Preparation of silk fibroin-based microspheres under high-gravity field

Abstract

The possibility of preparing regenerated silk fibroin (RSF)-based microspheres by a high-gravity anti-solvent precipitation method was explored. The high-gravity environment was generated by a rotating packed bed (RPB) reactor. Aqueous RSF solutions and ethanol were used as solvent and anti-solvent, respectively. The effects of liquid flow rates and anti-solvent/solvent ratios, as well as centrifugation and freezing time, on the formation, size distribution and morphology of RSF microspheres were investigated. The results showed that RSF microspheres, with diameters of 0.1–1.6 μm, can be prepared under high-gravity field via self-assembly of RSF molecular chains induced by ethanol and quenched by freezing and lyophilization. The mechanism of RSF microsphere formation was also discussed. In addition, rhodamine B was used as a model drug for evaluation of drug delivery capability of the RSF microspheres. The merits of this study lie in a simple low-cost apparatus with ease for scale-up and thereby potential high volume continuous production capacity, which is of practical advantages and industrial significance in preparation of protein microspheres for commercial mass production.