Iron and copper codoped carbon nanodots as oxidase mimics and fluorescent probes for detection of phenol and dimethoate

Fluorescent nanozymes represent a class of dual-functional nanomaterials that exhibit inherent enzyme-like catalytic properties alongside fluorescent emission, making them suitable for multiple detection applications. However, the number of publications on this subject is limited, primarily due to potential interference between the two processes. In this study, oxidase-like fluorescent iron and copper codoped carbon dots (Fe,Cu-CDs) were synthesized via a one-pot pyrolysis reaction. The results demonstrated that the carbon dots could catalyze the oxidative coupling reaction between phenol and 4-aminoantipyrine, while their fluorescence emission was enhanced upon coordination with thiol compounds. By integrating the dimethoate-mediated, acetylcholinesterase-catalyzed hydrolysis of thiocholine, a dual-detection platform was developed for the colorimetric detection of phenol and the fluorometric detection of dimethoate, achieving detection limits of 0.103 μM and 1.94 × 10 −5  µg/mL, respectively. This method was subsequently applied to detect these two pollutants in real water and vegetable samples, and the results demonstrated favorable recovery rates and good reproducibility. This work not only presents a novel strategy for the synthesis and application of dual-functional carbon dots in pollutant analysis but also offers new insights into the design of dual-functional carbon dots for efficient and cost-effective multidetection.