A series of block polyurethanes based on poly(3-hydroxybutyrate)(PHB-diol,Mn=6180)and poly(ethylene glycol,Mn=1500)segments were synthesized by a facil way of solution polymerization.The chemical structure was systematically characterized by’H,nuclear magnetic resonance spectrum(NMR)and Fourier transorm.infrared spectroscopy.The polyurethanes microspheres were loaded with lysozyme by double emulsion solvent evaporation and the influence of environment on degradation process was investigated.It was stated that an accelerated degradation process was carried out at pH=9 and 37°C.The cumulative release of drug-loaded microspheres was achieved about 85% in phosphate buffer solution when the degradation time reaches 20 weeks.Moreover,lower degradation of the microspheres was observed after 12 weeks in the release medium.Results showed that the microspheres exhibit different degradable performance in different media from surface erosion to diffusion bulk collapsing.
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