Copper-Modified Double-Emission Carbon Dots for Rapid Detection of Thiophanate Methyl in Food

Abstract

The detection of food safety and quality is very significant throughout the food supply. Stable dual-emission copper-modified fluorescent carbon dots (Cu-CDs) were successfully synthesized by a simple and environment-friendly hydrothermal, which was used for the real-time detection of pesticide residues in agricultural products. By optimizing the reaction conditions, Cu-CDs showed two emission peaks, with the highest fluorescence intensities at 375 and 450 nm. The structure, chemical composition and optical properties of Cu-CDs were investigated by XRD, TEM and IR. The results showed that thiophanate methyl (TM) could induce fluorescence quenching of Cu-CDs with no other ligands by the electron transfer through π-π stacking. The synchronous response of the dual-emission sensor enhanced the specificity of TM, which showed remarkable anti-interference capability. The fluorescence quenching degree of Cu-CDs had a good linear relationship with the TM concentration; the low detection limit for a pear was 0.75 μM, and for an apple, 0.78 μM. The recoveries in the fruit samples were 79.70–91.15% and 81.20–93.55%, respectively, and the relative standard deviations (RSDs) were less than 4.23% for the pear and less than 3.78% for the apple. Thus, our results indicate the feasibility and reliability of our methods in detecting pesticide residues in agricultural products.

Effect of Hydrothermal Conditions on Kenaf-Based Carbon Quantum Dots Properties and Photocatalytic Degradation

“…Unlike typical PL spectra CQDs reported, kenafbased CQDs displayed a multi-peak emission feature at ~400 and ~450 nm. The emission peak at ~400 nm is attributed to the fluorescence of the carbon nucleus [30] and the emission peak at ~450 nm is attributed to the flourescence caused by the nano-interparticles distances due to the CQDs agglomeration [31]. The narrow PL emission area with the emission band centred at ~400 nm validates the narrow size distribution of CQDs because of similar quantum effects and emission traps on the carbon surface, which matches well with the results of the HRTEM histogram [32].…”

Recent Advances in Nanomaterial-Based Sensing for Food Safety Analysis

“…Since carbonate quantum dots (CDs) were firstly discovered by Xu et al in 2004 [62], the fluorescence emission property of CD makes them attractive as sensing probes for food analysis [63,64]. For example, Yue et al [65] synthesized coppermodified fluorescent carbon dots (Cu-CDs) with stable double emission by hydrothermal methods, which were successfully applied to the detection of methyltobutazine (TM) in fruits according to the linear relationship between the degree of fluorescence quenching of Cu-CDs and the concentration of the target. Yin et al [66] prepared a novel N,Cl co-doped carbon dots (N,Cl-CDs) method based on deep eutectic solvent (DES) to achieve the rapid and accurate quantification of morphine fluorescence methods in food.…”