Koeppel, A., Laity, P.R. and Holland, C. orcid.org/0000-0003-0913-2221 (2020) The influence of metal ions on native silk rheology. Acta Biomaterialia, 117. pp. 204-212. ISSN 1742-7061
Abstract
Whilst flow is the basis for silk fibre formation, subtle changes in a silk feedstocks’ chemical environment may serve to increase both energetic efficiency and control hierarchical structure development during spinning. Despite the role of pH being largely understood, the influence of metal ions is not, only being inferred by correlative work and observations. Through a combination of rheology and microscopy, we provide a causative study of how the most abundant metal ions in the silk feedstock, Ca2+ and K+, affect its flow properties and structure. Our results show that Ca2+ ions increase viscosity and prevent molecular alignment and aggregation, providing ideal storage conditions for unspun silk. In contrast, the addition of K+ ions promotes molecular alignment and aggregation and therefore seems to transfer the silk feedstock into a spinning state which confirms recent ‘sticky reptation’ modelling hypotheses. Additionally, we characterised the influence of the ubiquitous kosmotropic agent Li+, used to prepare regenerated silk solutions, and find that it promotes molecular alignment and prevents aggregation which may permit a range of interesting artificial silk processing techniques to be developed. In summary, our results provide a clearer picture of how metal ions co-ordinate, control and thus contribute towards silk protein self-assembly which in turn can inspire structuring approaches in other biopolymer systems.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) |
Keywords: | Silk rheology; Metal ions; Silk spinning; Silk aggregation; Flow alignment |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Funding Information: | Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/K005693/1 EUROPEAN COMMISSION - HORIZON 2020 713475 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Oct 2020 15:14 |
Last Modified: | 21 Jan 2022 18:17 |
Status: | Published |
Publisher: | Elsevier BV |
Refereed: | Yes |
Identification Number: | 10.1016/j.actbio.2020.09.045 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:167046 |