Poly(2-oxazoline) hydrogels by photoinduced thiol-ene click reaction using different dithiol crosslinkers

Fabrication of a library of biocompatible hydrogels by photoinduced thiol-ene click reaction is described. The hydrogels are based on two different statistical copolymers consisting of 2-butenyl-2-oxazoline (EnOx) with either 2-methyl-2-oxazoline (MeOx) or 2-ethyl-2-oxazoline (EtOx). Crosslinking is achieved via pendant vinyl groups of EnOx in the copolymers with selected dithiol crosslinkers, namely dithiothreitol, 1,3-propanedithiol, 1,6-hexanedithiol, and 1,9-nonanedithiol by thiol-ene photocoupling. On the basis of different polarity and flexibility of particular dithiols and three different molar ratios to double bonds, it is possible to control swelling and mechanical characteristics of resulting hydrogels. Biocompatibility of all hydrogel types is verified by determination of toxicity of hydrogel extracts and contact direct toxicity towards mice 3T3 fibroblast cell line. The resulting low toxicity of all prepared hydrogels predetermines its utilization in biomedicine.