title: The impact of antibody/epitope affinity strength on the sensitivity of electrochemical immunosensors for detecting small molecules.
abstract: A displacement immunoassay involves having a labelled analogue of the analyte (the epitope) already bound to the antibody. The presence of the analyte causes a competition for antibodies, and some of the antibodies dissociates from the epitope so that it can bind with the analyte. Herein, the influence of the affinity of the surface-bound epitope for the antibody on the sensitivity and selectivity of a displacement immunosensor is explored both theoretically and experimentally. An electrochemical immunosensor described previously, where the dissociation of antibodies from an electrode surface causes an increase in current from surface-bound ferrocene species, is used for this purpose. As expected, the ease and effectiveness of the bound antibody being displaced is inversely related to the affinity of the antibody to the surface-bound epitope relative to the analyte in solution as expected. However, if the affinity constant is too low, selectivity and/or sensitivity are compromised. Experimental results are qualitatively compared with a simple mass-action model.
authors: School of Chemistry and Australian Centre for NanoMedicine, The University of New South Wales, Sydney 2052, Australia.
authors: Sook Mei
authors: SM
authors: Khor
authors: Pall
authors: P
authors: Thordarson
authors: J Justin
authors: JJ
authors: Gooding
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000915:Antibody Affinity; D000970:Antineoplastic Agents / Q000032:analysis* / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods; D055664:Electrochemical Techniques / Q000379:methods; D000077422:Enrofloxacin; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D024841:Fluoroquinolones / Q000032:analysis* / Q000276:immunology; D007118:Immunoassay / Q000379:methods*; D057230:Limit of Detection; D008958:Models, Molecular
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D000939:Epitopes; D024841:Fluoroquinolones; D000077422:Enrofloxacin