Signal on-off ratiometric electrochemical sensor coupled with a molecularly imprinted polymer for the detection of carbendazim.

A stable ratiometric electrochemical sensor is introduced for the selective detection of carbendazim (CBD). Specifically, the proposed sensor employs a Co@MoC bimetallic nanomaterial as the glassy carbon electrode substrate and a layer of molecularly imprinted polymer (MIP) was in situ fabricated on glassy carbon electrode by electropolymerization, with o-aminophenol as the functional monomer and CBD acting as template. A ratiometric MIP sensor was constructed by adding ferrocene (Fc) internal reference directly to the sample solution. The bimetallic nanomaterials provide a large loading platform for the MIP layer through synergistic effects, amplifying the signal. Excellent CBD binding selectivity is achieved by the templating effect of the three-dimensional (3D) MIP layer. The internal standard is added directly to the electrolyte solution to be tested, allowing the new type of ratiometric electrochemical sensor to avoid the cumbersome steps of other methods and reducing the difficulty and human error of the experimental procedure. Combining a ratiometric strategy with a 3D MIP structure realises the dual-signal detection of CBD. The optimised sensor showed an excellent linear relationship between 0.01 and 1 000 μM, with a correlation coefficient of 0.997 and a detection limit of 3.4 nM (S/N = 3).