Simultaneous detection of Pb2+ and Cu2+ based on catalytic etching of AgNTs@AuNHs colorimetric nanoprobe

A colorimetric gold nanohexagonals coated silver nanotriangles (AgNTs@AuNHs) nanoprobe has been constructed for the ultrasensitive detection of trace Pb 2+ and Cu 2+ , based on the fact that Pb 2+ and Cu 2+ as the catalyzer can selectively enhance the etching rate of AgNTs@AuNHs by S 2 O 3 2− . In the presence of Pb 2+ , the inner AgNTs within the AgNTs@AuNHs undergo complete etching to form the hollow AuNHs, leading to the marked decrease in both absorbance and chrominance at 585 nm. In contrast, Cu 2+ initiates an etching reaction on the AgNTs, subsequently extending to the AuNHs. These transformations give rise to the formation of hollow gold nanotriangles, accompanied by pronounced red-shifts in the absorption peaks of the detection system. The distinct optical responses induced by Pb 2+ and Cu 2+ in the AgNTs@AuNHs nanoprobe enable the sensitive and selective detection and quantification of these heavy metal ions. Furthermore, we successfully extracted RGB data from the color changes of AgNTs@AuNHs nanoprobe, enabling a straightforward visual readout for detection of Pb 2+ and Cu 2+ . This method yields satisfactory recoveries when applied to the analysis of Pb 2+ and Cu 2+ in river water, rice, and onion samples, with detection results closely matching those obtained using ICP-MS. These results collectively underscore the practical applicability of the AgNTs@AuNHs nanoprobe.