Determination of Organophosphorus Pesticides Using a “Turn-Off-On” Fluorescence Platform Based on the Inner Filtering Effect and Enzymatic Reaction

With the universal use of organophosphorus pesticides (OPs), the detection of pesticide residues has become increasingly essential for maintaining human health. In this study, 4-nitrophenyl phosphate/alkaline phosphatase/conjugated polymer nanoparticles (NPP/ALP/CNPsTEB) as a sensitive “turn-off-on” fluorescence platform, were constructed to detect OP residues. The CNPsTEB showed superior fluorescence properties at a 405 nm excitation wavelength. NPP could be catalyzed into 4-nitrophenol and PO43– (NTPmix, UV 405 nm) by ALP, and the fluorescence of CNPsTEB was markedly quenched owing to the strong inner filter effect (IFE). Moreover, the fluorescence recovered when ALP was suppressed by OPs. This platform exhibits a linear detection range of 3.60 nM-0.72 μM and an LOD of 1.22 nM. Meanwhile, the platform retains high sensitivity for detecting OP residues in vegetables and water, with the spiked recovery rate achieving 93.02–107.53%. Obviously, this novel fluorescence platform can also be universally extended to real-time environmental monitoring and food safety applications for various related OP residues.