Colorimetric Detection of Trace Arsenic(III) in Aqueous Solution Using Arsenic Aptamer and Gold Nanoparticles

In this study, trace arsenic(iii) (As-III) in aqueous solution was detected by applying a classical aptamer-based gold nanoparticles colorimetric sensing strategy. An arsenic aptamer was used as a sensing probe and gold nanoparticles as a colorimetric indicator. In the absence of As-III, the gold nanoparticles were stabilised by the arsenic aptamer and remained dispersed at high NaCl concentrations, displaying a red solution. Contrarily, in the presence of As-III, the gold nanoparticles were prone to aggregation, owing to the formation of aptamer-As-III complex between the arsenic aptamer and As-III, and thus exhibited a blue solution. By monitoring the colour change, a simple and fast colorimetric assay for As-III was established with a detection range of 1.26-200 ppb and a detection limit of 1.26 ppb. Because this colorimetric assay only involves common reagents and can be assessed visually, it holds great potential for arsenic(iii) monitoring in environment-related and other applications.