Cu Nanoclusters for Electrochemical Sensing of picomoles of Hg2+

The detection of Hg2+ is critical to health and environmental safety due to its high toxicity and widespread contamination. Therefore, the need for accurate and sensitive detection methods is driven by health risks and strict regulatory limits for mercury in water and food. In this context, in the present study we report on the development of the first electrochemical sensor based on copper nanoclusters for the selective and ultrasensitive detection of mercury ions (Hg2+). These copper nanoclusters were previously synthesized via a water-stable protocol and immobilized onto screen-printed carbon electrodes, resulting in a robust and conductive sensing interface. These electrodes exhibit outstanding sensing activity toward Hg2+, thus achieving a remarkably low limit of detection of just 30 picomolar. Moreover, the sensor demonstrates excellent selectivity against competing metal ions, long-term stability in aqueous environments, and high reproducibility. Its practical applicability was also validated through the quantification of Hg2+ in real-world samples, including seawater and fish tissue extracts. This work presents a cost-effective, scalable, and environmentally friendly approach to mercury monitoring, offering a compelling alternative to more sophisticated analytical techniques and the electrode platform establishes a precedent for future low-cost, nanomaterial-based electrochemical sensors aimed at environmental and food safety diagnostics.