Organophosphorus pesticides (OPPs) are extensively used
in agricultural
production, and the contamination caused by their residues has raised
significant concerns regarding potential threats to human health.
Herein, a novel fluorescence nanoprobe based on an enzyme-mediated
silver nanoparticle-modified metal organic framework (AgNPs@PCN-224)
was successfully prepared for the rapid detection of OPPs. Initially,
AgNPs@PCN-224 were synthesized by reducing silver nitrate (AgNO3) using sodium borohydride (NaBH4) embedded into
luminescent PCN-224. This triggered the inner filter effect, leading
to fluorescence quenching. Meanwhile, under the catalysis of acetylcholinesterase
(AChE) and choline oxidase (CHO), acetylcholine (ATCh) was decomposed
to hydrogen peroxide (H2O2), which could destroy
AgNPs to form Ag+ released from PCN-224 for fluorescence
recovery. Instead, fenitrothion, an OPP, inhibited AChE activity,
allowing the quenched fluorescence to be reactivated. Under the current
optimum conditions, the fluorescence intensity had a good correlation
(Y = −728.5370X + 2178.4248, R
2 = 0.9869) over a dynamic range of fenitrothion
concentrations from 0.1 to 500 ng/mL, with an LOD of 0.037 ng/mL.
In addition, the anti-interference ability and robustness of the proposed
sensor was verified for the monitoring of fenitrothion in tea with
recoveries of 87.67–103.72% and the relative standard deviations
(RSD) < 5.43%, indicating that the system has excellent prospects
for OPP determination in practical applications. Furthermore, this
work provides a universal platform for screening other enzyme inhibitors
to detect OPPs.