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

• Electrochemical detection of Cu2+ was proposed by using copper-catalyzed oxidation of cysteamine.
• Ag nanoparticle assembly on DSP-terminated sensor was regulated by a Cu2+-induced reaction.
• The low electron transfer resistance of the sensor improved greatly the detection sensitivity.
• The assay excluded the specific detection conditions needed in click chemistry-based assay.
• The sensor for Cu2+showed good performance.

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 nanoparticles (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.