Heterojunction of CuS/MnS Employed with Multiwalled Carbon Nanotubes in Molecularly Imprinted Sensor for Selective and Sensitive Determination of Trichlorfon Residual

The abuse of trichlorfon leading a threat to human health through the food chain, it is great important to establish a selective and sensitive determination method for trichlorfon residual. Herein, a functional molecularly imprinted electrochemical sensor was constructed using CuS/MnS heterojunction and multiwalled carbon nanotubes (MWCNTs). CuS/MnS possesses a highly efficient electron transfer capacity via ion exchange interactions at a given potential, resulting in a favorable signal response. Meanwhile, the signal transmitting efficiency was further promoted by the large specific surface area of MWCNTs. In the preparation of electrochemical sensor, the CuS/MnS was modified on the electrode surface with MWCNTs, and covered by molecularly imprinted layer. The sensor was first incubated into an indicator solution containing potassium ferricyanide, producing a distinct initial signal. Once the target was present, it was identified and captured by the imprinted cavity, which blocked the electron pathway, and the potassium ferricyanide signal subsequently reduced with a measurable level. Under the optimized conditions, the two-stage linear ranges were 1.0–10 and 10–100 nM, with a detection limit of 0.37 nM. In contrast to other complex electrochemical beacons, this work induced heterojunctions and MWCNTs to obtain a satisfactory result via synergistic effect. Furthermore, the recovery rates of 93.70%–105.18% in the real sample assays suggest a prospective application of the proposed sensor in monitoring of pesticide residuals.