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Lysozyme sorption in hydrogel contact lenses
Q Garrett1, R W Garrett, B K Milthorpe
1Cooperative Research Centre for Eye Research and Technology, The University of New South Wales, Sydney, Australia.
Investigative Ophthalmology & Visual Science
|April 2, 1999
Summary
Protein deposits on hydrogel contact lenses form through surface adsorption or matrix penetration. Lens material properties like charge density and water content dictate these reversible or irreversible binding processes for lysozyme.
Area of Science:
- Biomaterials Science
- Ophthalmic Materials
- Surface Chemistry
Background:
- Protein deposition on contact lenses is a significant factor affecting lens performance and wearer comfort.
- Understanding the mechanisms of protein-lens interaction is crucial for developing improved contact lens materials and care strategies.
Purpose of the Study:
- To investigate the mechanisms of lysozyme (a common tear protein) binding to hydrogel contact lenses.
- To elucidate the roles of surface adsorption and matrix penetration in protein deposit formation.
Main Methods:
- In vitro study using three hydrogel contact lens materials: etafilcon A, vifilcon A, and tefilcon.
- Utilized radiolabel-tracer technique, X-ray photoelectron spectroscopy (XPS), and laser scanning confocal microscopy (LSCM).
Main Results:
- Lysozyme binding to ionic, high-water-content lenses (etafilcon A, vifilcon A) was primarily through matrix penetration, influenced by lens charge density.
- Lysozyme binding to tefilcon lenses occurred via surface adsorption, with higher binding than human serum albumin (HSA) possibly due to lysozyme self-association.
- Both adsorption and penetration processes were time-dependent and could be reversible or irreversible.
Conclusions:
- Protein binding to hydrogel contact lenses involves either surface adsorption or matrix penetration.
- The specific binding mechanism (adsorption vs. penetration) and its kinetics are determined by the physicochemical properties of the lens material, including charge density and water content.
- These findings provide insights into the fundamental interactions governing protein fouling on contact lenses.