembly of Well-Defined 3D Bioarchitecture Using Two Active Enzymes. ACS Nano, 4 (3). 1580 - 1586 . ISSN 1936-0851
http://dx.doi.org/10.1021/nn900610u
10.1021/nn900610u
oai:eprints.whiterose.ac.uk:75721
2016-11-04T03:08:59Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75721/
Vancomycin dimer formation between analogues of bacterial peptidoglycan surfaces probed by force spectroscopy
Batchelor, M
Zhou, DJ
Cooper, MA
Abell, C
Rayment, T
Functionalised thiols presenting peptides found in the peptidoglycan from vancomycin-sensitive and -resistant bacteria were synthesised and used to form self-assembled monolayers (SAMs) on gold surfaces. This model bacterial cell-wall surface mimic was used to investigate binding interactions with vancomycin. Force spectroscopy, using the atomic force microscope (AFM), was used to investigate the specific rupture of interfacial vancomycin dimer complexes formed between pairs of vancomycin molecules bound to peptide-coated AFM probe and substrate surfaces. Clear adhesive contacts were observed between the vancomycin-sensitive peptide surfaces when vancomycin was present in solution, and the adhesion force demonstrated a clear dependence on antibiotic concentration.
Royal Society of Chemistry
2010-02-18
Article
NonPeerReviewed
Batchelor, M, Zhou, DJ, Cooper, MA et al. (2 more authors) (2010) Vancomycin dimer formation between analogues of bacterial peptidoglycan surfaces probed by force spectroscopy. Organic and Biomolecular Chemistry, 8 (5). 1142 - 1148 . ISSN 1477-0520
http://http//dx.doi.org%20/10.1039/b919347b
10.1039/b919347b
oai:eprints.whiterose.ac.uk:75722
2023-06-23T21:33:37Z
oai:eprints.whiterose.ac.uk:75723
2018-01-27T10:02:13Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/75723/
Nanomechanical detection of antibiotic– mucopeptide binding in a model for superbug drug resistance
Ndieyira, JW
Watari, M
Barrera, AD
Zhou, D
Vo¨gtli, M
Batchelor, M
Cooper, MA
Strunz, T
Horton, MA
Abell, C
Rayment, T
Aeppli, G
McKendry, RA
The alarming growth of the antibiotic-resistant superbugs methicillin-resistant Staphylococcus aureus (MRSA) and vancomycinresistant Enterococcus (VRE) is driving the development of new technologies to investigate antibiotics and their modes of action. We report the label-free detection of vancomycin binding to bacterial cell wall precursor analogues (mucopeptides) on cantilever arrays, with 10 nM sensitivity and at clinically relevant concentrations in blood serum. Differential measurements have quantified binding constants for vancomycin-sensitive and vancomycin-resistant mucopeptide analogues. Moreover, by systematically modifying the mucopeptide density we gain new insights into the origin of surface stress. We propose that stress is a product of a local chemical binding factor and a geometrical factor describing the mechanical connectivity of regions affected by local binding in terms of a percolation process. Our findings place BioMEMS devices in a new class of percolative systems. The percolation concept will underpin the design of devices and coatings to significantly lower the drug detection limit and may also have an impact on our understanding of antibiotic drug action in bacteria.
Nature publishing Group
2008-11
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/75723/14/Combine.pdf
Ndieyira, JW, Watari, M, Barrera, AD et al. (10 more authors) (2008) Nanomechanical detection of antibiotic– mucopeptide binding in a model for superbug drug resistance. Nature Nanotechnology, 3 (11). 691 - 696 . ISSN 1748-3387
http://dx.doi.org/10.1038/nnano.2008.275
10.1038/nnano.2008.275
oai:eprints.whiterose.ac.uk:75798
2016-11-04T02:28:57Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75798/
A pH-driven, reconfigurable DNA nanotriangle
Wang, WX
Yang, Y
Cheng, EJ
Zhao, MC
Meng, HF
Liu, DS
Zhou, DJ
A simple and robust DNA nanotriangle that can be conveniently reconfigured by environmental pH changes is demonstrated
Royal Society of Chemistry
2009
Article
NonPeerReviewed
Wang, WX, Yang, Y, Cheng, EJ et al. (4 more authors) (2009) A pH-driven, reconfigurable DNA nanotriangle. Chemical Communications, 2009 (7). 824 - 826 . ISSN 1359-7345
http://dx.doi.org/10.1039/b813064g
10.1039/b813064g
oai:eprints.whiterose.ac.uk:75844
2017-07-30T08:02:45Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/75844/
A Compact Functional Quantum Dot-DNA Conjugate: Preparation, Hybridization and Specific Label-free DNA Detection
Zhou, DJ
Ying, LM
Hong, X
Hall, EA
Abell, C
Klenerman, D
In this letter, we report the preparation of a compact, functional quantum dot (QD)-DNA conjugate, where the capturing target DNA is directly and covalently coupled to the QD surface. This enables the control of the separation distance between the QD donor and dye acceptor to within the range of the Förster radius. Moreover, a tri(ethylene glycol) linker is introduced to the QD surface coating to effectively eliminate the strong, non-specific adsorption of DNA on the QD surface. As a result, this QD-DNA conjugate hybridizes specifically to its complementary DNA with a hybridization rate constant comparable to that of free DNAs in solution. We show this system is capable of specific detection of nanomolar unlabeled complimentary DNA at low DNA probe:QD copy numbers via a ‘signal-on’ fluorescence resonance energy transfer (FRET) response.
American Chemical Society
2008-03
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/75844/8/Combine.pdf
Zhou, DJ, Ying, LM, Hong, X et al. (3 more authors) (2008) A Compact Functional Quantum Dot-DNA Conjugate: Preparation, Hybridization and Specific Label-free DNA Detection. Langmuir, 24 (5). 1659 - 1664. ISSN 0743-7463
http://dx.doi.org/10.1021/la703583u
10.1021/la703583u
oai:eprints.whiterose.ac.uk:75845
2016-11-04T02:28:45Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75845/
Selective diffusion barriers separate membrane compartments
Bruckbauer, A
Dunne, PD
James, P
Howes, E
Jones, R
Zhou, DJ
Klenerman, D
We have investigated exchange of molecules between different membrane domains on a highly compartmentalized cell, the spermatozoon. Using Alexa Fluor 555-cholera toxin B-subunit we have observed clustering of preexisting GM1 gangliosides which diffused across the anterior acrosome-equatorial segment interface but did not access the postacrosome. By contrast, single lipid and protein molecules readily exchanged between all three domains, although they diffused more slowly on nearing and crossing to the postacrosome. Thus, two types of diffusion interfaces are present on sperm heads, an ‘‘open’’ interface and a ‘‘mass filter’’ interface. The latter seems to be due to a protein-cytoskeleton network.
Biophysical Society
2010-07-07
Article
NonPeerReviewed
Bruckbauer, A, Dunne, PD, James, P et al. (4 more authors) (2010) Selective diffusion barriers separate membrane compartments. Biophysical Journal, 99 (1). L01 - L03. ISSN 0006-3495
http://dx.doi.org/10.1016/j.bpj.2010.03.067
10.1016/j.bpj.2010.03.067
oai:eprints.whiterose.ac.uk:75846
2013-06-27T11:48:21Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75846/
Single Molecule Force Spectroscopy on G-Quadruplex DNA
Lynch, S
Baker, H
Byker, SG
Zhou, DJ
Sinniah, K
Mechanical unfolding of a guanine (G)-quadruplex! A bimolecular Gquadruplex was formed between a pair of single-stranded DNAs on an AFM probe and a flat gold surface (see figure). The resulting G-quadruplex was studied by single-molecule force spectroscopy as a function of K+ concentration and the force loading rate. The mechanical stability and kinetic and thermodynamic parameters of the G-quadruplexes were estimated.
Wiley-VCH Verlag
2009-08-17
Article
NonPeerReviewed
Lynch, S, Baker, H, Byker, SG et al. (2 more authors) (2009) Single Molecule Force Spectroscopy on G-Quadruplex DNA. Chemistry - A European Journal, 15 (33). 8113 - 8116. ISSN 0947-6539
http://dx.doi.org/10.1002/chem.200901390
10.1002/chem.200901390
oai:eprints.whiterose.ac.uk:75847
2014-09-15T03:21:09Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75847/
DNA-templated CMV Viral Capsid Proteins Assembly Into Nanotubes
Xu, Y
Ye, J
Liu, HJ
Cheng, EJ
Yang, Y
Wang, WX
Zhao, MC
Zhou, D
Liu, DS
Fang, RX
This communication describes the in vitro assembly of genetically recombinant Cucumber Mosaic Virus (CMV) viral capsid proteins (CPs) into biological nanotubes, several micrometres long yet with a diameter of only 17 nm, triggered by double-stranded DNAs of different lengths.
Royal Society of Chemistry
2008
Article
NonPeerReviewed
Xu, Y, Ye, J, Liu, HJ et al. (7 more authors) (2008) DNA-templated CMV Viral Capsid Proteins Assembly Into Nanotubes. Chemical Communications (1). 49 - 51. ISSN 1359-7345
http://dx.doi.org/10.1039/b715299j
10.1039/b715299j
oai:eprints.whiterose.ac.uk:75848
2014-09-15T03:21:11Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75848/
Nanopipet delivery of individual molecules to cellular compartments for single molecule fluorescence tracking
Bruckbauer, A
James, P
Zhou, DJ
Yoon, JW
Excell, D
Korchev, YE
Jones, R
Klenerman, D
We have developed a new method, using a nanopipette, for controlled voltage-driven delivery of individual fluorescently labeled probe molecules to the plasma membrane which we used for single-molecule fluorescence tracking (SMT). The advantages of the method are 1), application of the probe to predefined regions on the membrane; 2), release of only one or a few molecules onto the cell surface; 3), when combined with total internal reflection fluorescence microscopy, very low background due to unbound molecules; and 4), the ability to first optimize the experiment and then repeat it on the same cell. We validated the method by performing an SMT study of the diffusion of individual membrane glycoproteins labeled with Atto 647-wheat germ agglutin in different surface domains of boar spermatozoa. We found little deviation from Brownian diffusion with a mean diffusion coefficient of 0.79 +/- 0.04 microm(2)/s in the acrosomal region and 0.10 +/- 0.02 microm(2)/s in the postacrosomal region; this difference probably reflects different membrane structures. We also showed that we can analyze diffusional properties of different subregions of the cell membrane and probe for the presence of diffusion barriers. It should be straightforward to extend this new method to other probes and cells, and it can be used as a new tool to investigate the cell membrane.
Biophysical Society
2007-10
Article
NonPeerReviewed
Bruckbauer, A, James, P, Zhou, DJ et al. (5 more authors) (2007) Nanopipet delivery of individual molecules to cellular compartments for single molecule fluorescence tracking. Biophysical Journal, 93 (9). 3120 - 3131. ISSN 0006-3495
http://http//dx.doi.org%20/10.1529/biophysj.107.104737
10.1529/biophysj.107.104737
oai:eprints.whiterose.ac.uk:75849
2016-10-30T21:57:56Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D:4C656564732E53522D494E4348
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75849/
Two-Color Fluorescence Analysis of Individual Virions Determines the Distribution of the Copy Number of Proteins in Herpes Simplex Virus Particles
Clarke, RW
Monnier, N
Li, HT
Zhou, DJ
Browne, H
Klenerman, D
We present a single virion method to determine absolute distributions of copy number in the protein composition of viruses and apply it to herpes simplex virus type 1. Using two-color coincidence fluorescence spectroscopy, we determine the virion- to-virion variability in copy numbers of fluorescently labeled tegument and envelope proteins relative to a capsid protein by analyzing fluorescence intensity ratios for ensembles of individual dual- labeled virions and fitting the resulting histogram of ratios. Using EYFP- tagged capsid protein VP26 as a reference for fluorescence intensity, we are able to calculate the mean and also, for the. rst time to our knowledge, the variation in numbers of gD, VP16, and VP22 tegument. The measurement of the number of glycoprotein D molecules was in good agreement with independent measurements of average numbers of these glycoproteins in bulk virus preparations, validating the method. The accuracy, straightforward data processing, and high throughput of this technique make it widely applicable to the analysis of the molecular composition of large complexes in general, and it is particularly suited to providing insights into virus structure, assembly, and infectivity.
Biophysical Society
2007-08
Article
NonPeerReviewed
Clarke, RW, Monnier, N, Li, HT et al. (3 more authors) (2007) Two-Color Fluorescence Analysis of Individual Virions Determines the Distribution of the Copy Number of Proteins in Herpes Simplex Virus Particles. Biophysical Journal, 93 (4). pp. 1329-1337. ISSN 0006-3495
http://dx.doi.org/10.1529/biophysj.107.106351
10.1529/biophysj.107.106351
oai:eprints.whiterose.ac.uk:75850
2014-09-15T03:21:13Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75850/
A Dendrimer-based Co32 Nanocluster: Synthesis and Application as Catalyst in the Growth of Nearly Uniform-diameter Single-wall Carbon Nanotubes
Geng, JF
Li, HW
Zhou, DJ
Huck, WTS
Johnson, BFG
We report the synthesis and characterization of a dendrimer-based Co-32 nanocluster molecule and its use as uniform-size catalytic seed for diameter-controlled growth of single-walled carbon nanotubes.
Elsevier Science Ltd., Pergamon
2006-03
Article
NonPeerReviewed
Geng, JF, Li, HW, Zhou, DJ et al. (2 more authors) (2006) A Dendrimer-based Co32 Nanocluster: Synthesis and Application as Catalyst in the Growth of Nearly Uniform-diameter Single-wall Carbon Nanotubes. Polyhedron, 25 (2). 585 - 590. ISSN 0277-5387
http://dx.doi.org/10.1016/j.poly.2005.08.036
10.1016/j.poly.2005.08.036
oai:eprints.whiterose.ac.uk:75851
2014-09-15T03:20:45Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75851/
Building three-dimensional nanostructures with functional enzymes by surface templated layer-by-layer assembly
Rauf, S
Zhou, DJ
Abell, C
Klenerman, D
Kang, DJ
We show that well-defined three-dimensional nanostructures of functional enzymes can be controllably fabricated by layer-by-layer assembly of avidin and biotinylated horseradish peroxidase on micro-contact printing patterned surface templates.
Royal Society of Chemistry
2006-03
Article
NonPeerReviewed
Rauf, S, Zhou, DJ, Abell, C et al. (2 more authors) (2006) Building three-dimensional nanostructures with functional enzymes by surface templated layer-by-layer assembly. Chemical Communications (16). 1721 - 1723. ISSN 1359-7345
http://dx.doi.org/10.1039/b517557g
10.1039/b517557g
oai:eprints.whiterose.ac.uk:75852
2014-09-15T03:20:47Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75852/
Fluorescence Resonance Energy Transfer between a Quantum Dot Donor and a Dye Acceptor Attached to a DNA
Zhou, DJ
Piper, JD
Abell, C
Klenerman, D
Kang, DJ
Ying, LM
We show that direct coupling of a dye-labelled DNA ( acceptor) to a quantum dot (QD) donor significantly reduces the donor acceptor distance and improves the FRET efficiency: a highly efficient FRET (similar to 88%) at a low acceptor-to-donor ratio of 2 has been achieved at the single-molecule level.
Royal Society of Chemistry
2005-10
Article
NonPeerReviewed
Zhou, DJ, Piper, JD, Abell, C et al. (3 more authors) (2005) Fluorescence Resonance Energy Transfer between a Quantum Dot Donor and a Dye Acceptor Attached to a DNA. Chemical Communications (38). 4807 - 4809. ISSN 1359-7345
http://dx.doi.org/10.1039/b508911e
10.1039/b508911e
oai:eprints.whiterose.ac.uk:75853
2014-09-15T03:20:49Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75853/
The scanned nanopipette: a new tool for high resolution bioimaging and controlled deposition of biomolecules
Ying, LM
Bruckbauer, A
Zhou, DJ
Gorelik, J
Schevchuk, AI
Lab, M
Korchev, YE
Klenerman, D
The boundary between the physical and biological sciences has been eroded in recent years with new physical methods applied to biology and biological molecules being used for new physical purposes. We have pioneered the application of a form of scanning probe microscopy based on a scanned nanopipette, originally developed by Hansma and co-workers, for reliable non-contact imaging over the surface of a live cell. We have found that the nanopipette can also be used for controlled local voltage-driven application of reagents or biomolecules and this can be used for controlled deposition and the local delivery of probes for mapping of specific species. In this article we review this progress, focussing on the physical principles and new phenomena that we have observed, and then outline the future applications that are now possible.
Royal Society of Chemistry
2005-10
Article
NonPeerReviewed
Ying, LM, Bruckbauer, A, Zhou, DJ et al. (5 more authors) (2005) The scanned nanopipette: a new tool for high resolution bioimaging and controlled deposition of biomolecules. Physical Chemistry, Chemical Physics: a journal of European Chemical Societies, 7 (15). 2859 - 2866. ISSN 1463-9076
http://dx.doi.org/10.1039/b506743j
10.1039/b506743j
oai:eprints.whiterose.ac.uk:75854
2014-09-15T03:20:51Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75854/
Systematic manipulation of surfaces by sequential nanoscale chemical reactions: a novel approach for constructing three dimensional nanostructures
Wang, XZ
Zhou, DJ
Rayment, T
Abell, C
Nanoscale patches, created by nanografting a maleimide-terminated thiol into a self-assembled monolayer, were elaborated by sequential chemical reactions. Each stage in the nanofabrication was followed by atomic force microscopy (AFM), providing a controlled approach to the fabrication of novel three-dimensional (3D) surface nanostructures.
Royal Society of Chemistry
2003-02
Article
NonPeerReviewed
Wang, XZ, Zhou, DJ, Rayment, T et al. (1 more author) (2003) Systematic manipulation of surfaces by sequential nanoscale chemical reactions: a novel approach for constructing three dimensional nanostructures. Chemical Communications, 9 (4). 474 - 475. ISSN 1359-7345
http://dx.doi.org/10.1039/b211906d
10.1039/b211906d
oai:eprints.whiterose.ac.uk:75855
2014-07-24T14:52:18Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75855/
Merocyanine dyes: self-assembled monolayers
Ashwell, GJ
Paxton, GAN
Whittam, AJ
Tyrrel, WD
Berry, M
Zhou, DJ
4-{2-[N-(10-Thiodecyl)quinolinium-4-yl]vinyl}phenolate self-assembles on gold with a contact area of 0.35 +/-0.03 nm(2) molecule(1), monolayer thickness of 1.64 +/- 0.07 nm, and dielectric permittivity components of epsilon(t) 2.8 and epsilon(i) approximate to 0.6 at 632.8 nm, which are reduced to ca. 2.0 and 0 respectively when exposed to an acidic medium. The films undergo a change from purple (merocyanine form) to yellow (protonated form) and, by monitoring changes in the reflectance, may be used as sensors with a detection limit of < 1 ppm for NH3 in a carrier gas. Langmuir-Blodgett (LB) films of the N- octadecyl analogue show similar behaviour but, for sensing applications, are disadvantaged because the phenolate group is adjacent to the substrate. They have a contact area and monolayer thickness of 0.46 +/- 0.03 nm 2 molecule(1) and 1.75 +/- 0.10 nm respectively, the dimensions indicating that the molecules are either less closely packed or more tilted compared with those of the self-assembled film.
Royal Society of Chemistry
2002-06
Article
NonPeerReviewed
Ashwell, GJ, Paxton, GAN, Whittam, AJ et al. (3 more authors) (2002) Merocyanine dyes: self-assembled monolayers. Journal of Materials Chemistry, 12 (6). 1631 - 1635 . ISSN 0959-9428
http://dx.doi.org/10.1039/b110676g
10.1039/b110676g
oai:eprints.whiterose.ac.uk:75878
2014-09-15T03:20:39Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75878/
Addressable Macroscopic 2D networks self-assembled from nanometre size protein/DNA complexes
Manzanera, M
Frankel, DJ
Li, HT
Zhou, DJ
Bruckbauer, A
Kreutzmann, P
Blackburn, J
Abell, C
Rayment, T
Klenerman, D
Barker, PD
We demonstrate the self-assembly of DNA and DNA binding proteins into two-dimensional networks that are then addressable by sending a second protein to a specific recognition site on the DNA network. These networks cover centimeters in area but can be addressed with nanometer precision, This hierarchical self-assembly of specific DNA protein complexes will be the basis for complex positioning of single molecules in two and three dimensions.
American Chemical Society
2006-02
Article
NonPeerReviewed
Manzanera, M, Frankel, DJ, Li, HT et al. (8 more authors) (2006) Addressable Macroscopic 2D networks self-assembled from nanometre size protein/DNA complexes. Nano Letters, 6 (3). 365 - 370. ISSN 1530-6984
http://dx.doi.org/10.1021/nl051599
10.1021/nl051599
oai:eprints.whiterose.ac.uk:75879
2014-09-15T03:20:43Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75879/
Molecular Lego: non-centrosymmetric alignment within interdigitating layers
Ashwell, GJ
Hamilton, R
Wood, BJ
Gentle, IR
Zhou, DJ
(E)-N-Hexadecyl-4-[2-(4-octadecyloxynaphthyl) ethenyl] quinolinium bromide, which has a wide-bodied chromophore and terminal n-alkyl groups, adopts a U-shape when spread at the air-water interface but a stretched conformation when compressed to ca. 35 mN m(-1). The high-pressure phase has a narrow stability range prior to collapse but may be extended from 40 to 60 mN m(-1) by co-spreading the dye in a 1 : 1 ratio with docosanoic acid. The mixed Langmuir-Blodgett (LB) film has a monolayer thickness of 4.6 +/- 0.2 nm which decreases to 2.5 +/- 0.1 nm layer(-1) in the bulk, the reduction arising from an interdigitating layer arrangement, both top and bottom. It is the first example of LB-Lego(R) and, in addition, represents the only fully interdigitating structure with non-centrosymmetrically aligned chromophores. They are tilted 38 degrees from the substrate normal. The second-harmonic intensity increases quadratically with the number of layers, i.e. as I-(N)(2 omega) = (I(1)N2)-N-2 omega, with a second-order susceptibility of chi ((2))(zzz) = 30 pm V-1 at 1064 nm for refractive indices of n(omega) = 1.55 and n(2 omega) = 1.73, d = 2.5 nm layer(-1) and phi = 38 degrees. Angle resolved X-ray photoelectron spectra (XPS) of these films provide no evidence of the bromide counterion, which suggests that it is replaced by OH 2 or HCO3-, which occur naturally in the aqueous subphase, or C21H43COO- from the co-deposited fatty acid. This probably applies to all cationic dyes deposited by the LB technique.
Royal Society of Chemistry
2001-10
Article
NonPeerReviewed
Ashwell, GJ, Hamilton, R, Wood, BJ et al. (2 more authors) (2001) Molecular Lego: non-centrosymmetric alignment within interdigitating layers. Journal of Materials Chemistry, 11 (12). 2966 - 2970. ISSN 0959-9428
http://dx.doi.org/10.1039/B105657N
10.1039/B105657N
oai:eprints.whiterose.ac.uk:75880
2014-09-15T03:19:45Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75880/
Photoelectro-chemical properties of anilino squaraine derivatives in LB films
Lang, AD
Huang, CH
Gan, LB
Zhou, D
Ashwell, GJ
Photocurrent generation from Langmuir-Blodgett (LB) overlays on indium tin oxide (ITO) electrodes, where the active components are 2,4-bis[4-(dibutylamino)-2-hydroxyphenyl]squaraine (1) and the unsubstituted analogue, 2,4-bis[4-(dibutylamino)phenyl]squaraine (2), have been investigated. Dye 1 shows improved behaviour compared with the latter and differences in performance are attributed to a modified aggregate structure, this being indicated by variations in the LB film spectra. The photocurrent generation is enhanced by the presence of electron accepters, e.g. N,N'-dimethyl-4,4'-bipyridinium diiodide (MV2+), but quenched by electron donors, e.g. hydroquinone (HQ). The concentration dependence is reported.
Royal Society of Chemistry
1999-10
Article
NonPeerReviewed
Lang, AD, Huang, CH, Gan, LB et al. (2 more authors) (1999) Photoelectro-chemical properties of anilino squaraine derivatives in LB films. Physical Chemistry, Chemical Physics: a journal of European Chemical Societies, 1. 2487 - 2490. ISSN 1463-9076
http://dx.doi.org/10.1039/A900268E
10.1039/A900268E
oai:eprints.whiterose.ac.uk:75881
2014-09-15T03:19:52Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75881/
Photoelectrochemical properties of a new C60 derivative: C60–glycine ester C60(C6H9NO4)
Luo, CP
Gan, LB
Zhou, DJ
Huang, CH
Photoelectrochemical investigations of C60–glycine ester derivative C60(C6H9NO4) monolayer-modified SnO2 electrodes have been carried out. The electrodes were fabricated by the Langmuir–Blodgett (LB) technique. The photocurrent was determined under an atmosphere of high-purity nitrogen since oxygen suppresses the photocurrent. Results show that electrons flow from the electrolyte through the LB film to the SnO2 electrode. Positive bias voltage and the presence of an electron donor are beneficial factors for generating higher photocurrent. The external quantum yield is ca. 2.5%.
Royal Society of Chemistry
1997-12
Article
NonPeerReviewed
Luo, CP, Gan, LB, Zhou, DJ et al. (1 more author) (1997) Photoelectrochemical properties of a new C60 derivative: C60–glycine ester C60(C6H9NO4). Journal of the Chemical Society - Faraday Transactions, 93 (12). 3115 - 3117. ISSN 0956-5000
http://dx.doi.org/10.1039/A702057K
10.1039/A702057K
oai:eprints.whiterose.ac.uk:75882
2014-09-15T03:19:54Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/75882/
The Synthesis, Langmuir Film Deposition and Optical Characterization of a 4-Acetalphenyl substitued C60-Pyrrolidine Derivative C60(C12H17NO2)
Zhou, DJ
Ashwell, GJ
Rajan, R
Gan, LB
Luo, C
Huang, CH
A new 4-acetalphenyl-substituted C-60-pyrrolidine derivative, C-60(C12H17NO2) (1), has been prepared and its Langmuir films, with and without 22-tricosenoic acid [CH2=CH-(CH2)(20)CO2H(TA)], at the air/water interface have been investigated. Pure 1 forms monolayers more easily than the parent molecule, C-60, and can be transferred onto solid substrates to form Langmuir-Blodgett (LB) films. The mixed Langmuir films of 1 and TA were transferred onto hydrophilically pretreated quartz, glass substrates and silicon wafers. Reflectometric measurement of a 63-layer 1:2 mixed film on a silicon wafer using an He-Ne laser (lambda = 632.8 nm) provided a film thickness and refractive index of 171 nm and 1.73, respectively. Weak second harmonic generation (SHG) from LB monolayers of pure 1 and 1:2 and 1:4 mixed LB monolayer films of 1 and TA was observed. The second-order susceptibilities, chi(pp)((2)), Were evaluated to be in the range (4-6) x 10(-9) esu.
Royal Society of Chemistry
1997-11
Article
NonPeerReviewed
Zhou, DJ, Ashwell, GJ, Rajan, R et al. (3 more authors) (1997) The Synthesis, Langmuir Film Deposition and Optical Characterization of a 4-Acetalphenyl substitued C60-Pyrrolidine Derivative C60(C12H17NO2). Journal of the Chemical Society, Faraday Transactions, 93 (11). 2077 - 2082. ISSN 0956-5000
http://dx.doi.org/10.1039/A608570I
10.1039/A608570I
oai:eprints.whiterose.ac.uk:76241
2013-08-15T13:00:48Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76241/
Robust, specific ratiometric biosensing using a copper-free clicked quantum dot-DNA aptamer sensor
Zhang, HY
Feng, GQ
Guo, Y
Zhou, DJ
We report herein the successful preparation of a compact, functional CdSe/ZnS core/shell quantum dot (QD)-DNA conjugate via the highly efficient copper-free “click chemistry” (CFCC) between a dihydro-lipoic acid-polyethylene glycol-azide (DHLA-PEG-N3) capped QD and a cyclooctyne modified DNA. This represents an excellent balance between the requirements of high sensing sensitivity, robustness and specificity for the QD-FRET (Förster resonance energy transfer) based sensor as confirmed by a detailed FRET analysis on the QD-DNA conjugate, yielding a relatively short donor-acceptor distance of ~5.8 nm. We show not only is this CFCC clicked QD-DNA conjugate able to retain the native fluorescence quantum yield (QY) of the parent DHLA-PEG-N3 capped QD, but also is well-suited for robust, specific biosensing: it can directly quantitate pM level of both labelled and unlabelled complementary DNA probes with good SNP (single-nucleotide polymorphism) discrimination ability in complex media, e.g. 10% human serum via target-binding induced FRET changes between the QD donor and dye accepter. Further, this sensor has also been successfully exploited for the detection of pM level of a specific protein target (thrombin) via the encoded anti-thrombin aptamer sequence in the QD-DNA conjugate.
Royal Society of Chemistry
2013-08-15
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76241/3/Click%2520QD%2520Manu-revised-3_with_coversheet.pdf
Zhang, HY, Feng, GQ, Guo, Y et al. (1 more author) (2013) Robust, specific ratiometric biosensing using a copper-free clicked quantum dot-DNA aptamer sensor. Nanoscale, 5. ISSN 2040-3364
http://dx.doi.org/10.1039/C3NR02897F
10.1039/C3NR02897F
oai:eprints.whiterose.ac.uk:76322
2016-03-11T06:09:51Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D:4C656564732E53522D494E4348
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153:4C656564732E53522D434F4E4D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76322/
Sensitive, Simultaneous Quantitation of Two Unlabeled DNA Targets Using a Magnetic Nanoparticle-Enzyme Sandwich Assay
Zhang, Y
Pilapong, C
Guo, Y
Ling, Z
Cespedes, O
Quirke, P
Zhou, D
We report herein the development of a simple, sensitive colorimetric magnetic nanoparticle (MNP)- enzyme based DNA sandwich assay that is suitable for simultaneous label-free quantitation of two DNA targets down to 50 fM level. It can also effectively discriminate single-nucleotide polymorphisms (SNPs) in genes associated with human cancers (KRAS codon 12/13 SNPs). This assay uses a pair of specific DNA probes, one being covalently conjugated to a MNP for target capture while the other being linked to an enzyme for signal amplification, to sandwich a DNA target, allowing for convenient magnetic separation and subsequently efficient enzymatic signal amplification for high sensitivity. Careful optimization of the MNP surfaces and assay conditions greatly reduced the background, allowing for sensitive, specific detection of as little as 5 attomole (50 fM in 100 L) of target-DNA. Moreover, this sensor is robust, it can effectively discriminate cancer specific SNPs against the wild-type non-cancer target, and works efficiently in 10% human serum. Furthermore, this sensor can simultaneously quantitate two different DNA targets by using two pairs of unique capture- and signal- DNA probes specific for each target. This general, simple and sensitive DNA sensor appears to be well-suited for a wide range of genetics based biosensing and diagnostic applications.
American Chemical Society
2013-08-26
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76322/3/DNA%20SENSOR-manu-revised.pdf
Zhang, Y, Pilapong, C, Guo, Y et al. (4 more authors) (2013) Sensitive, Simultaneous Quantitation of Two Unlabeled DNA Targets Using a Magnetic Nanoparticle-Enzyme Sandwich Assay. Analytical Chemistry, 85 (19). pp. 9238-9244. ISSN 0003-2700
http://dx.doi.org/10.1021/ac402081u
10.1021/ac402081u
oai:eprints.whiterose.ac.uk:76417
2019-06-06T08:45:40Z
oai:eprints.whiterose.ac.uk:76460
2014-09-15T03:03:31Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76460/
On the nucleation of dust in oxygen-rich stellar outflows
Plane, JMC
Understanding the nature of dust condensation in the outflow from oxygen-rich AGB stars is a continuing problem. A kinetic model has been developed to describe the formation of gas-phase precursors from Ca, Mg, Fe, SiO and TiO in an outflow cooling from 1500 to 1000 K. Electronic structure calculations are used to identify efficient reaction pathways which lead to the formation of metal titanates and silicates. The molecular properties of the stationary points on the relevant potential energy surfaces are then used in a multi-well master equation solver to calculate pertinent rate coefficients. The outflow model couples an explicit treatment of gas-phase chemistry to a volume-conserving particle growth model. CaTiO3 is shown to be the overwhelming contributor to the formation of condensation nuclei (CN), withless than 0.01% provided by CaSiO3, (TiO2)2 and FeTiO3. Magnesium species make a negligible contribution. Defining CN as particles with radii greater than 2 nm, the model shows that for stellar mass loss rates above 3 × 10-5M⊙yr-1 more than 10-13 CN per H nucleus will be produced when the outflow temperature is still well above 1000 K. This is sufficient to explain the observed number density of grains in circumstellar dust shells.
The Royal Society
2013-07-13
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76460/7/Stellar%20outflow%20%20-%20published_with_coversheet.pdf
Plane, JMC (2013) On the nucleation of dust in oxygen-rich stellar outflows. Philosophical Transactions A: Mathematical, Physical and Engineering Sciences, 371 (1994). 20120335. 1 - 18. ISSN 1364-503X
http://dx.doi.org/10.1098/rsta.2012.0335
10.1098/rsta.2012.0335
oai:eprints.whiterose.ac.uk:76461
2018-03-28T23:04:47Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76461/
Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine
Carpenter, LJ
Shaw, MD
Parthipan, R
Wilson, J
MacDonald, SM
Kumar, R
Saunders, RW
Plane, JMC
Naturally occurring bromine- and iodine-containing compounds substantially reduce regional, and possibly even global, tropospheric ozone levels. As such, these halogen gases reduce the global warming effects of ozone in the troposphere, and its capacity to initiate the chemical removal of hydrocarbons such as methane. The majority of halogen-related surface ozone destruction is attributable to iodine chemistry. So far, organic iodine compounds have been assumed to serve as the main source of oceanic iodine emissions. However, known organic sources of atmospheric iodine cannot account for gas-phase iodine oxide concentrations in the lower troposphere over the tropical oceans. Here, we quantify gaseous emissions of inorganic iodine following the reaction of iodide with ozone in a series of laboratory experiments. We show that the reaction of iodide with ozone leads to the formation of both molecular iodine and hypoiodous acid. Using a kinetic box model of the sea surface layer and a one-dimensional model of the marine boundary layer, we show that the reaction of ozone with iodide on the sea surface could account for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean. According to the sea surface model, hypoiodous acid - not previously considered as an oceanic source of iodine - is emitted at a rate ten-fold higher than that of molecular iodine under ambient conditions.
Nature Publishing Group
2013-02
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76461/7/Nge01687%20-%20pre-publication%20version_with_coversheet.pdf
Carpenter, LJ, Shaw, MD, Parthipan, R et al. (5 more authors) (2013) Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine. Nature Geoscience, 6 (2). 108 - 111. ISSN 1752-0894
http://dx.doi.org/10.1038/ngeo1687
10.1038/ngeo1687
oai:eprints.whiterose.ac.uk:76462
2018-03-29T06:36:05Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76462/
O2(a1Δg) + Mg, Fe, and Ca: experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping.
Plane, JM
Whalley, CL
Frances-Soriano, L
Goddard, A
Harvey, JN
Glowacki, DR
Viggiano, AA
The first excited electronic state of molecular oxygen, O(2)(a(1)Δ(g)), is formed in the upper atmosphere by the photolysis of O(3). Its lifetime is over 70 min above 75 km, so that during the day its concentration is about 30 times greater than that of O(3). In order to explore its potential reactivity with atmospheric constituents produced by meteoric ablation, the reactions of Mg, Fe, and Ca with O(2)(a) were studied in a fast flow tube, where the metal atoms were produced either by thermal evaporation (Ca and Mg) or by pulsed laser ablation of a metal target (Fe), and detected by laser induced fluorescence spectroscopy. O(2)(a) was produced by bubbling a flow of Cl(2) through chilled alkaline H(2)O(2), and its absolute concentration determined from its optical emission at 1270 nm (O(2)(a(1)Δ(g) - X(3)Σ(g) (-)). The following results were obtained at 296 K: k(Mg + O(2)(a) + N(2) → MgO(2) + N(2)) = (1.8 ± 0.2) × 10(-30) cm(6) molecule(-2) s(-1); k(Fe + O(2)(a) → FeO + O) = (1.1 ± 0.1) × 10(-13) cm(3) molecule(-1) s(-1); k(Ca + O(2)(a) + N(2) → CaO(2) + N(2)) = (2.9 ± 0.2) × 10(-28) cm(6) molecule(-2) s(-1); and k(Ca + O(2)(a) → CaO + O) = (2.7 ± 1.0) × 10(-12) cm(3) molecule(-1) s(-1). The total uncertainty in these rate coefficients, which mostly arises from the systematic uncertainty in the O(2)(a) concentration, is estimated to be ±40%. Mg + O(2)(a) occurs exclusively by association on the singlet surface, producing MgO(2)((1)A(1)), with a pressure dependent rate coefficient. Fe + O(2)(a), on the other hand, shows pressure independent kinetics. FeO + O is produced with a probability of only ∼0.1%. There is no evidence for an association complex, suggesting that this reaction proceeds mostly by near-resonant electronic energy transfer to Fe(a(5)F) + O(2)(X). The reaction of Ca + O(2)(a) occurs in an intermediate regime with two competing pressure dependent channels: (1) a recombination to produce CaO(2)((1)A(1)), and (2) a singlet∕triplet non-adiabatic hopping channel leading to CaO + O((3)P). In order to interpret the Ca + O(2)(a) results, we utilized density functional theory along with multireference and explicitly correlated CCSD(T)-F12 electronic structure calculations to examine the lowest lying singlet and triplet surfaces. In addition to mapping stationary points, we used a genetic algorithm to locate minimum energy crossing points between the two surfaces. Simulations of the Ca + O(2)(a) kinetics were then carried out using a combination of both standard and non-adiabatic Rice-Ramsperger-Kassel-Marcus (RRKM) theory implemented within a weak collision, multiwell master equation model. In terms of atmospheric significance, only in the case of Ca does reaction with O(2)(a) compete with O(3) during the daytime between 85 and 110 km.
American Institute of Physics
2012-07-07
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76462/7/Metals%2BO2%20final_with_coversheet.pdf
Plane, JM, Whalley, CL, Frances-Soriano, L et al. (4 more authors) (2012) O2(a1Δg) + Mg, Fe, and Ca: experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping. Journal of Chemical Physics, 137 (1). 014310.
http://dx.doi.org/10.1063/1.4730423
10.1063/1.4730423
oai:eprints.whiterose.ac.uk:76634
2016-11-03T18:45:47Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/76634/
Enhancing curcumin anticancer efficacy through poly(anhydride ester)-b-poly(ethylene glycol) block copolymer micelle encapsulation
Lv, L
Shen, YY
Li, M
Wang, F
Li, MN
Guo, JJ
Wang, Y
Zhou, DJ
Guo, SR
We report herein the development of a novel aqueous formulation and improved antitumor activity for curcumin by encapsulating it into a biocompatible and biodegradable poly (L-lactic acid) based poly(anhydride-ester)-b-poly(ethylene glycol) (PAE-b-PEG) block copolymer micelle. The resulting curcumin loaded micelles (Cur-micelles) were completely water-dispersible, overcoming the problem of poor water solubility that has limited its efficacy and bioavailability. In vitro cellular studies revealed that the Cur-micelles were taken up mainly via endocytosis route and exhibited higher cytotoxicities toward model cancer cell lines (Hela and EMT6) than free curcumin. An in vivo biodistribution study revealed that the Cur-micelles displayed significantly enhanced accumulation inside the tumor of EMT6 breast tumor-bearing mice. More impressively, the Cur-micelles exhibited better antitumor activity, higher anti-angiogenesis effects and induced apoptosis on the EMT6 breast tumor model bearing mice than free curcumin. Furthermore, the Cur-micelles showed no significant toxicity towards the hemotological system, major organs or tissues in mice. Combining high antitumor activity and low toxic side-effects, the Cur-micelles developed here appear to be a highly attractive nanomedicine for effective, targeted cancer therapy.
American Scientific Publishers
2014-02
Article
NonPeerReviewed
Lv, L, Shen, YY, Li, M et al. (6 more authors) (2014) Enhancing curcumin anticancer efficacy through poly(anhydride ester)-b-poly(ethylene glycol) block copolymer micelle encapsulation. Journal of Biomedical Nanotechnology, 10 (2). pp. 179-193. ISSN 1550-7033
http://dx.doi.org/10.1166/jbn.2014.1809
oai:eprints.whiterose.ac.uk:76684
2018-01-20T17:43:33Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76684/
CH2OO Criegee biradical yields following photolysis of CH2I2 in O2.
Stone, D
Blitz, M
Daubney, L
Ingham, T
Seakins, P
Yields of CH2OO and CH2IO2 from the reaction of CH2I radicals with O2 are reported as a function of total pressure, [N2] and [O2] at T = 295 K using three complementary methods. Results from the three methods are similar, with no observed additional dependence on [O2]. The CH2I + O2 reaction has a yield of ∼18% CH2OO at atmospheric pressure.
Royal Society of Chemistry
2013-10-10
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76684/1/c3cp52466c.pdf
Stone, D, Blitz, M, Daubney, L et al. (2 more authors) (2013) CH2OO Criegee biradical yields following photolysis of CH2I2 in O2. Physical Chemistry Chemical Physics. ISSN 1463-9076
http://dx.doi.org/10.1039/c3cp52466c
10.1039/c3cp52466c
oai:eprints.whiterose.ac.uk:76860
2018-01-16T08:07:30Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/76860/
Isostructural salts of the same complex showing contrasting thermal spin-crossover mediated by multiple phase changes.
Roberts, TD
Little, MA
Tuna, F
Kilner, CA
Halcrow, MA
Two salts of [FeL2](2+) (L = 2,6-bis[5-methyl-1H-pyrazol-3-yl]pyridine) are isostructural under ambient conditions but show different thermal spin-crossover behaviour, involving a variety of crystallographic phase changes.
Royal Society of Chemistry
2013-06-05
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/76860/7/Fe%20Me2-3-bpp%20Chem%20Comm%202013.pdf
Roberts, TD, Little, MA, Tuna, F et al. (2 more authors) (2013) Isostructural salts of the same complex showing contrasting thermal spin-crossover mediated by multiple phase changes. Chemical Communications, 49 (56). 6280 - 6282. ISSN 1359-7345
http://dx.doi.org/10.1039/c3cc43613f
10.1039/c3cc43613f
oai:eprints.whiterose.ac.uk:77046
2018-01-25T14:06:38Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/77046/
Protein-Protein Interaction Regulates the Direction of Catalysis and Electron Transfer in a Redox Enzyme Complex.
McMillan, DG
Marritt, SJ
Firer-Sherwood, MA
Shi, L
Richardson, DJ
Evans, SD
Elliott, SJ
Butt, JN
Jeuken, LJ
Protein-protein interactions are well-known to regulate enzyme activity in cell signaling and metabolism. Here, we show that protein-protein interactions regulate the activity of a respiratory-chain enzyme, CymA, by changing the direction or bias of catalysis. CymA, a member of the widespread NapC/NirT superfamily, is a menaquinol-7 (MQ-7) dehydrogenase that donates electrons to several distinct terminal reductases in the versatile respiratory network of Shewanella oneidensis . We report the incorporation of CymA within solid-supported membranes that mimic the inner membrane architecture of S. oneidensis . Quartz-crystal microbalance with dissipation (QCM-D) resolved the formation of a stable complex between CymA and one of its native redox partners, flavocytochrome c3 (Fcc3) fumarate reductase. Cyclic voltammetry revealed that CymA alone could only reduce MQ-7, while the CymA-Fcc3 complex catalyzed the reaction required to support anaerobic respiration, the oxidation of MQ-7. We propose that MQ-7 oxidation in CymA is limited by electron transfer to the hemes and that complex formation with Fcc3 facilitates the electron-transfer rate along the heme redox chain. These results reveal a yet unexplored mechanism by which bacteria can regulate multibranched respiratory networks through protein-protein interactions.
American Chemical Society
2013-07-08
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/77046/1/McMillan2013.pdf
McMillan, DG, Marritt, SJ, Firer-Sherwood, MA et al. (6 more authors) (2013) Protein-Protein Interaction Regulates the Direction of Catalysis and Electron Transfer in a Redox Enzyme Complex. Journal of the American Chemical Society, 135 (28). 10550 - 10556. ISSN 0002-7863
http://dx.doi.org/10.1021/ja405072z
10.1021/ja405072z
oai:eprints.whiterose.ac.uk:77052
2014-04-25T12:23:30Z
oai:eprints.whiterose.ac.uk:77053
2014-09-15T02:43:08Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
696E737469747574696F6E3D4C65656473
7072696D6F3D6E6F5F646F63756D656E74735F617661696C61626C65
https://eprints.whiterose.ac.uk/77053/
Impedance Spectroscopy of Bacterial Membranes: Coenzyme-Q Diffusion in a Finite Diffusion Layer
Jeuken, LJC
Weiss, SA
Henderson, PJF
Evans, SD
Bushby, RJ
The inner membrane of Escherichia coli, overexpressing an ubiquinol oxidase, cytochrome bo3 (cbo3), was "tethered" in a planar configuration to a gold electrode. Electron transfer to cbo 3 was achieved via native ubiquinol-8 or added ubiquinol-10, and impedance spectroscopy was used to characterize the diffusion properties of the ubiquinol/ubiquinone in the tethered membrane system. Spectra were obtained at varying direct current (DC) potentials covering the potential window in which the voltammetric catalytic wave of cbo3 is visible. These spectra were compared to those obtained after addition of a potent inhibitor of cbo 3, cyanide, and the difference in impedance was analyzed using a derived equivalent circuit, which is similar to that of open finite-length diffusion (OFLD) or the finite Warburg circuit, but with the boundary conditions modified to account for the fact that ubiquinol reoxidation is limited by enzyme activity. Analysis of the impedance spectra of the tethered membrane system gave kinetic parameters that are consistent with values obtained using cyclic voltammetry. Importantly, the diffusion rate of ubiquinone (10 -13-10-12 cm2/s) was found to be orders of magnitude lower than accepted values for lateral diffusion (10 -8-10-7 cm2/s). It is hypothesized that this result represent perpendicular diffusion of quinone across the membrane, corresponding to a "flip" time between 0.05 and 1 s.
American Chemical Society
2008-12-01
Article
NonPeerReviewed
Jeuken, LJC, Weiss, SA, Henderson, PJF et al. (2 more authors) (2008) Impedance Spectroscopy of Bacterial Membranes: Coenzyme-Q Diffusion in a Finite Diffusion Layer. Analytical Chemistry, 80 (23). 9084 - 9090. ISSN 0003-2700
http://dx.doi.org/10.1021/ac8015856
10.1021/ac8015856
oai:eprints.whiterose.ac.uk:77054
2014-09-15T02:43:11Z
7374617475733D707562
74797065733D61727469636C65
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D50484153
756E69743D4C65656473:4C656564732E46412D46455053:4C656564732E52432D4348454D
696E737469747574696F6E3D4C65656473
7072696D6F3D6861735F7075626C6963
https://eprints.whiterose.ac.uk/77054/
AFM study on the electric-field effects on supported bilayer lipid membranes
Jeuken, LJC
Electric-field induced changes in structure and conductivity of supported bilayer lipid membranes (SLM) have been studied at submicroscopic resolution using atomic force microscopy and electrochemical impedance spectroscopy. The SLMs are formed on gold surfaces modified with mixed self-assembled monolayers of a cholesterol-tether and 6-mercaptohexanol. At applied potentials of ≤-0.25 V versus standard hydrogen electrode, the conductance of the SLM increases and membrane areas of <150 nm in size are found to elevate from the surface up to 15 nm in height. To estimate the electric field experienced by the lipid membrane, electrowetting has been used to determine the point of zero charge of a 6-mercaptohexanol-modified surface (0.19 6 ± 0.13 V versus standard hydrogen electrode). The effects of electric fields on the structure and conductance of supported membranes are discussed.
Biophysical Society
2008-06-15
Article
NonPeerReviewed
text
en
https://eprints.whiterose.ac.uk/77054/7/Jeuken2008_with_coversheet.pdf
Jeuken, LJC (2008) AFM study on the electric-field effects on supported bilayer lipid membranes. Biophysical Journal, 94 (12). 4711 - 4717. ISSN 0006-3495
http://dx.doi.org/10.1529/biophysj.107.122887
10.1529/biophysj.107.122887
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