Electrochemical modulation of antigen-antibody binding.
The label-free amperometric detection of a rabbit IgG antigen by an anti-rabbit IgG antibody is achieved by observing the electrochemistry at a glassy carbon electrode modified with antibody entrapped in an electrodeposited polypyrrole membrane. In a flow injection apparatus the electrode is pulsed between -0.2 and +0.4 V versus Ag/AgCl. The pulsing of the electrode switches the polypyrrole membrane between the oxidised and reduced states. When antigen is injected into the flow stream a change in current is observed at the electrode despite the antigen or antibody being redox inactive at the potentials employed. It is proposed that this current is due to a change in the flux of ions into and out of the polypyrrole matrix during a pulse when the poly-anionic antigen is present. The immunoreaction was reversible because the 200 ms pulse at each potential was too short to allow secondary bonding forces (hydrogen bonding and hydrophobic forces) which are responsible for the strength of the antibody-antigen complex to be established. The consequence of the reversibility of the antigen-antibody binding is a low apparent affinity constant but an easily regenerated recognition interface.
School of Chemical Sciences, The University of New South Wales, Sydney, NSW 2052, Australia. justin.gooding@unsw.edu.au
J Justin
JJ
Gooding
Christine
C
Wasiowych
Donald
D
Barnett
D Brynn
DB
Hibbert
Joseph N
JN
Barisci
Gordon G
GG
Wallace
D000818:Animals; D000936:Antigen-Antibody Complex / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods*; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007074:Immunoglobulin G / Q000032:analysis*; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000936:Antigen-Antibody Complex; D020099:Coated Materials, Biocompatible; D007074:Immunoglobulin G