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

The inclusion of methylmercury (CH3Hg+) 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 (MnO2)/gold nanoparticles (AuNPs) composites is fabricated for CH3Hg+ detection in food. The MnO2/AuNPs nanocomposites were synthesized in situ 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 MnO2/AuNPs modified electrode exhibited a large active surface area, enhanced conductivity and excellent electrocatalytic activity toward CH3Hg+ due to the synergistic effect of MnO2 and AuNPs. Square wave anodic stripping voltammetry (SWASV) was used as the sensing technique for CH3Hg+, and the stripping peak current showed a good linear relationship with CH3Hg+ concentration in the range of 0.7-15 μg L-1 with a detection limit of 0.051 μg L-1. Besides, the interference from Hg2+ associated with CH3Hg+ detection can be avoided by the addition of diethylene triamine pentaacetic acid (DTPA). The as-prepared sensor was applied to detect CH3Hg+ in various food samples with satisfactory recoveries, thus providing a promising platform for rapid screening of methylmercury residues.