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

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.