循环应力下PLGA多孔支架对地塞米松的控制释放

Controlled release of dexamethasone from porous PLGA scaffolds under cyclic loading

采用喷雾干燥法制备包载地塞米松(Dex)的聚L-丙交酯-b-聚乙二醇(PLLA-PEG)微球,以热致相分离/粒子洗去法制备聚乙交酯-co-丙交酯(PLGA)多孔支架,通过复合溶结法将载药微球固定于PLGA多孔支架中,制得载药微球-支架(记为MS-S).另外,在支架制备过程中将Dex直接加入PLGA溶液中,制得对比的直接载药支架(记为D-S).以扫描电镜观察微球和支架的微观形貌,在循环压应力与水浴摇床两种环境下分别对上述两种载药支架进行控制释放Dex的实验,用紫外-可见光分光光度计测定Dex的累积释放量.结果表明,Dex及微球的载入对PLGA支架的整体形貌影响较小;循环压应力显著提高了Dex从载药支架中的释放速率,与D-S相比,MS-S延缓了药物的释放.研究模拟体内循环压应力下支架控制释放药物规律对于实现理想的临床效果具有重要意义.

Poly（l-lactide）-b-poly（ethylene glycol）（PLLA-PEG） microspheres containing dexamethasone（Dex） were fabricated using a spray-drying technique.Porous poly（lactic-co-glycolic acid）（PLGA） scaffolds were prepared using a method combining thermally induced phase separation and porogen leaching.A post-seeding technique was used to immobilize Dex-containing PLLA-PEG microspheres on porous PLGA scaffolds,obtaining drug-containing microspheres-scaffolds（MS-S）.Simple Dex-containing scaffolds（D-S） were also made as control by directly dissolving Dex in the PLGA solution during scaffold fabrication.The morphology of microspheres and scaffolds were studied by scanning electron microscopy.Drug release profiles of both MS-S and D-S were determined under cyclic loading and shaking water bath,respectively.The cumulative release of Dex was measured using an ultraviolet visible spectrophotometer.The results showed that the incorporation of Dex and microspheres have little effect on the overall morphology of the porous PLGA scaffolds.Cyclic loading accelerated the release of Dex from the drug-containing scaffolds significantly.Compared with D-S,MS-S reduced the drug release rate.The controlled drug delivery of tissue engineering scaffolds under cyclic loading is a key factor to mimic the in vivo mechanical environments and achieve optical clinical efficacy.