Rapid Detection\nof Methyl Parathion Based on SiONPs-Eu<sup>3+</sup> Dual-Emitting\nFluoroprobe and Its On-Site Application

Herein, we pioneered an innovative methodology for the\nrapid identification\nand quantitation of methyl parathion (MP) residues, overcoming the\ndrawbacks of existing methods such as poor selectivity, high costs,\nand intricate operational procedures. A dual-emitting fluoroprobe\nSiONPs-Eu<sup>3+</sup> was engineered based on silica oxide nanoparticles\n(SiONPs) conjugated with Eu<sup>3+</sup>, and the synthetic conditions\nwere meticulously optimized to ensure exceptional sensitivity and\nselectivity to 4-nitrophenol (4-NP), one of the MP hydrolytic products.\nUpon excitation at 317 nm, the blue fluorescence of SiONPs at 400\nnm was quenched, while the red fluorescence of Eu<sup>3+</sup> at\n616 nm remained nearly unchanged, constituting a ratiometric fluorescent\nchange that significantly enhanced the detection stability. The fluoroprobe\nrapidly detected 4-NP at concentrations below 80 μM within 10\ns and gave a limit of detection (LOD) as low as 0.16 μM, markedly\nlower than the allowable residue limit of MP in China food safety\nstandards. Also, it exhibited excellent anti-interference properties\nin complex matrices, remaining unaffected by common amino acids, cations,\nand pesticides. The underlying mechanism of the fluoroprobe was elucidated\nthrough time-dependent density functional theory (TD-DFT) calculations.\nUnder optimized hydrolysis conditions, the detection of MP in real\nrice samples was successfully achieved. Furthermore, the self-developed\nand dual-channel portable device was conducive to on-site fluorescence\ndetection of 4-NP, offering enhanced stability in contrast to traditional\nphotography-based methods.