Electrochemical aptasensor based on Mo2C/Mo2N and gold nanoparticles for determination of chlorpyrifos

Two-dimensional Mo2C/Mo2N composites were synthesized by high temperature ball milling and used as support materials for fabricating a chlorpyrifos (CPF) aptasensor. Gold nanoparticles (Au NPs) were electrodeposited on the surface of a Mo2C/Mo2N-modified electrode to connect with the ferrocene (Fc) probe via Au–S bonds. The Fc probe can hybridize with the aptamer probe to form a double-stranded structure. The addition of CPF made the double strands melt and the Fc probe approached the surface of the electrode, thereby resulting in amplification of the electrochemical response. The current response of the aptasensor for detecting CPF in solutions linearly varied from 0 to 400 ng mL−1 (with a maximum at 0.98 V vs. Ag/AgCl). The Au NPs/Mo2C/Mo2N composites exhibited satisfactory electrochemical behavior due to their excellent electrical conductivity and large surface area. This ultrasensitive aptasensor showed a low limit of detection of 0.036 ng mL−1. It was applied to determine CPF in real samples with acceptable recoveries from 94.7 to 116.7%, and the relative standard deviation was from 2.57 to 7.08%.