MnO2 nanosheets anchored gold nanoclusters@ZIF-8 based ratiometric fluorescence sensor for monitoring chlorpyrifos degradation

Abstract

Given the potential hazards of organophosphorus pesticides (OPs) to food safety, developing sensitive and reliable sensors for OPs is highly urgent. Herein, a new ratiometric fluorescence strategy with high sensitivity and good anti-interference ability is developed for monitoring chlorpyrifos based on manganese dioxide nanosheets anchored gold nanoclusters@zeolitic imidazolate framework-8 composite (MnO2-AuNCs@ZIF-8). The MnO2-AuNCs@ZIF-8 composite integrates the fluorescence property of AuNCs, the protection capacity of ZIF-8 and the dual function of MnO2 (quencher and inorganic catalyst), which enhanced sensing sensitivity via boosting the energy transfer and anti-interference ability by avoiding background effect. The fluorescence emission intensity of AuNCs@ZIF-8 at 635 nm and MnO2 catalytic products (2,3-diaminophenazine) at 535 nm can form a typical ratiometric with good anti-interference ability. MnO2-AuNCs@ZIF-8 composites can recognize the acetylcholinesterase hydrolysis products (thiocholine), owing to the analyte-initiated reduction of MnO2. Coupling with OPs inhibition effect, a ratiometric fluorescence platform is constructed for sensitive detection of chlorpyrifos with a detection limit of 0.22 ng mL−1. The ratiometric fluorescence sensor is effectively applied for precisely monitoring the residue and degradation of chlorpyrifos in pakchoi, endowing the practical application in food safety monitoring.