A Silk Fibroin Methacryloyl-Modified Hydrogel Promoting Cell Adhesion for Customized 3D Cell-Laden Structures

Cell adhesion is the physical basis of tissue formation. Developing a kind of bioink with tunable mechanical properties and the promotion of cell adhesion is a major challenge for tissue engineering. In the present paper, a kind of hydrogel with good printable performance was developed, and cell adhesion was promoted in cell-laden DLP (Digital Light Processing) 3D bioprinting as a flexible solution for customized 3D structures. The hydrogel was prepared by modifying gelatin methacryloyl (GelMA)/hyaluronic acid methacryloyl (HAMA) with silk fibroin methacryloyl (SilMA). The three kinds of materials contain significant components of the extracellular matrix (ECM), such as glycosaminoglycan and proteins. Rheological results indicate that the multicomponent hydrogel precursors exhibit good photocuring behavior and are very suitable for DLP 3D bioprinting. The mechanical and biological properties of hydrogel can be tuned flexibly by SilMA content. Besides this, the SilMA/GelMA/HAMA hydrogel shows higher adhesion strength than the GelMA/HAMA hydrogel. The addition of SilMA into GelMA/HAMA significantly increased cell actin expression and promoted cell adhesion. Furthermore, the cell-laden 3D printed SilMA/GelMA/HAMA porous scaffold structure can remain stable after 7 days of in vitro culture. The survival rate of L929 fibroblasts can be up to 87%, exhibiting a good cell morphology and proliferation. All these results indicate that the SilMA/GelMA/HAMA hydrogel promoting cell adhesion will have broad implications for customized 3D structures in tissue engineering.