Nowadays, the clinical administration of siRNA therapeutics is still challenging due to the need of safe and efficient delivery carriers. In this context, biodegradable and amphiphilic triblock copolymers (ABC) containing amine–based cationic segments could be a powerful tool for siRNA delivery. Herein, we propose a range of poly(ethylene glycol) (PEG)–poly(2-dimethyl(aminoethyl) methacrylate) (pDMAEMA)–polycaprolactone (PCL) copolymers with different lengths of the blocks and hydrophilic/lipophilic balance to deliver siRNA alone or in association with a conventional anticancer drug. mPEG–pDMAEMA–PCL copolymers were synthesized by a combination of techniques and characterized by NMR analysis, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Copolymers were then employed to prepare NPs through nanoprecipitation. NPs based on copolymers with long PCL chains (SSL-NPs and LLL-NPs) showed the best colloidal properties and a highly stable core–shell structure with a better orientation of the PEG fringe on the surface. Concerning siRNA delivery, SSL-NPs based on copolymers with short PEG and pDMAEMA chains showed optimized ability to complex and then deliver siRNA at the cell level. The strong interaction between the nucleic acid and the cationic pDMAEMA blocks of NPs was then confirmed by release studies that showed a sustained release of siRNA within 48 h. The transfection efficiency of NPs was assessed in human melanoma cells. NPs were complexed with a therapeutic siRNA against TUBB3 (TUB-siRNA). We observed the best results with SSL-NPs, probably due to the higher preserved buffer capacity of the pDMAEMA blocks. Finally, in order to give a proof of concept of a possible application in the combined chemo/gene-therapy of cancer, SSL-NPs complexed with TUB-siRNA were loaded with docetaxel (DTX) and then cytotoxicity was evaluated in the same cell line. The co-delivery of TUB-siRNA into NPs appeared to strongly potentiate the anti-proliferative activity of DTX, thus highlighting the combinatory activity of the NPs.

中文翻译：

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基于三嵌段共聚物的聚乙二醇化阳离子纳米组件将 siRNA 疗法与抗癌药物相结合

如今，由于需要安全有效的递送载体，siRNA疗法的临床管理仍然具有挑战性。在这种情况下，含有胺基阳离子链段的可生物降解和两亲性三嵌段共聚物 (ABC) 可能是 siRNA 传递的有力工具。在此，我们提出了一系列具有不同嵌段长度和亲水/亲油平衡的聚（乙二醇）（PEG）-聚（2-二甲基（氨乙基）甲基丙烯酸酯）（pDMAEMA）-聚己内酯（PCL）共聚物来单独递送 siRNA或与常规抗癌药物联合使用。mPEG-pDMAEMA-PCL 共聚物通过多种技术合成，并通过 NMR 分析、傅里叶变换红外 (FTIR) 光谱、凝胶渗透色谱 (GPC) 和差示扫描量热法 (DSC) 进行表征。然后使用共聚物通过纳米沉淀制备纳米颗粒。基于具有长 PCL 链的共聚物（SSL-NPs 和 LLL-NPs）的 NPs 显示出最好的胶体性质和高度稳定的核壳结构，具有更好的表面 PEG 条纹取向。关于 siRNA 传递，基于具有短 PEG 和 pDMAEMA 链的共聚物的 SSL-NP 显示出优化的复合能力，然后在细胞水平上传递 siRNA。然后通过释放研究证实了核酸与 NPs 的阳离子 pDMAEMA 块之间的强相互作用，该研究表明 siRNA 在 48 小时内持续释放。在人黑色素瘤细胞中评估了 NPs 的转染效率。NPs 与针对 TUBB3 的治疗性 siRNA (TUB-siRNA) 复合。我们观察到 SSL-NP 的最佳结果，可能是由于 pDMAEMA 块具有更高的保留缓冲容量。最后，为了证明在癌症联合化疗/基因治疗中可能应用的概念，与 TUB-siRNA 复合的 SSL-NPs 加载多西紫杉醇 (DTX)，然后在同一细胞系中评估细胞毒性. 将 TUB-siRNA 共递送到 NPs 似乎强烈增强了 DTX 的抗增殖活性，从而突出了 NPs 的组合活性。