Precise Construction of Cell-Instructive 3D Microenvironments by Photopatterning a Biodegradable Hydrogel

On the basis of the complexity of the extracellular matrix, it is very important to control the three-dimensional (3D) biochemical and physical properties of hydrogels at the microscale level. In this study, we demonstrated a synthetic strategy to construct biomimetic hydrogels (HA-MMP) for 3D cell culture that uses thiol-Michael chemistry to encapsulate cells in situ, o-nitrobenzyl alcohol photochemistry (a photogenerated-aldehyde-amine-ligation sequence, which is also referred to as a PAAL sequence) to permit biochemical patterning, and an enzyme-cleavable reaction to facilitate cell-responsive degradation in hydrogels. The effects of biochemical and mechanical parameters on 3D cell culture were studied using a user-programmed Boolean logic-based algorithm, which provided an “AND” logic gate for cell survival, spreading, and migration. Finally, using the spatial controllability of light, cell-instructive 3D microenvironments can be constructed to guide cell behavior in hydrogels. This approach enables the versatile nature of chemistry to create programmable niches in hydrogels, which provides valuable insights into the cell fate by changing the local hydrogel microenvironments.