| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 94 === Amphiphilic block copolymers which synthesized from biodegradable polymers have been explored in recent years. In an aqueous environment, they can self-assemble into polymeric micelles. Due to their characteristics such as small particle size, long-circulation time and enhanced drug loading efficiency, micelles are widely used in drug delivery system.
In this study, the diblock copolymers mPEG-PLLA were synthesized by ring-opening polymerization. The copolymers with different hydrophilic and hydrophobic chain length have been named as mPEGLA4k, mPEGLA6k and mPEGLA8k. Moreover, critical micelle concentration (CMC) have been measured by fluorescence probe techniques. The polymeric micelles were prepared by o/w emulsion method, and the mPEGLA6k polymer was chosen to be the main material of micelles during a series of experiments. Besides, folate-conjugated PEG-PLLA was also synthesized in this study, and this polymer was mixed with mPEGLA6k to form the targeting polymeric micelles. The particle size of mPEGLA6k micelle was 127.3 ± 11.1 nm and that of targeting micelle was 121.3 ± 7.8 nm. The degradation rate of both systems were very slow, and there were no significant size change for 30 days, which showed high stability.
The particles size of two micelle systems encapsulated with camptothecin were 20 nm large than micelles without drug, and the encapsulation efficiency were both about 13 %. The results implied that the drug release from micelles was mainly controlled by diffusion. Nearly 40 % of drug released in 2 hours while the rest drug released within 1 day.
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