Au@Ag Core/Shell Nanorods Based Colorimetric Assay for the Rapid and Selective Detection of Cyanide Anions

Abstract

A colorimetric assay based on Au@Ag core/shell nanorods was developed to rapidly determine cyanide in aqueous solution. The aspect ratios of Au@Ag core/shell nanorods were changed with the dissolution of metals in cyanide solution, which led to the decrease of Ag shell absorption spectra and the blue shift of longitudinal plasmon absorption band of Au core, as well as the color change of Au@Ag core/shell nanorods. In contrast to spherical Au@Ag nanoparticles with less sample analysis time (1 min per sample), the distinguish ability of this assay was proven to be higher. Under optimal conditions, the developed colorimetric assay gave a linear range of 1–200 μM for cyanide in water solution and a naked-eye detection limit of 0.5 μM. On the side, the colorimetric assay exhibited high selectivity towards cyanide over other common anions. The developed Au@Ag nanorods probes have been successfully applied to determine the level of cyanide in local lake, river and industrial water samples.