Synthesis and on-demand gelation of multifunctional poly(ethylene glycol)-based polymers.

The synthesis of a novel photoreactive poly(ethylene glycol) (PEG)-based polymer with caged carbonyl groups is reported. We further demonstrate its use for the on-demand fabrication of hydrogels. For rapid gelation, a hydrazide-functionalized PEG is used as the second component for the hydrogel preparation. The photoreactive PEG-based polymer is designed for controlled cleavage of the protecting groups upon exposure to UV light releases free aldehyde moieties, which readily react with hydrazide groups in situ. This hydrogel system may find applications in controlled release drug delivery applications, when combined with in situ gelation. Furthermore, the possibility of forming gels specifically upon UV irradiation gives an opportunity for 3D fabrication of degradable scaffolds.