Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
Mitsubishi-Chemical Foods Co., 1-1-1 Marunouchi, Chiyoda-ku, Tokyo 100-8251, Japan.
Langmuir. 2020 Jun 23;36(24):6698-6705. doi: 10.1021/acs.langmuir.0c00695. Epub 2020 Jun 11.
Drying a suspension of nanoparticles typically results in the irreversible aggregation of nanoparticles; however, solutions that contain unstable ingredients are often converted into dried powders to prolong their shelf lives. In this study, the use of a combination of a surface-active agent and sugar was investigated with regard to avoiding the aggregation of nanoparticles during drying. Suspensions of Au nanoparticles (∼60 nm diameter, AuNPs) were freeze-dried in the presence of different combinations of various sugars with a surfactant. Sucrose monopalmitate (SEC16) was mainly used as the surfactant, based on a comparison of antiaggregation effects conferred by various surfactants. The freeze-dried AuNP suspension was then reconstituted, and the avoidance of AuNP aggregation was then examined. The results demonstrated that the use of a combination of a small amount of SEC16 and sugar resulted in a greater redispersibility of AuNPs after freeze-drying than when the individual components were used. Repetition tests of freeze-drying and reconstitution were conducted. The sucrose/SEC16 mixture was freeze-dried on an electroless-plated Au film and then analyzed by infrared spectroscopy. Strong interactions between SEC16 and the Au surface were detected, and these interactions appear to play a crucial role in the antiaggregation of AuNPs during freeze-drying.
干燥悬浮的纳米粒子通常会导致纳米粒子不可逆地聚集；然而，含有不稳定成分的溶液通常被转化为干燥粉末以延长其保质期。在这项研究中，研究了表面活性剂和糖的组合在干燥过程中避免纳米粒子聚集的作用。在存在各种糖与表面活性剂的不同组合的情况下，将直径约为 60nm 的 Au 纳米粒子（AuNPs）悬浮液冷冻干燥。根据各种表面活性剂赋予的抗聚集效果的比较，主要使用蔗糖单棕榈酸酯（SEC16）作为表面活性剂。然后重新配制冷冻干燥的 AuNP 悬浮液，并检查 AuNP 聚集的避免情况。结果表明，使用少量 SEC16 和糖的组合在冷冻干燥后使 AuNP 具有更好的再分散性，而单独使用这些成分时则不然。进行了冷冻干燥和再配制的重复测试。将蔗糖/SEC16 混合物冷冻干燥在化学镀 Au 膜上，然后通过红外光谱进行分析。检测到 SEC16 和 Au 表面之间存在强烈的相互作用，这些相互作用似乎在冷冻干燥过程中对 AuNP 的抗聚集起着至关重要的作用。
