Ultrasensitive adsorptive stripping voltammetry-free electrochemical sensor for Cu based on its specific catalytic etching to cytosine-rich oligonucleotide templated silver nanoparticles.

The development of reliable and highly sensitive copper ions (Cu) detection technologies is crucial for both environmental conservation and health surveillance. To address the challenges associated with conventional adsorptive stripping voltammetry, such as potential matrix interference, lengthy pre-electrolysis times, and limited detection sensitivity, we herein introduce an innovative electrochemical sensing approach for Cu. This method utilizes the unique catalytic etching capability of Cu on cytosine-rich oligonucleotide (CRO)-templated silver nanoparticles (AgNPs). The thiolated CRO was assembled onto the Au electrode through the Au-S bond. Subsequently, the AgNPs were generated by in-situ chemical reduction of Ag, which pre-absorbed on CRO via the cytosine-Ag-cytosine (C-Ag-C) structure. The results demonstrated that Cu could markedly speed up the etching of AgNPs, which in turn reduced the solid-state electrochemical response of AgNPs. This reduction allowed for the detection of Cu within a wide concentration range from 0.1 pM to 1.0 nM, with an impressively low detection limit of 0.03 pM. The practicality of this method has been validated through its successful application in analyzing Cu levels of the actual water samples.