目的 通过引入壳聚糖增加丙交酯乙交酯共聚物（PLGA）载体中小干扰RNA（siRNA）的包封率，对制备的携siRNA-壳聚糖（siRNA-CS）的PLGA纳米载体（siRNA-CPG）进行表征。方法 选用传统的乳化-溶剂挥发法制备siRNACPG，以粒径、Zeta电位及包封率为指标，对处方（siRNA与壳聚糖质量比，PLGA质量浓度，内水相、二氯甲烷、外水相的体积比）进行单因素考察及星点设计-响应面法优化。对优化后制备的siRNA-CPG进行粒径、Zeta电位、包封率质量评价；根据粒径及包封率考察siRNA-CPG在生理盐水及血清中的稳定性；制备荧光标记的siRNA-CPG，与MCF-7细胞孵育4 h，观察细胞摄取情况。结果 壳聚糖的引入可将siRNA包封率从3.14%提高到90%以上。优化后的处方中壳聚糖、siRNA、PLGA质量浓度分别为1、0.5、10 mg·mL^-1，内水相、二氯甲烷、外水相的体积比为1∶10∶100。制备3批siRNA-CPG冻干粉，复溶后室温放置48 h及血清中24 h内粒径和包封率均无明显变化；siRNA-CPG可被细胞摄取并从溶酶体中逃逸出来。结论 制备的siRNA-CPG包封率高、稳定性好，可以实现siRNA的细胞质有效递送。

Objective To increase the encapsulation efficiency of siRNA in PLGA nano particles by incorprating chitosan, to prepare and characterise the PLGA nanoparticles carrying siRNA (siRNA-CPG). Methods The traditional emulsification solvent volatilization method was used to prepare siRNA-CPG. The formulation (mass ratio of siRNA to chitosan, mass concentration of PLGA, volume ratio of internal water phase, dichloromethane and external water phase) was optimized with the particle size, Zeta potential, entrapment efficiency as the index by single factor experiment and central composite design-response surface method. The particle size, Zeta potential and encapsulation rate of the optimized siRNA-CPG were evaluated. The stability of siRNA-CPG in normal saline and serum was investigated according to particle size and encapsulation rate. Fluorescent-labeled siRNA-CPG was prepared and incubated with MCF-7 cells for 4 h to observe cell uptake. Results The addition of chitosan increased the entrapment efficiency of siRNA from 3.14% to more than 90% in the PLGA nanoparticles. The optimized formula was as follows:the concentrations of chitosan, siRNA and PLGA were 1, 0.5 and 10 mg·mL^-1 respectively. Three batches of siRNA-CPG had little change in particle size and entrapment efficiency after redissolution by normal saline at room temperature for 48 h, and it could be uptaken by cells and then escape from lysosomes. Conclusion The siRNA-CPG prepared in this study has high encapsulation efficiency and good stability, and can realize cytoplasmic delivery of siRNA.

R943

中国博士后基金（2020M682926）