主动包封siRNA/多柔比星肿瘤靶向纳米囊泡的研究

The translational research of Polymersome based siRNA therapy is retarded due to the lack of the mechanism for high encapsulation efficiency. We developed a novel kind of self-assembly of polymer vesicles that can co-deliver siRNA and chemotherapeutic agents Doxorubicin with enhanced stability, low toxicity and high targeting efficiency. Based on our previous work, PEG-PCL-Dextran polymersome can drive protamine and siRNA into the hydrophilic core under the guidance of the PEG continuous phase with high encapsulation efficiency (encapsulating rate 90%). The enhanced serum stability and low toxicity of the nanoparticles were confirmed in vitro. This work focuses on conjugating folate to PEG-PCL-Dextran with optimized density to the target delivery of therapeutic agents with high efficiency. The.encapsulation features and characterization of the combined delivery of hydrophobic compounds Doxorubicin and MDR-1 siRNA mentioned above was studied to offer a promising method for disease cell targeting with high efficiency and low toxicity.

本课题针对目前Polymersome缺乏主动包封siRNA的机制，制备了用于输送化疗药物多柔比星与siRNA至肿瘤细胞降低其耐药性的纳米颗粒。所设计的Polymersome具有高效、不泄漏、低毒和高靶向性特点，通过自组装方式可同时担载核酸药物和疏水药物。前期研究证明，通过在聚乙二醇（PEG）水相系统里包封，siRNA能主动高效的包封于PEG-PCL-Dextran纳米囊泡中（包封率90%），体外实验中，证明了核酸纳米材料体系具有较好的血清稳定性和低毒等特点。本次申请在PEG-PCL-Dextran Polymersome的基础上，连接靶向基团叶酸，并对载体表面靶向密度进行优化，期望实现高效靶向输送效果。同时探讨载体担载疏水药物多柔比星及靶向肿瘤MDR-1基因的siRNA包封效果、表征及释放特性，证明其同时实现高效、低毒和病变细胞靶向输送的可行性。

siRNA治疗是目前研究较多的方向之一，其针对疾病作用位点具有高效的靶向性、低毒性等优势，但存在在体内外稳定性差，血浆半衰期短，同时，相对较大的分子量及荷负电的理化特征使之不易被细胞内吞。另一方面，体内环境相对较为复杂，载体对病变细胞的识别与药物的靶位点释放等问题限制了siRNA的应用。针对以上所述，本课题对于目前采用Polymersome作为核酸包裹载体缺乏主动包封siRNA的机制，设计、合成并优化出了聚乙二醇-聚己内酯-糖结构的嵌段高分子，并通过PEG作为连续相组装制备了纳米颗粒。所设计的Polymersome具有高效、稳定、低毒和高靶向性特点，通过自组装方式可形成170nm左右、电位在0mV附近纳米颗粒。通过在聚乙二醇（PEG）水相系统里包封，siRNA能主动高效的包封于纳米囊泡中，体外实验中，证明了核酸纳米材料体系具有较好的稳定性和低毒等特点，并设计了连接靶向基团的高分子，达到了靶向输送效果。