School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China; Guangxi Key Laboratory of Green Processing of Sugar Resources, Liuzhou 545006, China; Guangxi Liuzhou Luosifen Research Center of Engineering Technology, Liuzhou 545006, China.
School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China; Guangxi Key Laboratory of Green Processing of Sugar Resources, Liuzhou 545006, China.
Ultrason Sonochem. 2020 Jun;64:105018. doi: 10.1016/j.ultsonch.2020.105018. Epub 2020 Feb 11.
An ultrasonic technique was applied to formulation of two-phase water-in-paraffin oil emulsions loading a high-molecular polysaccharide chitosan (CS) and stabilized by an oil-soluble surfactant (Span80) at different operational conditions. The influence of chitosan molecular properties, phase volume ratio (φ), Span80 volume fraction (φ) and ultrasonic processing parameters were systemically investigated on the basis of mean droplet diameter (MDD) and polydispersity index (PDI) of emulsions. It was observed that the molecular weight (M) of CS was an important influential factor to MDD due to the non-Newtonian properties of CS solution varying with M. The minimum MDD of 198.5 nm with PDI of 0.326 was obtained with ultrasonic amplitude of 32% for 15 min at an optimum φ of 35%, φ of 8%, probe position of 2.2 cm to the top of emulsion, while CS with M of 400 kDa and deacetylation degree of 84.6% was used. The rise of emulsion viscosity and the reduction of negative zeta potential at φ increasing from 5% to 35% were beneficial to obtain finer droplets and more uniform distribution of emulsions, and emulsion viscosity could be represented as a monotonically-decreasing power function of MDD at the same φ. FTIR analysis indicated that the molecular structure of paraffin oil was unaffected during ultrasonication. Moreover, the emulsions exhibited a good stability at 4 °C with a slight phase separation at 25 °C after 24 h of storage. By analyzing the evolution of MDD, PDI and sedimentation index (SI) with time, coalescence model showed better fitting results as comparison to Ostwald ripening model, which demonstrated that the coalescence or flocculation was the dominant destabilizing mechanism for such W/O emulsions encapsulating CS. This study may provide a valuable contribution for the application of a non-Newtonian macromolecule solution as dispersed phase to generate nano-size W/O emulsions via ultrasound, and widen knowledge and interest of such emulsions in the functional biomaterial field.
超声技术应用于两相水包油乳液的制备，该乳液中装载了高分子多糖壳聚糖（CS），并由油溶性表面活性剂（Span80）稳定，在不同的操作条件下。在乳液的平均液滴直径（MDD）和多分散指数（PDI）的基础上，系统研究了壳聚糖分子特性、相体积比（φ）、Span80 体积分数（φ）和超声处理参数对乳液的影响。结果表明，CS 的分子量（M）是影响 MDD 的重要因素，这是由于 CS 溶液的非牛顿特性随 M 而变化。在最佳φ为 35%、φ为 8%、探头位置为乳液顶部 2.2cm 时，使用 M 为 400kDa、脱乙酰度为 84.6%的 CS，超声幅度为 32%，处理 15min，可得到最小的 MDD 为 198.5nm 和 PDI 为 0.326。随着φ从 5%增加到 35%，乳液粘度的增加和负 ζ 电位的降低有利于获得更细的液滴和更均匀的乳液分布，并且在相同的φ下，乳液粘度可以表示为 MDD 的单调递减幂函数。FTIR 分析表明，超声处理过程中石蜡油的分子结构没有受到影响。此外，在 4°C 下储存 24h 后，乳液在 25°C 时略有相分离，但仍具有良好的稳定性。通过分析 MDD、PDI 和沉降指数（SI）随时间的变化，与奥斯特瓦尔德成熟模型相比，聚结模型具有更好的拟合效果，这表明对于这种包封 CS 的 W/O 乳液，聚结或絮凝是主要的失稳机制。这项研究可能为将非牛顿大分子溶液作为分散相通过超声生成纳米级 W/O 乳液的应用提供有价值的贡献，并拓宽人们对这种在功能生物材料领域的乳液的认识和兴趣。
