This study report an human serum IgG antibodies to Helicobacter pylori quantitation procedure based on the multiple use of an immobilized H. pylori antigen on an immuno-column incorporated into an a flow-injection (FI) analytical system. The immuno-adsorbent column was prepared by packing 3-aminopropyl-modified controlled-pore glass (APCPG) covalently linking H. pylori antigens in a 3-cm of Teflon tubing (0.5 i.d.). Antibodies in the serum sample are allowed to react immunologically with the immobilized H. pylori antigen, and the bound antibodies are quantified by alkaline phosphatase (AP) enzyme-labeled second antibodies specific to human IgG. p-Aminophenyl phosphate (pAPP) was converted to p-aminophenol (pAP) by AP and an electroactive product was quantified on glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNT) (GCE-CNTs) at 0.30 V. The total assay time was 25 min. The calculated detection limits for amperometric detection and the ELISA procedure are 0.62 and 1.8 UmL(-1), respectively. Reproducibility assays were made using repetitive standards of H. pylori-specific antibody and the intra- and inter-assay coefficients of variation were below 5%. The immuno-affinity method showed higher sensitivity and lower time-consumed, demonstrate its potential usefulness for early assessment of human serum immunoglobulin G (IgG) antibodies to H. pylori. 相似文献
Abstract 2‐Acetylbutyrolactone was characterized as a novel reagent of analytical potential in polarographic and voltammetric analyses. It forms α‐oxo‐γ‐butyrolactone arylhydrazones through Japp‐Klingemann coupling reaction with primary arylamines. α‐Oxo‐γ‐butyrolactone arylhydrazones possess an electro‐active site (azomethine center) that displays a cathodic activity at the mercury electrode. The protonated azomethine center of α‐oxo‐γ‐butyrolactone arylhydrazones is reduced by 2e/2H+ reaction to the hydrazo form. The differential pulse polarographic behavior of α‐oxo‐γ‐butyrolactone arylhydrazones was investigated in aqueous media ranging from pH 2 to 10.5. In aqueous acidic solution, α‐oxo‐γ‐butyrolactone arylhydrazones were shown to adsorb on a hanging mercury drop electrode and to be amenable to determination by adsorptive stripping voltammetry. Procedures for applying the polarographic and voltammetric methods to determination of sulfadiazine and sulfamethoxazole in pharmaceutical preparations have been developed. An analogous study on sulfas‐azo derivatives of ethyl acetoacetate was also considered. Furthermore, the differential pulse voltammetric method was adopted for determination of sulfamethoxazole in spiked plasma and urine samples. The recoveries turned out to be satisfactory, showing relative standard deviations from 2.4 to 4.6%. 相似文献
Valacyclovir (VCH) is an antiviral drug, used in the management of viral infections such as herpes simplex and varicella-zoster in humans. It is rapidly converted to acyclovir which has antiviral activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and Varicella-zoster virus (VZV) both in vitro and in vivo. Electrochemical behavior was studied using cyclic voltammetric method, and the analytical application was studied using differential pulse voltammetric technique. The process on the surface of electrode was found to be irreversible and diffusion controlled. The charge transfer coefficient, heterogeneous rate constant, the number of electron transferred and activation parameters were calculated. Possible free radical reaction mechanism taking place on the surface of electrode was proposed. Calibration plot constructed using differential pulse voltammetric technique and applied for quantitative analysis in pharmaceutical and human urine sample. Limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 0.028 and 0.09 μM, respectively. The present work describes the electrochemical behavior of an antiviral drug, VCH and its determination in pharmaceutical samples. The method shows the development of a sensor for selective and sensitive determination of VCH. 相似文献
The electrochemical enzyme-linked immunoassay increases the sensitivity of the detection of cucumber mosaic virus (CMV) by 5-fold compared with the spectrophotometric o-phenylenediamine (OPD) enzyme-linked immunosorbent assay (ELISA). The detection limit for the purified CMV is 1.0 ng/mL and the highest dilution ratio of the infected leaf sap is 1:5.0 x 10(4). The method is based on coupling the oxidation reaction of o-aminophenol (OAP)-H2O2 catalyzed by HRP-IgG conjugate with the electro-reduction of the enzymatic product. The enzymatic product 2-aminophenoxazine-3-one exhibits a sensitive second order derivative linear-sweep voltammetric response at the potential of -0.65 V (vs. Ag/AgCl) in pH 8.0 Britton-Robinson (B-R) buffer solution. So it can be applied to the detection of the plant virus with highly improved sensitivity. 相似文献
The acid-treated multi-walled carbon nanotubes (MWNTs), which were modified on the surface of gold electrode, offers substantial improvements in voltammetric sensitivity and selectivity towards the determination of dopamine (DA). It can inhibit the voltammetric response of ascorbic acid (AA) while the redox reaction of dopamine is promoted. When a differential pulse voltammetric (DPV) technique was used, the peak separation between DAs and AAs was 244 mV. Based on this, a selective method could be constructed to detect DA in the presence of 1,000 times higher concentration of AA. The effect of various experimental parameters on the voltammetric response of dopamine was investigated. Under the chosen conditions, the peak currents are correspondent linearly to the concentrations of DA in the range of 5 x 10(-7) approximately 4 x 10(-4) mol L(-1) with a limit of detection of 2 x 10(-7) mol L(-1). The proposed method can be applied to detect DA in real samples. 相似文献
Poly(X) (polyriboxanthylic acid) gives up to two differential pulse voltammetric oxidation peaks (peaks I and II) at the PGE. Xanthine, which appears to be a trace contaminant of commercial poly(X) samples, exhibits a differential pulse voltammetric oxidation peak at more negative potentials than the peaks of poly(X). Xanthosine-5'-monophosphate also gives up to two differential pulse voltammetric oxidation peaks at the PGE. An analytical method has been developed to determine trace amounts of xanthine and xanthosine-5'-monophosphate in poly(X) samples based on differential pulse voltammetry. 相似文献
The electrochemical enzyme-linked immunoassay increases the sensitivity of the detection of cucumber mosaic virus (CMV) by 5-fold compared with the spectrophotometric o-phenylenediamine (OPD) enzyme-linked immunosorbent assay (ELISA). The detection limit for the purified CMV is 1.0 ng/mL and the highest dilution ratio of the infected leaf sap is 1?:?5.0 × 104. The method is based on coupling the oxidation reaction of o-aminophenol (OAP)-H2O2 catalyzed by HRP-IgG conjugate with the electro-reduction of the enzymatic product. The enzymatic product 2-aminophenoxazine-3-one exhibits a sensitive second order derivative linear-sweep voltammetric response at the potential of –0.65 V (vs. Ag/AgCl) in pH 8.0 Britton-Robinson (B-R) buffer solution. So it can be applied to the detection of the plant virus with highly improved sensitivity. 相似文献
An allele‐specific voltammetric genoassay for the detection of allele‐specific toll‐like receptor‐2 gene arg753gln polymorphism (TLR‐2) from polymerase chain reaction (PCR) amplified real samples was described in this study. Meldola blue (MDB), an intercalator molecule, was used as hybridization label. The wild‐type and mutant type oligonucleotide probes were immobilized onto disposable graphite electrode surfaces by covalent attachment method. The extent of hybridization between probe and target sequences was determined by using differential pulse voltammetry (DPV). As a result of the interaction between MDB and DNA at electrode surface, the MDB signal observed from probe sequence before hybridization and after hybridization with MM sequence is lower than that observed after hybridization with complementary sequence. The differences between the MDB reduction peaks obtained from probe modified, hybrid modified and MM modified electrode were used to detect TLR‐2 from PCR amplified real samples. The discrimination of homozygous and heterozygous alleles was also established by comparing the peak currents of MDB reduction signals. Numerous factors affecting the target hybridization and indicator binding reactions are optimized to maximize the sensitivity. 相似文献
A flow injection (FI) method using multiple differential pulse voltammetric detection for the simultaneous determination of two metal ions was developed and applied to the resolution of Cd(II)-Pb(II) mixtures. The metals are detected by applying two sequential pulses to a three-electrode voltammetric system that uses a flow-through cell accommodating a static mercury-drop working electrode. The influence of the electrode area, flow-rate, pulse frequency, pulse width and sampling time was investigated. Under the experimental conditions used, the two metals were found to interfere with each other. The use of a neural network allows the simultaneous determination of both, in mixtures, with good accuracy. The proposed method is applicable to other complex systems involving different working electrodes and more than two electroactive species. 相似文献
The utility of carbon-paste electrodes modified with 2,2'-bipyridyl and Nafion for the differential pulse voltammetric determination of iron(II) in aqueous medium is demonstrated. The method is based on formation of the 2,2'-bipyridyl complex of iron(II) and its accumulation by the Nafion. The differential pulse voltammetric response of the accumulated complex is used as the analytical signal. The response was evaluated with respect to carbon-paste composition, preconcentration time, pH, iron(II) concentration and other variables. A 3-min accumulation period permits measurement of iron(II) down to 10(-8)M, and a relative standard deviation of 3.8% for 2 x 10(-6)M iron(II). Rapid and convenient chemical renewal allows use of a single modified carbon-paste electrode in multiple analytical measurements over several days. The proposed procedure was applied to the determination of iron in certified standard reference materials and trace iron in natural waters. 相似文献
A voltammetric study of the oxidation of Ceftazidime (CEFT) has been carried out at the glassy carbon electrode by cyclic, differential pulse (DPV) and square wave (SWV) voltammetry. The oxidation of CEFT was irreversible and exhibited diffusion controlled process depending on pH. The oxidation mechanism was proposed and discussed. According to the linear relationship between the peak current and concentration, DPV and SWV voltammetric methods for CEFT assay in pharmaceutical dosage forms and human urine were developed. For analytical purposes, a well resolved diffusion controlled voltammetric peak was obtained in 0.1 M H2SO4 at 1.00 and 1.02 V for differential pulse and square wave voltammetric techniques, respectively. The linear response was obtained within the range of 4 × 10?6?8 × 10?5 M with a detection limit of 6 × 10?7 M for differential pulse and 4 × 10?6–2 × 10?4 M with a detection limit of 1 × 10?6 M for square wave voltammetric technique. The determination of CEFT in 0.1 M H2SO4 was possible over the 2 × 10?6–1 × 10?4 M range in urine sample for both techniques. The standard addition method was used for the recovery studies. 相似文献
A novel experimental methodology based on a Prussian blue (PB) and gold nanoparticles (AuNPs) modified carbon ionic liquid
electrode (CILE) was developed for use in a label-free amperometric immunosensor for the sensitive detection of human immunoglobulin
G (HIgG) as a model protein. The CILE was fabricated by using the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate
as binder. Controllable electrodeposition of PB on the surface of the CILE and coating with 3-aminopropyl triethylene silane
(APS) formed a film with high electronic catalytic activity and large surface area for the assembly of AuNPs and further immobilization
of HIgG antibody. The electrochemistry of the formed nanocomposite biofilm was investigated by electrochemical techniques
including cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The HIgG concentration
was measured through the decrease of amperometric responses in the corresponding specific binding of antigen and antibody.
The decreased differential pulse voltammetric values were proportional to the HIgG concentration in two ranges, 0.05–1.25 ng mL−1 and 1.25–40 ng mL−1, with a detection limit of 0.001 ng mL−1 (S/N = 3). This electrochemical immunoassay combined the specificity of the immunological reaction with the sensitivity of
the AuNPs, ionic liquid, and PB amplified electrochemical detection and would therefore be valuable for clinical immunoassays. 相似文献
We report on a new amplification strategy for use in an immunoassay for influenza virus subtype H7N9. Graphene sheets were first placed on a glassy carbon electrode (GCE), and gold nanoparticles were then electrodeposited as a support for a layer of alcohol dehydrogenase (ADH) in a sol–gel containing thiol groups. Protein A was used to properly orientate immobilized antibody against H7N9 on the sol–gel, and this is shown to result in strongly improved specificity of the antigen-antibody binding. Thus, a sensitive and specific immunosensor was obtained in which a quadruple signal amplification strategy is employed, viz. (a) via the use of graphene sheets, (b) via a hybridization chain reaction, (c) the use of hemin/G-quadruplex DNAzyme concatamers, and (d) the use of ADH. The hemin/G-quadruplex is a typical DNAzyme, which simultaneously acts as NADH oxidase and HRP-mimicking DNAzyme. The hybridization chain reaction-based DNAzyme concatamers assembled on multi-walled carbon nanotubes (MWCNTs) and the ADH represent a triple electrocatalytic enzyme cascade system. Sandwich immunoreactions occurred between the capture antibody on the electrode and the secondary antibody labeled with MWCNTs. Positively charged Methylene Blue (MB) was then used as an intercalator to detect the DNAzyme concatamer formed. The differential pulse voltammetric signals for MB are related to the concentration of H7N9 in the range from 8 to 60 pg · mL−1, and the detection limit is 0.81 pg · mL−1 (at an S/N ratio of 3). This immunoassay is very sensitive, specific and robust.
An electrochemical sandwich immunosensor has been developed for sensitive and specific detection of influenza virus subtype H7N9. Protein A was used to properly orientate antibody. The hybridization chain reaction based DNAzyme concatamers assembled on multi-walled carbon nanotubes (MWCNTs) and the ADH represent a triple electrocatalytic enzyme cascade system.
A voltammetric study of the oxidation of etodolac has been carried out at the glassy carbon electrode. The electrochemical oxidation of etodolac was investigated by cyclic, linear sweep, differential pulse and square wave voltammetry using glassy carbon electrode. Different parameters were tested to optimize the conditions for the determination of etodolac. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton-Robinson buffer at pH 2.15 for differential pulse and square wave voltammetric techniques. The linear response was obtained in the ranges of 2.10(-6)-8.10(-5) M with a detection limit of 6.8x10(-7) and 6x10(-6)-8x10(-5) M with a detection limit of 1.1x10(-6) M for differential pulse and square wave voltammetric techniques, respectively. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of the etodolac in tablet dosage form and human serum. 相似文献
The electrochemical oxidation of salicylic acid (SA) has been studied on a glassy carbon electrode using cyclic voltammetry and differential pulse voltammetric (DPV) method. SA gives a single irreversible oxidation wave over the wide pH range studied. The irreversibility of the electrode process was verified by different criteria. The mechanism of oxidation is discussed. Using differential pulse voltammetry, SA yielded a well-defined voltammetric response in Britton-Robinson buffer solution, pH 2.37 at 1.088 V (versus Ag/AgCl). The method was linear over the SA concentration range: 1-60 μg ml−1. The method was successfully applied for the analysis of SA as a hydrolysis product, in solid pharmaceutical formulations containing acetylsalicylic acid (ASA). 相似文献