α生育酚脂质体的配方优化及其稳定性分析

Optimization of formula for α-tocopherol liposomes and their stability analysis

摘要:

为保护α-生育酚的活性并提高其稳定性,以蛋黄卵磷脂和胆固醇为壁材,吐温80作乳化剂,采用薄膜水化法制备α-生育酚脂质体. 以包封率、粒径及Zeta电位为考察指标,通过单因素试验分析磷脂与胆固醇的质量比、磷脂与α-生育酚质量比及无水乙醇体积对脂质体质量的影响. 在单因素实验的基础上,以包封率为响应值,采用响应面法优化α-生育酚脂质体的配方,并探究各个因素对其稳定性的影响. 结果表明,α-生育酚脂质体制备的最优工艺参数为:磷脂质量为280.00 mg,磷脂与胆固醇的质量比为6.22∶1,磷脂与α-生育酚的质量比为18.70∶1,无水乙醇体积为14.65 mL. 在此条件下脂质体包封率为87.39±1.12%,平均粒径为181.30±3.45 nm（PDI=0.201±0.013）,Zeta电位值为-38.90±0.32 mV. 通过电镜观察α-生育酚脂质体为球形结构,大小均匀且有较好的分散性. 稳定性分析显示脂质体在蔗糖浓度为0.5%及以下时可以很好地保持稳定,但pH、离子浓度、加热温度及时间、储藏温度及时间均显著影响其稳定性. 结果表明脂质体可以很好的保持α-生育酚的活性并提高其生物利用率,有效扩大产品的应用范围.

Abstract:

To protect the activity of α-tocopherol and improve its stability, α-tocopherol liposomes were prepared by using thin film hydration method with egg yolk lecithin and cholesterol as wall materials and Tween 80 as emulsifier. The effects of the mass ratio of phospholipids to cholesterol, the mass ratio of phospholipids to α-tocopherol, and the volume of absolute ethanol on the quality of liposomes were analyzed by single factor experiments with the entrapment efficiency, particle size, and Zeta potential as indexes. Based on the single factor experiments, response surface methodology was adopted to optimize the formula of α-tocopherol liposome with the entrapment efficiency of α-tocopherol as response value, and the influence of different factors on the stability of α-tocopherol liposomes was investigated. Results show that the optimum parameters for the preparation of α-tocopherol liposome were as follows: phospholipid, 280.00 mg; mass ratio of phospholipids to cholesterol, 6.22∶1; mass ratio of phospholipids to α-tocopherol, 18.70∶1; absolute ethanol, 14.65 mL. Under these conditions, the entrapment efficiency of α-tocopherol liposomes was 87.39±1.12%, the average particle size was 181.30±3.45 nm (PDI=0.201±0.013), and the Zeta potential value was -38.90±0.32 mV. The spherical structure of α-tocopherol liposomes, which has uniform size and good dispersion, was observed by electron microscope. Stability analysis results suggest that liposomes could be well stabilized at a sucrose concentration of 0.5% or less, but pH, ion concentration, heating temperature and time, as well as storage temperature and time all significantly affected the stability. The study indicates that liposomes can maintain the activity of α-tocopherol and improve its bioavailability to effectively expand the range of applications.