Physical characteristics and curcumin entrapment efficiency of gelatin/Thai silk fibroin microspheres

In this study, Gelatin/Thai silk fibroin microspheres with the size of less than 100 μm were fabricated by water in oil emulsion technique using Span80, an oil-soluble emulsifier. The G/SF microspheres were crosslinked by dehydrothermal treatment (DHT). The effectiveness of crosslinking on G/SF microspheres was investigated by the free amino contents of microspheres before and after crosslinking using a modified 2,4,6-trinitrobenzene sulphonic acid (TNBS) method. It was found that the DHT-crosslinked G/SF microspheres showed low crosslinking degree (36–37%) in comparison to chemical crosslinking. For the in vitro enzymatic biodegradation test, the results showed that the DHT-crosslinked G/SF microspheres were rapidly degraded in protease XIV solution (pH 7.4) at 37°C. For the entrapment efficiency of curcumin, we found that the microspheres containing high content of silk fibroin could entrap more curcumin because of the hydrophobic interaction between curcumin and silk fibroin. In addition, we found the effect of mixed solvent of ethanol and DI water on entrapment efficiency of curcumin in the microspheres. Increasing DI water content in mixed solvent result in an increased entrapment efficiency of curcumin, possibly due to water swelling ability of gelatin content leading the diffusion of curcumin into the microspheres. It was suggested that the G/SF microspheres with the size of 32–74 μm might be suitably for applied as injectable carriers for controlled release of curcumin for anti-cancer treatment.