Fig. 5

Biomimetic spinning based on LLPS in silk protein. A Condensate structures formed upon mixing labeled MaSp2 N-R12-C with 0.5 M potassium phosphate at different pH values. Liquid droplets that exhibited dynamic fusion behavior were observed at pH 7 and 8. At lower pH, the resulting structures presented a more gel-like appearance (pH 6) or rapidly underwent self-assembly into extended fibril networks (pH 5). Scale bars, 10 µm. B Overview of the microfluidic device used for spinning MaSp2 N-R12-C fibers under biomimetic conditions. The device design includes three inlets (1, 2, and 3), one outlet, and three monitoring sections (A, B, and C). The confluence of the protein solution (1) and citrate-phosphate buffer (pH 7.0) streams (2) induced the formation of LLPS droplets (region A), while subsequent exposure to citrate-phosphate buffer at pH 5.0 (section B) produced a continuous fiber along section C with a hierarchical organization of oriented nanofibrillar bundles. Scale bar, 30 µm. Panel (A) reprinted with permission from Reference [42]; copyright by The American Association for the Advancement of Science. Panel (B) reprinted from [17] under the Creative Commons CC BY license