An acylaminoacyl-peptide hydrolase-activated fluorescent probe for ultrasensitive detection of pesticide residue

Abstract

Due to increasing threats to global public health and widespread environmental pollution issues caused by improper and excessive application of pesticides, the detection of pesticide residues is important in securing food safety and responding to public health. However, conventional methods for pesticide residues detection were usually labor- and time-consuming, making the acquisition of efficient tools for rapid and sensitive detection of pesticide residues an urgent need. Enzyme-targeted organic fluorescent probes, which displayed high simplicity and sensitivity, have shown great potential in enzyme inhibition-based pesticide residues detection and related bioimaging. Among these, fluorescent probes-based biosensors for pesticide targeted serine hydrolyses such as carboxylesterases and cholinesterases have been widely developed.

Acylaminoacyl-peptidase hydrolase (APEH), a serine hydrolase with typical α/β fold structure, is a promising protein target for pesticides such as organophosphorus (OPs) and carbamate. However, no fluorescent probe targeting APEH has been reported for pesticide detection or related research. To address this, an enzyme-activated fluorescent probe (named as RH-AcA) with high sensitivity (limit of detection = 3.7 mU/mL), binding affinity (K_m = 6.49 ± 0.29 μM) and high specificity toward APEH was constructed whilst inhibitory efficacy of different pesticides toward APEH in living cells and zebrafish was first visualized. Most importantly, APEH-inhibition-based pesticide residues detection was first achieved using RH-AcA, revealing significantly higher detection sensitivity toward OPs compared to esterase-based fluorescent probes This demonstrated APEH is a promising non-esterase target for enzyme-inhibition-based pesticide residues detection, and RH-AcA could serve as an ultrasensitive and practical tool for pesticides detection and related bioimaging.