Abstract: Objective: To prepare the multilayer alginate chitosan microspheres loading vascular endothelial growth factor (VEGF) and vancomycin (VAN), and to study in vitro release characteristics.Methods: The microspheres were prepared by emulsion cross-linking and self-assembly techniques. The effects of sodium alginate concentration, calcium chloride concentration, oil/water ratio and span80 concentration on the entrapment efficiency(EE) and drug loading(DL) of VEGFand VAN were investigated by orthogonal experimental design to optimize the preparation process. The surface morphology and particle size of microspheres were observed by scanning electron microscope (SEM). Self-assembly was detected by Fourier transform infrared spectroscope (FTIR). The EE, DL and in vitro release of VEGF and VAN were detected by ELISA double antibody sandwich method and ultraviolet spectrophotometry,and the cumulative release curve was drawn.Results: The prepared microspheres were yellowish brown powder. The SEM results showed that the microspheres were spherical, the surface was smoothy, and the dispersity was better. The average particle size was about 50 μm. Sodium alginate concentration of 1.0g·mL^-1, CaCl₂ concentration of 8g·mL^-1, oil to water ratio of 3:1, and span80 concentration of 2% were the best formula. The EE of VEGF and VAN were 49.63% and 16.67%, respectively. In vitro, the cumulative release last 16.5 d and 12.5 d respectively and the amount reached up to 95%.Conclusion: The multilayer alginate chitosan microspheres loading VEGF and VAN present several advantages, such as smaller particle size, higher EE and better controlled release.

Key words: vascular endothelial growth factor, controlled release, chitosan, vancomycin, alginate, microsphere