Recombinant spider silk-based bioinks.

Bioinks, 3D cell culture systems which can be printed, are still in the early development stages. Currently, extensive research is going into designing printers to be more accommodating to bioinks, designing scaffolds with stiff materials as support structures for the often soft bioinks, and modifying the bioinks themselves. Recombinant spider silk proteins, a potential biomaterial component for bioinks, have high biocompatibility, can be processed into several morphologies and can be modified with cell adhesion motifs to enhance their bioactivity. In this work, thermally gelled hydrogels made from recombinant spider silk protein encapsulating mouse fibroblast cell line BALB/3T3 were prepared and characterized. The bioinks were evaluated for performance in vitro both before and after printing, and it was observed that unprinted bioinks provided a good platform for cell spreading and proliferation, while proliferation in printed scaffolds was prohibited. To improve the properties of the printed hydrogels, gelatin was given as an additive and thereby served indirectly as a plasticizer, improving the resolution of printed strands. Taken together, recombinant spider silk proteins and hydrogels made thereof show good potential as a bioink, warranting further development.