电化学发光免疫分析方法检测蔬菜中噻虫啉的含量

化学农药的广泛使用,不可避免的产生了农药残留问题.蔬菜作为人类食物之一,其农药残留问题尤其重要.本文采用饱和硫酸铵盐析法提纯噻虫啉,并合成了Cd S纳米晶,制备了具有稳定且强电致化学发光的Cd S纳米晶膜,在纳米晶膜上建立了农药残留物噻虫啉含量的电化学发光免疫检测方法.该方法利用具有优良导电性的石墨烯作为抗原标记物,实现了噻虫啉的灵敏检测.标记上石墨烯的噻虫啉与纳米晶膜表面的抗体免疫结合后引起纳米晶膜发光的增强,发光强度的增加随着噻虫啉的含量的增加而增大.发光强度的对数与噻虫啉浓度的对数在0.1~10 pg·m L-1范围内呈线性关系（R=0.99）.在S/N比为3时,检测限为0.1 pg·m L-1.利用该方法检测实际蔬菜样品中的农药残留量,取得了令人满意的结果.鉴于石墨烯良好的可修饰性,其作为标记物在其他免疫反应、DNA杂化分析中具有十分广阔的前景.     

An anti-passivation ink for the preparation of electrodes for use in electrochemical immunoassays

p-Nitrophenylphosphate (PNPP) is usually employed as the substrate for enzyme-linked immunosorbent assays. p-Nitrophenol (PNP), the product of PNPP, with the catalyst alkaline phosphatase (ALP), will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited (rGO/IL/Chi) electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Chi electrode had the best performance according to its low peak potential and large peak current. Amperometric responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.     

Production of a monoclonal antibody against oxytetracycline and its application for oxytetracycline residue detection in shrimp简

A novel monoclonal antibody (MAb) against oxytetracycline (OTC) was generated and characterized. The MAb was used in the development of an enzyme-linked immunosorbant assay (ELISA)-based detection system. An OTC-bovine serum albumin (BSA) conjugate was prepared and used in the immunization of mice. A conventional somatic cell fusion technique was used to generate MAb-secreting hybridomas denoted 2–4F, 7–3G, and 11–11A. An indirect competitive ELISA (icELISA) was applied to measure the sensitivity and specificity of each MAb in terms of its 50% inhibitory concentration (IC50) and percentage of cross-reactivity, respectively. MAb 2–4F exhibited the highest sensitivity, with an IC₅₀ of 7.01 ng/ml. This MAb showed strong cross-reactivity to rolitetracycline, but no cross-reactivity to other unrelated antibiotics. When MAb 2–4F was used to detect OTC from shrimp samples, the recoveries were in the range of 82%–118% for an intra-assay and 96%–113% for an inter-assay. The coefficients of variation of the assays were 3.9%–13.9% and 5.5%–14.9%, respectively.     

Portable 4-channel electrochemical noise test system

A portable 4-channel electrochemical noise(EN) test system with high precision was developed.The modular instrument cRIO was used as its core and the signal conditioning module included zero resistance ammeter(ZRA),fly line,screening box and shielded wire.The EN data were acquired from two Q235 carbon steel specimens placed in 0.5 mol/L H2SO4 solution and 0.1 mol/L NaCl solution.The experimental result shows that this system can achieve an accuracy of 10 pA and 10 μV,and it can be applied to on-site multi-channel EN test.     

Sensing Escherichia coli O157：H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance (QCM) biosensor for Escherichia coli O157H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid (MHDA) was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide (NHS) raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor's resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×102 colony forming units (CFU)/ml E. coli O157H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed.     

Preparation of high-affinity rabbit monoclonal antibodies for ciprofloxacin and development of an indirect competitive ELISA for residues in milk

A convenient competitive enzyme-linked immunosorbent assay (ELISA) for ciprofloxacin (CPFX) was developed by using rabbit monoclonal antibodies (RabMAbs) against a hapten-protein conjugate of CPFX-bovine serum albumin (BSA). The indirect competitive ELISA of CPFX had a concentration at 50% inhibition (IC₅₀) of 1.47 ng/ml and a limit of detection (LOD) of 0.095 ng/ml. The mAb exhibited some cross-reactivity, however, not so high with enrofloxacin (28.8%), ofloxacin (13.1%), norfloxacin (11.0%), fleroxacin (22.6%), and pefloxacin (20.4%). And it showed almost no cross-reactivity with other antibiotics or sulfonamides evaluated in this study. The competitive ELISA kit developed here could be used as a screening tool to detect and control illegal addition of CPFX in food products. This kit had been applied to milk detection and the recovery rates from samples spiked by CPFX were in a range of 63.02%–84.60%, with coefficients of variation of less than 12.2%.     

Enantioselective assay of S(+)- and R(-)-propafenone in human urine by using RP-HPLC with pre-column chiral derivatization

The enantioselective assay for S( )- and R(-)-propafenone (PPF) in human urine that developed in this work involves extraction of propafenone from human urine and using S( )-propafenone as internal standard, chiral derivatization with 2,3,4,6-tetra-O-β-D-glucopranosyl isothiocyanate, and quantitation by an RP-HPLC system with UV detection (λ=220nm). A baseline separation ofpropafenone enantiomers was achieved on a 5-μm reverse phase ODS column, with a mixture of methanol:water:glacial acetic acid (25:12:0.02,v/v) as mobile phase. There was good linear relationship from 24.9 ng/ml to 1875.0 ng/ml for both of enantiomers. The regression equations of the standard curves based on Cs-PPF (or CR-PPF ) versus ratio of As-PPF/As (or AR-PPF/As ) were y=0.0032x-0.081, (r=0.999) for S-PPF and y=0.0033x 0.0039, (r=0.998) for R-PPF,respectively. The method's limit of detection was 12.5 ng/ml for both enantiomers, and the method's limit ofquantitation was 28.2±0.52 ng/ml for S-PPF, 30.4±0.53 ng/ml for R-PPF (RSD＜8%, n=5). The analytical method yielded average recovery of 98.9% and 100.4% for S-PPF and R-PPF, respectively. The relative standard deviation was no more than 6.11% and 6.22% for S-PPF and R-PPF, respectively. The method enabled study of metabolism of S( )- and R(-)-propafenone in human urine. The results from 7 volunteers administered 150 mg racemic propafenone indicated that propafenone enantiomers undergo stereoselective metabolism and that in the human body, S( )-propafenone is metabolized more extensively than R(-)propafenone.     

Catalytic Activity of Cr(VI) in the Degradation of Phenol by H2O2 Under Acidic Conditions

Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H₂O₂. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H₂O₂. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ^·OH generated from the catalysis of H₂O₂ by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H₂O₂ system, complexes with the Cr(V) intermediate rapidly formed and inhibited H₂O₂ decomposition, implying that the decomposition of H₂O₂ to ^·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO₂ and H₂O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO₂ and H₂O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H₂O₂ system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater.

     

基于褐藻酸钠改性纳米金静电排斥作用的新型电化学免疫传感器的研制

通过胱胺将负电性的褐藻酸钠(AS)共价结合到纳米金表面形成聚合体，并以此来标记三碘甲状腺氨酸(T3)．T3抗体固定在金电极上构成检测T3的电化学免疫传感器．通过免疫反应，标记T3和待检测的T3结合到金电极表面，使电极表面微环境发生显著改变，用Fe(CN)6^4 为电化学探针，用循环伏安法获取电极表面微环境改变的电化学信息来检测T3、其检测的线性范围为100—10000pg／mL，检测限为45pg/mL.     

生物技术在药物残留检测中的应用

综述了近年来在药物残留分析中应用的一些基于生物学原理的检测技术,包括免疫分析法、生物传感器法、生物芯片技术和活体生物分析技术等,具体介绍了每种技术的基本原理、特点及其在药物残留检测中的应用情况。     

Triethoxysilane with oligo（ethylene oxide） substituent as film forming additive for graphite anode

{3-[2-(2-methoxyethoxy) ethoxy]-propyl} triethoxysilane (TESM2) was synthesized and used as an electrolyte additive to improve the performances of lithium-ion batteries (LIBs). The electrochemical properties of the electrolyte (1 mol/L lithium hexafluorophosphate (LiPF₆)/ethylene carbonate (EC):diethylene carbonate (DEC):dimethyl carbonate (DMC), 1:1:1) with different contents of TESM2 were characterized by ionic conductivity measurement, galvanostatic charge/discharge test of graphite/Li half cells, and electrochemical impedance spectroscopy. Both the cycling performances and C-rate capabilities of graphite/Li half cells were significantly improved with an optimized content of 15% TESM2 in the electrolyte. The graphite/Li half cell delivered a very high specific capacity of 370 mAh/g at 0.2C rate without any capacity loss for 60 cycles, and retained a capacity of 292 mAh/g at 2C rate. The solid electrolyte interphase (SEI) film on the surface of the graphite anode was investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), indicating that TESM2 was effectively involved in the formation of SEI film on the surface of graphite.     

Effects of N source and nitrification pretreatment on growth of Arthrospiraplatensis in human urine

Culture of Arthrospira platensis (Spirulina platensis) in human urine was investigated to get valuable biomass. NO3-N was the proper N source, in comparison with other N source, including urea, NH4-N and NO2-N. As a result, aerobic nitrification of human urine was performed, with above 93.6% nitrification percentage finally achieved with total-N (TN) load of 46.52 mg/(L·d), in which Arthrospira platensis was successfully grown. The main compositions of the obtained biomass are close to those in Zarrouk medium. Thus, it is possible to culture Arthrospira platensis in nitrified human urine for food production within bioregenerative life support systems (BLSSs).     

长春市戊型肝炎的流行病学调查

通过长春市戊型肝炎流行病学调查,了解长春市戊肝病毒在动物与人群中的感染情况为戊肝防治提供宝贵的参考资料。对长春市采集的动物血清包括猪820份、牛506份、羊273份及人血清,包括农村饲养猪人群182份、农村非饲养猪人群102份,城镇人群546份,采用戊肝病毒抗原及抗体试剂盒检测血清中的病毒抗原及抗体。结果感染率分别为猪72.80%、牛11.86%、羊10.26%、农村饲养猪人群20.88%、农村非饲养猪人群15.38%、城镇人群4.58%。结果表明戊肝病毒在长春市的动物及人群中均有流行,且猪HEV感染比牛和羊及人都普遍,农村饲养猪人群和农村非饲养猪人群感染率都远高于普通人群,为戊肝是人畜共患病提供有力证据。     

Development and evaluation of immunoassay for zeranol in bovine urine

A high affinity polyclonal antibody-based enzyme linked immunosorbent assay （ELISA） was developed for the quantification of zeranol in bovine urine. On the basis of urine matrix studies, the optimized dilution factors producing insignificant matrix interference were selected as 1：5 in pretreatment. In the improved ELISA, the linear response range was between 0.02 and 1 μg/ml, and the detection limit was 0.02 μg/ml for the assay. The overall recoveries and the coefficients of variation （CVs） were in the range of 82%-127% and 3.5%-8.8%, respectively. Thirty-six bovine urine samples spiked with zeranol （ranging from 0.2 to 10 μg/ml） were detected by the ELISA and liquid chromatography （LC） method, and good correlations were obtained between the two methods （R^2=0.9643）. We conclude that this improved ELISA is suitable tool for a mass zeranol screening and can be an altemative for the conventional LC method for zeranol in bovine urine.     

The Effect of Supplementing Instruction with Conceptual Change Texts on Students’ Conceptions of Electrochemical Cells

The aim of this study was to investigate the effectiveness of instruction supplemented by conceptual change texts (CCTs) over traditional instruction on students’ understanding of electrochemical (galvanic and electrolytic) cell concepts. The participants of the study consisted of 64 students from the two classes of a high school located in Turkey. Classes were randomly assigned to experimental group, which was exposed to CCTs as a supplementary material, and to control group, which was exposed to traditional instruction. A 23-item multiple-choice test was developed assess students’ conceptual understanding of electrochemical cells. This test was administered to both groups before and after the instruction. The results of ANCOVA indicated that students who were instructed by using CCTs had better conceptual understanding of electrochemical cells than those experiencing traditional instruction when their prior electrochemical cell concepts understanding was statistically controlled. The findings of this study suggest that CCTs can be used as a cost- and resource-effective supplement to classroom instruction to promote students’ understanding science concepts.     

Preparation of nanometer γ-Fe2O3 by electrochemical oxidation in non-aqueous medium

1IntroductionThe synthesis and characterization of nano-struc-tured materials are the subject of intense current re-search.Hyperfineγ-Fe2O3particle with good perfor-mance,such as magnetism,catalysis,gas-sensitivityand so on,are widely applied in various fields[1].It ishighly significant to research and develop the methodsfor synthesis of nanometerγ-Fe2O3.With the development of nano-science and nano-technology,the methods for preparation ofγ-Fe2O3have been greatly progressed,for example,…     

Preparation and electrochemical application of praseodymium modified TiO<Subscript>2</Subscript>-NTs/SnO<Subscript>2</Subscript>-Sb anode by cyclic voltammetry method

A Pr-doped TiO₂-NTs/SnO₂-Sb electrode was prepared by a simple method, cyclic voltammetry(CV). The methyl orange(MO)aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO₂-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseodymium oxide was successfully doped into the SnO₂-Sb film by CV method. Due to the doped Pr, the oxygen evolution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The C _t /C ₀ (φ) was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min^-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.     

酶联免疫吸附反应的技术进展及应用

以常规的酶联免疫吸附法为基础，不断改进，形成了多种酶联免疫吸附法，如模块化ELISA，双位点一步法，捕获法测IgM抗体，生物素、亲和素系统，斑点酶链免疫吸附试验，硝酸纤维素膜微粒ELISA等方法。酶链免疫吸附法在医药，食品加工业，农牧渔业等领域有着广泛的应用：如乙型肝炎，莱姆病，急性心肌梗死的早期诊断，定量检测内毒素，HIV抗体初筛，SARS病毒的快速检测；检测食品中的毒素，残留农药，微生物及其它成分；检测香蕉有关病毒，小麦黄花叶病毒，棉花黄萎病菌毒素，转Bt基因抗虫棉，检测水产品中氯霉素的残留量，猪细小病毒(PPV)血清抗体，禽脑脊髓抗体等。     

一步合成氧化铟液化气传感器

A liquefied petroleum gas （LPG） sensor with high selectivity, sensitivity and low power consumption has been developed based on indium oxide with very low resistance. Nanocrystalline In203 gas sensing materials were directly synthesized through a one-step controllable solvothermal process at 210 ℃ for 24 h, using InCI3.4H2O as the starting material, cetyltrimethyl ammonium bromide （CTAB） as additive and ethanol as the solvent. The obtained samples were characterized by X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. The results showed that indium oxide takes on uniform cubic shape with range size of 10~30 nm and fine dispersivity. Gas sensitivity was measured in a mixing static gas. The results indicated that 3.0 V is the best working voltage of the sensor to LPG. Sensitivity is 12.6. The response-time and recovery-time are 3 s and 10 s respectively. Power consumption is only around 200 mW.     

热加工食品中α-乳白蛋白双抗夹心酶联免疫分析法的建立

建立热加工食品中α-乳球蛋白的双抗夹心酶联免疫检测检测方法。以热处理的α-乳白蛋白为抗原,制备抗α-乳白蛋白的高特异性单克隆抗体,并将以此蛋白作为包被抗体,构建双抗夹心ELISA方法。本方法标准曲线的IC50为360 ng/mL,方法的灵敏度为10 ng/mL。以尿素作为提取液可以大大提高热加工食品中α-乳白蛋白的提取率,添加回收率在76%~89%之间,相对标准偏差小于15%。该方法能准确地识别热加工的奶制品,避免了传统免疫方法在热加工奶制品检测上的假阴性。