Molybdenum Disulfide/Diselenide-Laser-Induced Graphene-Glycine Oxidase Composite for Electrochemical Sensing of Glyphosate

The widespread use of the pesticide glyphosate has raised concerns regarding its potential health and environmental impacts. Consequently, there is an increasing demand for monitoring glyphosate levels in surface waters and food products. Currently, there is no commercially available rapid, field-deployable sensor capable of quantifying glyphosate concentrations in environmental samples. This study presents the development of a biosensor based on laser-induced graphene (LIG) that is functionalized with transition metal dichalcogenides (TMDs) and the enzyme glycine oxidase. The LIG is created through a scalable process using a CO2 laser to convert polyimide into a porous, nano/microstructured graphene architecture. The high surface area of LIG acts as a conductive scaffold for subsequent functionalization of both molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) to further improve the electroactive surface area of the electrode. The resultant sensors, functionalizesd with the enzyme, demonstrate linear sensing ranges from 10 to 90 mu M for glyphosate with detection limits of 4.0 and 6.1 mu M for LIG electrodes modified with MoS2 and MoSe2, respectively. Furthermore, the sensors detect glyphosphate at negative working potentials, helping to minimize interference from endogeneous electroactive species and to provide consistent glyphosphate monitoring in actual food products (i.e., soybeans and pinto beans). Overall, the biosensors integrate scalable manufacturing with cost-effective TMDs and LIG, eliminating the need for costly noble metals in the biosensor design, and offering a reliable method for assessing glyphosate in food products.