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Tatyana F Svitova, K. Michael F Sommerschuh, Meng C Lin; Protein uptake by model soft contact lens materials in vitro: effects of surface charges and modifications. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3068.
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© ARVO (1962-2015); The Authors (2016-present)
To study the influences of surface charges of pHEMA-based model soft contact lens (SCL) polymers and surface modifications on model tear-protein uptake in vitro.
Quartz crystal microbalance with dissipation (QCM-D) method was used to quantify the adsorption of model tear proteins onto model pure pHEMA and pHEMA + 5% PMAA surfaces in vitro. Gold QCM-D sensors were spin-coated with 25-35 nm-thick films of model polymer and saturated in a buffered model-tear-electrolyte (MTE, pH 7.3) solution overnight in a flow rate of 30 µl/min. Egg white lysozyme (Lys, 1 mg/ml in MTE), milk β-lactoglobulin (Lg, proteins from lipocalin family, 1 mg/ml in MTE), and Bovine mucin (Bm, 0.03 mg/ml in MTE) were used as model tear proteins either as individuals or as mixed (Lys:Lg:Bm = 2:1:0.0.3,1 mg/ml total) solutions. Adsorption on model surfaces was studied at 35.5°C for 16-20 hours and then proteins were washed out with MTE. Aqueous solutions of Polyacrylic acid (PAA), quaternized hydroxyethylcellulose ethoxylate (QHECE), sodium carboxymethyl cellulose (CMC), and sodium alginate (SA) were used for surface modifications of spin-coated SCL materials. Sauerbrey model was employed to calculate the masses.
The amounts of proteins adsorbed on pHEMA were 1.02±0.18, 2.2±0.7, and 3.3±0.93 µg/cm2 for Lys, Lg, and Bm, respectively, and 0.5±0.12 µg/cm2 for mixed proteins. The amounts of proteins adsorbed on pHEMA+5% PMAA were 4.4±0.55, 1.4±0.33, and 2.6±0.85 µg/cm2 for Lys, Lg, and Bm, respectively, and 1.9±0.19 µg/cm2 for mixed proteins. An increase of Bm in a mixture from 3% to 10% reduced total proteins adsorption by 20±2%. PAA and CMC polymers were reversibly adsorbed onto pHEMA and pHEMA+5%PMAA surfaces and were washed out with MTE whereas QHECE and SA were bound irreversibly. Adsorptions of individual and mixed proteins increased 2.3±0.2 times on QHECE-modified pHEMA compared with 1.3±0.1 times on QHECE-modified pHEMA+5%PMAA (p= 0.07). Modification of both model polymers with SA reduced total proteins adsorption by 25-30% (p=0.082).
Introduction of either negative or positive charge into/onto model SCL polymers increased adsorption of individual proteins and their mixtures. However, model SCL surface modification with SA slightly reduced protein binding to pHEMA-based model materials.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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