School of Chemical and Biological Engineering, Seoul National University , Seoul, 151-742, Republic of Korea.
ACS Appl Mater Interfaces. 2014 Aug 13;6(15):12541-9. doi: 10.1021/am502435x. Epub 2014 Jul 15.
We explored a single-step approach for the rapid growth of Ag nanoshells (Ag NSs) under mild conditions. Without predeposition of seed metals, a uniform and complete layer of Ag shells was rapidly formed on silica core particles within 2 min at 25 °C via single electron transfer from octylamine to Ag(+) ions. The size and thickness of the Ag NSs were effectively tuned by adjusting the concentration of silica nanoparticles (silica NPs) with optimal concentrations of AgNO3 and octylamine. This unusually rapid growth of Ag NSs was attributed to a significant increase in the reduction potential of the Ag(+) ions in ethylene glycol (EG) through the formation of an Ag/EG complex, which in turn led to their facile reduction by octylamine, even at room temperature. A substantial enhancement in the surface-enhanced Raman scattering (SERS) of the prepared Ag NSs was demonstrated. The Ag NSs were also utilized as SERS-active nanostructures for label-free detection of the pesticide thiram. The Ag NS-based SERS approach successfully detected thiram on apple peel down to the level of 38 ng/cm(2) in a label-free manner, which is very promising with respect to its potential use for the on-site detection of residual pesticides.
我们探索了一种在温和条件下快速生长 Ag 纳米壳（Ag NSs）的单步方法。在没有预沉积种子金属的情况下，Ag(+)离子通过单电子转移在 25°C 下在 2 分钟内迅速在二氧化硅核粒子上形成均匀且完整的 Ag 壳层。通过调整二氧化硅纳米粒子（SiO2 NPs）的浓度，可以有效地调节 Ag NSs 的尺寸和厚度，同时优化 AgNO3 和辛胺的浓度。这种异常快速的 Ag NSs 生长归因于 Ag/EG 配合物的形成，从而使乙二醇（EG）中 Ag(+)离子的还原电位显著增加，这反过来又使它们易于被辛胺还原，即使在室温下也是如此。所制备的 Ag NSs 的表面增强拉曼散射（SERS）得到了显著增强。Ag NSs 还被用作无标记检测农药 thiram 的 SERS 活性纳米结构。基于 Ag NS 的 SERS 方法成功地以无标记方式检测到苹果皮上的 thiram，其浓度低至 38ng/cm(2)，这对于其在现场检测残留农药方面的潜在用途非常有前途。
