School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China.
College of Pharmacy, Zhejiang University of Technology, Hangzhou 310018, PR China.
Int J Pharm. 2020 Nov 30;590:119939. doi: 10.1016/j.ijpharm.2020.119939. Epub 2020 Oct 2.
Polysorbates (Tweens) are one of the most used excipients for essential oils encapsulation. In this work, the polysorbate based microemulsions (PMEs) for R-(+)-limonene (LMN) encapsulation were investigated for the structural and antimicrobial properties. PMEs were constructed using the pseudoternary phase diagrams, and then characterized for electrical conductivity, rheology, size distribution and particle geometry. Conductivity and rheological measurement results showed that Tween 80 and Tween 60 based microemulsions have identical phase transitions. Dynamic light scattering demonstrated that hydrodynamic diameters of oil-in-water microemulsions decreased from 30 nm to 25 nm during the dilution, while small-angle X-ray scattering indicated that their spherical geometries were maintained. PMEs exhibited enhanced antimicrobial efficiencies in vitro against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Interestingly, when Tween 80 was replaced by Tween 60, PME was observed more effective against S. aureus. The two PMEs structural analogues exhibited different antimicrobial efficiencies corresponding to the bioactivity of polysorbates. In conclusion, PMEs can be considered as a desirable system for LMN encapsulation to enhance its solubility and antimicrobial efficiency. Furthermore, the difference in the antimicrobial efficiency suggested that the choice of emulsifiers should be concerned to improve further applications.
聚山梨酯（吐温）是包封精油最常用的赋形剂之一。在这项工作中，研究了基于聚山梨酯的微乳液（PME）对 R-(+)-柠檬烯（LMN）的包封结构和抗菌性能。使用拟三元相图构建了 PME，并对其电导率、流变学、粒径分布和颗粒几何形状进行了表征。电导率和流变学测量结果表明，Tween 80 和 Tween 60 基微乳液具有相同的相转变。动态光散射表明，油包水乳状液的水动力直径在稀释过程中从 30nm 减小到 25nm，而小角 X 射线散射表明其球形几何形状得以保持。PME 对金黄色葡萄球菌、大肠杆菌和铜绿假单胞菌的体外抗菌效率均有提高。有趣的是，当 Tween 80 被 Tween 60 取代时，PME 对金黄色葡萄球菌的抑菌效果更为显著。两种 PME 结构类似物表现出不同的抗菌效率，这与聚山梨酯的生物活性相对应。总之，PME 可以被认为是一种理想的 LMN 包封系统，以提高其溶解度和抗菌效率。此外，抗菌效率的差异表明，应该关注乳化剂的选择，以进一步改善其应用。
