Microfluidics-based wet spinning of protein microfibers as solid scaffolds for 3D cell cultivation

Here we propose a facile and versatile process to fabricate cell-sized protein microfibers using microfluidic spinning system and sacrificial layers of alginate. A precursor solution containing protein molecules and sodium alginate (Na-Alg), a buffer solution, and a gelation solution were introduced into the microfluidic devices, forming composite microfibers comprising Ca-Alg and the protein. After chemically cross-linking the protein molecules and removing the alginate polymer, microfibers made of proteins were obtained. We demonstrated two processes, uniform fiber production using a simple microchannel and parallel production of narrow fibers using multilayered microfluidic devices. As an application, we cultured mammalian cells within hydrogel matrices incorporating gelatin microfibers, and evaluated the effects of the fibers on cell proliferation and network formation. The presented microfluidic process would be useful for fabricating cell-sized microfibers made of proteins which are applicable to 3D cell cultivation and tissue engineering.