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

Abstract

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 µg/L with limits of detection (LOD) of 0.03 × 10−2 μg/L for CV, DPV and 0.04 × 10–2 μg/L for EIS. The minimum detectable Pb2+ concentration was calculated to be 0.8 μM. Graphic abstract: [Figure not available: see fulltext.].