Dual-Probe SERS Chip: A Rapid and Ratiometric Detection of Trace Hg²⁺ in Food Samples

Rapidly and accurately identifying ultratrace mercury ions (Hg2+) to protect people’s lives and health is still challenging work. A dual-probe ratiometric SERS chip was developed by growing spiderweb-like Au nanowires (AuNWs) on an AuNP array, enhancing SERS signals and selectivity for trace Hg2+ detection. Due to the strong coordination ability of Hg2+ to form Au-SH bonds, 4-mercaptobenzoic acid (4-MBA) was replaced by the adsorption of 4-aminothiophenol (4-ATP), thereby creating a sandwich structure (Au/Hg2+/4-ATP). Moreover, the sensor exhibits excellent anti-interference capabilities, high selectivity, and rapid detection within 3 min, with a wide linear detection range of 10–3 to 10–11 M and a low detection limit of 1.35 × 10–13 M. It has been successfully used to detect Hg2+ in fish, offering a rapid and reliable method for on-site heavy metal monitoring and mitigating mercury-related risks.