Affordable and sensitive dual-system electrochemical detection of organophosphorus pesticide residues based on hybridized lipase/AuNPs sensor

Organophosphorus pesticides (OPs) are one of the most widely used pesticides in agricultural production, which can cause accumulation of acetylcholine, overstimulation of synaptic receptors, and ultimately lead to neurological damage. Based on the activity of hybrid lipase to catalyze the hydrolysis of OPs to produce P-NP and the inhibition of its ability to hydrolyze P-NPP by OPs, a dual assay system has been developed, which enables the detection of OPs with high sensitivity and low cost. Meanwhile, a hybridization lipase (BCL@Zn-hNF) with high catalytic activity and large surface area was prepared, and a cascaded sensor simulating peroxidase activity (BCL@Zn-hNF/AuNPs/Au) was established and used for electrochemical biosensor detection of OPs residues. In addition, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results show that BCL@Zn-hNF consists of interlaced lamellar structures. Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and particle size analysis confirm the presence of phosphates. The hybridization process did not significantly affect its crystal morphology with good stability and dispersion. These results confirm the successful preparation of BCL@Zn-hNF. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) verified that adding BCL@Zn-hNF increased the sensor's catalytic rate. The sensor exhibited good sensitivity (5.182 × 10 8 A M −1  cm −2 ), a wide linear range (3.80 × 10 −8 –4.56 × 10 −5  M), and a low detection limit (1.03 × 10 −9  M) for the indirect detection of OPs compared with the direct detection. Meanwhile, it has good reproducibility, stability, and immunity to interference in the detection of OPs, and good recovery for the detection of MP residues in real samples.