The development of cell-adhesive hydrogel for 3D printing

Biofabrication has gained tremendous attention for manufacturing functional organs or tissues. To fabricate functional organs or tissues, it is necessary to reproduce tissue-specific micro to macro structures. Previously, we de-veloped a custom-made 3D-bioprinter with the capability to print and fabricate 3D complicated hydrogel structures composed of living cells. Through the gelation reaction, fine and complicated 3D gel structures can be fabricated via layer by layer printing. Alginate hydrogel has been used mainly due to its good fabricating properties. However, it is not a reliable platform for tissue regeneration because of its inadequate cell-adhesiveness. Therefore, our laboratory is in-terested to explore more suitable hydrogels for bioprinting and 3D tissue fabrication. In this study, we tried to fabricate 3D gel structures with enough cell-adhesive properties. We focused on hydrogel formation through enzymatic reaction by incorporating materials bearing phenolic hydroxyl moieties and horseradish peroxidase. We examined Alg-Ph and Alg-Ph/Gelatin-Ph gels. We used a mixed solution of applied materials as bioink and printed into H2O2 solution. We successfully fabricated the 3D gel sheet structures including fibroblasts cultures. Fibroblast proliferation and viability were also observed in the 3D gel sheet for more than one week. In conclusion, the hydrogel obtained through enzymatic reaction is a biocompatible bioink material which can be applied to fabricate 3D cell-adhesive gel structures using a 3D-bioprinter.