胸腺五肽pH-敏感壳聚糖纳米粒的制备、体外释放及生物活性

 目的为了提高胸腺五肽口服的稳定性及生物利用度,制备胸腺五肽pH-敏感壳聚糖纳米粒并考察其理化性质、体外释放及生物活性。方法采用离子胶凝法制备胸腺五肽壳聚糖纳米粒并用Eudragit S100包衣制备pH-敏感纳米粒;透射电镜和环境扫描电镜观察纳米粒形态;粒度及表面电位分析仪测量纳米粒的粒径及Zeta电位;超速离心法测定载药纳米粒的包封率;动态透析法研究载药纳米粒的体外释放特性;模拟人工消化液考察纳米粒中胸腺五肽的生物稳定性;淋巴细胞增殖反应评价制剂的生物活性。结果pH-敏感胸腺五肽壳聚糖纳米粒的平均粒径为(175.6±17)nm,Zeta电位为(28.44±0.5)mV,包封率为(76.70±2.6)%。胸腺五肽pH-敏感壳聚糖纳米粒具有良好的pH依赖性:在0.1 mol·L^-1HCl溶液中累积释放24.65%,在pH5.0 PBS溶液中累积释放41.01%,在pH7.4 PBS溶液中累积释放81.44%。pH敏感壳聚糖纳米粒制剂中的胸腺五肽在人工胃液中稳定,在人工肠液中半衰期为15 min。淋巴细胞体外转化实验表明,胸腺五肽pH-敏感壳聚糖纳米粒保留了TP5的生物活性并且具有浓度依赖性。结论pH-敏感壳聚糖纳米粒可能是口服胸腺五肽的良好载体。

Study on Preparation Release in Vitro and Biological Activity of Thymopentin-Loaded pH-Sensitive Chitosan Nanoparticles for Oral Administration

OBJECTIVE To prepare pH-sensitive chitosan nanoparticles,and investigate their physicochemical characteristics,drug release in vitro and biological activity in order to improve the stability and the oral bioavailability of thymopentin evaluated.METHODS Thymopentin-loaded chitosan nanoparticles were achieved by ionic gelation methods,which were coated by Eudragit S100 in order to obtain pH-sensitive nanoparticles.Nanoparticle morphology was examined by transmission electron microscope and environment scan electron microscope.Nanoparticle size and Zeta potential were measured by zetasizer nano analyser.The entrapment efficiency of TP5-loaded nanoparticles was surveyed by supercentrifugate.Dynamic dialysis technique was used to determine the releasing characteristic of nanoparticles in vitro.The biological stability of TP5-loaded nanoparticles was explored in artificial digestive juice.Biological activity was assayed by lymphocyte transformation test.RESULTS The average sizes of pH-sensitive chitosan nanoparticles were (175.6±17)nm,and the Zeta potential of the nanoparticles was(28.44±0.5)mV.The entrapment efficiency of the nanoparticles was(76.70±2.6)%.The release behavior of the pH-sensitive chitosan nanoparticles was carried in three kinds of release medium: 0.1 mol·L^-1 HCl,pH 5.0 PBS and pH 7.4 PBS,and the accumulated release percentages of thymopentin from these medium were 24.65%,41.01% and 81.44% respectively.TP5 loaded in pH-sensitive chitosan nanoparticles had good biological stability in artifical gastric fluid and its halflife in artifical intestinal fluid was 15 min.Lymphocyte transformation test verified that the pH-sensitive chitosan nanoparticles had the same biological activity as TP5 did and were concerntration-dependented.CONCLUSION These results indicate pH-sensitive chitosan nanoparticles may be used as the vector in oral drug delivery system for TP5.