Dual thermal- and pH-responsive polypeptide-based hydrogels

Smart hydrogels have received increasing attention for their great potential for the applications in many fields. Herein, we report a facile approach to prepare a class of dual-responsive hydrogels assembled from synthetic statistical/block thermal-responsive copoly(L-glutamate)s copolymerized with poly(ethylene glycol), which were prepared by ring-opening polymerization(ROP) and post-modification strategy. The incorporation of oligo(ethylene glycol)(OEG) and glutamic acid residues offers the gels with thermal-and p H-responsive properties simultaneously. We have systematically studied the influence of both temperature and p H on the gelation behaviors of these copolymers. It is found that the increase of glutamic acid content and solution p H values can significantly suppress the gelation ability of the samples. Circular dichroism(CD) results show that the α-helix conformation appears to be the dominant secondary conformation. More interestingly, the gelation property of the block copolymer with statistical thermal-responsive copoly(L-glutamate)s shows greater dependence on p H as compared to that with block segments due to the distinct morphology of the self-assemblies. The obtained hydrogels exhibit p H-dependent and thermal-responsive gelation behaviors, which enable them as an ideal smart hydrogel system for biomedical applications.