Effect of shear viscosity on the preparation of sphere-like silk fibroin microparticles by electrospraying

Silk fibroin (SF) is known to be a biocompatible material, and different forms of SF are used for various applications. However, the application of SF in particle form is rarely reported, compared to other forms. In this study, SF microparticles with a diameter of approximately 250μm were prepared by the electrospray method, using 1M LiCl/DMSO as a solvent. The dissolution time of SF in the CaCl₂/CH₃CH₂OH/H₂O solution and the concentration of the SF dope solution affected the final morphology of the microparticles. A long dissolution time and a low SF concentration led to the formation of irregular microparticles, but a short dissolution time and a high concentration produced sphere-like microparticles. The shear viscosity of the SF dope solution was the main parameter that affected the morphology of the SF microparticles. Regardless of the dissolution time in the CaCl₂/CH₃CH₂OH/H₂O solution and the concentration of the SF dope solution, the shear viscosity of the dope solution must be higher than 0.33Pas to produce sphere-like microparticles. Finally, cell adhesion experiments demonstrated that these SF microparticles show potential for use as cell carriers.