Disposable tungsten sulfide framed polydopamine nanostructure modified sensor for non-enzymatic electrochemical detection of organophosphate pesticide

Pesticide residues pose a global threat to human health, and conventional sensors cannot simultaneously detect pesticide residues on the surface and inside agricultural products. Therefore, it opens up an opportunity to develop efficient techniques for the optimal detection of pesticides residues, enhancing agricultural productivity while simultaneously reducing associated health risks This work presents a polydopamine functionalized tungsten sulfide self-assembled nanostructure (WS2-PDA) electrocatalyst capable of detecting organophosphorus paraoxon ethyl (PXL) pesticide. The structural properties of the WS2-PDA nanostructure were analyzed for their morphology, crystallinity using various microscopy and spectroscopic techniques. The electrochemical experiments involving cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were conducted to investigate the electrochemical behavior of the WS2-PDA modified screen-printed carbon electrode (SPCE) toward PXL. Intermolecular interactions of polydopamine, presenting catechol, imine and amine functional group on the WS2 ionic surface via coordination complex enhance the binding ability, leading to improved ionic conductivity, electrode activity, and a higher active surface area ensued fast electron transferability. According to the findings, the DPV cathodic peak current response of the modified electrode revealed sensitive detection of PXL, with a lower detection limit (LOD) of 0.0021 μM (S/N = 3). Following that, the electrode exhibited two linear concentration ranges from 0.01 μM to 443.09 μM, and 443.09 μM to 521.34 μM, with a sensitivity of 0.310 µA µM−1 cm2. Likewise, the proposed sensors exhibited excellent repeatability, reproducibility, and selectivity over common interferents. Subsequently, it demonstrated outstanding stability with a relative standard deviation (RSD) of < 2.24%. Finally, the WS2-PDA/SPCE sensor achieved good recovery results in the presence of water, soil, and food samples.