南方医科大学学报

南方医科大学学报 ›› 2018, Vol. 38 ›› Issue (09): 1139-.doi: 10.12122/j.issn.1673-4254.2018.09.20

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两亲性嵌段聚合物PLGA-b-（PEI-co-PEG）的合成及其自组装电正性胶束的表征

王俊，张辉武，曾庆冰   

  • 出版日期:2018-09-20 发布日期:2018-09-20

Synthesis of amphiphilic block copolymer of PLGA-b-(PEI-co-PEG) and characterization of the self-assembled cationic micelles

  • Online:2018-09-20 Published:2018-09-20

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摘要： 目的合成一种生物可降解与低细胞毒性的两亲性嵌段共聚物PLGA-b-（PEI-co-PEG），并研究其胶束化行为。方法采用 开环聚合法合成PLGA；使用低相对分子质量的聚乙烯亚胺（PEI1800）与聚乙二醇（PEG2000)相互交联合成水溶性PEI-co-PEG共聚 物；采用脱水缩合法，合成PLGA-b-（PEI-co-PEG）。根据PEI-co-PEG在37 ℃ PBS中孵育不同时间的相对分子质量变化情况， 评估其生物降解性。通过MTT法测定PLGA-b-（PEI-co-PEG）与PEI-co-PEG对MCF-7的细胞毒性。采用标准透析法制备电正 性PLGA-b-（PEI-co-PEG）胶束，使用马尔文激光粒度分析仪测定其粒径分布与Zeta电位；采用简单混合法制备PLGA-b-（PEIco- PEG）胶束/胰岛素复合物；使用透射电镜表征胶束及胶束/胰岛素复合物的形貌。采用荧光猝灭法，测定胶束/胰岛素复合物 在不同浓度盐离子溶液中的稳定性。结果成功合成了两亲性嵌段共聚物PLGA-b-（PEI-co-PEG）。PEI-co-PEG在37 ℃ PBS 溶液中的降解半衰期约为48 h。PLGA-b-（PEI-co-PEG）与PEI-co-PEG对MCF-7的半数抑制浓度（IC50）分别为1375.7 μg/mL与 425.1 μg/mL。PLGA-b-（PEI-co-PEG）胶束（粒径：99.5±2.61 nm，Zeta电位：52.9±2.38 mV）可与胰岛素形成纳米尺寸的胶束/胰 岛素复合物；胶束/胰岛素复合物在150 mmol/L NaCl溶液中的解离率为27.6%。结论PEI-co-PEG在体外条件下展现了较好的 降解性。PLGA-b-（PEI-co-PEG）的细胞毒性显著低于PEI-co-PEG（P<0.05）。PLGA-b-（PEI-co-PEG）胶束/胰岛素复合物在生 理条件下具有良好的盐离子稳定性。

Abstract: Objective To synthesize a biodegradable and minimally cytotoxic amphiphilic block copolymer of PLGA-b-(PEI-co- PEG) and study its micellization behavior. Methods PLGA was synthesized by ring-opening polymerization. The cross-linked copolymer of PEI-co-PEG was synthesized from the low-molecular-weight polyethyleneimine (PEI, 1800 D) and hydrophilic poly(ethylene glycol) (PEG, 2000 D). PLGA-b-(PEI-co-PEG) was synthesized by dehydration condensation reaction of PLGA and water soluble PEI-co-PEG. The biodegradability of PEI-co-PEG was evaluated according to the molecular weight change after incubation at 37 ℃ for different time. The cytotoxicity of PLGA- b-(PEI-co-PEG) and PEI-co-PEG in MCF-7 cells was determined by MTT assay. The cationic PLGA-b-(PEI-co-PEG) micelles were prepared by standard dialysis method. The particle size and Zeta potential of the micelles were measured by a Malvern laser particle size analyzer. Micelle/insulin complexes were prepared by simple mixing method and their morphology were characterized by transmission electron microscopy (TEM). The fluorescence quenching method was used to determine the stability of the micelle/insulin complexes at different salt concentrations. Results Amphiphilic block copolymer of PLGA-b-(PEI-co-PEG) was successfully synthesized. The half-life of PEI-co-PEG degradation in PBS at 37 ℃ was about 48 h. The 50% cell inhibiting concentration (IC50) of PLGA-b-(PEIco- PEG) and PEI-co-PEG in MCF-7 cells were 1375.7 μg/mL and 425.1 μg/mL, respectively. The micelles of PLGA-b-(PEI-co- PEG) (particle size: 99.5±2.61 nm, Zeta potential: 52.9±2.38 mV) were complexed with insulin via electrostatic interaction and formed nanoscale micelle/insulin complexes. The dissociation rate of micelle/insulin complexes in 150 mmol/L NaCl solution was 27.6%. Conclusion The synthesized PEI-co-PEG shows good degradability in vitro. The cytotoxicity of PLGA-b-(PEI-co- PEG) is significantly lower than PEI-co-PEG, and PLGA-b-(PEI-co-PEG) micelle/insulin complexes have good salt- resistant stability in physiological condition.