MoS2 quantum-dots as a label-free fluorescent nanoprobe for the highly selective detection of methyl parathion pesticide

Abstract

A reliable, simple, and sensitive fluorescence method was developed for the determination of methyl parathion (MP) in rice using MoS₂ quantum dots (QDs). Rapid hydrolysis of MP under alkaline conditions, and thus the formation of p-nitrophenol (p-NP) can be used for MP detection. The functional mechanism of the nanoprobe relies on p-nitrophenol-induced photoluminescence quenching of MoS₂ QDs. The high probability of resonance energy transfer (RET) stems from the spectral overlap of MoS₂ QD emission spectra and the absorption spectra of p-NP. The high value of the Stern–Volmer constant (K_SV = 3.73 × 10⁴ M⁻¹) suggests the efficient quenching of MoS₂ QDs by MP in the course of the ET process. Under optimum conditions, a linear calibration curve was obtained for the range of 0.1 μg mL⁻¹ to 30 μg mL⁻¹ of MP with a detection limit as low as 0.085 μg mL⁻¹ (S/N = 3). Furthermore, this platform allows the detection of MP in rice and tap water with satisfactory results.