通过生物素-亲和素桥接技术成功制备了转铁蛋白-生物素/亲和素/生物素-Pluronic F127-聚乳酸（Tf-F127-PLA）共轭聚合物囊泡，以研究其抑制癌细胞多药耐药性的能力。选择亲水性阿霉素（DOX）作为模型药物加载到 Tf-F127-PLA 聚合物囊泡中。 Tf-F127-PLA 聚合物囊泡中负载的 DOX 最初快速释放，然后缓慢释放。通过针对 A549 肺癌细胞的细胞毒性和细胞摄取测定，研究了 Tf-F127-PLA/DOX 聚合物囊泡的转铁蛋白配体密度对其靶向特性的影响。结果表明，Tf-F127-PLA/DOX 聚合物囊泡比非靶向载药聚合物囊泡具有更好的靶向能力。此外，Tf摩尔含量为2%的Tf-F127-PLA/DOX聚合物囊泡比Tf摩尔含量为4%和5%的Tf-F127-PLA/DOX聚合物囊泡具有更有效的抗肿瘤活性和更高的细胞摄取率。 2% Tf-F127-PLA/DOX 聚合物囊泡在多药耐药癌细胞 A549/ADR 中也表现出比非靶向 PLA-F127-PLA/DOX 聚合物囊泡更好的抗癌能力。进一步证明A549/ADR细胞对聚合物囊泡的内吞是一个能量依赖性内吞过程，与网格蛋白、大细胞作用和小窝蛋白有关。此外，Tf-F127-PLA/DOX 聚合物囊泡的内吞作用被证明是由转铁蛋白受体介导的。

Transferrin-conjugated polymersomes, transferrin-biotin/avidin/biotin-Pluronic F127-poly(lactic acid) (Tf-F127-PLA), were successfully prepared through a biotin-avidin bridging technique to study their ability to inhibit multidrug resistance of cancer cells. Hydrophilic doxorubicin (DOX) was selected as the model drug to be loaded into Tf-F127-PLA polymersomes. DOX loaded in Tf-F127-PLA polymersomes was released fast initially, followed by a slow release. The effect of the transferrin ligand density of Tf-F127-PLA/DOX polymersomes on their targeting properties was studied by both cytotoxicity and cellular uptake assays against A549 lung cancer cells. It was shown that Tf-F127-PLA/DOX polymersomes had better targeting ability than nontargeted drug-loaded polymersomes. Furthermore, Tf-F127-PLA/DOX polymersomes with 2% Tf molar content have more effective antitumor activity and a higher cellular uptake than those with 4 and 5% Tf molar content. 2% Tf-F127-PLA/DOX polymersomes also exhibited better anticancer ability in multidrug resistant cancer cells A549/ADR than nontargeted PLA-F127-PLA/DOX polymersomes. It was further proved that the endocytosis of polymersomes by A549/ADR cells was an energy-dependent endocytosis process, which was related to clathrin, macrocytosis, and caveolin. Also, the endocytosis of Tf-F127-PLA/DOX polymersomes was proven to be mediated by the transferrin receptor.