Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, People's Republic of China.
Biomacromolecules. 2012 Aug 13;13(8):2429-38. doi: 10.1021/bm3006819. Epub 2012 Jul 13.
Reduction-sensitive reversibly core-cross-linked micelles were developed based on poly(ethylene glycol)-b-poly(N-2-hydroxypropyl methacrylamide)-lipoic acid (PEG-b-PHPMA-LA) conjugates and investigated for triggered doxorubicin (DOX) release. Water-soluble PEG-b-PHPMA block copolymers were obtained with M(n,PEG) of 5.0 kg/mol and M(n,HPMA) varying from 1.7 and 4.1 to 7.0 kg/mol by reversible addition-fragmentation chain transfer (RAFT) polymerization. The esterification of the hydroxyl groups in the PEG-b-PHPMA copolymers with lipoic acid (LA) gave amphiphilic PEG-b-PHPMA-LA conjugates with degrees of substitution (DS) of 71-86%, which formed monodispersed micelles with average sizes ranging from 85.3 to 142.5 nm, depending on PHPMA molecular weights, in phosphate buffer (PB, 10 mM, pH 7.4). These micelles were readily cross-linked with a catalytic amount of dithiothreitol (DTT). Notably, PEG-b-PHPMA(7.0k)-LA micelles displayed superior DOX loading content (21.3 wt %) and loading efficiency (90%). The in vitro release studies showed that only about 23.0% of DOX was released in 12 h from cross-linked micelles at 37 °C at a low micelle concentration of 40 μg/mL, whereas about 87.0% of DOX was released in the presence of 10 mM DTT under otherwise the same conditions. MTT assays showed that DOX-loaded core-cross-linked PEG-b-PHPMA-LA micelles exhibited high antitumor activity in HeLa and HepG2 cells with low IC(50) (half inhibitory concentration) of 6.7 and 12.8 μg DOX equiv/mL, respectively, following 48 h incubation, while blank micelles were practically nontoxic up to a tested concentration of 1.0 mg/mL. Confocal laser scanning microscope (CLSM) studies showed that DOX-loaded core-cross-linked micelles released DOX into the cell nuclei of HeLa cells in 12 h. These reduction-sensitive disassemblable core-cross-linked micelles with excellent biocompatibility, superior drug loading, high extracellular stability, and triggered intracellular drug release are promising for tumor-targeted anticancer drug delivery.
基于聚乙二醇-聚（N-2-羟丙基甲基丙烯酰胺）- 巯基乙酸（PEG-b-PHPMA-LA）缀合物开发了具有还原敏感性的可还原交联的胶束，并研究了其触发阿霉素（DOX）释放的性能。通过可逆加成-断裂链转移（RAFT）聚合得到了水溶性 PEG-b-PHPMA 嵌段共聚物，其数均分子量（M n，PEG）为 5.0 kg/mol，M n，HPMA 分别为 1.7、4.1 和 7.0 kg/mol。PEG-b-PHPMA 共聚物中羟基与巯基乙酸（LA）的酯化反应得到了具有取代度（DS）为 71-86%的两亲性 PEG-b-PHPMA-LA 缀合物，这些缀合物在磷酸盐缓冲液（PB，10 mM，pH 7.4）中形成平均粒径为 85.3-142.5 nm 的单分散胶束，这取决于 PHPMA 的分子量。这些胶束可以用少量的二硫苏糖醇（DTT）很容易地交联。值得注意的是，PEG-b-PHPMA（7.0k）-LA 胶束具有较高的 DOX 载药量（21.3 wt%）和载药效率（90%）。体外释放研究表明，在 37°C 下，在低胶束浓度为 40 μg/mL 时，交联胶束在 12 h 内仅释放约 23.0%的 DOX，而在相同条件下存在 10 mM DTT 时，约 87.0%的 DOX 被释放。MTT 分析表明，负载 DOX 的核交联 PEG-b-PHPMA-LA 胶束在 HeLa 和 HepG2 细胞中具有高抗肿瘤活性，孵育 48 h 后，IC 50（半抑制浓度）分别为 6.7 和 12.8 μg DOX 当量/mL，而空白胶束在测试浓度高达 1.0 mg/mL 时几乎没有毒性。共聚焦激光扫描显微镜（CLSM）研究表明，负载 DOX 的核交联胶束在 12 h 内将 DOX 释放到 HeLa 细胞的细胞核中。这些具有良好生物相容性、高载药量、高细胞外稳定性和触发细胞内药物释放的还原敏感性可分解核交联胶束，有望用于肿瘤靶向抗癌药物递送。
