Curated Optogenetic Publication Database

Abstract: Hydrogel biomaterials offer great promise for 3D cell culture and therapeutic delivery. Despite many successes, challenges persist in that gels formed from natural proteins are only marginally tunable while those derived from synthetic polymers lack intrinsic bioinstructivity. Towards 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 multi-stimuli responsiveness. Physical crosslinking through coiled-coil interactions promotes rapid shear-thinning and self-healing behavior, rendering the gel injectable, while 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 enable new applications in tissue engineering and regenerative medicine.

Abstract: Given the critical role that proteins play in almost all biological processes, there is great interest in controlling their presentation within and release from biomaterials. Despite such outstanding enthusiasm, previously developed strategies in this regard result in ill-defined and heterogeneous populations with substantially decreased activity, precluding their successful application to fragile species including growth factors. Here, we introduce a modular and scalable method for creating monodisperse, genetically encoded chimeras that enable bioactive proteins to be immobilized within and subsequently photoreleased from polymeric hydrogels. Building upon recent developments in chemoenzymatic reactions, bioorthogonal chemistry, and optogenetics, we tether fluorescent proteins, model enzymes, and growth factors site-specifically to gel biomaterials through a photocleavable protein (PhoCl) that undergoes irreversible backbone photoscission upon exposure to cytocompatible visible light (λ ≈ 400 nm) in a dose-dependent manner. Mask-based and laser-scanning lithographic strategies using commonly available light sources are employed to spatiotemporally pattern protein release from hydrogels while retaining their full activity. The photopatterned epidermal growth factor presentation is exploited to promote anisotropic cellular proliferation in 3D. We expect these methods to be broadly useful for applications in diagnostics, drug delivery, and regenerative medicine.

Abstract: Although mechanical signals presented by the extracellular matrix are known to regulate many essential cell functions, the specific effects of these interactions, particularly in response to dynamic and heterogeneous cues, remain largely unknown. Here, a modular semisynthetic approach is introduced to create protein–polymer hydrogel biomaterials that undergo reversible stiffening in response to user‐specified inputs. Employing a novel dual‐chemoenzymatic modification strategy, fusion protein‐based gel crosslinkers are created that exhibit stimuli‐dependent intramolecular association. Linkers based on calmodulin yield calcium‐sensitive materials, while those containing the photosensitive light, oxygen, and voltage sensing domain 2 (LOV2) protein give phototunable constructs whose moduli can be cycled on demand with spatiotemporal control about living cells. These unique materials are exploited to demonstrate the significant role that cyclic mechanical loading plays on fibroblast‐to‐myofibroblast transdifferentiation in 3D space. The moduli‐switchable materials should prove useful for studies in mechanobiology, providing new avenues to probe and direct matrix‐driven changes in 4D cell physiology.