A new chemically amplified electrochemical system for the detection of biological affinity reactions: direct and competitive biotin assay

Guo, Liang; Yang, Xiqiang

doi:10.1039/b413089h

Cited by 15 publications

(25 citation statements)

References 40 publications

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“…The two-layer structure investigated in the current work differs from the previous study [36] by having an additional layer of IgG. Yet the difference in the electrochemical response is substantial.…”

Section: Resultsmentioning

confidence: 79%

“…It has been shown in our earlier report that the redox label, when bound to a protein layer either covalently or through biotin/avidin interaction, produces electrochemical current high enough to enable quantitative determination of the bio-affinity reaction [36]. However, in many formats of electrochemical immunoassays, usually two or more protein or antibody layers are assembled on an electrode surface, with the redox label attached to the outmost layer of the multi-layer film.…”

Section: Resultsmentioning

confidence: 99%

“…Avidin was immobilized on ITO surface by the strong electrostatic interaction between the positive charges on the protein and negative charges on ITO [36]. IgG was covalently labeled with both biotin and Ru-bipy (BT-IgG-Ru) so that it can be recognized specifically by the interaction between avidin and biotin, and can be detected by the electrochemical signal from Ru-bipy.…”

Section: Resultsmentioning

confidence: 99%

“…To carry out the avidin/biotin binding reaction, either a sputtered or nanoparticle ITO electrode was first immobilized with avidin [36] by covering the bottom 0.25 cm 2 area with 25 L protein solution (0.3 mg mL −1 in 20 mM phosphate, pH 7.3) and standing still for 1 h (the optimized adsorption time). After rinsing with the buffer, the electrode was blocked for non-specific binding with bovine serum albumin (10 mg mL −1 , 1 h).…”

Section: Methodsmentioning

confidence: 99%

“…The system has been applied successfully to the determination of DNA in solution [34] and on electrode surface [35]. In another report, the avidin/biotin binding pair was employed as a model for the competitive immunoassay of small molecules [36]. In this work, the protein avidin was immobilized on an ITO electrode, and its binding reaction with a biotin-Ru-bipy conjugate was detected quantitatively by catalytic voltammetry.…”

Section: E-mail Addressmentioning

confidence: 99%

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Enhanced electrochemical activity of redox-labels in multi-layered protein films on indium tin oxide nanoparticle-based electrode

Yang

Guo

2009

Analytica Chimica Acta

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a b s t r a c tFacile electrical communication between redox-active labeling molecules and electrode is essential in the electrochemical detection of bio-affinity reactions. In this report, nanometer-sized indium tin oxide (ITO) particles were employed in the fabrication of porous thick film electrodes to enhance the otherwise impeded electrochemical activity of redox labels in multi-layered protein films, and to enable quantitative detection of avidin/biotin binding interaction. To carry out the affinity reaction, avidin immobilized on an ITO electrode was reacted with mouse IgG labeled with both biotin and ruthenium Tris-(2,2 -bipyridine) (Ru-bipy). The binding reaction between avidin and biotin was detected by the catalytic voltammetry of Ru-bipy in an oxalate-containing electrolyte. On sputtered ITO thin film electrode, although a single layer of Ru-bipy labeled avidin exhibited substantial anodic current, attaching the label to the outer IgG layer of the avidin/biotin-IgG binding pair resulted in almost complete loss of the signal. However, electrochemical current was recovered on ITO film electrodes prepared from nanometer-sized particles. The surface of the nanoparticle structured electrode was found by scanning electron microscopy to be very porous, and had twice as much surface binding capacity for avidin as the sputtered electrode. The results were rationalized by the assumption of different packing density of avidin inner layer on the two surfaces, and consequently different electron transfer distance between the electrode and Ru-bipy on the IgG outer layer. A linear relationship between electrochemical current and IgG concentration was obtained in the range of 40-4000 nmol L −1 on the nanoparticle-based electrode. The approach can be employed in the electrochemical detection of immunoassays using non-enzymatic redox labels.

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Section: Resultsmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: E-mail Addressmentioning

confidence: 99%

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Enhanced electrochemical activity of redox-labels in multi-layered protein films on indium tin oxide nanoparticle-based electrode

Yang

Guo

2009

Analytica Chimica Acta

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Synthesis, characterization, X‐ray structure, DNA binding, antioxidant and docking study of new organotin(IV) complexes

Ramzan

Rahim

Hussain

et al. 2023

Applied Organom Chemis

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Four new diorganotin(IV) complexes, including Me2SnL(1), Bu2SnL(2), Ph2SnL(3) and Oct2SnL(4), were synthesized by reacting R2SnCl2 (where R = Me, Bu, Ph, Oct) with N′‐(3,5‐dichloro‐2‐hydroxybenzylidene)‐2‐phenylacetohydrazide H2L. The synthesized ligand and complexes were structurally characterized by various techniques, including Fourier transform infrared (FT‐IR), 1H and 13C nuclear magnetic resonance (NMR) and mass spectrometry. The data suggested that tin–oxygen and tin–nitrogen bonds are formed during complex formation, confirming the coordination of ligand with dialkyltin(IV) moieties and the presence of penta‐coordinated structures. The single‐crystal X‐ray study was performed to confirm the molecular structure of complex 1, which revealed that the molecular structure is distorted towards square pyramidal geometry. The compound–DNA interaction was investigated via spectroscopic, electrochemical and molecular docking studies; the mode of interaction found in all cases was intercalative in nature. The complex 3 showed the highest binding ability with sodium salt of salmon sperm DNA (SS‐DNA) (1.93 × 105 M−1). The data obtained for DNA interaction studies from theoretical calculation via docking studies match well with those observed from spectroscopic and electrochemical analyses. Electrochemical and thermodynamic parameters, including diffusion coefficient, ∆H, ∆G and ∆S, were also calculated. The DPPH antioxidant results showed that complex 2 is an active antioxidant.

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Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

2006

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Abstract. DNA films immobilized on an indium tin oxide (ITO) electrode surface were detected and determined employing a high-affinity intercalator, Ru(bpy) 2 (dppz) 2þ (bpy ¼ 2,2 0 -bipyridine, dppz ¼ dipyrido[3,2-a:2 0 ,3 0 -c]phenazine), as a redox indicator, and oxalate as a sacrificial electron donor in solution to chemically amplify the voltammetric signal of the indicator. Nucleic acids were immobilized on ITO by layer-by-layer electrostatic adsorption, using avidin as the first layer and nucleic acid as the second layer. In quartz crystal microbalance (QCM) measurements on an avidin-coated gold surface, the amount of adsorption from a 200 mg mL À1 nucleic acid solution was found to be 3.2 ng mm À2 for both double-stranded (ds-) and single-stranded (ss-) calf-thymus DNA as well as polycytidylic acid (Poly-C). After binding with Ru(bpy) 2 (dppz) 2þ (Ru-dppz), voltammetry of the ds-DNA film on ITO was carried out in an indicator-free phosphate buffer. An anodic peak at about 1.15 V was observed, and it was assigned to Ru-dppz oxidation. When measured in an oxalate buffer, however, a catalytic current was observed due to the oxidation of oxalate by electrochemically generated Ru(bpy) 2 (dppz) 3þ , resulting in a 120-fold increase in the signal. Since oxalate itself produces a very low oxidation current on ITO, catalytic voltammetry produces about a 14-fold improvement in the signal-to-blank ratio over the nonamplified determination. As a result, ds-DNA adsorbed from 20 ng mL À1 solution could be detected, which was estimated by QCM to be 160 pg mm À2 on the surface. The catalytic current of ds-DNA was substantially higher than that of ss-DNA and poly-C, indicative of selective binding of the redox indicator to ds-DNA. The results serve as a basis for the catalytic voltammetric detection of DNA hybridization in future work.

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A new chemically amplified electrochemical system for the detection of biological affinity reactions: direct and competitive biotin assay

Cited by 15 publications

References 40 publications

Enhanced electrochemical activity of redox-labels in multi-layered protein films on indium tin oxide nanoparticle-based electrode

Enhanced electrochemical activity of redox-labels in multi-layered protein films on indium tin oxide nanoparticle-based electrode

Synthesis, characterization, X‐ray structure, DNA binding, antioxidant and docking study of new organotin(IV) complexes

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

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