In this study, a model hydrophilic drug (porphyrin) was encapsulated within hydrophobic polylactic acid (PLA) nanoparticles (NPs) with different crystallinity and the relevant release behaviors were investigated. The crystalline modification was done using a modified nanoprecipitation method, where homo and stereocomplexed PLA NPs with different average diameters based on varying polymer concentrations and solvent/nonsolvent ratios (S/N) were prepared. Entrapment efficiency and drug release of sterocomplexed-PLA NPs were compared with neat poly(l-lactic acid) (PLLA) NPs. Furthermore, to get the more sustained release, porphyrin-loaded NPs were immobilized within electrospun poly(d,l-lactide-co-glycolide (PLGA) nanofibers (NFs). Outcomes revealed that solution concentration and solvent/nonsolvent ratio play significant roles in the formation of homo and stereocomplexed NPs. On the other hand, it was found that the formation of stereocrystals did not significantly affect the size and morphology of NPs compared with neat NPs. With regard to the entrapment efficiency and drug content, stereocomplexd-PLA NPs behave relatively the same as neat PLLA NPs while the more sustained release was observed for stereocomplexed NPs. Also, it was observed that electrospinning of PLGA solution loaded by NPs led to the uniform distribution of NPs into PLGA fibers. Encapsulating the drug-loaded NPs into nanofibers decreased the rate of drug release by 50% after 24 h, compared with direct loading of drug into PLGA NFs. We conclude that it is possible to tune the entrapment efficiency and modify the release rate of the drug by giving small changes in the process parameters without altering the physical properties of the original drug substance and polymer.

中文翻译：

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可调自组装立体络合聚乳酸纳米粒子作为药物载体

在这项研究中，模型亲水性药物（卟啉）被封装在具有不同结晶度的疏水性聚乳酸（PLA）纳米颗粒（NPs）中，并研究了相关的释放行为。结晶改性是使用改进的纳米沉淀方法完成的，其中根据不同的聚合物浓度和溶剂/非溶剂比 (S/N) 制备具有不同平均直径的均质和立体络合 PLA NP。将立体复合的 PLA NPs 的包封率和药物释放与纯聚（l-乳酸）（PLLA）NPs 进行比较。此外，为了获得更持续的释放，负载卟啉的 NPs 被固定在电纺聚（d , l-丙交酯-共-乙交酯（PLGA）纳米纤维（NFs）。结果表明，溶液浓度和溶剂/非溶剂比在均质和立体络合 NPs 的形成中起着重要作用。另一方面，发现与纯 NPs 相比，立体晶体的形成不会显着影响 NPs 的尺寸和形态。关于包封率和药物含量，立体络合的 PLA NPs 与纯 PLLA NPs 的表现相对相同，而立体络合的 NPs 则观察到更持续的释放。此外，观察到由 NPs 负载的 PLGA 溶液的静电纺丝导致 NPs 均匀分布到 PLGA 纤维中。与直接将药物装入 PLGA NFs 相比，将载药 NPs 封装到纳米纤维中使药物释放率在 24 小时后降低了 50%。