Ionic Strength and pH Responsive Permeability of Soy Glycinin Microcapsules
Ionic Strength and pH Responsive Permeability of Soy Glycinin Microcapsules
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DOI：
10.1021/acs.langmuir.8b01559
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发表时间：
2018-08-21
期刊：
影响因子：
3.9
通讯作者：
Wang, Qin
中科院分区：
文献类型：
--
作者：
Chen, Nannan;Zhang, Jinglin;Wang, Qin
近年来，通过加热微相分离的大豆球蛋白微区，简单地制备了中空蛋白微胶囊。然而，属性（例如，机械性能和渗透性）是未知的。在这项研究中，大豆球蛋白微胶囊的渗透性进行了研究，通过共聚焦激光扫描显微镜（CLSM），离子强度和pH值的影响，使用异硫氰酸荧光素-葡聚糖（FITC-葡聚糖）。大豆球蛋白微囊在pH 1 ~ 11.5范围内保持完整性，pH低于3或高于11时膨胀，pH高于11.5时解离，pH 1时略有消胀。当pH值增加到11以上时，微胶囊的渗透性显著增加。值得注意的是，当pH低于大豆球蛋白的等电点（接近pH 5）时，FITC-葡聚糖自发地积累在微胶囊内，其浓度显著高于本体溶液中的浓度，如荧光强度的强烈增加所证明的。这种独特的特征显著增加了FITC-葡聚糖的负载量。微胶囊的渗透性也增加，通过添加盐，但不显着比通过调节pH值。微胶囊的表面变得粗糙时，渗透性增加，这是揭示了通过扫描电子显微镜。结果表明，大豆球蛋白作为壁材制备中空微胶囊具有很大的潜力，可在生物医药和食品工业中得到应用。
Recently, hollow protein microcapsules have been made simply by heating the microphase separated soy glycinin microdomains. However, the properties (e.g., mechanical properties and permeability) that relate to the application of these microcapsules are unknown. In this study, the permeability of the soy glycinin microcapsules was investigated by confocal laser scanning microscopy (CLSM), as influenced by ionic strength and pH using fluorescein isothiocyanate-dextran (FITC-dextran). The glycinin microcapsules kept the integrity between pH 1 and 11.5, swelled when pH was below 3 or above pH 11, dissociated at pH above 11.5 and deswelled slightly at pH 1. When the pH increased above 11, the permeability of the microcapsule significantly increased. Remarkably, when the pH was below the isoelectric point of glycinin (approximate to pH 5), FITC-dextran spontaneously accumulated inside the microcapsule with a significantly higher concentration than that in bulk solution, as evidenced by the strong intensity increase of fluorescence. This unique feature significantly increased the loading amount of FITC-dextran. The permeability of microcapsules was also increased by adding salt but less significant than by adjusting pH. The surface of the microcapsules became coarser when the permeability increased, which was revealed by scanning electron microscopy. These results show that soy glycinin has a great potential to be used as a wall material to fabricate hollow microcapsules that could find applications in biomedicine and food industry.