Brotherton, E.E., Johnson, E.C. orcid.org/0000-0002-0092-1008, Smallridge, M.J. et al. (3 more authors) (2022) Hydrophilic aldehyde-functional polymer brushes: synthesis, characterization, and potential bioapplications. Macromolecules, 56 (5). pp. 2070-2080. ISSN 0024-9297
Abstract
Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) is used to polymerize a cis-diol-functional methacrylic monomer (herein denoted GEO5MA) from planar silicon wafers. Ellipsometry studies indicated dry brush thicknesses ranging from 40 to 120 nm. The hydrophilic PGEO5MA brush is then selectively oxidized using sodium periodate to produce an aldehyde-functional hydrophilic PAGEO5MA brush. This post-polymerization modification strategy provides access to significantly thicker brushes compared to those obtained by surface-initiated ARGET ATRP of the corresponding aldehyde-functional methacrylic monomer (AGEO5MA). The much slower brush growth achieved in the latter case is attributed to the relatively low aqueous solubility of the AGEO5MA monomer. X-ray photoelectron spectroscopy (XPS) analysis confirmed that precursor PGEO5MA brushes were essentially fully oxidized to the corresponding PAGEO5MA brushes within 30 min of exposure to a dilute aqueous solution of sodium periodate at 22 °C. PAGEO5MA brushes were then functionalized via Schiff base chemistry using an amino acid (histidine), followed by reductive amination with sodium cyanoborohydride. Subsequent XPS analysis indicated that the mean degree of histidine functionalization achieved under optimized conditions was approximately 81%. Moreover, an XPS depth profiling experiment confirmed that the histidine groups were uniformly distributed throughout the brush layer. Surface ζ potential measurements indicated a significant change in the electrophoretic behavior of the zwitterionic histidine-functionalized brush relative to that of the non-ionic PGEO5MA precursor brush. The former brush exhibited cationic character at low pH and anionic character at high pH, with an isoelectric point being observed at around pH 7. Finally, quartz crystal microbalance studies indicated minimal adsorption of a model globular protein (BSA) on a PGEO5MA brush-coated substrate, whereas strong protein adsorption via Schiff base chemistry occurred on a PAGEO5MA brush-coated substrate.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Functionalization; Monomers; Peptides and proteins; Thickness; X-ray photoelectron spectroscopy |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) |
Funding Information: | Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/R003009/1 Engineering and Physical Sciences Research Council EP/L016281/1 Engineering and Physical Sciences Research Council EP/T012455/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 21 Mar 2023 12:48 |
Last Modified: | 21 Mar 2023 12:48 |
Status: | Published |
Publisher: | American Chemical Society (ACS) |
Refereed: | Yes |
Identification Number: | 10.1021/acs.macromol.2c02471 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:197510 |