Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Langmuir. 2021 Jun 29;37(25):7712-7719. doi: 10.1021/acs.langmuir.1c00744. Epub 2021 May 23.
Composite colloidal nanoparticles were prepared by a carbonate controlled-addition method in the presence of phytic acid, in which an aqueous ammonium carbonate solution was added into an aqueous solution of phytic acid and CaCl. The number-average particle size of the colloidal particles was 76 ± 18 nm formed by using the molar ratio [phytic acid]/[Ca] = 0.5 from the complexation time of 1 h. The composite nanoparticles were stable for more than 5 days in the suspension under the quiescent condition. After isolation of the nanoparticles by ultrafiltration, the dried samples could be redispersed in water. Effects of the complexation times of the aqueous solution of phytic acid and CaCl and the molar ratio ([phytic acid]/[Ca]) were studied. Increasing the concentration of the calcium reagents as well as increasing the complexation times increased the particle sizes. The minimum and maximum average particle sizes of 29 and 142 nm were obtained. The plot of the transmittance at 350 nm of the aqueous solution of the dispersion against pH values after addition of 0.05 M HCl for 6 h showed that, by gradually increasing turbidity with decreasing pH from 9.6 to 7.3, precipitates were recognized at below pH 7.5, and turbidity decreased with further decreasing pH beyond 7.2. Dynamic light scattering analysis showed that the particle diameters increased from 90 to 200 nm with decreasing pH from 9.6 to 7.2. When increasing the pH from 6.2, the precipitate was redispersed and the turbidity increased to a pH of 7.4. No precipitates were observed above a pH of 7.4. These results suggest that the present phytic acid stabilized nanoparticles exhibit pH-dependent reversible precipitation and redispersion without degradation under slightly acidic conditions.
复合胶体纳米粒子是通过在植酸存在下采用碳酸盐控制添加法制备的，其中将碳酸铵水溶液加入到植酸和 CaCl 的水溶液中。使用[植酸]/[Ca]摩尔比为 0.5，复合物时间为 1 h 时，胶体颗粒的数均粒径为 76±18nm。在静置条件下，复合纳米粒子在悬浮液中稳定 5 天以上。通过超滤分离纳米粒子后，干燥样品可以重新分散在水中。研究了植酸水溶液和 CaCl 的复合物时间以及摩尔比([植酸]/[Ca])的影响。增加钙试剂的浓度以及增加复合物时间会增加粒径。获得的最小和最大平均粒径分别为 29nm 和 142nm。在添加 0.05 M HCl 6 h 后，分散体水溶液在 350nm 处的透光率与 pH 值的关系图表明，随着 pH 值从 9.6 逐渐降低至 7.3，浊度逐渐增加，在 pH 低于 7.5 时可以识别出沉淀物，而在 pH 超过 7.2 时浊度会进一步降低。动态光散射分析表明，随着 pH 值从 9.6 降低至 7.2，粒径从 90nm 增加至 200nm。当 pH 值从 6.2 增加时，沉淀物重新分散，浊度增加到 pH 值为 7.4。当 pH 值高于 7.4 时，没有观察到沉淀物。这些结果表明，本研究中的植酸稳定的纳米粒子在略微酸性条件下表现出 pH 依赖性的可逆沉淀和再分散，而不会降解。
