Study On Preparation And Drug Controlled Release Properties Of Poly(Ethylene Glycol)/Polyanhydrides Block Copolymers

Methoxy poly(ethylene glycol)-b-Poly(octadecane diacid)-b- Methoxy poly(ethylene glycol) (mPEG-b-POA-b-mPEG) were synthesized by melt polycondensation. The block copolymer was characterized by FT-IR, 1H-NMR, DSC. The aqueous dispersion of the amphiphilic block copolymer has Gel-Sol phase transition property and the phase transition temperature increases with increasing of hydrophobic block and concentration of copolymers in aqueous dispersion. mPEG/POA nanoparticles were prepared by the nanoprecipitation technology. The results of laser particle size analyzer (LPSA) and transmission electron microscopy (TEM) show that the nanoparticles are of spherical morphology with the size of about 200 nm. The size of nanoparticles significantly depends on the concentration and the ratio of hydrophobic block of the copolymers.mPEG-b-P(OA-LA)-b-mPEG were also synthesized by melt polycondensation. The block copolymer was characterized by FT-IR, 1H-NMR, DSC. The results indicate that the crystallinity of POA is significantly decreased by copolymerization with D,L-lactic acid. The aqueous dispersion of the amphiphilic block copolymer has Sol-Gel-Sol phase transition property. With increasing of hydrophobic block and concentration of copolymers in aqueous dispersion, the Sol-Gel phase transition temperature reduces and the Gel-Sol phase transition temperature increases. mPEG/P(OA-LA) nanoparticles were prepared by the nanoprecipitation technology. The results of LPSA and TEM show that the nanoparticles are of spherical morphology with the size of about 200 nm. The size of nanoparticles significantly depends on the concentration and the ratio of hydrophobic block of the copolymers.Using paclitaxel as model drug, the in vitro controlled release of drug-loaded in situ hydrogel and nanoparticals was studied. The results indicate that the release of in situ hydrogel displays a zero-order release profile for 7 days, the release rate and accumulated release amount of paclitaxel reduce as hydrophobic block increases. The accumulated release amount of drug-loaded nanoparticals increases with increasing of hydrophobic block.