PhoCoil: A photodegradable and injectable single-component recombinant protein hydrogel for minimally invasive delivery and degradation.

Hydrogel biomaterials offer great promise for three-dimensional cell culture and therapeutic delivery. Despite many successes, challenges persist in that gels formed from natural proteins are only marginally tunable whereas those derived from synthetic polymers lack intrinsic bioinstructivity. Toward the creation of biomaterials with both excellent biocompatibility and customizability, recombinant protein-based hydrogels have emerged as molecularly defined and user-programmable platforms that mimic the proteinaceous nature of the extracellular matrix. Here, we introduce PhoCoil, a dynamically tunable recombinant hydrogel formed from a single protein component with unique multistimuli responsiveness. Physical cross-linking through coiled-coil interactions promotes rapid shear-thinning and self-healing behavior, rendering the gel injectable, whereas an included photodegradable motif affords on-demand network dissolution via visible light. PhoCoil gel photodegradation can be spatiotemporally and lithographically controlled in a dose-dependent manner, through complex tissue, and without harm to encapsulated cells. We anticipate that PhoCoil will further enable applications in tissue engineering and regenerative medicine.