Microfabrication of Photo-Cross-Linked Hyaluronan Hydrogels by Single- and Two-Photon Tyramine Oxidation

Photo-cross-linking of tyramine-substituted hyaluronan (HA-Tyr) hydrogels is demonstrated for the first time. HA-Tyr hydrogels are fabricated via a rapid photo-sensitized process using visible light illumination. Nontoxic conditions offer photoencapsulation of human mesenchymal stromal cells (hMSCs) with high viability. Macroscopic gels can be formed in less than 10 s, and one- and two-photon photopatteming enable 2D and 3D microfabrication. Different degrees of cross-linking induce different swelling/shrinking, allowing for light-induced microactuation. These new tools are complementary to the previously reported horseradish peroxidase/hydrogen peroxide cross-linking and allow sequential cross-linking of HA-Tyr matrices.