Electrochemical detection of Cu2+ through Ag nanoparticle assembly regulated by copper-catalyzed oxidation of cysteamine

A highly sensitive and selective electrochemical sensor was developed for the detection of Cu2+ by the assembly of Ag nanoparticles (AgNPs) at dithiobis[succinimidylpropionate] encapsulated Au nanopartides (DSP-AuNPs), which was regulated by copper-catalyzed oxidation of cysteamine (Cys). The electrochemical sensor was constructed by layer-by-layer modification of glassy carbon electrode with carbon nanotubes, poly(amidoamine) dendrimers and DSP-AuNPs. In the absence of Cu2+ Cys could bind to the surface of citrate-stabilized AgNPs via Ag-S bond, thus AgNPs could be assembled on the sensor surface through the reaction between DSP and Cys. In contrast, the copper-catalyzed oxidation of Cys by dissolved oxygen in the presence of Cu2+ inhibited the Cys-induced aggregation of AgNPs, leading to the decrease of the electrochemical stripping signal of AgNPs. Under the optimized conditions, this method could detect Cu2+ in the range of 1.0-1000 nM with a detection limit of 0.48 nM. The proposed Cu2+ sensor showed good reproducibility, stability and selectivity. It has been satisfactorily applied to determine Cu2 in water samples. (C) 2013 Elsevier B.V. All rights reserved.