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 (CH Hg ) 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 CH Hg 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 CH Hg due to the synergistic effect of MnO and AuNPs. Square wave anodic stripping voltammetry (SWASV) was used as the sensing technique for CH Hg , and the stripping peak current showed a good linear relationship with CH Hg 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 CH Hg detection can be avoided by the addition of diethylene triamine pentaacetic acid (DTPA). The as-prepared sensor was applied to detect CH Hg in various food samples with satisfactory recoveries, thus providing a promising platform for rapid screening of methylmercury residues.