Rapid and selective electrochemical detection of pb2+ ions using aptamer-conjugated alloy nanoparticles

Heavy metals are an important class of technogenic toxicants that pollute rivers and underground water. Here we proposed the use of electrochemical methods using silver (Ag)-gold (Au) alloy nanoparticle (NP)-aptamer-modified glassy carbon electrode (GCE) for the detection of lead ions (Pb2+). Alloy Ag-Au NPs were electrodeposited on the electrode using the potentiostatic double-pulse method. The NPs were characterized by high-resolution transmission electron microscopy, which revealed that the average NP size was 44 nm. The binding of Pb2+ induced conformational changes of the aptamer and corresponding modulation of electrochemical signals. As a result, we were able to detect Pb2+ with a straight slope of 0.01-10 mu g/L with limits of detection (LOD) of 0.03 x 10(-2) mu g/L for CV, DPV and 0.04 x 10(-2) mu g/L for EIS. The minimum detectable Pb2+ concentration was calculated to be 0.8 mu M.