Ionic liquid assisted growth of poly(3,4-ethylenedioxythiophene)/reduced graphene oxide based electrode: An improved electro-catalytic performance for the detection of organophosphorus pesticides in beverages

Abstract

An enzyme based nanocomposite host matrix comprising of Poly(3,4-ethylenedioxythiophene) and 1-Butyl-3-methylimidazolium trifluoromethanesulfonate based ionic liquid functionalized reduced graphene oxide (PEDOT/ILRGO) has been designed for the electrochemical detection of organophosphorus pesticides (OPs). Interactions between reduced graphene oxide and ionic liquid have resulted in better loading of the same onto the PEDOT matrix. A detail redox analysis highlights the increased surface area and more number of charge carriers enabling the redox inhibition mechanism more efficient in the designed electrode. The biosensor works on the principle of generation of thiocholine by reaction between acetylcholinesterase (AChE) and substrate acethylthiocholine iodide (ATChI), which undergoes oxidation resulting in redox peaks. Under the optimized conditions, three different OPs chlorpyrifos (CP), malathion (ML) and methyl parathion (MP) were analyzed by varying concentrations with limit of detection calculated to be 0.04 ng ml−1, 0.117 ng ml−1 and 0.108 ng ml−1 respectively, all below 0.2 µg ml−1 concentration which is their maximum residual limit, hence exhibiting good sensitivity. The prepared sensor offers 91.7% of reactivation and good stability for 15–20 days with 95.7% of initial current response retainment, reflecting its excellent potency as an organophosphorus pesticide sensor.