Electrochemical Sensing of Neonicotinoids Using Laser-Induced\nGraphene

Abstract

Neonicotinoids are\nthe fastest-growing insecticide accounting for\nover 25% of the global pesticide market and are capable of controlling\na range of pests that damage croplands, home yards/gardens, and golf\ncourse greens. However, widespread use has led to nontarget organism\ndecline in pollinators, insects, and birds, while chronic, sublethal\neffects on humans are still largely unknown. Therefore, there is a\nneed to understand how prevalent neonicotinoids are in the environment\nas there are currently no commercially available field-deployable\nsensors capable of measuring neonicotinoid concentrations in surface\nwaters. Herein, we report the first example of a laser-induced graphene\n(LIG) platform that utilizes electrochemical sensing for neonicotinoid\ndetection. These graphene-based sensors are created through a scalable\ndirect-write laser fabrication process that converts polyimide into\nLIG, which eliminates the need for chemical synthesis of graphene,\nink formulation, masks, stencils, pattern rolls, and postprint annealing\ncommonly associated with other printed graphene sensors. The LIG electrodes\nwere capable of monitoring four major neonicotinoids (CLO, IMD, TMX,\nand DNT) with low detection limits (CLO, 823 nM; IMD, 384 nM; TMX,\n338 nM; and DNT, 682 nM) and a rapid response time (∼10 s)\nusing square-wave voltammetry without chemical/biological functionalization.\nInterference testing exhibited negligible responses from widely used\npesticides including the broad-leaf insecticides parathion, paraoxon,\nand fipronil, as well as systemic herbicides glyphosate (roundup),\natrazine, dicamba, and 2,4-dichlorophenoxyacetic acid. These scalable,\ngraphene-based sensors have the potential for wide-scale mapping of\nneonicotinoids in watersheds and potential use in numerous electrochemical\nsensor devices.