An ultrasensitive electrochemical sensor based on synthesized manganese dioxide/gold nanoparticles nanocomposites for rapid detection of methylmercury in foodstuffs.

The inclusion of methylmercury (CHHg) in the environment and food chain has aroused wide concern due to its high neurotoxicity and cumulative effects. Herein, a highly sensitive electrochemical sensor based on manganese dioxide (MnO)/gold nanoparticles (AuNPs) composites is fabricated for CHHg detection in food. The MnO/AuNPs nanocomposites were synthesized on the surface of a glassy carbon electrode by an electrodeposition method and were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The resulting MnO/AuNPs modified electrode exhibited a large active surface area, enhanced conductivity and excellent electrocatalytic activity toward CHHg due to the synergistic effect of MnO and AuNPs. Square wave anodic stripping voltammetry (SWASV) was used as the sensing technique for CHHg, and the stripping peak current showed a good linear relationship with CHHg concentration in the range of 0.7-15 μg L with a detection limit of 0.051 μg L. Besides, the interference from Hg associated with CHHg detection can be avoided by the addition of diethylene triamine pentaacetic acid (DTPA). The as-prepared sensor was applied to detect CHHg in various food samples with satisfactory recoveries, thus providing a promising platform for rapid screening of methylmercury residues.