One-step preparation and characterization of silk nano- and microspheres

The present study described a new method with one step to fabricate silk fibroin nano- and microspheres, with the size of spheres and crystalline structure being controllable during processing. Polyethylene glycol, a type of synthetic polymer that is widely used in the pharmaceutical industry as a formulation excipient, was utilized to induce silk fibroin to self-assemble into nano- and microspheres. The addition of a certain amount of salt in the blending solution with subsequent titration into ethanol could improve the size dispersion, yield, and crystalline β-sheet structure (silk II) compared to those prepared without salt addition during preparation. Silk microspheres prepared in the presence of salts were less porous and more homogeneous in size than those prepared in the absence of salts.