Design and Synthesis of Hybrid Thermo-Responsive Hydrogels Based on Poly(2-oxazoline) and Gelatin Derivatives

The combination of natural and synthetic polymers to form hybrid hydrogels offers the potential of fabricating new materials that possess a combination of properties resulting from both types of polymer classes. Within this work, two alkene-functionalized poly(2-alkyl/aryl-2-oxazoline) (PAOx) copolymers and one gelatin derivative, thiolated gelatin (gel-SH), are synthesized as precursors for hybrid hydrogels through a photo-induced radical thiol-ene crosslinking process. In-situ photo-rheology revealed an increased mechanical stability for hydrogels that possess an excess amount of PAOx precursor. A final qualitative investigation of the thermo-responsive properties of a P(EtOx(270)-norbornenOx(30)):gel-SH (2:1) hydrogel film revealed a cloud point temperature (T-cp) in the same range as the T-cp of the P(EtOx(270)-norbornenOx(30)) polymer precursor, which is around 30 degrees C. This promising result demonstrates that thermo-responsive hybrid poly(2-oxazoline)-gelatin hydrogels could be prepared with predictable T(cp)s and that further investigation into this appealing feature might be of interest. Ultimately, this work shows a proof-of-concept of using PAOx as potential hybrid hydrogel precursor in combination with cell-interactive gelatin derivatives to potentially improve the mechanical stability of the final scaffolds and introduce additional features such as thermo-responsiveness for the purpose of drug delivery.

Automated summary

The combination of natural and synthetic polymers to form hybrid hydrogels offers the potential of fabricating new materials with dual polymer properties. This study synthesized two alkene-functionalized poly(2-alkyl/aryl-2-oxazoline) (PAOx) copolymers and one gelatin derivative, thiolated gelatin (gel-SH), as precursors for hybrid hydrogels through a photo-induced radical thiol-ene crosslinking process. The results showed that hydrogels with an excess amount of PAOx precursor exhibited increased mechanical stability. The thermo-responsive properties of a specific hydrogel film were also investigated, showing promise for developing hybrid poly(2-oxazoline)-gelatin hydrogels with predictable properties.