Study On PCL And MPEG-PCL Microspheres

In recent years, poly (ε-caprolactone) (PCL), a biodegradable polymer, is widely used as sustained and controlled drug release carrier, due to its excellent biocompatibility and drug penetrability. PCL was used as drug carrying material and 5-Fluorouracil (5-Fu) as the model drug to prepare microspheres, by an S/O/W emulsion/solvent evaporation method. The effects of dispersing methods and the evaporation rate of organic solvent on entrapment efficiency were investigated. The microspheres with different sizes were characterized by drug loading, surface morphology and in-vitro drug release. Results showed that Microspheres with average entrapment efficiency of 69.3 % were obtained under the optimized condition. It took more than 9 days for the drug to release completely from the microspheres. There was no obvious change in the surface morphology of microspheres after the drug was completely released. It could be concluded that 5-Fu loaded sustained release PCL microspheres with high entrapment efficiency were prepared by S/O/W emulsion/solvent evaporation method.To modify the properties of PCL, we synthesized mPEG-PCL amphiphilic block copolymers by ring-opening polymerization of caprolactone using mPEG as macromolecular initiator, which were characterized by nuclear magnetic and GPC (gel penetration chromatogram).Microspheres were prepared with mPEG-PCl as carrier and 5-Fu as model drug by an S/O/W emulsion/solvent evaporation method. It was found that only those copolymers with low mPEG content could form microspheres, which boasted average drug loading of 7.93% and entrapment efficiency of 39.65%. The drug release from these microspheres reached nearly 100% within 24 hours. SEM images showed that mPEG could modify the surface of microsphere to some extent. It could also accelerate the rate of drug release.Microspheres were prepared with other copolymers with higher mPEG content by an O/O emulsion/solvent evaporation method. The whole formation process was observed by optical microscope. Additionally, the effects of temperature, the content of emulsion agent, the sorts of copolymer and the volume ratios of dispersed phase to continuous phase on the preparation of microspheres were investigated and the optimized procedure was formed.