Electrochemical measurement of antibody-antigen recognition biophysics

Thermodynamics and kinetics of human chorionic gonadotropin (hCG) binding to redox-tagged antibodies

Lee I. Partington, Stephen Atkin, Eric S. Kilpatrick, Samuel H. Morris, Mark Piper, Nathan S. Lawrence, Jay D. Wadhawan

Research output: Contribution to journalArticle

Abstract

The thermodynamics and kinetics of antigen binding under diffusive conditions to an electrode surface modified with ferrocene-tagged antibodies is studied within this work, and realised experimentally for the case of human chorionic gonadotropin (hGC) as the antigen with monoclonal anti-hCG antibodies immobilised on an electrode surface via a molecular wire platform. The formation of the antigen-antibody complex is monitored through the blocking of the ferrocene voltammetry, thereby enabling the fractional coverage of the electrode binding sites to be unravelled as a function of time. It is found that, at low antigen concentrations, a Frumkin adsorption isotherm fits the data, with repulsive interactions between bound antigens playing a significant rôle, with an affinity constant that is an order of magnitude larger than in the case of an untagged antibody, suggesting that the chemical hydrophobicity of the redox tag may encourage stronger binding. Comparison of the experimental temporal data with relevant diffusion-adsorption models under activation control allows for the extraction of the kinetic parameters; at zero coverage, the rate constants for adsorption and desorption are, respectively, larger and smaller than the untagged antibody. The kinetic study enables the confirmation that this type of platform may be utilised for rapid (15 min) and quantitative electroimmunoassay. This is validated through proof-of-concept analytical measurements, yielding a limit of detection around 25 mIU mL−1 (corresponding to 2.7 ng mL−1) – a value used clinically for urine hCG measurements corresponding to around four weeks of gestational age.

Original languageEnglish
Pages (from-to)533-541
Number of pages9
JournalJournal of Electroanalytical Chemistry
Volume819
DOIs
Publication statusPublished - 15 Jun 2018

Fingerprint

Biophysics
Chorionic Gonadotropin
Antigens
Antibodies
Thermodynamics
Kinetics
Electrodes
Immobilized Antibodies
Adsorption
Voltammetry
Hydrophobicity
Antigen-Antibody Complex
Adsorption isotherms
Kinetic parameters
Binding sites
Rate constants
Desorption
Chemical activation
Binding Sites
Wire

Keywords

  • Chemoreception biophysics
  • Electroimmunoassay
  • Frumkin isotherm
  • Molecular wire
  • Partially blocked electrodes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

Cite this

Electrochemical measurement of antibody-antigen recognition biophysics : Thermodynamics and kinetics of human chorionic gonadotropin (hCG) binding to redox-tagged antibodies. / Partington, Lee I.; Atkin, Stephen; Kilpatrick, Eric S.; Morris, Samuel H.; Piper, Mark; Lawrence, Nathan S.; Wadhawan, Jay D.

In: Journal of Electroanalytical Chemistry, Vol. 819, 15.06.2018, p. 533-541.

Research output: Contribution to journalArticle

Partington, Lee I. ; Atkin, Stephen ; Kilpatrick, Eric S. ; Morris, Samuel H. ; Piper, Mark ; Lawrence, Nathan S. ; Wadhawan, Jay D. / Electrochemical measurement of antibody-antigen recognition biophysics : Thermodynamics and kinetics of human chorionic gonadotropin (hCG) binding to redox-tagged antibodies. In: Journal of Electroanalytical Chemistry. 2018 ; Vol. 819. pp. 533-541.
@article{3bcf57bdfd81406ea719e868548b55bc,
title = "Electrochemical measurement of antibody-antigen recognition biophysics: Thermodynamics and kinetics of human chorionic gonadotropin (hCG) binding to redox-tagged antibodies",
abstract = "The thermodynamics and kinetics of antigen binding under diffusive conditions to an electrode surface modified with ferrocene-tagged antibodies is studied within this work, and realised experimentally for the case of human chorionic gonadotropin (hGC) as the antigen with monoclonal anti-hCG antibodies immobilised on an electrode surface via a molecular wire platform. The formation of the antigen-antibody complex is monitored through the blocking of the ferrocene voltammetry, thereby enabling the fractional coverage of the electrode binding sites to be unravelled as a function of time. It is found that, at low antigen concentrations, a Frumkin adsorption isotherm fits the data, with repulsive interactions between bound antigens playing a significant r{\^o}le, with an affinity constant that is an order of magnitude larger than in the case of an untagged antibody, suggesting that the chemical hydrophobicity of the redox tag may encourage stronger binding. Comparison of the experimental temporal data with relevant diffusion-adsorption models under activation control allows for the extraction of the kinetic parameters; at zero coverage, the rate constants for adsorption and desorption are, respectively, larger and smaller than the untagged antibody. The kinetic study enables the confirmation that this type of platform may be utilised for rapid (15 min) and quantitative electroimmunoassay. This is validated through proof-of-concept analytical measurements, yielding a limit of detection around 25 mIU mL−1 (corresponding to 2.7 ng mL−1) – a value used clinically for urine hCG measurements corresponding to around four weeks of gestational age.",
keywords = "Chemoreception biophysics, Electroimmunoassay, Frumkin isotherm, Molecular wire, Partially blocked electrodes",
author = "Partington, {Lee I.} and Stephen Atkin and Kilpatrick, {Eric S.} and Morris, {Samuel H.} and Mark Piper and Lawrence, {Nathan S.} and Wadhawan, {Jay D.}",
year = "2018",
month = "6",
day = "15",
doi = "10.1016/j.jelechem.2018.02.062",
language = "English",
volume = "819",
pages = "533--541",
journal = "Journal of Electroanalytical Chemistry",
issn = "0022-0728",
publisher = "Elsevier Sequoia",

}

TY - JOUR

T1 - Electrochemical measurement of antibody-antigen recognition biophysics

T2 - Thermodynamics and kinetics of human chorionic gonadotropin (hCG) binding to redox-tagged antibodies

AU - Partington, Lee I.

AU - Atkin, Stephen

AU - Kilpatrick, Eric S.

AU - Morris, Samuel H.

AU - Piper, Mark

AU - Lawrence, Nathan S.

AU - Wadhawan, Jay D.

PY - 2018/6/15

Y1 - 2018/6/15

N2 - The thermodynamics and kinetics of antigen binding under diffusive conditions to an electrode surface modified with ferrocene-tagged antibodies is studied within this work, and realised experimentally for the case of human chorionic gonadotropin (hGC) as the antigen with monoclonal anti-hCG antibodies immobilised on an electrode surface via a molecular wire platform. The formation of the antigen-antibody complex is monitored through the blocking of the ferrocene voltammetry, thereby enabling the fractional coverage of the electrode binding sites to be unravelled as a function of time. It is found that, at low antigen concentrations, a Frumkin adsorption isotherm fits the data, with repulsive interactions between bound antigens playing a significant rôle, with an affinity constant that is an order of magnitude larger than in the case of an untagged antibody, suggesting that the chemical hydrophobicity of the redox tag may encourage stronger binding. Comparison of the experimental temporal data with relevant diffusion-adsorption models under activation control allows for the extraction of the kinetic parameters; at zero coverage, the rate constants for adsorption and desorption are, respectively, larger and smaller than the untagged antibody. The kinetic study enables the confirmation that this type of platform may be utilised for rapid (15 min) and quantitative electroimmunoassay. This is validated through proof-of-concept analytical measurements, yielding a limit of detection around 25 mIU mL−1 (corresponding to 2.7 ng mL−1) – a value used clinically for urine hCG measurements corresponding to around four weeks of gestational age.

AB - The thermodynamics and kinetics of antigen binding under diffusive conditions to an electrode surface modified with ferrocene-tagged antibodies is studied within this work, and realised experimentally for the case of human chorionic gonadotropin (hGC) as the antigen with monoclonal anti-hCG antibodies immobilised on an electrode surface via a molecular wire platform. The formation of the antigen-antibody complex is monitored through the blocking of the ferrocene voltammetry, thereby enabling the fractional coverage of the electrode binding sites to be unravelled as a function of time. It is found that, at low antigen concentrations, a Frumkin adsorption isotherm fits the data, with repulsive interactions between bound antigens playing a significant rôle, with an affinity constant that is an order of magnitude larger than in the case of an untagged antibody, suggesting that the chemical hydrophobicity of the redox tag may encourage stronger binding. Comparison of the experimental temporal data with relevant diffusion-adsorption models under activation control allows for the extraction of the kinetic parameters; at zero coverage, the rate constants for adsorption and desorption are, respectively, larger and smaller than the untagged antibody. The kinetic study enables the confirmation that this type of platform may be utilised for rapid (15 min) and quantitative electroimmunoassay. This is validated through proof-of-concept analytical measurements, yielding a limit of detection around 25 mIU mL−1 (corresponding to 2.7 ng mL−1) – a value used clinically for urine hCG measurements corresponding to around four weeks of gestational age.

KW - Chemoreception biophysics

KW - Electroimmunoassay

KW - Frumkin isotherm

KW - Molecular wire

KW - Partially blocked electrodes

UR - http://www.scopus.com/inward/record.url?scp=85044510540&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85044510540&partnerID=8YFLogxK

U2 - 10.1016/j.jelechem.2018.02.062

DO - 10.1016/j.jelechem.2018.02.062

M3 - Article

VL - 819

SP - 533

EP - 541

JO - Journal of Electroanalytical Chemistry

JF - Journal of Electroanalytical Chemistry

SN - 0022-0728

ER -