Search

Herein, the CuInS2/ZnS/TGA quantum dots (QDs) were prepared by the oil phase reaction containing thioglycolic acid (TGA) as a functional modification agent under a nitrogen atmosphere. The CuInS2/ZnS/TGA QDs using as the photocatalysts exhibited high photocatalytic activity for the degradation of Rhodamine B (RhB) under ultraviolet irradiation. The photocatalytic conditions were optimized to degrade RhB with superior performances, including the initial RhB and CuInS2/ZnS/TGA QDs concentrations, solution pH values and ultraviolet light intensities. Furthermore, the kinetic equations of photocatalytic reaction and possible photocatalytic degradation mechanism were investigated. The results indicated that it belongs to the typical first order kinetic in accordance with the Langmuir–Hinshelwood mechanism, and the electrons and holes on the surface of the CuInS2/ZnS/TGA microspheres are the main acting forces during the RhB photocatalytic degradation.

A sensitive non-derivatization method for the determination of the highly polar compound 3-aminopiperidine was developed using a mixed-mode column combined with a charged aerosol detector (CAD). Chromatographic conditions, including the type of detector, separation mode, and mobile phase composition, were optimized to achieve high sensitivity towards and sufficient retention of 3-aminopiperidine. Compared to the precolumn derivatization UV method, the current method showed higher recovery and greater simplicify. High sensitivity (LOQ

A rapid and sensitive high-performance liquid chromatography-mass spectrometry method was established to determine the trace residues of piperazine in vortioxetine hydrobromide. The presence of piperazine was determined by precolumn derivatization with dansyl chloride. Chromatographic separation was performed on a Waters SunFire C8 column (150 × 4.6 mm, 3.5 μm) in gradient elution mode, using formic acid and acetonitrile as mobile phase. Detection was performed in a single quadrupole mass spectrometer in single ion monitoring mode using positive ionization. An m/z value of 553 was selected for monitoring disubstituted piperazine by DNS-Cl. Linearity, accuracy, and precision were found to be acceptable over the piperazine concentration range of 0.3525 - 2.35 ng mL-1. The limit of detection and limit of quantification of piperazine were 0.1175 and 0.3525 ng mL-1, respectively, which complied with the requirements of qualitative and quantitative analyses. The method was deemed sensitive and efficient.

A facile strategy for detecting xanthine in serum samples by copper nanocluster (CuNCs) with high intrinsic peroxidase-like activity was reported. Firstly, a simple, mild and time-saving method for preparing CuNCs was developed, in which dithiothreitol (DTT) and bovine serum albumin (BSA) were used as reductant and stabilizer, respectively. The as-prepared CuNCs exhibited a fluorescence emission at 590 nm with a quantum yield (QY) of approximately 5.29%, the fluorescence intensity of the as-prepared CuNCs exhibited no considerable change when stored under ambient condition with the lifetime is 1.75 μs. Moreover, the as-prepared CuNCs exhibited high intrinsic peroxidase-like activity with lower K m (K m = 8.90 × 10−6 mol L−1) for H2O2, which indicated that CuNCs have a higher affinity for H2O2. Compared with natural enzyme, the as-synthesized CuNCs are more catalytic stable over a wide range of pH (4.0~13.0) and temperature (4~80 °C). Finally, an indirect method for sensing xanthine was established because xanthine oxidase can catalyse the oxidation of xanthine to produce H2O2. Xanthine could be detected as low as 3.8 × 10−7 mol L−1 with a linear range from 5.0 × 10−7 to 1.0 × 10−4 mol L−1. These results proved that the proposed method is sensitive and accurate and could be successfully applied to the determination of xanthine in the serum sample with satisfaction.

1,4-Butane sultone is an impurity in sulfobutyl ether β-cyclodextrin (SBE-β-CD), and has been reported to be a weak carcinogen. There is, however, no report of any method of determining 1,4-butane sultone in SBE-β-CD. In this paper, a gas chromatography–mass spectrometry (GC–MS) method was developed for the determination of 1,4-butane sultone. The samples were dissolved in water and extracted with chloroform. An Agilent DB-17MS column was used to separate the samples, and then the Agilent 5975B MS detector was employed. The selected ion monitoring mode (SIM: m/z 92, 120 for 1,4-butane sultone, m/z 54, 71, 106 for methyl salicylate—used as the internal standard) was used. The method showed a linear response across the concentration range 0.0256–1.024 μg mL−1 (r = 0.9997, n = 6). The detection limit of 1,4-butane sultone was found to be 12.8 ng mL−1, and the recovery (assessed via spiking) ranged from 96.28 to 100.45 %. The relative standard deviation of the precision for the proposed method was 2.68 %. The method developed here is fast and sensitive, and can be used to analyze the 1,4-butane sultone content of SBE-β-CD.

A simple method for the synthesis of water-soluble carbon quantum dots (CQDs) has been developed by chemical oxidation treatment of the flour. The as-synthesized CQDs were monodispersed sphere particles with the approximate diameter of 5-8 nm, and exhibited strong fluorescence, excitation-dependent photoluminescence behavior and high photostability in a wide range of pH values. We investigated the cytotoxicity of as-prepared CQDs using rat mesangial cells (RMC). Compared with CdTe quantum dots, CQDs show no apparent cytotoxicity and much better biosafety property. The as-synthesized CQDs were also tested to label and image RMC in vitro and demonstrated to be highly promising biological fluorescent probes.

Based on the excellent optical properties of quantum dots (QDs), a simple and efficient method was proposed and established to produce a singlet oxygen activating QDs-denatured Bovine Serum Albumin (dBSA)-Chlorin e6 (Ce6) bioprobe. In this work, a quick synthesis of water-soluble CdTe QDs was accomplished and showed a good linear fit between synthetic heating duration and its maximum fluorescence emission wavelength. Moreover, dBSA which is a convenient and widely used agent was employed as a bridge to conjugate the selective CdTe QDs with a suitable emitting wavelength and photosensitizer Ce6, simply using N-ethyl-N-(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide as coupling agents. UV–Vis, fluorescence, and IR spectroscopy confirmed the successful conjugation of QDs and Ce6. The as-produced QDs-dBSA-Ce6 bioconjugates demonstrated an effective fluorescence resonance energy transfer efficiency of as high as 0.90, which also proved to be well conserved of its singlet oxygen-generating in oxidation–extraction photometry tests and might be a potential bioprobe in the research of photo dynamic therapy.