(745a) Directed Differentiation in 3D Gels Via Photoreversible Protein Patterning

Synthetic hydrogels have emerged as a unique class of biomaterials that enable stem cells to be cultured in three-dimensions within near-physiological, synthetic microenvironments.  Recent strategies have been developed that permit bioepitopes (e.g., peptides, full-length proteins) to be introduced at any point in time and space to affect cell function spatiotemporally within user-defined subvolumes of the bulk material.  While these techniques have been successfully utilized to direct a variety of basic cellular functions, advanced platforms that permit biological cues to be both introduced and subsequently removed would be beneficial in recapitulating the dynamic abundance of signaling biomolecules in the native, temporally-variable niche and in modulating complex cellular behavior.  In this work, we demonstrate that the combination of two bioorthogonal light-based chemistries provides for the reversible immobilization of protein cues spatially within a hydrogel.  The highlighted approach enables precise control over 4D biochemical functionalization of a synthetic polymer network in response to user-defined photonic stimuli.  Results further illustrate the versatility of such dynamic biomacromolecular signal presentation in directing 4D progenitor cell fate.