Surface Modification of pHEMA with Phenylboronic Acid for Corneal Regeneration

Abstract

Corneal diseases and insults can result in opacification of the cornea and ultimately lead to blindness. Treatment options for patients are limited due to limited donor availability and the fact that many patients are not eligible for certain treatments due to the nature of their condition. When conventional treatment options are not beneficial for a patient, artificial corneal replacement is necessary. Current artificial replacements induce epithelial downgrowth, where the remaining host corneal cells grow underneath the replacement ultimately leading to implant extrusion. Therefore, surface modification of these synthetic materials is necessary in order to allow proper epithelialization on the surface. This work focuses on the creation of a novel corneal scaffold consisting of poly(2-hydroxyethyl methacrylate) (pHEMA) which is surface modified by 3-(acrylamido)phenylboronic acid (APBA), a molecule known to have cell-binding properties through its ability to bind sugars found throughout the cell membrane. Surfaces were modified using two different polymerization techniques: conventional free radical polymerization (CFRP) and a controlled polymerization technique known as atom transfer radical polymerization (ATRP). It was hypothesized that ATRP would yield more uniform APBA brushes than the conventional method, and therefore create a more efficient cell-binding surface than the conventional method. Following each modification, the surface chemical composition of the materials was confirmed by ATR-FTIR, XPS and surface wettability measurements. Once prepared, NIH 3T3 mouse embryo fibroblasts were seeded onto the surfaces and cell viability was assessed through an MTT assay. The results revealed no cell viability on the APBA-modified surfaces, with surface hydrophobicity, grafting density and surface toxicity (for surfaces modified through ATRP) contributing to the lack of cell attachment.