具有 pH 响应和聚乙二醇可分离特性的智能聚合物纳米粒，用于共递送紫杉醇和生存素 siRNA 以增强抗肿瘤效果。

BACKGROUND: The co-delivery of chemotherapeutic agents and small interfering RNA (siRNA) within one cargo can enhance the anticancer outcomes through its synergistic therapeutic effects. MATERIALS AND METHODS: We prepared smart polymeric nanoparticles (NPs) with pH-responsive and poly(ethylene glycol) (PEG)-detachable properties to systemically co-deliver paclitaxel (PTX) and siRNA against survivin gene for lung cancer therapy. The cationic polyethyleneimine-block-polylactic acid (PEI-PLA) was first synthesized and characterized, with good biocompatibility. PTX was encapsulated into the hydrophobic core of the PEI-PLA polymers by dialysis, and then the survivin siRNA was loaded onto the PTX-loaded NPs (PEI-PLA/PTX) through electrostatic interaction between siRNA and PEI block. Finally, the negatively charged poly(ethylene glycol)-block-poly(L-aspartic acid sodium salt) (PEG-PAsp) was coated onto the surface of NPs by electrostatic interaction to form final smart polymeric NPs with mean particle size of 82.4 nm and zeta potential of 4.1 mV. After uptake of NPs by tumor cells, the PEG-PAsp segments became electrically neutral owing to the lower endosome pH and consequently detached from the smart NPs. This process allowed endosomal escape of the NPs through the proton-sponge effect of the exposed PEI moiety. RESULTS: The resulting NPs achieved drug loading of 6.04 wt% and exhibited good dispersibility within 24 h in 10% fetal bovine serum (FBS). At pH 5.5, the NPs presented better drug release and cellular uptake than at pH 7.4. The NPs with survivin siRNA effectively knocked down the expression of survivin mRNA and protein owing to enhanced cell uptake of NPs. Cell counting kit-8 (CCK-8) assay showed that the NPs presented low systemic toxicity and improved antiproliferation effect of PTX on A549 cells. Moreover, in vivo studies demonstrated that accumulated NPs in the tumor site were capable of inhibiting the tumor growth and extending the survival rate of the mice by silencing the survivin gene and delivering PTX into tumor cells simultaneously. CONCLUSION: These results indicate that the prepared nano-vectors could be a promising co-delivery system for novel chemo/gene combination therapy.

背景：在一个载体中同时递送化疗药物和小干扰 RNA（siRNA）可以通过协同治疗效果增强抗癌效果。

材料和方法：我们制备了具有 pH 响应和聚乙二醇（PEG）可分离特性的智能聚合物纳米粒子（NPs），用于系统地共递送紫杉醇（PTX）和针对生存素基因的 siRNA 用于肺癌治疗。首先合成并表征阳离子聚乙烯亚胺-聚乳酸（PEI-PLA），具有良好的生物相容性。PTX 通过透析被包封到 PEI-PLA 聚合物的疏水性内核中，然后通过 siRNA 与 PEI 嵌段之间的静电相互作用将生存素 siRNA 装载到负载 PTX 的 NPs（PEI-PLA/PTX）上。最后，通过静电相互作用将带负电荷的聚乙二醇-聚（L-天冬氨酸钠盐）（PEG-PAsp）涂覆到 NPs 的表面上，形成最终的智能聚合物 NPs，平均粒径为 82.4nm，zeta 电位为 4.1mV。当肿瘤细胞摄取 NPs 后，由于内涵体 pH 值较低，PEG-PAsp 段变得电中性，因此从智能 NPs 上脱离。这个过程通过暴露的 PEI 部分的质子海绵效应允许 NPs 逃离内涵体。

结果：所得 NPs 的药物载量为 6.04wt%，在 10%胎牛血清（FBS）中 24 小时内表现出良好的分散性。在 pH5.5 下，与 pH7.4 相比，NPs 具有更好的药物释放和细胞摄取。带有生存素 siRNA 的 NPs 由于 NPs 的细胞摄取增强，有效地降低了生存素 mRNA 和蛋白的表达。细胞计数试剂盒-8（CCK-8）试验表明，NPs 具有较低的全身毒性，并提高了 PTX 对 A549 细胞的增殖抑制作用。此外，体内研究表明，通过沉默生存素基因和同时将 PTX 递送至肿瘤细胞，在肿瘤部位积累的 NPs 能够抑制肿瘤生长并延长小鼠的存活率。