Phosphate based 2-hydroxyethyl methacrylate hydrogels for biomedical applications

Poly(2-hydroxyethyl methacrylate) pHEMA is a widely used hydrogel for several biomedical applications, however, cell adhesion and proliferation are limited in these polymers. In this study the strategy of phosphate containing monomer based copolymerisation has been used to molecularly engineer poly(2-hydroxyethyl methacrylate) hydrogels. Ethylene glycol methacrylate phosphate EGMP, a proton conducting electrolyte, was copolymerised with HEMA and incorporated at varying monomer feed ratios to enhance the swelling dynamics and improve the ability of pHEMA based hydrogel sponges to facilitate cell adhesion and mineralization and hence expand their biomedical application. The hydration of the copolymer gels showed that there was a direct correlation to the amount of EGMP incorporated within the polymeric network and the degree of hydration increased with increasing concentration of EGMP. EGMP in its polymeric form is a polyelectrolyte due to the readiness of the pendant phosphate group to ionise in low or high pH solution. Evaluation of the thermal behaviour showed that T-g increased with increasing EGMP and although presence of water influenced transitions within these novel EGMP polymer networks, it did not have a deteriorating effect on the stiffness within the target temperature range even when fully hydrated. Furthermore, the damping or energy dissipation of the system increases in the ambient body temperature range, which is of particular interest for in vivo use.