嵌段材料的分子量对PLGA-mPEG载药微球降解和释药行为的影响

Effects of Molecular Weight of Blocks on in vitro Degradation and Drug Release Perfomance of PLGA-mPEG Microparticle

改变嵌段材料PLGA-mPEG亲、疏水端的分子量,通过体外降解和释药实验,考察材料性质对PLGA-mPEG载药微球的性质、降解以及释药行为的影响。当亲水链段mPEG较短时,PLGA-mPEG材料疏水链段的分子量越高,微球对药物包封率越高;微球的降解取决于材料的性质和水渗入的速度,亲水链段mPEG的引入增强了微球的吸水性,加速了材料的水解,释药速率相应提高,低分子量mPEG加速水解的效应更明显;但mPEG对微球有增塑作用,使微球在降解过程中维持了一定机械强度和完整形态,降低了降解后期微球崩解造成药物突释的风险。

The degradation and drug release profiles of poly （dl-lactide-co-glycolic acid） - methoxypoly （ethyleneglycol） （PLGA-mPEG） microparticles were investigated by altering the molecular weights （Mw） of both PLGA and mPEG chains through in vitro test. Higher encapsulation efficiency was achieved with higher PLGA molecular weight but lower mPEG molecular weight. The degradation of microparticles depends on the properties of polymer and the penetrating rate of water. The incorporation of hydrophilic mPEG chains acting as a surface modifier of hydrophobic PLGA network could enhance the permeation of water into the center of microparticles, and increase the polymer hydrolysis rate as well as drug release rate. But as the increase of mPEG molecular weight, both polymer hydrolysis rate and drug release rate of the PLGA-mPEG microparticles will be reduced. However, the incorporation of hydrophilic mPEG chains plasticizes the PLGA polymer, promotes the mechanical intensity of the microparticles and maintains the shape of PLGA-mPEG microparticles during the whole degradation, which reduce the risk of severe drug release caused by microparticle collapse during degradation.