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Silk fibroin (SF) microspheres were prepared by the simple water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous SF solution and dichloromethane were used as water and oil phases, respectively. Influence of water : oil phase ratios on SF microsphere characteristics was investigated. From FTIR spectra, the resulting SF microspheres showed predominantly random coil SF conformation. SF microspheres observed from SEM images were spherical with deflated surfaces in some cases. Particle sizes of the SF microspheres were in the range 45-92 µm. Finally, bovine serum albumin (BSA) was used as a model protein for entrapment within the SF microspheres. The BSA-loaded SF microspheres were larger than unloaded SF microspheres. In vitro release tests indicate that BSA release from the SF microspheres was influenced by BSA content.

Silk fibroin (SF) microspheres containing a model drug were prepared by a simple water-in-oil emulsification-diffusion method. Aqueous SF solution and ethyl acetate were used as water and oil phases, respectively. Methylene Blue was used as a water-soluble model drug. Effect of drug content on microsphere characteristics, drug loading efficiency and drug release behavior was determined. Scanning electron microscopy revealed that drug-loaded SF microspheres were spherical in shape with a smooth surface. The SF microspheres showed predominant random coil SF conformation. All drug loading efficiencies were approximately 50%. An increase in drug/SF ratio could lead to an increase in %drug release and surface erosion after the drug release test. Drug release from SF microspheres is due to SF matrix swelling and surface erosion processes.

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