Nitrogen-doped carbon dots with bright fluorescence for highly sensitive detection of Fe in environmental waters.

In this study, we synthesized stable nitrogen-doped carbon dots by a simple and economical one-step hydrothermal method using l-cysteine and anhydrous ethylenediamine as precursors. The prepared carbon dots have bright and stable blue light emission near 383 nm and can be used as fluorescent probes to detect the concentration of Fe in environmental waters. It was demonstrated that due to intermolecular electrostatic interaction, a non-fluorescent complex N-CDs/Fe is formed by coordination of Fe with amino and carboxyl functional groups on the surface of carbon dots.

Detection of melamine by using carboxyl-functionalized Ag-COF as a novel SERS substrate.

Melamine, a nitrogen-containing organic molecule, has received widespread attention as it had been illegally added in dairy products to increase the content of nitrogen, leading to kidney stones in healthy people after long-term ingestion. Based on SERS technology and Covalent Organic Framework (COF) materials, we developed carboxyl-functionalized Ag-COF-COOH materials as SERS substrates for the detection of melamine adulteration. Using COF material as a ligand can effectively reduce the influence of interferents in milk.

Synthesis and photoluminescence properties of orange-red carbon dots from the paper tissues as the precursor.

In recent years, stable and photoluminescence (PL) tunable fluorescent materials known as carbon dots (CDs) have seen rapid development. Here, a simple, low-cost, and environmentally friendly approach has been developed to synthesize the orange-red CDs (OR-CDs) with paper tissues as the precursor in the presence of ethanol and concentrated sulfuric acid. The average diameter of the OR-CDs was measured at around 1.

Urea detection in milk by urease-assisted pH-sensitive carbon dots.

Excessive urea in milk will lead to serious health problems. To detect whether the urea concentration in milk exceeds the standard and ensure the quality of milk, it is necessary to develop detection technology for urea in milk. But it is difficult to detect urea in milk conveniently and accurately by traditional methods.

SERS Detection of Benzoic Acid in Milk by Using Ag-COF SERS Substrate.

Benzoic acid, which has a pivotal role in food additive, is prohibited to add as a preservative in dairy products. China, Brazil, and other countries have proposed standard methods to detect the addition of benzoic acid in food. Surface-enhanced Raman scattering (SERS) is an upcoming spectral detection technique, which has been widely used in the field of material analysis with the advantages of non-invasive, fast detection speed and complex environment with little interference.