The influence of structure and morphology on ion permeation in commercial silicone hydrogel contact lenses
| Autor: | Brian J. Tighe, Sian Layton, Paul D. Topham, Aisling Mann, Frank Molock, Fiona Lydon, Virginia Saez-Martinez, Daniel T. W. Toolan, Jonathan R. Howse |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Silicones Biomedical Engineering Biocompatible Materials 010402 general chemistry 01 natural sciences Permeability Biomaterials 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Differential scanning calorimetry Silicone Materials Testing Humans Environmental scanning electron microscope Nanoscopic scale chemistry.chemical_classification Small-angle X-ray scattering Water Hydrogels Equipment Design Polymer Contact Lenses Hydrophilic 0104 chemical sciences Oxygen Contact lens chemistry Chemical engineering Self-healing hydrogels 030221 ophthalmology & optometry Hydrophobic and Hydrophilic Interactions |
| Zdroj: | Journal of Biomedical Materials Research Part B: Applied Biomaterials. 109:137-148 |
| ISSN: | 1552-4981 1552-4973 |
| DOI: | 10.1002/jbm.b.34689 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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