Covalent anchoring of multifunctionized gold nanoparticles on electrodes towards an electrochemical sensor for the detection of cadmium ions

This paper reports an electrochemical sensor based on the covalent anchoring of aryldiazonium salt modified AuNPs to gold electrodes for the sensitive detection of cadmium ions (Cd²⁺). AuNPs modified with 4-nitrophenyl and 4-carboxylphenyl were first prepared, which were then immobilized in situ on gold electrodes to achieve Au-Ph-AuNP modified interfaces. Glutathione (GSH) was finally modified to Au-Ph-AuNP by amide bonding to achieve an Au-Ph-AuNP-GSH sensing interface, which was used to detect Cd²⁺ over the concentration range from 0.1 nM to 100 nM with a detection limit of 0.1 nM. This electrochemical sensor demonstrated high stability and sensitivity to Cd²⁺. It has potential use in an in situ anchoring AuNP strategy to fabricate portable devices for the onsite monitoring of trace amounts of heavy metals.