Box-behnken响应面法优化茶树精油纳米脂质体的制备及其表征与抑菌活性分析

Optimization of teatree oil nanoliposomes prepared by Box-Behnken response surface method and its characterization and analysis of antibacterial activity

筛选茶树精油纳米脂质体(TTONL)最佳制备工艺并对其进行表征和抑菌效果评价。采用薄膜水化超声法制备TTONL,Box-behnken响应面法优化TTONL的制备最佳条件,并对其性能和抑菌效果进行测定。结果显示,TTONL的最佳制备条件:卵磷脂和胆固醇质量比3.7∶1,茶树精油(tea tree oil,TTO)浓度0.5%,水化介质pH 7.4,包封率为(80.31±0.56)%。透射电镜显示TTONL形状接近球形,平均粒径为(227.8±25.3)nm。红外光谱结果显示TTO被包合到脂质体内腔中。对TTONL的缓释性和稳定性进行考察,TTONL中的药物能在pH 7.4条件下缓慢释放,在42 d内,4℃环境下TTONL的粒径和多散性指数(PDI)变化都不大。体外抑菌试验表明TTONL对大肠杆菌具有很好的抑制和杀灭效果,最低抑菌浓度(MIC)为0.08%,最低杀菌浓度(MBC)为0.16%,较TTO原液相比降低;TTONL的抑菌活性与浓度呈正相关,1 MIC的TTONL处理大肠杆菌后,在8 h已完全达到杀菌效果。经优化后的TTONL形态表征良好,稳定性较好,缓释效果明显,对大肠杆菌具有显著的抑菌活性。

The aim of this study is to screen the optimal preparation process of tea tree essential oil nanoliposomes(TTONL)and to characterize and evaluate their bacterial inhibitory effects.The TTONL was prepared by thin film hydration ultrasonication method,and the Box-Behnken response surface method was used to optimize the optimal conditions for the preparation of TTONL and to determine its performance and bacterial inhibition effect.The optimal preparation conditions for TTONL were:lecithin to cholesterol mass ratio of 3.7∶1,TTO concentration of 0.5%,hydration medium pH7.4,and encapsulation rate of(80.31±0.56)%.Transmission electron microscopy showed that the shape of TTONL was close to spherical with a mean particle size of(227.8±25.3)nm,and the results of infrared spectroscopy showed that TTO was encapsulated into the inner lumen of liposomes.The slow release and stability of TTONL were investigated.The drug in TTONL was slowly released at pH7.4,and the particle size and PDI of TTONL at 4℃did not change much during 42 d.The in vitro inhibition test showed that TTONL had a good inhibitory and killing effect on E.coli with MIC of 0.08%and MBC of 0.16%,which was 4 times lower compared with the original TTO solution;the inhibition activity of TTONL was positively correlated with the concentration,and the bactericidal effect was fully achieved at 8 h after 1 MIC of TTONL treated E.coli.The optimized TTONL has good morphological characterization,good stability,obvious slow-release effect and significant bactericidal activity against E.coli.