Synthesis and Characterization of Star-Shaped Poly(Lactide-Co-Glycolide) Using Poss as An Initiator, and Its Drug-Loaded Microspheres

In this paper, a series of star-shaped poly(lactide-co-glycolide)s (sPLGA) with different block ratios were prepared by the ring-opening copolymerization of D,L-lactide (LA) and glycolide (GA) with multi-hydroxyl polyhedral oligomeric silsesquioxane core as an initiator and tin (II) 2-ethylhexanoate (Sn(Oct)2) as the catalyst. The products were characterized by NMR, FT-IR, GPC, XRD, DSC, TGA and viscosity measurements. The results show that the contents of PLA and PGA segments in sPLGA can be controlled by the feed ratios of the copolymerization. The glass transition temperature and crystallinity of sPLGA decrease and the crystalline sPLGA becomes amorphous with increasing the molar feed ratio between GA and LA from 10:90 to 50:50. The drug-loaded sPLGA microspheres were prepared by an emulsion solvent evaporation method. The morphology and the drug release property were investigated by SEM, dynamic light scattering (DLS) and ultraviolet spectrophotometry (UV). The results indicate that the sPLGA80 microsphere surface was smooth and the mean diameter was about 1.27μm. The sPLGA80 microspheres showed good drug loading and release properties.