(718i) 4D Patterning of Gel Biomaterials with Bioactive Site-Specifically Modified Proteins

Polymer-based hydrogels have emerged as a unique class of biomaterials that enable stem cells to be cultured in three-dimensions within near-physiological, synthetic microenvironments. Recently developed strategies permit user-defined spatiotemporal introduction of bioepitopes to control cell function within subvolumes of the bulk material. Though such initial attempts have proven successful in the tethering of small molecules and short synthetic peptides within 3D culture platforms, there is a growing interest to direct cell fate through the patterned immobilization of biomacromolecules including full-length proteins. The high degree of protein-substrate specificity, as well as their ability to modulate complex cellular behavior (e.g., stem cell differentiation, protein secretion, and cell-cell interactions) generally exceeds that from simple chemical moieties. In this work, we demonstrate that site-specifically-modified proteins can be photoreversibly immobilized within a 3D material using a combination of bioorthogonal light-based chemistries. As the exact residue of protein conjugation to the material is explicitly defined a priori, proteins maintain wild-type levels of bioactivity and substrate specificity throughout modification and usage. Results further highlight the versatility of such dynamic biochemical signal presentation to probe and direct changes in cell fate.