革兰氏阴性菌WaaP蛋白的表达与纯化对比研究

采用基因重组方法构建来源于大肠杆菌和铜绿假单胞菌的waa P基因的克隆,利用多种感受态细胞表达出带有不同纯化标签的可溶性Waa P蛋白,并利用亲合层析和凝胶过滤层析对可溶性Waa P蛋白进行纯化,用SDS-PAGE进行检测。对比大肠杆菌和铜绿假单胞菌中Waa P的表达和纯化结果,为蛋白结晶选取能够得到大量稳定和高纯度Waa P蛋白的表达纯化方法,并用该方法,使用硒代甲硫氨酸培养基表达出硒代甲硫氨酸标记的Waa P,为蛋白结构解析时相位的确定提供依据。     

Efficient synthesis of enantiomeric pairs of thiolactomycin and its 3-demethyl derivative

Starting with commercially available tiglic aldehyde, the title synthesis was achieved by employing deconjugative asymmetric α-sulfenylation of the chiral 3-(α,β,γ,δ-unsaturated acyl)-2-oxazolidinone with a methanethiosulfonate as a key step.     

Development of an optical surface plasmon resonance biosensor assay for (fluoro)quinolones in egg, fish, and poultry meat

The aim of this study was to develop an optical biosensor inhibition immunoassay, based on the surface plasmon resonance (SPR) principle, for use as a screening test for 13 (fluoro)quinolones, including flumequine, used as veterinary drugs in food-producing animals. For this, we immobilised various quinolone derivatives on the sensor chip and tested binding of a range of different antibodies (polyclonal and one engineered antibody) in the presence and absence of free (fluoro)quinolones. The main challenge was to detect flumequine in an assay giving good results for the other compounds. One antigen–antibody combination proved satisfactory: polyclonal antibodies raised against a dual immunogen and, on the sensor chip, a fluoroquinolone derivative. It was the first time that this concept of the bi-active antibody was described in the literature.The assay, optimised for detection in three matrices (poultry muscle, fish, and egg), was tested on incurred samples prepared by liquid extraction followed by two washing steps. This rapid, simple method proved adequate for detecting at least 13 (fluoro)quinolones at concentrations below established maximum residue levels (MRLs). The reference molecule norfloxacin could be detected in the range of 0.1–10 μg kg⁻¹ in extracts of egg and poultry meat and in the range of 0.1–100 μg kg⁻¹ in extracts of fish. The determined midpoints of these calibration curves were about 1, 1.5 and 3 μg kg⁻¹ in poultry meat, egg and fish, respectively.     

Process optimization and kinetics study for photocatalytic ciprofloxacin degradation using TiO2 nanoparticle: A comparative study of Artificial Neural Network and Surface Response Methodology

The photocatalytic degradation of ciprofloxacin was investigated by developing a predictive mathematical model using response surface methodology and an artificial neural network. The four independent variables involve solution pH, reaction time, catalyst dose, and initial antibiotic concentration considered as factors in central composite design to observe the response in the form of antibiotic degradation. Accordingly, at an optimum antibiotic concentration of 5.02 mg/L, catalyst dose of 44.51 mg/L, solution pH of 5.04, and reaction time of 75.80 min, the photocatalysis method achieved a ciprofloxacin degradation of 88.30%. The experimental outputs were very much consistent along with the predicted output of experiments through response surface methodology (R² = 0.9969) and artificial neural network (R² = 0.975). The adsorption isotherm and kinetic study reveal that Langmuir isotherm and pseudo-second-order kinetic models respectively were best fitted for degradation of ciprofloxacin through photocatalysis. The finding provides a novel method for evaluating the photocatalysis process for the optimization of ciprofloxacin antibiotic removal from pharmaceutical waste using experiments and computer simulation tools.     

Poly(acrylamide-co-itaconic acid) as a Potential Ion-Exchange Sorbent for Effective Removal of Antibiotic Drug-Ciprofloxacin from Aqueous Solution

This study describes equilibrium and kinetic sorption studies to remove the antibiotic drug Ciprofloxacin (CF) from aqueous solutions using poly(acrylamide-co-itaconic acid) [poly(AAm-co-IA)] as polymeric cation exchanger sorbent material. The co-polymeric sorbent was prepared by free radical induced aqueous polymerization and was characterized by FTIR spectroscopy and TGA analysis. In addition, its physicochemical parameters were also determined. The various isotherm models, when applied to equilibrium sorption data at 28°C, followed the following order: Langmuir > Temkin > Freundlich, with the fair maximum sorption capacity (Q _o ) of 178.5 mg g^?1. The kinetic sorption data, obtained at 28°C, was applied to kinetic models such as pseudo first order equation, pseudo second order model and a simple Elovich model. Based on regression values, the order of fitness of these models was pseudo second order > pseudo first order > simple Elovich model. The second order adsorption coefficients k_2adswere found to be 58 × 10^?3, 52.7 × 10^?3, 34.01×10^?3 g/mg min for drug solutions with initial concentrations of 10, 20 and 30 mg L^?1 respectively The sorption mean free energy from the Dubinin–Raduschkevich (DR) isotherm was found to be nearly 8.839 kJ mol^?1 indicating an ion-exchange mechanism for drug uptake. The optimum pH value of sorbate solution for drug uptake was found to be around 6.0. Finally, the antibacterial action of drug was investigated and it was found that after adsorption there was a decrease in bacterial growth inhibition efficiency of drug solution.     

High-resolution surface plasmon resonance sensors based on a dove prism

Wavelength interrogation surface plasmon resonance (SPR) spectroscopy using a dove prism combines a simple and inexpensive optical design with high-resolution refractive index monitoring and biosensing. A BK7 dove prism inverts an optical image with a total internal reflection angle of 72.8°, an angle active in SPR. Hence, a unique system can accomplish SPR biosensing using wavelength interrogation and also perform SPR imaging. This optical configuration advantageously uses a single axis optical path between each optical component, simplifying the optical design of SPR instruments without compromise of the analytical performance. Fluidics were also incorporated to the instrument design for efficient sample delivery. The SPR instrument is characterized in terms of refractive index (RI) sensitivity, RI resolution, reproducibility, and application for monitoring low concentration biological events. Data analysis methodologies are compared for improved resolution of the measured response. Raw data analyzed using a minimum hunting procedure results in RI resolution in the 10⁻⁶ range, while pre-treating data with singular value decomposition improves the resolution by one order of magnitude. Depending on the spectrophotometer employed, the RI range accessible can be easily tuned; examples with a 550-850 nm and a 550-1100 nm spectrophotometers are shown and results respectively in RI ranges of 1.32-1.39 RIU and 1.32-1.42 RIU. Monitoring of μM concentration of β-lactamase is performed using the wavelength interrogation configuration of the biosensor. Finally, a SPR image of a surface with a water droplet (volume = 500 nL) was obtained using the dove prism SPR with a band pass filter and a CCD camera. SPR using a dove prism configuration combines advantages of portable SPR instruments, SPR imagers and research-grade SPR instruments in a unique platform.     

Trace analysis of cefotaxime at carbon paste electrode modified with novel Schiff base Zn(II) complex

Cefotaxime a third generation cephalosporin drug estimation in nanomolar concentration range is demonstrated for the first time in aqueous and human blood samples using novel Schiff base octahedral Zn(II) complex. The cefotaxime electrochemistry is studied over graphite paste and Zn(II) complex modified graphite paste capillary electrodes in H₂SO₄ (pH 2.3) using cyclic voltammetry and differential pulse voltammetry. Cefotaxime enrichment is observed over Zn(II) complex modified graphite paste electrode probably due to interaction of functional groups of cefotaxime with Zn(II) complex. Possible interactions between metal complex and cefotaxime drug is examined by UV-vis and electrochemical quartz crystal microbalance (EQCM) techniques and further supported by voltammetric analysis. Differential pulse voltammetry (DPV) with modified electrode is applied for the determination of cefotaxime in acidified aqueous and blood samples. Cefotaxime estimation is successfully demonstrated in the range of 1-500 nM for aqueous samples and 0.1-100 μM in human blood samples. Reproducibility, accuracy and repeatability of the method are checked by triplicate reading for large number of samples. The variation in the measurements is obtained less than 10% without any interference of electrolyte or blood constituents.     

First synthesis of (±)-cedarmycin B

The synthesis of racemic cedarmycin B,an antibiotic from Streptomyces sp.TP-A0456 was achieved firstly fromγ- butyrolactone.The key step was a Barbier-type addition of 3-bromomethyl-5H-furan-2-one to formaldehyde mediated by zinc, which afforded the soleγ-addition product 4-hydroxymethyl-3-methylene-dihydrofuran-2-one.The final compound was confirmed by ~1H NMR,~(13)C NMR and HRMS.     

共振瑞利散射法在抗生素类药物分析中的研究进展

对近6年来共振瑞利散射法在抗生素类药物分析中的研究与应用做了简要综述,主要从反应体系,线性范围,检出限等方面对几大类药物的研究现状进行了介绍。