Preparation of One-Emission Nitrogen-Fluorine-Doped Carbon Quantum Dots and Their Applications in Environmental Water Samples and Living Cells for ClO- Detection and Imaging.

Hypochlorite (ClO-) has received extensive attention owing to its significant roles in the immune defense and pathogenesis of numerous diseases. However, excessive or misplaced production of ClO- may pose certain diseases. Thus, to determine its biological functions in depth, ClO- should be tested in biosystems. In this study, a facile, one-pot synthesis of nitrogen-fluorine-doped carbon quantum dots (N, F-CDs) was developed using ammonium citrate tribasic, L-alanine, and ammonium fluoride as raw materials under hydrothermal conditions. The prepared N, F-CDs demonstrate not only strong blue fluorescence emission with a high fluorescence quantum yield (26.3%) but also a small particle size of approximately 2.9 nm, as well as excellent water solubility and biocompatibility. Meanwhile, the as-prepared N, F-CDs exhibit good performance in the highly selective and sensitive detection of ClO-. Thus, a wide concentration response range of 0-600 µM with a low limit of detection (0.75 µM) was favorably obtained for the N, F-CDs. Based on the excellent fluorescence stability, excellent water solubility, and low cell toxicity, the practicality and viability of the fluorescent composites were also successfully verified via detecting ClO- in water samples and living RAW 264.7 cells. The proposed probe is expected to provide a new approach for detecting ClO- in other organelles.

Silver Nanoparticle-Functionalised Nitrogen-Doped Carbon Quantum Dots for the Highly Efficient Determination of Uric Acid.

The fabrication of efficient fluorescent probes that possess an excellent sensitivity and selectivity for uric acid is highly desirable and challenging. In this study, composites of silver nanoparticles (AgNPs) wrapped with nitrogen-doped carbon quantum dots (N-CQDs) were synthesised utilising N-CQDs as the reducing and stabilising agents in a single reaction with AgNO3. The morphology and structure, absorption properties, functional groups, and fluorescence properties were characterised by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, fluorescence spectroscopy, and X-ray diffraction spectroscopy. In addition, we developed a novel method based on AgNPs/N-CQDs for the detection of uric acid using the enzymatic reaction of uric acid oxidase. The fluorescence enhancement of the AgNPs/N-CQDs composite was linear (R2 = 0.9971) in the range of 2.0-60 µmol/L, and gave a detection limit of 0.53 µmol/L. Trace uric acid was successfully determined in real serum samples from the serum of 10 healthy candidates and 10 gout patients, and the results were consistent with those recorded by Qianxinan Prefecture People's Hospital. These results indicate that the developed AgNP/N-CQD system can provide a universal platform for detecting the multispecies ratio fluorescence of H2O2 generation in other biological systems.

Study on the interaction between albendazole and eosin Y by fluorescence, resonance Rayleigh scattering and frequency doubling scattering spectra and their analytical applications.

In pH 3.25-3.35 Britton-Robinson (BR) buffer solution, albendazole (ABZ) could react with eosin Y (EY) to form a 1:1 ion-association complex, which not only results in the quenching of fluorescence, but also resulted in the great enhancement of resonance Rayleigh scattering (RRS) and frequency doubling scattering (FDS). Furthermore, a new RRS spectrum will appear, and the maximum RRS wavelength was located at about 356nm. The detection limit for ABZ were 21.51ng mL(-)(1) for the fluorophotometry, 6.93ng mL(-)(1) for the RRS method and 12.89ng mL(-)(1) for the FDS method. Among them, the RRS method had the highest sensitivity. The experimental conditions were optimized and effects of coexisting substances were evaluated. Meanwhile, the influences of coexisting substances were tested. The methods have been successfully applied to the determination of ABZ in capsules and human urine samples. The composition and structure of the ion-association complex and the reaction mechanism were discussed.

Direct determination of polymyxin B sulfate using resonance Rayleigh scattering and resonance non-linear scattering methods with hexatungstate.

At pH 1.3-1.6, tungstate WO4(2-) , can be converted to hexatungstate W6 O19(2-) , which can react with positively charged polymyxin B sulfate (PMB) to result in enhancement of resonance Rayleigh scattering (RRS) and resonance non-linear scattering, including second order scattering and frequency doubling scattering. Linear relationships can be established between enhanced scattering intensity and PMB concentration. The detection limits (3σ) were 5.5 ng/mL (RRS), 10.1 ng/mL (second order scattering) and 34.6 ng/mL (frequency doubling scattering). The optimum reaction conditions, influencing factors and related analytical properties were tested. The interaction mechanism was investigated via absorption spectrum, circular dichroism spectra and atomic force microscopy imaging. The basis of scattering enhancement is discussed. PMB in eardrops, human serum and urine, were quantified satisfactorily by RRS.

Resonance Rayleigh scattering, frequency doubling scattering and absorption spectrum of the interaction for mebendazole with 12-tungstophosphoric acid and its analytical applications.

The interaction of mebendazole (MBZ) with 12-tungstophosphoric acid (TP) has been investigated by using resonance Rayleigh scattering (RRS) and frequency doubling scattering (FDS) combining with absorption spectrum. In pH 1.0 HCl medium, MBZ reacted with TP to form 3:1 ion-association complex. As a result, not only the spectrum of absorption was changed, but also the intensities of RRS and FDS were enhanced greatly. The maximum RRS, FDS and absorption wavelengths are located at 372, 392 and 260 nm, respectively. The increments of scattering intensity (ΔI) and absorption (ΔA) are directly proportional to the concentrations of MBZ in certain ranges. The detection limits (3σ) of RRS, FDS and absorption are 0.56, 0.86 and 130.16 ng/mL, respectively. The sensitivity of RRS method is higher than FDS and absorption methods. The optimum conditions of RRS method and the influence factors were discussed in the paper, in addition, the structure of ion-association complex and the reaction mechanism were investigated. Based on the ion-association reaction and its spectral response, the rapid, simple and sensitive RRS method for the determination of MBZ has been developed.

Genotyping of calves rotavirus in China by reverse transcription polymerase chain reaction.

To investigate the epidemical characteristics and genotype distributions of bovine rotavirus (BRV) in China, 195 fecal samples were collected from calves with diarrhea in China. Fecal samples were detected for rotavirus A antigen using ELISA. The positive samples were screened for VP7 and VP4 by RT-PCR. G serotyping and P genotyping were conducted on 53 VP7 and VP4 positive samples using RT-PCR. The results showed that 82 samples were found positive for BRV. 752bp, 660bp and 285bp bands were amplified for G-typing. 478bp, 375bp and 361bp bands were amplified for P-typing. The G6 and G10 serotypes were 29 (54.7%) and 8 (15.1%) in positive samples for VP7. P[5] and P[11] genotypes were 28 (52.8%) and 10 (18.9%) in the positive samples for VP4. The main combinations of BRV G serotype and P genotype were G6P[5] (28.3%), G6P[5]P[11] (5.7%), G10P[5] (5.7%) and G10G6P[5] (5.7%), respectively. Other combinations (including untypable) of G serotype and P genotype were 54.6%. The dominant G serotype and P genotype were G6 and P[5] respectively. The predominant combination of G and P serotypes was G6P[5]. This has significance for establishing the preventive measures against diarrhea caused by group A rotaviruses in cattle.