Hydrogels Incorporating Donor-Acceptor Stenhouse Adducts as a Platform for Photoinduced, On-Off Switchable Release of Small Molecule Cargos.

Modulating biomaterial properties using light holds great promise for biomedical applications, such as drug delivery, as it is non-invasive and offers both spatial and temporal control. Visible light is particularly salient for stimulation of cell-interfacing materials, as it is cyto-compatible; however, this limits the number of photoswitches appropriate for these applications. In this work, we use donor-acceptor Stenhouse adduct (DASA) functionalized polymers comprising poly(ethylene glycol)-b-poly(hexyl methacrylate) to make visible light-responsive polymersomes, and use these to encapsulate a model drug cargo. We demonstrate that release of the model cargo can be triggered using visible light when the polymersomes are loaded into poly(ethylene glycol) hydrogels. Moreover, ON/OFF switchable cargo release was demonstrated by modulating the light stimulation of the hydrogel. We envisage this could be used to dynamically modulate hydrogel properties in clinically relevant applications for controlled delivery of small molecule therapeutic agents, such as advanced in vitro tissue models and implantable drug-eluting scaffolds.