von Recum H A, Cleek R L, Eskin S G, Mikos A G
Department of Chemical Engineering, Cox Laboratory for Biomedical Engineering, Rice University, Houston, TX 77251, USA.
Biomaterials. 1995 Apr;16(6):441-7. doi: 10.1016/0142-9612(95)98816-w.
Polydispersed poly(L-lactic acid) (PLLA) membranes comprised of blends of monodispersed PLLA of weight average molecular weight of 82,500 and 7600 were fabricated to investigate the effect of polydispersity on degradation characteristics. The PLLA blends exhibited large spherulites of high molecular weight chains embedded in a low molecular weight matrix. During degradation in phosphate buffer at pH 7.4 and 37 degrees C for 28 d, the release rate of lactic acid increased as the percentage of the low molecular weight component in the blend was increased. For low molecular weight compositions larger than 50%, voids were created in the degrading blends due to the degradation of low molecular weight chains and the concurrent dissolution of lactic acid, and also the release of undegraded particles of high molecular weight. These studies demonstrate the feasibility of modulating lactic acid release during in vivo degradation of PLLA implants by adjusting the polymer polydispersity.
制备了由重均分子量分别为82,500和7600的单分散聚L-乳酸（PLLA）共混物组成的多分散PLLA膜，以研究多分散性对降解特性的影响。PLLA共混物呈现出高分子量链的大球晶嵌入低分子量基质中。在pH 7.4、37℃的磷酸盐缓冲液中降解28天期间，随着共混物中低分子量组分百分比的增加，乳酸的释放速率增加。对于大于50%的低分子量组成，由于低分子量链的降解以及乳酸的同时溶解，以及高分子量未降解颗粒的释放，在降解的共混物中产生了空隙。这些研究证明了通过调节聚合物多分散性来调节PLLA植入物体内降解过程中乳酸释放的可行性。
