Adhesion of corneal epithelial cells to cell adhesion peptide modified pHEMA surfaces

Epithelialization of a corneal implant is a desirable property. In this stu dy we compared surface modification of poly (2-hydroxyethyl methacrylate) ( pHEMA) with the cell adhesion peptides RGDS and YIGSR. Various parameters i n the tresyl chloride activation and modification reactions were considered in order to maximize surface coverage with the peptide including tresyl ch loride reaction solvent, tresyl chloride reaction time, tresyl chloride con centration, peptide concentration, and peptide reaction pH. Surface chemist ry and corneal epithelial cell adhesion to the modified surfaces were exami ned. X-ray photoelectron spectroscopy data suggested that while peptide mod ification had occurred, surface coverage with the peptide was incomplete. A cetone was found to result in a higher fraction of nitrogen and surface bou nd carboxyl groups compared to dioxane and ether. Furthermore, corneal epit helial cell adhesion to the surfaces for which acetone was used for the act ivation reaction was significantly greater. Statistical analysis of the var ious samples suggests that lower peptide concentrations and higher tresyl c hloride reaction times result in better cell adhesion. Furthermore, modific ation with YIGSR resulted in higher surface concentrations and better cell adhesion than modification with RGDS. Little or no cell adhesion was noted on the unmodified pHEMA controls. Protein adsorption results suggest that t he differences in cell adhesion cannot be attributed to differences in seru m protein adsorption from the culture medium. We conclude that YIGSR modifi ed surfaces have significant potential for further development in corneal a pplications.