Facile hydrothermal synthesis of N-doped fluorescent carbon dots for selective detection of insecticide parathion.

Pesticides are enormously important to industry requirements and in agriculture for improving yields. Parathion is widely used to control pests in vegetables, fruits, and flowers. However, excessive use of parathion poses a threat to food safety, the environment, and human health. Due to low cost, ease to use, and high selectivity and sensitivity, a fluorescent nanoprobe is a candidate for parathion detection. Blue fluorescent carbon dots were prepared by a hydrothermal method with rutinum and o-phenylenediamine as precursors. The Rut-CDs were purified by using dialysis, thin layer chromatography, and a chromatographic column. Excellent linear ranges of 0-7.5 µg L-1 and 12.5-62.5 µg L-1 parathion were obtained with a low detection limit of 0.11 ng mL-1. In addition, the quenching mechanism of parathion to the fluorescence of Rut-CDs was illuminated. Furthermore, the nanoprobe was efficiently applied to determine the parathion content in Chinese cabbage, cantaloupe, and cowpea samples. It shows great potential to detect parathion.

Facile hydrothermal synthesis and purification of fluorescent carbon dots for food colorant tartrazine detection based on a dual-mode nanosensor.

Colorant tartrazine is widely used in the food industry, but its long-term and excessive consumption is harmful to human health. Therefore, it is necessary to establish a sensitive detection method for tartrazine. Blue fluorescent carbon dots with L-arginine and o-phenylenediamine as precursors, namely L-Arg/oPD-CDs, were prepared via the hydrothermal method. Then, L-Arg/oPD-CDs were further purified by dialysis, thin layer chromatography and column chromatography. A dual-mode nanosensor based on fluorescent and UV absorption was successfully developed. Excellent linear ranges of 0-5 µM and 10-50 µM were obtained with a low detection limit of 42.3 nM based on fluorescence. A good linear range of 0-50 µM was obtained with a low detection limit of 130.15 nM based on UV absorption. The quenching mechanism of tartrazine towards L-Arg/oPD-CDs fluorescence was the inner filter effect. In addition, a dual-mode nanosensor was used for tartrazine determination in millet, maize flour, carbonated drink, and sugar samples. This study provides new insight into the detection of tartrazine by applying a dual-mode nanosensor.

Novel Fluorescent Nano Carbon Quantum Dots Derived From Lactarius Hatsudake for High Selective Vitamin B12 Detection.

BACKGROUND: VB12 is involved in the production of bone marrow red blood cells, preventing pernicious anemia and brain nerve damage. OBJECTIVE: A large edible fungus Lactarius hatsudake (Lh) was used as a carbon source to produce fluorescent carbon dots (CDs) with high quantum yield and high photostability by a one-step hydrothermal method. METHOD: The structure and optical properties of Lh-CDs were characterized by XRD, XPS, FTIR, and UV-Vis, and the stability of Lh-CDs was studied. The maximum excitation wavelength and emission wavelength of Lh-CDs were 324 and 408 nm, respectively, and the average fluorescence lifetime was 2.29 ns. RESULTS: The linear range is 0∼20 µM (R2 = 0.9972) with a detection limit of 36.9 nM. At the same time, the mechanism of fluorescence quenching was internal filtration effect. CONCLUSIONS: It showed that Lh-CDS had good selectivity, high sensitivity, and good anti-interference ability to VB12, which provided a new detection method for VB12.Highlights The fluorescence intensity of the LH-CDs could be effectively quenched by VB12. HIGHLIGHTS: The fluorescence intensity of the LH-CDs could be effectively quenched by VB12.