Flow Injection Immunoanalysis Based on a Magnetoimmunosensor System

Solé, Sílvia; Alegret, Salvador; Céspedes, Francisco; Fàbregas, Esteve; Díez-Caballero, Teófilo

doi:10.1021/ac970441+

Cited by 56 publications

(8 citation statements)

References 22 publications

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“…43 The proposed concept can be easily adapted to other applications in the fields of biological and medical research, diagnostic medicine, genetics, and drug testing, since procedures for covalent immobilization of immunoreagents on superparamagnetic microspheres are well-established and antibody-coated magnetic beads are increasingly utilized in immunoassays. [44][45][46][47][48][49] …”

Section: Resultsmentioning

confidence: 99%

“…The on-chip procedure offers several advantages compared with electrochemical immunosensors, including easy and precise handling of the immunomagnetic beads (accurate control of the amount of the added immunoreagent), as well as uniform dispersion of the IMBs throughout the immunoreaction mixture, providing faster reaction kinetics . The proposed concept can be easily adapted to other applications in the fields of biological and medical research, diagnostic medicine, genetics, and drug testing, since procedures for covalent immobilization of immunoreagents on superparamagnetic microspheres are well-established and antibody-coated magnetic beads are increasingly utilized in immunoassays. − …”

Section: Discussionmentioning

confidence: 99%

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An Immunomagnetic Electrochemical Sensor Based on a Perfluorosulfonate-Coated Screen-Printed Electrode for the Determination of 2,4-Dichlorophenoxyacetic Acid

1999

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A disposable immunomagnetic electrochemical sensor involving a magnetic particle-based solid phase and a Nafion film-coated screen-printed electrode (Nafion-SPE) stuck at the bottom of a polystyrene cylinder (microwell of 300 microL) was developed and evaluated in a competitive immunoassay of the widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The competitive binding of 2,4-D and 2,4-D labled with alkaline phosphatase (AP) for a limited amount of polyclonal anti-2,4-D antibody-coated magnetic beads was monitored electrochemically by measuring the AP labled++ activity bound to the beads. The phosphoric acid ester of [[(4-hydroxyphenyl)amino]-carbonyl]cobaltocenium hexafluorophosphate was used as the AP substrate. This anionic substrate (S-) is enzymatically transformed at pH 9.0 into a cationic phenol derivative (P+) which can be easily accumulated in the polyanionic Nafion coating and determined by cyclic voltammetry. During the enzyme reaction, the AP-associated beads were localized on the surface of the Nafion-SPE with the aid of a magnet, thus effectively increasing the concentration of P+ in the Nafion-modified electrode vicinity. The enzyme generation of P+ close to the electrode surface, and thereby to the Nafion film, resulted in a high amplification of the response. A detection limit of 0.01 microgram L-1 2,4-D was thus achieved. The performance of the sensor was successfully evaluated on river water samples spiked with 2,4-D, indicating that this convenient and sensitive technique offers great promise for decentralized environmental applications.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

An Immunomagnetic Electrochemical Sensor Based on a Perfluorosulfonate-Coated Screen-Printed Electrode for the Determination of 2,4-Dichlorophenoxyacetic Acid

1999

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“…So far most of the electrochemical immunosensors have been structured by immobilizing various kinds of antibody or antigen on the electrode surfaces. After being incubated in the sample and enzyme conjugate solutions, the electrochemical immunosensors can determine the levels of analytes by the potential change − or the oxidation and reduction of electrochemically active species, generated by the action of the enzyme conjugate. , The enzyme-catalyzed potential change results from the bioelectrocatalysis of laccase or peroxidase enzyme as an electrocatalyst label to the oxygen or H 2 O 2 electroreduction or the urease-catalyzed hydrolysis reaction of urea to produce NH 3 that is determined by a gaseous diffusion potentiometric electrode − alkaline phosphatase, , laccase, and glucose oxidase. ,,, These enzymes are usually labeled to the immunoreagents.…”

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confidence: 99%

Reagentless Amperometric Immunosensors Based on Direct Electrochemistry of Horseradish Peroxidase for Determination of Carcinoma Antigen-125

et al. 2003

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A novel strategy for immunoassay and the preparation of reagentless immunosensors was proposed. This strategy was based on the immobilization of antigen and the direct electrochemistry of horseradish peroxidase (HRP) that was labeled to an antibody. A reagentless immunosensor for carcinoma antigen-125 (CA 125) determination was developed. The immunosensor was prepared by immobilizing CA 125 with titania sol-gel on a glassy carbon electrode by the vapor deposition method. The incubation of the immunosensor in phosphate buffer solution (PBS) including HRP-labeled CA 125 antibody led to the formation of a HRP-modified surface. The immobilized HRP displayed its direct electrochemistry with a rate constant of 3.04 +/- 1.21 s(-1). With a competition mechanism, a differential pulse voltammetric determination method for CA 125 was established by the peak current decrease of the immobilized HRP. The current decrease resulted from the competitive binding of the CA 125 in sample solution and the immobilized CA 125 to the limited amount of HRP-labeled CA 125 antibody. Under optimal conditions, the current decrease was proportional to CA 125 concentration ranging from 2 to 14 units mL(-1) with a detection limit of 1.29 units mL(-1) at a current decrease by 10%. The CA 125 immunosensor showed good accuracy and acceptable precision and fabrication reproducibility with intraassay CVs of 8.7 and 5.5% at 8 and 14 units mL(-1) CA 125 concentrations, respectively, and interassay CV of 19.8% at 8 units mL(-1). The storage stability was acceptable in a pH 7.0 PBS at 4 degrees C for 15 days. The proposed method provided a new promising platform for clinical immunoassay.

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“…This technique seems very attractive, although the construction of magneto-immunosensors requires sufficient experimental skills, and the immobilization of magnetic particles with immunologic material requires a relatively long period of incubation. Fàbregas also reported renewable amperometric immunosensors based on rigid conducting immunocomposites consisting of graphite powder, rabbit IgG, and methacrylate or epoxy resins. The surface of immunosensors can be renewed by simply polishing to obtain a fresh layer of immunocomposite that is ready to be used in a new competitive assay.…”

mentioning

confidence: 99%

Renewable Amperometric Immunosensor for Schistosoma japonium Antibody Assay

et al. 2001

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A renewable amperometric immunosensor has been proposed for the determination of Schistosoma japonium antibody (SjAb) in rabbit serum. A paraffin-graphite-Schistosoma japonium antigen (SjAg) biocomposite, which needs no additional curing, was directly used to construct the immunosensors. The analytical sample containing the desired SjAb was mixed with SjAb labeled with horseradish peroxidase (HRP) to form the incubation solution for the competitive binding assay. Amperometry was used to determine the amount of HRP fixed on the sensor surface, which was related to the content of desired SjAb. Assay conditions were optimized, including the selection of substrate, the loading of SjAg in the biocomposite, the amount of labeled SjAb in the incubation solution, the incubation time, and the temperature. Using o-aminophenol (o-AP) as a substrate, amperometric detection at -200 mV (vs SCE) resulted in a pseudolinear detection range of about 0.36 to 14 microg/mL, with a detection limit of 0.36 microg/mL. Rabbit serum samples with varying infection degrees were analyzed, and the results demonstrated that the concentration that is detectable in this system meets the demands of clinical analyses. A new surface on the immunosensor for use in another competitive assay can be obtained by removing the original one and polishing the surface.

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Flow Injection Immunoanalysis Based on a Magnetoimmunosensor System

Cited by 56 publications

References 22 publications

An Immunomagnetic Electrochemical Sensor Based on a Perfluorosulfonate-Coated Screen-Printed Electrode for the Determination of 2,4-Dichlorophenoxyacetic Acid

An Immunomagnetic Electrochemical Sensor Based on a Perfluorosulfonate-Coated Screen-Printed Electrode for the Determination of 2,4-Dichlorophenoxyacetic Acid

Reagentless Amperometric Immunosensors Based on Direct Electrochemistry of Horseradish Peroxidase for Determination of Carcinoma Antigen-125

Renewable Amperometric Immunosensor for Schistosoma japonium Antibody Assay

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