Unleashing the power of MnMoO4/rGO nanocomposite towards the electrochemical aptasensing of neurotoxic pesticide fenitrothion
J. Vinoth Kumar, Ragi Adham Elkaffas, Shimaa Eissa
Abstract
• MnMoO 4 was synthesized and engineered into a novel hexagonal morphology. • Combining MnMoO 4 with reduced graphene oxide, creates a synergistic nanostructure with enhanced properties. • Functionalized with a specific DNA aptamer, the MnMoO 4 /rGO-based aptasensor demonstrated remarkable sensitivity. • The aptasensor was successfully applied to real-world matrices such as wastewater, tap water, and rice extracts. This work presents a manganese molybdate/reduced graphene oxide (MnMoO 4 /rGO) nanocomposite as the foundation for an advanced aptamer-based electrochemical biosensor for fenitrothion (FNT), a neurotoxic organophosphate pesticide. Utilizing a modified hydrothermal synthesis method with citric acid as a surfactant, MnMoO 4 was engineered into a hexagonal morphology that, when combined with reduced graphene oxide, creates a synergistic nanostructure with enhanced conductivity, electron transfer, and active site exposure. Extensive characterization was conducted using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) to confirm the successful synthesis of the composite. The prepared composite demonstrated superior electrochemical properties compared to MnMoO 4 synthesized through urea-assisted hydrothermal and co-precipitation methods. Functionalized with a specific DNA aptamer, the MnMoO 4 /rGO-based aptasensor with an optimized ratio demonstrated remarkable sensitivity with an ultra-low detection limit of 0.3 pg/mL with wide linear ranges of 1 pg/mL to 100 µg/mL. Its high selectivity against other pesticides such as malathion, edifenphos, and imidacloprid, low relative standard deviation (RSD) values, and robust stability underscore its reliability and practicality. Successfully applied to real-world matrices such as wastewater, tap water, and rice extracts, this MnMoO 4 /rGO-based aptasensor sets a benchmark in electrochemical biosensing for environmental and food safety applications.