Moran Christine H, Rycenga Matthew, Zhang Qiang, Xia Younan
Department of Biomedical Engineering, Washington University, St Louis, Missouri 63130, United States.
J Phys Chem C Nanomater Interfaces. 2011 Nov 10;115(44):21852-21857. doi: 10.1021/jp207868a.
In this work, we used surface-enhanced Raman scattering (SERS) to monitor the replacement of poly(vinyl pyrrolidone) (PVP) on Ag nanocubes by cysteamine, thiol-terminated PEG, and benzenedithiol. PVP is widely used as a colloidal stabilizer and capping agent to control the shape of Ag (as well as many other noble metals) nanocrystals during synthesis, and to stabilize the final colloidal suspension. However, the surface chemistry of Ag nanocrystals often needs to be tailored for specific applications, so the PVP coating must be removed and/or replaced by other ligands. By monitoring the signature peak from the carbonyl groups of PVP, we show, for the first time, that the PVP adsorbed on the surface of Ag nanocubes was completely replaced by the thiol molecules at room temperature over the course of a few hours. We observed the same trend no matter if the Ag nanocubes were suspended in an aqueous solution of the thiol or supported on a silicon substrate and then immersed in the thiol solution.
在这项工作中，我们使用表面增强拉曼散射（SERS）来监测半胱胺、巯基封端的聚乙二醇和苯二硫醇对银纳米立方体上聚乙烯吡咯烷酮（PVP）的取代情况。PVP被广泛用作胶体稳定剂和封端剂，以在合成过程中控制银（以及许多其他贵金属）纳米晶体的形状，并稳定最终的胶体悬浮液。然而，银纳米晶体的表面化学性质通常需要针对特定应用进行调整，因此必须去除PVP涂层和/或用其他配体取代它。通过监测PVP羰基的特征峰，我们首次表明，在室温下，吸附在银纳米立方体表面的PVP在几个小时内被硫醇分子完全取代。无论银纳米立方体是悬浮在硫醇的水溶液中，还是支撑在硅基板上然后浸入硫醇溶液中，我们都观察到了相同的趋势。
