Novel electrochemical sensor from magnetic carbon dots and cetyltrimethylammonium bromide for sensitive measurement of tetrabromobisphenol A in beverages.

Present work depicted a novel electrochemical sensor fabricated with magnetic carbon dots (M-CDs) and cetyltrimethylammonium bromide (CTAB) modified glassy carbon electrode (GCE) for selective measurement of 3,3',5,5'-tetrabromobisphenol A (TBBPA) in beverages. The M-CDs composite material revealed good electrocatalytic activity, and CTAB has strong hydrophobic interaction which enable it have good enrichment capacity of hydrophobic compounds, and combination of them further enhances the electrochemical signal. Hence CTAB decoration can markedly improve the detection performance of TBBPA. Electrochemical properties of the fabricated sensor was investigated through performing cyclic voltammetry (CV). The morphology and functional groups of the modified materials were examined with transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the synthesized material had a spherical-like structure, good dispersion properties and plenty of functional groups on the surface. The effects of incubation potential, incubation time, pH of electrolyte, and scanning rate on oxidation peak current were investigated. Under optimal conditions, the designed sensor had good linear range of 1 nM-1000 nM, and the detection of limit of the constructed sensor was 0.75 nM. The constructed sensor was utilized to detect TBBPA in vitamin water, scream drink and genki forest, and satisfactory detection performance had been achieved.

Preparation of Polyamidoamine Dendrimer Modified Magnetic Nanoparticles and Its Application for Reliable Measurement of Sudan Red Contaminants in Natural Waters at Parts-Per-Billion Levels.

The health threat from Sudan red dyes has been the subject of much attention in recent years and is crucial to design and establish reliable measurement technologies. In the present study, a new magnetic nanomaterial, polyamidoamine dendrimer-modified magnetic nanoparticles (Gn-MNPs), was synthesized and characterized. The nanomaterials had good adsorption capacity for Sudan dyes from natural waters. G1.5-MNPs possessed excellent adsorption capacity and a linear adsorption relationship over the range from 0.02 to 300 µg L-1 of Sudan dyes with relative coefficients all larger than 0.996. The sensitivity of the proposed method was excellent with detection limits over the range from 1.8 to 5.5 ng L-1 and the precision was less than 3.0%. G1.5-MNPs showed a remarkable application potential for the enrichment of trace environment pollutants in aqueous samples and the developed method based on this nanomaterial could be a robust and reliable alternative tool for routine monitoring of such pollutants.

Selective detection of Cu2+ using nitrogen-doped carbon dots derived from humic acid and urea based on specific inner filter effect.

A new kind of nitrogen-doped carbon dots (N-CDs) was synthesized via a simple hydrothermal strategy using humic acid as the carbon source and urea as the nitrogen source. The fluorescence intensity of as-prepared N-CDs was quenched significantly in presence of Cu2+ based on a specific inner filter effect, which could be utilized to construct a selective sensor for monitoring Cu2+ in aqueous samples. The sensor exhibited good linearity over the range of 0.1-2 µM, and high sensitivity with a detection limit of 25 nM. Under the optimal conditions, there was no significant interference by other metal ions such as Cd2+, Al3+, Cr3+, Fe3+, Pb2+, Na+, Ni+, Fe2+, Ba2+, Ca2+, Co2+, Mg2+, As3+, K+, Zn2+ for Cu2+ detecting except Hg2+.The interference of Hg2+ can be masked by addition of sodium chloride. The experimental results demonstrated that the prepared N-CDs owned strong fluorescence, high monodispersity, good stability and good water solubility, and the constructed sensor had many advances and great application prospect in environmental field.

Highly selective fluorescence sensor sensing benzo[a]pyrene in water utilizing carbon dots derived from 4-carboxyphenylboronic acid.

4-Carboxyphenylboronic acid was used as the single precursor to facilely prepare fluorescent carbon quantum dots by one-step solvothermal method. The as-obtained carbon dots (CDs) exhibited highly selective and sensitive for benzo[a]pyrene (BaP), and may be a splendid sensor for sensing BaP. The principle was that the as-prepared CDs could form a complex with BaP through hydrophobic interaction which causes the decrease of fluorescence intensity of CDs by static quenching principle. The constructed fluorescent sensor exhibited excellent linearity ranged from 0.002 to 0.06 µg mL-1 and provided a low limit of detection of 0.16 ng mL-1. The experimental results showed that this fluorescent sensor resulted in simplicity, rapidness, low cost, short analytical time, and high sensitivity and stability. Validation with real water samples endowed the sensor high reliability and feasibility for BaP determination in practical application in various samples.

Measurement of mercury with highly selective fluorescent chemoprobe by carbon dots and silver nanoparticles.

This work describes a novel fluorescent chemoprobe that uses carbon dots and silver nanoparticles (AgNPs) to monitor mercury ions in aqueous samples attributed to the principle of inner filter effect. The fluorescent response signal of the carbon dots is diminished by AgNPs, attributed to inner filter effect, and is restored with the addition of Hg2+. The fluorescent chemoprobe was specific over the range from 0.01 to 2.5 µM and a high sensitivity of 3.6 nM. The chemoprobe was validated using real local aqueous samples, and the spike recoveries of 97.4%-103% were excellent and satisfied. The data indicated that the developed fluorescent chemoprobe was sensitive, selective, stable and reliable. This fluorescent chemoprobe provides a sensitive tool with broad prospects for mercury detection in aqueous samples and the work will offer ideas for designing and constructing novel fluorescent probes.