A Strecker-like reaction triggering fluorescent sensing platform for enzyme-free and visual quantitative monitoring of carbamates

Abstract

Utilization of organic reactions can offer more counterparts to design organic fluorescent probes and expand the probe libraries. Herein, a Strecker-like reaction was induced to prepare fluorescent probe for enzyme-free and visual quantitative monitoring of carbamates. Carbamate pesticides (CPs) are representative pesticides whose residues in water bodies and agricultural and sideline products seriously endanger human health. It is particularly important to develop a real-time/on-site sensing method to monitor the residue levels of CPs. The bottleneck of traditional detection methods is that only one of the pesticides can be selectively detected, so the full-spectrum detection of CPs can improve the practical application value. Based on the principle of Strecker-like reaction induced by 2, 3-naphthalenedialdehyde (NDA) and sulfite, we constructed an enzyme-free ratiometric fluorescent probe with CdTe quantum dots (CdTe QDs) as the background fluorescence for full-spectrum visual recognition of CPs. After addi-tion of CPs, isoindole with green fluorescence is generated by nucleophilic condensation reaction, and this fluorescent probe provides a distinct color variation from red to green, which shows a good linear relationship to CPs residues concentrations in the range of 0.1–4.5 μM with a sensitive limit of detection (LOD) of 18.6 nM. In addition, we developed a novel enzyme-free ratiometric fluorescence intelligent detection platform combined with a smartphone, which can visually quantitatively detect CPs in water, apple, and cabbage by identifying the RGB values of the fluorescent probe solution and the corresponding paper-based sensor with a sensitive limit of detection (LOD) of 34.5 nM. The present sensing strategy realizes the rapid visual and quantitative detection of CPs residues in food and the environment, and provides an effective way to utilization of organic reactions for trace hazardous substances detection.