The regenerated silk fibroin hydrogel with designed architecture bioprinted by its microhydrogel

Bioprinting technology has received wide attention in recent years, while silk fibroin has also been attracted as a promising biomaterial with excellent comprehensive mechanical properties and biocompatibility. However, due to its non-melting point feature and the difficulty in curing of its aqueous solution, the silk fibroin based materials, such as scaffold, hydrogel etc., with designed shape and morphology have hardly been fabricated via bioprinting process. To solve this problem, a two-steps procedure was employed in this work. Firstly, the microhydrogel of regenerated silk fibroin (RSF) with a little amount of hydroxypropyl methylcellulose (HPMC) was prepared by heating the mixture of RSF and HPMC aqueous solutions. Secondly, the microhydrogel was directly printed to the pre-set architecture using a bioprinter, as it was not only self-standing but also displayed remarkable thixotropic property originated from “the second network”. After such bioprinted microhydrogel was ripened in ethanol to improve the β-sheet domain which physically crosslinked the network, the RSF hydrogel presented significant mechanical properties which could be adjusted by the initial concentration of RSF aqueous solution. Like other RSF materials produced by various ways, this 3D printed RSF hydrogel demonstrated good cytocompatibility for hMSCs. Therefore, it may have great potential to apply in the tissue replacement with complex structure.