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Rachel Williams, Andrew Gallagher, Ahmed Elsheikh, Don Wellings; Design of peptide gels for bandage contact lenses. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6081.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal bandage lenses have an important role to play in the treatment of corneal infection and disease. This laboratory study aimed to develop novel peptide gels with appropriate mechanical properties, transparency and water content for this application.
Peptide gels were synthesised from poly-ε-lysine (Pεk) and cross-linked with dicarboxylic acids (hexanedioic acid (C6), heptanedioic acid (C7), octanedioic acid (C8), nonanedioic acid (C9) and decanedioic acid (C10)). The density of the Pεk was between 0.07-0.1 g/ml and the crosslink density was 60% or 80%. Ultimate tensile strength and elasticity was measured using a Linkam Tensile Stress Tester. Water content was measured gravimetrically. Transparency was measured using spectrophotometry at 544nm. Cytotoxicity was measured using the HCE-T corneal epithelial cell line and the CCK-8 assay. A scratch assay was used to evaluate the re-epithelialisation under the peptide gels. Data were analysed statistically with a one-way ANOVA with Tukey’s post-test analysis.
The ultimate tensile strength increased with the Pεk density, crosslink density and an increase in crosslinker molecular chain length up until the hexanedioic acid (C9) and then reduced for decanedioic acid (C10). The optimal gel composition to give the highest mechanical properties without detrimentally affecting the transparency had a Pεk density of 0.071 g/ml, suberic acid as the crosslinker and a crosslink density of 60%. This produced a gel (Su6014) with an elasticity of 0.50 ± 0.11 MPa (n=9), a transparency of 90% ± 4.5% (n=9) and a water content of 69% ± 5.5% (n=9). This gel showed no cytotoxicity in the CCK-8 assay with no statistically significant differences in cell growth in normal culture medium and medium after incubation with the gel for 3 days. Rate of wound closure of the scratch assay was the same with or without the presence of the gel.
The mechanical properties, transparency and water content of a gel based on Pεk are comparable to commercially available soft contact lenses and are non-cytotoxic and are thus appropriate for further development as bandage contact lenses.
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