Polarographic immunoassay coupled with catalytic amplification of labeled copper ions

A new approach of polarographlc immunoassay based on the catalytic amplification of the labeled metal ions and the polarographlc detection of the catalytic product was developed.In this approach,the copper ions used as the catalyst for substrate conversion instead of natural enzyme were labeled to model antigen diphtheria toxoid (DT) through the bifunctional chelating reagent diethylenetriamine pentaacetic acid (DTPA).After heterogeneous competitive imrnunoreaction,the oxidation of substrate o-phenylenediatnine (OPD) was catalyzed by the labeled copper ions to generate an electroactive product 2,3-diammophenazine (DAP); subsequently,the product DAP was detected with linear-sweep polarography The proposed assay can determine the concentration in the range of 10-1 000 ng/mL of DT,two orders of magnitude more sensitive than those based on the direct detection of the metal ion labels The proposed immunoassay can be applied to detecting various proteins of interest.     

偶合标记铜离子催化放大的极谱免疫分析法测定破伤风类毒素

建立了测定破伤风类毒素的铜离子标记极谱免疫分析方法．用二乙三胺五乙酸（ＤＴＰＡ）酸酐法将用离子标记于抗原破伤风类毒素（ＴＴ）．所得标记物中ＴＴ：ＤＴＰＡ：Ｃｕ的摩尔标记比为 １：６：６、铜离子催化底ｏ－苯二胺（ＯＰＤ）的氧化反应，生成电活性产物 ２，３－二氧基吩嗪（ＤＡＰ），以单扫描极谱法检测ＤＡＰ．采用异相竞争免疫分析模式，本方法可测定０．０５～１ｍｇ／Ｌ ＴＴ。     

过硫酸钾存在下极谱催化波法测定芬布芬

过硫酸钾存在下极谱催化波法测定芬布芬;芬布芬;过硫酸盐;平行催化波;线性扫描极谱法     

血清蛋白-荧光素复合物单扫极谱波与应用

在0．08mol／L的HAc中，荧光素与牛血清白蛋白(BSA)或人血清白蛋白(HSA)相互作用形成复合物。复合物使荧光素在-0．58V(vs．SCE)处的还原峰电流增大，峰电流的增大值与加入的BSA或HSA的浓度在一定的范围内呈线性关系。BSA在2—24μg／mL范围内呈线性关系，检出限为1μg／mL；HSA在2—22μg／mL范围里呈线性关系，检出限为0．8μg／mL。应用该法测定了人血清蛋白样品，结果令人满意。     

Microchip electrophoresis coupled with on-line magnetic separation and chemiluminescence detection for multiplexed immunoassay

A facile and universal strategy for multiplexed immunoassay is proposed. The strategy is based on microchip electrophoresis (MCE) coupled with on-line magnetic separation and chemiluminescence (CL) detection. The system consisted of a microchip, an electromagnet, and a photomultiplier. The realization of multiplexed immunoassay protocol involves sampling magnetic nanoparticles (MNPs) labeled antibodies, N-(4-aminobutyl)-N-ethyl-isoluminol (ABEI) labeled antigens and free antigens in the precolumn reactor, on-line immunoreaction, capturing the MNPs-immunocomplexes, and the separation of unconjugated ABEI-labeled antigens. After on-line magnetic separation, the free ABEI-labeled antigens were transported into the separation channel, and mixed with hydrogen peroxide (H(2) O(2) ) in the presence of horseradish peroxidase in the postcolumn reactor, and producing CL emission. Using this arrangement, multiple analytes could be measured simultaneously by performing the technical operations for a single assay. As a proof-of-concept, the multiplexed immunoassay was evaluated for the simultaneous determination of five model analytes (i.e. hydrocortisone, corticosterone, digoxin, testosterone, and estriol). The results exhibited excellent precision and sensitivity, the relative standard deviations for nine times detection were lower than 4.7% for all the five components, and the detection limits of five analytes were in the range of 3.6-4.9 nM. The MCE system was validated using two human serum-based control samples containing five analytes.     

Polarographic Eiectroreduction of Some Complexes of Uranium with Macrocyclic Polyethers

Abstract

The polarographic behaviour of uranium(VI) in aqueous C. 1 N nitric acid medium, in the presence of some polyoxa macrocyclic ligands (15-crown-5, benzo-15-crown-5, 18-crown-6, dicyclohexyl-18-crown-6), at 25°C, was investigated. Both in the absence and in the presence of the polyoxa macrocyclic ligands, the reduction of hexavalent uranium in aqueous medium takes place in two steps, each of which involving the transfer of an electron. Under diffusion-controlled conditions, the two steps of the reduction in acid medium proceed reversibly. The results of the polarographic measurements enabled to estimate the ratio of the stability constants of the complex ions of U(111) and of U(IV) with macrocyclic polyethers.     

Polarographic behaviour and determination of paracetamol and salicylamide after treatment with nitrous acid

A polarographic procedure is described for the determination of paracetamol (acetaminophen) and salicylamide after treatment with nitrous acid. The different experimental parameters affecting the derivatization process and the polarographic analysis were studied. The derivatization products were found to be reduced at the dropping mercury electrode over the whole pH range in Britton-Robinson buffers. At pH 7.0, well defined diffusion-controlled cathodic waves were produced for both compounds. Plots of limiting current vs. concentration were linear over the ranges 0.05–0.75 and 0.25–1.5mM for paracetamol and salicylamide, respectively, in the d.c. mode, with minimum detectability of 2.5 × 10^–6 and 1.25 × 10^–5 M, respectively. The procedure was applied to the analysis of some pharmaceutical dosage forms and the results were in good agreement with those obtained by official and compendial methods.     

Element-tagged immunoassay with inductively coupled plasma mass spectrometry for multianalyte detection

The multianalyte immunoassay approach is currently attracting increasing attention due to its high sample throughput, short assay time, low sample consumption and reduced overall cost per assay. This paper reviews progress in the field of multianalyte immunoassays using inductively coupled plasma mass spectrometry, as well as applications of this approach in different fields. Examples related to the combination of protein microarray technology with the multitag approach of the immunoassay ICP-MS method and to the use of ICP-MS in the field of imaging are described. A novel strategy that involves tagging antibodies for ICP-MS detection in sensitive multitag bioassays is also presented. Finally, the outlook for this promising technique is discussed.     

Study and Application on Polarographic Catalytic Wave of Human Serum Albumin in the Presence of Kio3

ABSTRACT

A polarographic catalytic wave of human serum albumin (HSA) in the presence of KIO³ was reported. In 0.1 M NaAc～HAc buffer (pH4.7) solution, a reduction wave of HSA with peak potential ?0.60 V (vs., Ag/AgCl) resulted from the reduction of five disulfide linkages to sulfhydryl group. In the presence of KIO³, HSA yielded a polarographic catalytic wave at the original potential due to reduction and regeneration of these disulfide linkages. The catalytic wave can be used to determine trace of HSA. In the 0.1 M HAc～NaAc (pH4.7±0.2) ～1×10^?3 M KIO³ solution, the peak current was linearly proportional to HSA concentration in the range of 1.5×10^?7～7.5×10^?7 M. The catalytic wave improved two orders of magnitude in sensitivity compared with corresponding reduction wave.     

用鸡冠花红线性扫描极谱法测定蛋白质及其应用

在pH3．0的Britton—Robinson(B-R)缓冲溶液中，鸡冠花红与蛋白质能够发生相互作用形成超分子复合物，使鸡冠花红在-0．25V(vs．SCE)处的极谱还原峰峰电流下降。在最佳条件下，峰电流的下降值同人血清白蛋白(HSA)的浓度在1．0～20．0mg／L范围内呈线性关系，其线性回归方程为△ip″(nA)=184．86 111．23c(mg／L)．r=0.987。将该方法应用于实际人血清样品的测定，结果与经典的考马斯亮蓝G-250光度法一致。此方法还可应用于牛血清白蛋白、牛血红蛋白、卵清白蛋白等蛋白质的测定。     

Polarographic investigation of the Cu(II) complex with ampicillin

The complex of Cu(II) ion and ampicillin is investigated polarographically in aqueous medium, at pH = 6, an ionic strength = 0.2, and room temperature. The stoichiometric ratio of Cu(II) and ampicillin in the complex, and the stability constant, logK = 5.1, were determined by Lingane's method.     

蒸馏-催化极谱法测定复杂物料中微量砷

提出了用催化极谱法测定复杂物料中微量砷的含量。选择测定的溶液介质中含碲(Ⅳ)硫酸溶液5mL和150g.L-1碘化钾溶液5mL。仪器扫描速率为250mV.s-1,并采用二阶导数测定。试样(0.01～1.0g)用氯酸钾0.5g、氢氟酸5滴、硝酸5～10mL溶解,用蒸馏法分离其中的砷。砷的质量浓度在0.4mg·L-1以内与相应的峰电流呈线性关系。按此方法测定了12个矿样中砷含量,其测定值与已知值相符。方法的回收率在97%～100%之间,相对标准偏差(n=6)在2.3%～7.2%之间。     

Polarographic and spectrophotometric determination of isocarboxazid and tranylcypromine sulphate through treatment with nitrous acid

Two methods are described for the determination of two widely prescribed antidepressants, namely isocarboxazid and tranylcypromine sulphate as the pure drugs and in dosage forms. Both methods involve prior treatment with nitrous acid. In the Spectrophotometric method, the two derivatives obey Beer's law over the concentration range 1–20 g/ml. The derivatives are polarographically reducible withE _1/2 values of –0.84 and –0.73 V for isocarboxazid and tranylcypromine sulphate, respectively. The calibration plots are linear over the range 4.3 × 10^–5–3.0 × 10^–4 and 1.1 × 10^–5–1.65 × 10^–4 mol/1 for isocarboxazid and tranylcypromine sulphate, respectively. The results obtained for assays for the two drugs compare satisfactorily with those given by the official methods.     

Polarographic Determination of Lisinopril in Pharmaceuticals and Biological Fluids Through Treatment with Nitrous Acid

 A simple and highly sensitive polarographic method was developed for the determination of lisinopril in dosage forms and biological fluids. The method is based on treatment of the compound with nitrous acid followed by measuring the cathodic current produced by the resulting nitroso derivative. The polarographic behavior was studied adopting direct current (DC_t), differential pulse (DP) and alternating current (AC_t) polarography. A well-defined, diffusion-controlled cathodic wave over the pH range of 1.0–8.0 was obtained in Britton-Robinson buffers (BRb). At pH 3.0, the value of limiting diffusion-current constant (K) was 8.42 ± 0.23 (n = 7). The limiting diffusion current-concentration relationship was found to be rectilinear over the range of 2–24 μg/mL and 0.1–20 μg/mL using DC_t and DP polarographic modes, respectively. The minimum detectability was (S/N = 2) 0.02 μg/mL (4.54 × 10⁻⁸ M). The proposed method was successfully applied to the determination of lisinopril either per se or in dosage forms and the results obtained were in good agreement with those given using a reference method. The proposed method was further applied to the determination of lisinopril in spiked human urine and plasma. The percentage recoveries adopting the DP polarographic mode were 99.71 ± 1.87 and 97.16 ± 1.09, respectively. Received October 18, 2001; accepted July 31, 2002     

Differential Pulse Polarographic Determination of Trace Molybdenum in Uranium with α-Benzoinoxime Extraction

A method for the determination of trace molybdenum in uranium is described based on its specific catalytic reduction wave in the presence of nitric acid. Molybdenum is separated from uranium by α-benzoin oxime extraction and determined by differential pulse polarography. As lower as 1 ng/ml of Mo(VI) is determinable and 98% of recovery can be obtained at present work.     

Polarographic Studies on Associations of Midecamycin and Chloroquine with Hydrogen Peroxide

IntroductionReactive oxygen species( ROS) including su-peroxide anion O· -2 ,hydrogen peroxide H2 O2 andhydroxyl radical OH· form in human body as a re-sult of various biochemical processes.ROS may beessential for many cellular functions such as bacte-rial ingestion and the redox regulation of signaltransduction.However,it is also recognized thatROS as harmful agents cause severe damage to sev-eral cell components ( nucleic acids,proteins,polyoses,lipoids,DNA,etc.) ,resulting in thepat…     

Mesoporous carbon-enriched palladium nanostructures with redox activity for enzyme-free electrochemical immunoassay of brevetoxin B

A new signal amplification strategy based on mesoporous carbon-enriched palladium nanostructure (MSC-PdNS) was designed for enzyme-free electrochemical immunoassay of brevetoxin B (BTB) in marine toxins. The assay was carried out on a BTB-bovine serum albumin-functionalized electrode by using monoclonal mouse anti-BTB-labeling MSC-PdNS as the signal-transduction tag. A competitive-type assay protocol was successfully introduced to develop a high-efficiency enzyme-free immunoassay accompanying the doped palladium nanostructure into MSC-PdNS toward reduction of H₂O₂. Under the optimal conditions, the catalytic current decreased with the increment of BTB concentration in the range from 0.01 to 10 ng mL⁻¹ with a detection limit (LOD) of 5.0 pg mL⁻¹ BTB at the 3s_blank criterion. The selectivity and precision were acceptable. In addition, the methodology was further validated for assaying spiked seafood samples, and consistent results between the electrochemical immunoassay and the referenced enzyme immunoassay were obtained. Importantly, the enzyme-free electrochemical immunoassay provides a promising approach for rapid screening of marine toxin because of its simplicity, low cost, sensitivity, specificity and without the need of sample pretreatment.     

One-pot access to pyridocoumarins via Povarov-hydrogen transfer cascade under auto-tandem catalysis of iodine in aqueous micelles

A cascade of inverse electron demand Diels–Alder reaction of 6-aminocoumarin-derived aldimines with an excess of styrene and oxidative aromatization of the formal Povarov adducts under autotandem iodine catalysis in aqueous micellar conditions provides direct access to a small library of substituted pyridine annulated coumarins in good to acceptable yields (12 examples). The unusual formation of linearly annulated pyridocoumarins under essentially neutral conditions is a remarkable feature of the protocol.