Saez‐Martinez, V., Mann, A., Lydon, F. et al. (6 more authors) (2020) The influence of structure and morphology on ion permeation in commercial silicone hydrogel contact lenses. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 109 (1). pp. 137-148. ISSN 1552-4973
Abstract
The importance of the microstzructure of silicone hydrogels is widely appreciated but is poorly understood and minimally investigated. To ensure comfort and eye health, these materials must simultaneously exhibit both high oxygen and high water permeability. In contrast with most conventional hydrogels, the water content and water structuring within silicone hydrogels cannot be solely used to predict permeability. The materials achieve these opposing requirements based on a composite of nanoscale domains of oxygen‐permeable (silicone) and water‐permeable hydrophilic components. This study correlated characteristic ion permeation coefficients of a selection of commercially available silicone hydrogel contact lenses with their morphological structure and chemical composition. Differential scanning calorimetry measured the water structuring properties through subdivision of the freezing water component into polymer‐associated water (loosely bound to the polymer matrix) and ice‐like water (unimpeded with a melting point close to that of pure water). Small‐angle x‐ray scattering, and environmental scanning electron microscopy techniques were used to investigate the structural morphology of the materials over a range of length scales. Significant, and previously unrecognized, differences in morphology between individual materials at nanometer length scales were determined; this will aid the design and performance of the next generation of ocular biomaterials, capable of maintaining ocular homeostasis.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | contact lens; ESEM; ion permeation; SAXS; silicone hydrogels |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Chemical and Biological Engineering (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 07 Aug 2020 07:03 |
Last Modified: | 21 Jan 2022 14:33 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1002/jbm.b.34689 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:164084 |