Biodegradable colloidal microgels with tunable thermosensitive volume phase transitions for controllable drug delivery.

In this study, we present gelatin-based thermoresponsive colloidal microgels that enable the controlled release of drugs by volume phase transition. The microgel was fabricated by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within three-dimensional gelatin networks crosslinked by genipin. We demonstrate that our gelatin-based thermoresponsive microgel exhibits a tunable deswelling to temperature increase, which positively correlated to the release of bovine serum albumin (BSA) as a function of poly(N-isopropylacrylamide-co-acrylamide) concentration. The microgel was enzymatically degradable by collagenase treatment. The extent of BSA release and biodegradability were tuned by controlling the crosslinking degree of the gelatin matrix. Meeting a great need for design and synthesis of auto-degenerating smart microgels that enable the controlled release of therapeutic proteins in responsive to external stimuli, our gelatin-based microgels that satisfy both thermoresponsivity and biodegradability have a great potential in tissue engineering applications as a soft microdevice element for drug delivery.