Search

In this work, different types of Mn-doped ZnS QDs were prepared and applied to study of the chemiluminescence reaction of hydrogen peroxide and periodate. The effects of the size of nanoparticles, shell protection and the stabilizing agents on chemiluminescence intensity were studied. The results indicated that the size of quantum dots was not the only factor to enhance the intensity of chemiluminescence system. Different stabilizing agents and the silica film protection will also influence the performance of the quantum dots in the chemiluminescence reaction. A CL spectrum was examined by using a series of high-energy cut-off optical filters and a possible mechanism of the CL was also proposed. [ABSTRACT FROM AUTHOR]

Abstract: Peroxymonocarbonate (HCO4 −) was produced by the online reaction of bicarbonate with hydrogen peroxide. A strong chemiluminescence (CL) was observed when HCO4 − reacted with AuCl4 − without any special CL reagent. When bisphenol A (BPA) was added to AuCl4 −–HCO4 − CL system, the CL emission was inhibited significantly. This new CL system was developed as a flow-injection method for the determination of BPA. Under the optimum experimental conditions, the inhibited CL intensity was linearly related to the concentration of BPA from 0.3 to 80μM (R =0.9958). The detection limit of BPA was 0.08μM. The relative standard deviation for 12 repeated measurements of 1.0μM BPA was 2.9%. The interferences of some cationic ions can be removed by an online cation-exchange column. The applicability of the present CL system was demonstrated for the sensitive and selective determination of BPA in real samples (mineral water bottle, baby bottle, beverage bottle and polycarbonate container). Based on the CL spectrum, UV–visible adsorption spectra, and the quenching effect of reactive oxygen species scavengers, a possible CL mechanism was proposed. [ABSTRACT FROM AUTHOR]

0.675CaTiO 3 –0.325LaAlO 3 perovskite ceramics were prepared by a conventional sintering process through four reaction routes. The solid-state reaction mechanisms were investigated by X-ray diffraction and thermogravimetric/differential scanning calorimetric analysis techniques. The results show that interactions occurred between mixtures of CaCO 3 and TiO 2 as well as La 2 O 3 and Al 2 O 3 , and they can influence the sintering behavior of the mixtures. Prior to the formation of solid solutions, the perovskite phases CaTiO 3 and LaAlO 3 were formed regardless of the combination of oxide powders used as reagents. From the powder mixtures which were calcined at 1200 °C, a Ca-rich Ca 9 Al 6 O 18 phase was present at 1400 °C if free La 2 O 3 and Al 2 O 3 used in the reaction mixtures. Ca-rich phases were also formed at higher temperature (1450 °C) if LaAlO 3 was present. The densities of the ceramics obtained by the four routes were different at specific sintering temperatures, and the highest density was obtained for the reaction route two. Results indicated that the preparation pathways had more influence on Q × f and temperature coefficient of the resonant frequency ( τ f ) than on the dielectric constants ( ε r ), and Q × f decreased and τ f increased rapidly when the secondary phase presented. Route four is considered as an optimal pathway for the preparation of 0.675CaTiO 3 –0.325LaAlO 3 ceramics. [ABSTRACT FROM AUTHOR]

Water in organic solvents is a prevalent impurity that significantly influences chemical reactions and industrial processes. Carbon dots (CDs) gained attention as promising tools for chemosensing due to their advantageous characteristics, including easy synthesis, cost-effectiveness, and excellent adjustability and stability. However, limited solubility in water and turn off fluorescence response mode hinder the practical utilization of CDs for water sensing. To tackle such dilemma, a highly water-soluble CDs with distinctive hydrogen-bond-induced emission (HBIE) was rationally designed through introducing sulfone group into the widely employed p -phenylenediamine precursor. The inclusion of sulfone group imparts the CDs with notable water solubility, as well as distinctive ratiometric fluorescent response towards water content, exhibiting high sensitivity and selectivity. Upon exposure to water, the emission color of CDs undergoes a real-time transition from blue to yellow-green, which can be readily discerned by naked eyes. The CDs have been successfully applied in detecting water in commercially available alcohol. This study presents a straightforward yet efficacious approach for rationally design of CDs with unique HBIE characteristics and ratiometric fluorescent response, offering great potential for practical chemosensing applications. [Display omitted] • A water-soluble CDs was synthesized by introducing sulfone group into the p-phenylenediamine precursor. • Hydrogen-bond-induced emission between CDs and water contributes to ratiometric fluorescent detection of water content. • The CDs have been successfully applied in detecting water in commercially available alcohol. [ABSTRACT FROM AUTHOR]

Abstract: It was found that CdTe semiconductor nanocrystals (NCs) can induce a great sensitized effect on chemiluminescence (CL) emission from peroxynitrous acid (ONOOH)–Na2CO3 system. CL spectra, fluorescence (FL) spectra, and the quenching effect of reactive oxygen species were used to investigate the CL reaction mechanism. The CL intensity was proportional to the concentration of nitrite in the range from 0.05 to 50μM. The detection limit (S/N =3) was 0.024μM and the relative standard deviation (RSD) for five repeated measurements of 0.5μM nitrite was 4.2%. This method has been successfully applied to determine nitrite in well water samples with recoveries of 94.0–100.5%. This was the first work for direct (not inhibition effect) determination of analytes using semiconductor NCs-based CL sensor. [Copyright &y& Elsevier]

[Display omitted] • The effective formation of azamonardine on nanostructure surface was proved. • Ratiometric dopamine evaluation system was proposed by using catechin-inspired gold nanoclusters as signal reporters. • Analysis of dopamine in nM level was realized with the proposed system. • Catechol analogues had no interference on dopamine sensing. • The practical application of the present system in urine and cell lysate samples was validated. The sensitive and selective perception of dopamine (DA, a typical neurotransmitter) is important to evaluate the biological environment. In this study, a catechin-functionalized gold nanocluster (C-Au NC) nanoprobe has been explored for the ratiometric DA sensing. The detection mechanism is based on the formation of azamonardine via selective DA-catechin chemical reaction and subsequent enhanced fluorescence emission. Using Au NC emission as the internal reference, ratiometric fluorescence variation is realized, which allows sensitive DA analysis with a limit of detection of 1.0 nM (S/N = 3) and linear response concentration range from 0 to 500 nM. The characteristic chemical reaction between catechin and DA affords favorable selectivity over other amino acids, metal ions and small molecules. In addition, the practical application of the proposed nanoprobe is validated by the accurate detection of DA content in urea and cell lysate samples. [ABSTRACT FROM AUTHOR]