An ultrasensitive label-free electrochemical aptasensing platform for thiamethoxam detection based on ZIF-67 derived Co-N doped porous carbon

Herein, a new electrochemical aptasensor was developed for the highly selective and sensitive detection of thiamethoxam (TMX). Co-N doped porous carbon (Co N C) was first modified on the glassy carbon electrode (GCE) as a conductive substrate. Then, nickel hexacyanoferrate nanoparticles (NiHCFNPs) were drop-coated on Co N C as signal probes to generate measurable redox peaks. Benefiting from the superior structural features and catalytic activity, Co N C not only facilitated the immobilization of NiHCFNPs, but also exhibited good catalytic activity for the redox of NiHCFNPs, thus clearly amplifying the sensing signal. Subsequently, gold nanoparticles (AuNPs) were deposited on NiHCFNPs/Co N C/GCE to anchor the aptamer of TMX. When TMX was captured onto the sensor via specific affinity of the aptamer, the formed TMX-Apt complex impeded electron transfer, resulting in a decrease in the peak current. Thus, TMX can be easily detected by measuring the change in peak current. The label-free aptasensor displays high sensitivity to TMX with a quite low LOD of 3.65 × 10 -3 μg/L. The acceptable recoveries of environmental water and potato samples varied from 94.05 % to 105.20 %, demonstrating the proposed aptasensor will be a promising tool for the highly sensitive, specific and reliable detection of TMX in both environmental and food matrices.