Metal Organic Framework steered electrosynthesis of anisotropic gold nanorods for specific sensing of organophosphate pesticides in vegetables collected from the field

Abstract

The uncontrolled use of organophosphate (OP) group of pesticides has led to their accumulation in food and vegetables, causing major health issues. Hence, the development of a reliable sensor is imperative for the detection of neurotoxic organophosphates (OP). In the present study, we have intertwined the interfaces of a Metal Organic Framework (MOF), MOF-directed rapid electrochemically grown gold nanorods (aAuNR), cysteamine (Cys) functionalization, and the neurotransmitter acetylcholinesterase (AChE) to fabricate a novel electrochemical bioprobe AChE/Cys/aAuNR/MOF/ITO for sensing OP pesticides with an ultra-low detection limit of 3 ng L⁻¹ over a linear range of 30 to 600 ng L⁻¹. Prior to sensing, in silico docking studies were employed for tracking the structural aspects of the molecular recognition of specific OP as potential inhibitors. The sensor can quantify residues of sprayed OP (chlorpyrifos, malathion, parathion, methyl parathion, ethion) in field vegetables (Abelmoschus esculentus, Solanum melongena, Capsicum annuum, Momordica charantia Linn) using a single calibration curve designed using chlorpyrifos, and the results were validated via gas chromatography-electron capture detector (GC-ECD) measurements. The inhibition rate kinetics of structurally different OP (chlorpyrifos, malathion, methyl parathion) were studied via the bioprobe and further validated using the standard Ellman method, confirming the practical applicability of the sensor for the detection of a specific group of OP. The bioprobe AChE/Cys/aAuNR/MOF/ITO offers good stability, specificity, and anti-interference properties for the detection of OP in real samples.