Detection of methyl parathion using a novel oxidized polylevodopa fluorescence nanosensor.

INTRODUCTION: An ultra-sensitive fluorescence sensing system was constructed for methyl parathion (MP) detection using oxidized polymer of levodopa (L-DOPA) as a novel fluorescent probe. METHODS: L-DOPA was first polymerized under alkaline conditions to form black L-DOPA polymer (PDOPA), and then H2O2 was added to oxidize it to form oxidized polymer of L-DOPA (OPDOPA), which exhibits strong blue fluorescence. Based on the alkaline-catalyzed hydrolysis of MP and the inner filter effect (IFE) between its hydrolysis product p-nitrophenol (p-NP) and OPDOPA, the detection of MP was successfully achieved. RESULTS: The OPDOPA fluorescence nanoprobe presents excellent selectivity and sensitivity for MP detection. A linear response was achieved from 0.5 to 30 µg/mL, and the limit of detection was determined to be 0.08 µg/mL. The fluorescence detection system was utilized for the determination of MP in potato and Codonopsis pilosula samples. For the actual analysis of the two sample matrices, the sensor exhibited recovery rates spanning 92.00%-106.42% and a relative standard deviation (RSD) of ≤5.83%. DISCUSSION: In this study, a functional polymer material with excellent fluorescence properties was synthesized from L-DOPA and applied to the highly sensitive and selective detection of MP. This approach not only offers a novel strategy for the detection of organophosphorus pesticides but also substantially broadens the application horizon of functional polymer materials.