Microwave-assisted Polymerization Of PLA-PEG-PLA And Characterization, Drug Release For Drug-loaded Microspheres

In this thesis, PLA-PEG-PLA triblock copolymer was synthesized by micro-wave-assisted polymerization. Nano ferroferric oxide(Fe₃O₄)was prepared by wa-ter-in-oil single microemulsion(one reactant) processing. On that basis, drug-loaded microspheres with aspirin, 1,10-phenanthroline monohydrate, podophyllotoxin were prepared, respectively. The microstructure of drug-loaded microspheres were charac-terized. Moreover in vitro drug release of drug-loaded microspheres were studied.These studies were mainly as follows:(1) PLA and PLA-PEG-PLA was synthesized by microwave-assisted polymeri-zation with lactide. It was shown that PLA-PEG-PLA was a ABA type triblock co-polymer by FT-IR ,1^H-NMR and XRD. The optimum preparation conditions for PLA-PEG-PLA were as follows : microwave power was 200W and microwave re-action time was 30 min.(2) Nano ferroferric oxide(nano-Fe₃O₄)was prepared by water-in-oil single mi-croemulsion. XRD showed that nano-Fe₃O₄ had a higher crystallinity when the aging time was 60min. TEM photos of nano-Fe₃O₄ showed that its mean diameter was 11.4 nm .(3) ASA/PLA-PEG-PLA-MS were prepared by emulsion-solvent evaporation. The optimal preparation conditions were determined by orthogonal experiment as follows: PVA solution concentration was 2.0%, the addition amount of PLA-PEG-PLA was 100mg, the dosage of ASA was 30mg, emulsion time was 40min.The drug release of ASA/PLA-PEG-PLA–MS showed that the various size of microspheres all had obvious sustained-release properties.(4) Phen/PLA-PEG-PLA-MS were prepared with 1,10-Phenanthroline monohy-drate as model drug. SEM showed that the mean diameter of Phen/PLA-PEG-PLA- MS and Phen-Fe₃O₄/PLA-PEG-PLA-MS was 30μm and 12μm,respectively, fur- thermore their structures were more regular. The drug release showed that Phen/PLA-PEG-PLA-MS and Phen-Fe₃O₄/PLA-PEG-PLA-MS all had obvious sus-tained-release properties.(5) PPT/PLA-PEG-PLA-MS was prepared with podophyllotoxin. SEM showed that the mean diameter of PPT/PLA-PEG-PLA-MS was 20μm, furthermore its structure was more regular and the distribution of particle size was even . The drug release showed that PPT/PLA-PEG-PLA-MS also had obvious sustained-release property.