文献：Phosphatidylserine targeting peptide-functionalized pH sensitive mixed micelles for enhanced anti-tumor drug delivery

文献链接：https://pubmed.ncbi.nlm.nih.gov/31899369/

作者：Siyu Guana, Qianqian Zhanga, Jianwei Baoa, Tijie Duana, Rongfeng Hub, Tori Czechc, Jihui Tanga

相关产品：

HCOO-PEG-PDLLA  甲酸酯基-聚乙二醇-聚（D-丙交酯）

H2N-PEG-PDLLA   聚乙二醇-聚（D-丙交酯）-氨基

原文摘要： In recent decades, targeted drug delivery systems (TDDS) have been widely used as an ideal method of improving therapeutic effects and reducing systemic side effects of chemotherapeutic agents. Historically, a handful of methods have been developed to further improve the targeting ability of delivery systems. Thus, in this study, two methods, taking advantage of tumor characteristics, were used for the creation of a multi-targeted delivery system. The first was the fabrication of pHsensitive micelles, lending the ability to increase drug release by exploiting the acidic tumor environment. The second method was through utilization of the surface-exposed phosphatidylserine (PS) of tumors, which is normally found in the inner leaflet in healthy cells. Using PS as a target site, PS binding peptide (PSBP-6) was conjugated to pH-sensitive mixed micelles, (consisting of poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PDLLA) and poly (ethylene glycol)-b-poly (L-histidine) (PEG-PHIS)). After successful preparation of micelles, paclitaxel (PTX), a common chemotherapeutic agent, was selected to measure drug loading capacity and encapsulation efficiency, showing 7.9% and 83.5%, respectively. The in vitro release of PTX from mixed micelles at pH 5.0, 6.5, and 7.4 was 78.1, 56.8, and 51.4%, respectively, indicating acidtriggered drug release. The PSBP-6-modified, mixed micelles exhibited significantly enhanced in vitro cytotoxicity and demonstrated more efficient cellular uptake compared to unmodified mixed micelles in the HeLa cell line. Moreover,pharmacokinetic, in vivo biodistribution, and fluorescence imaging studies showed that PSBP-6-PEG-PDLLA/PEG-PHIS mixed micelles provide prolonged time in blood circulation and enhanced tumor accumulation. These results suggest that the use of PS as a novel targeting site is advantageous, and that these new multi-targeted mixed micelles show great potential for realization of broad prospects in the targeted treatment of tumors for chemotherapeutic delivery.

HCOO-PEG-PDLLA 是一种嵌段共聚物，主要由甲酸酯基（HCOO-）、聚乙二醇（PEG）和聚（D-丙交酯）（PDLLA）三部分组成。聚乙二醇是一种亲水性的聚合物，具有良好的水溶性和生物相容性。其分子链由多个乙二醇单元（- CH₂CH₂O-）重复连接而成，能够在水溶液中形成水合层，为整个共聚物提供亲水性。聚（D-丙交酯）是一种聚酯，由 D-丙交酯单体通过开环聚合反应得到。它具有一定的疏水性，其分子链中含有大量的酯键，这是其可降解特性的关键结构。PDLLA 在体内或合适的环境下可以通过酯键的水解逐渐降解为小分子。H2N-PEG-PDLLA可能是一种结合了聚乙二醇（PEG）和外消旋聚乳酸（PDLLA）特性的化合物，并通过某种方式引入了氨基（-NH2）官能团，PDLLA是一种可降解的合成聚合物，由乳酸单体聚合而成。它具有良好的可降解性质，因此在医学和组织工程领域中常用于制备可降解的支架、微球或载体。氨基的引入可能使得H2N-PEG-PDLLA具有更多的化学反应活性，能够与其他分子或材料发生偶联反应。PSBP-6-PEG-PDLLA/PEG-PHIS混合胶束可延长血液循环时间，增强tumor积累。HCOO-PEG-PDLLA和H2N-PEG-PDLLA都有着许多的应用，例如在PSBP-6-PEG-PDLLA等相关物质的合成中。

图为:PSBP-6-PEG-PDLLA的共轭方案。

HCOO-PEG-PDLLA在PSBP-6-PEG-PDLLA合成中的应用：

PSBP-6-PEG-PDLLA采用碳二亚胺介导的EDC和NHS两步反应法合成。PSBP-6与HCOO-PEG-PDLLA进行共轭。首先，将HCOO-PEG-PDLLA溶解在DMSO中。用EDC和NHS激活HCOO-PEG-PDLLA的羧基。然后，在溶液中加入PSBP-6，用三乙胺调整pH。然后在室温下搅拌三天。然后，将得到的混合物在MWCO透析袋中用去离子水进行透析。透析袋中的内容物被冻干。通过1H NMR谱证实了PSBP-6-PEG-PDLLA的结构。

HCOO-PEG-PDLLA在共聚物合成中的应用：

PEG-PHIS的合成途径和PSBP-6-PEG-PDLLA的结合。PSBP-6-PEG-PDLLA通过1H NMR波谱分析（DMSO-d6与TMS）验证了PSBP-6-PEG-PDLLA的结构。PSBP-6-PEG-PDLLA共聚物表现出PSBP-6的特征峰。同时，HCOO-PEG-PDLLA的group-羧基在PSBP-6-PEG-PDLLA共聚物的光谱中消失，表明PSBP-6和PEG-PDLLA的酰胺化成功。

H2N-PEG-PDLLA在细胞摄取研究中的应用：

为了研究混合胶束的细胞摄取效率，合成了一种FITC-PEG-PDLLA嵌段共聚物来标记胶束，以追踪胶束的分布。标记共聚物是根据之前的研究制备的，将H2N-PEG-PDLLA和荧光素异硫氰酸酯（FITC）加入二异丙基乙胺（DIEA）/DMF混合溶液中，搅拌两天。然后将反应溶液用去离子水透析，然后冷冻干燥。制备用于共聚焦激光扫描显微镜（CLSM）和流式细胞仪分析的混合胶束；使用PEG-PHIS、 PSBP- 6-PEG-PDLLA或PEG-PDLLA和FITC-PEG-PDLLA。PSBP-6-PEG-PDLLA，FITC标记胶束的制备类似，使用PEG-PDLLA，PSBP-6-PEG-PDLLA和FITC-PEG-PDLLA。

图为：用HCOO-PEG-PDLLA、PSBP-6和PSBP-6-PEG-PDLLA的1H NMR谱进行了结构确认

结论：制备得到的多靶点系统，利用了tumor的两个共同特征，即表面可用的PS和酸性tumor微环境。利用PSBP-6功能化PEG-PDLLA共聚物，并将其与酸敏感的PEG-PHIS结合，构建PSBP-6-PEGPDLLA/PEG-PHIS，用于主动靶向并随后在tumor内释放Chemotherapy 化合物，以增强效果。