Unleashing the power of MnMoO₄/rGO nanocomposite towards the electrochemical aptasensing of neurotoxic pesticide fenitrothion

This work presents a manganese molybdate/reduced graphene oxide (MnMoO₄/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, MnMoO₄ 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 MnMoO₄ synthesized through urea-assisted hydrothermal and co-precipitation methods. Functionalized with a specific DNA aptamer, the MnMoO₄/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 MnMoO₄/rGO-based aptasensor sets a benchmark in electrochemical biosensing for environmental and food safety applications.