Poly (lactic-co-glycolic acid) (PLGA) microspheres loaded bovine serum albumin were prepared by WOW double emulsion method. The influence of homogenization speed during primary emulsion（5 000

10 000

15 000 r/min） on the physicochemical properties was investigated. Encapsulation efficiency

drug loading and particle size were used to evaluate the physicochemical properties of the microspheres. The surface and internal morphology of the microspheres was investigated by scanning electron microscopy (SEM). The structure parameters were analyzed by image analysis software. Confocal laser scanning microscopy was utilized to observe protein distribution within the skeletons of the microspheres. Finally

the connectivity of the microspheres was examined by the uptake experiments. Moreover

the release behaviors and the surface and internal structural evolution were also systematically studied. When the homogenization speed increased

the number of surface and internal pores increased

pore size of internal pores decreased. Besides

higher homogenization speed may result in slower drug release and degradation of the microspheres. But it caused no significant difference in the particle size and cross-sectioned porosity. In 10 000 r/min group

the microspheres showed highest encapsulation efficiency and lowest burst release rate in the first day and lowest surface pore connectivity. While in 5 000 r/min and 15 000 r/min group

microspheres released faster

with a higher burst release. The microspheres prepared at different homogenization speed showed different surface and internal morphology

which play a significant role in 〖WTBX〗in vitro〖WTBZ〗 release behaviors.