Highly sensitive turn-on electrochemical sensing of organophosphorus pesticides by integration of homogeneous reaction and heterogeneous catalytic signal amplification.

Enzyme-inhibited electrochemical sensor is a promising strategy for detecting organophosphorus pesticides (OPs). However, the poor stability of enzymes and the high oxidation potential of thiocholine signal probe limit their potential applications. To address this issue, an indirect strategy was proposed for highly sensitive and reliable detection of chlorpyrifos by integrating homogeneous reaction and heterogeneous catalysis. In the homogeneous reaction, Hg2+ with low oxidation potential was employed as signal probe for chlorpyrifos detection since its electroactivity can be inhibited by thiocholine, which was the hydrolysate of acetylthiocholine catalyzed by acetylcholinesterase. Additionally, Co,N-doped hollow porous carbon nanocage@carbon nanotubes (Co,N-HPNC@CNT) derived from ZIF-8@ZIF-67 was utilized as high-performance electrode material to amplify the stripping voltammetry signal of Hg2+. Thanks to their synergistic effect, the sensor exhibited outstanding sensing performance, excellent stability and good anti-interference ability. This strategy paves the way for the development of high-performance OP sensors and their application in food safety.