A Cu-triggered turn-on fluorescence non-enzymatic probe based on covalent organic framework for the detection of methyl parathion.

Background: Methyl parathion, a potent organophosphorus insecticide, is extensively employed in agriculture and animal husbandry, leading to significant environmental contamination with pesticide residues, posing a grave threat to human health. This compound irreversibly inhibits acetylcholinesterase (AChE) in the human nervous system, resulting in the accumulation of acetylcholine (ACh), which is detrimental. Various enzyme activity-based assays have been explored due to its pathogenic mechanism, yet these methods are fraught with limitations. Thus, the development of a highly selective, sensitive, rapid, and effective method for detecting methyl parathion residues is crucial.

Result: In this study, we introduce a novel, non-enzymatic fluorescent probe for methyl parathion detection. This probe is designed to specifically trigger the fluorescence signal of TAPB-DMTA-COF through the interaction of copper ions with the imine moiety within the TAPB-DMTA-COF structure. The detection of methyl parathion in aqueous environments is facilitated by the Inner filter effect. Compared to previously reported enzyme-catalyzed reaction probes, this probe exhibits a faster reaction time, is not influenced by enzyme activity, and demonstrates high specificity and sensitivity. The probe exhibits a good linear response in the concentration range of 0.56-5.46 μM, with a detection limit of 30.698 nM. Furthermore, the probe yielded satisfactory recoveries of methyl parathion (93.47 %-99.5 %) in different real water samples through spiking recovery experiments.

Significance: The fluorescent probe based on Cu/TAPB-DMTA-COF realizes the fluorescence detection of methyl parathion. The establishment of this simple, efficient, and rapid detection platform offers a new approach for the detection of pesticide residues in aquatic environments. The introduction of metal ions, along with the construction of COF materials and the use of fluorescence signal turn-on, provides a rational design strategy for such detection methods.