Biomimetic spinning of silk fibers and in situ cell encapsulation

In situ embedding of sensitive materials (e.g., cells and proteins) in silk fibers without damage presents a significant challenge due to the lack of mild and efficient methods. Here, we report the development of a microfluidic chip-based method for preparation of meter-long silk fibroin (SF) hydrogel fibers by mimicking the silkworm-spinning process. For the spinning of SF fibers, alginate was used as a sericin-like material to induce SF phase separation and entrap liquid SFs, making it possible to shape the outline of SF-based fibers under mild physicochemical conditions. L929 fibroblasts were encapsulated in the fibric hydrogel and displayed excellent viability. Cell-laden SF fibric hydrogels prepared using our method offer a new type of SF-based biomedical device with potential utility in biomedicine.