title: An electro-active system of immuno-assay (EASI assay) utilising self assembled monolayer modified electrodes.
abstract: Most immunoassays currently rely on optical methods for signal generation e.g. in ELISA and rapid assay formats. It has become apparent as in the Glucose sensor market that there is a need for simple direct electrical immuno-sensors. We have investigated the novel use of organic conducting monolayers used as a direct electrochemical detection support for an immuno-reaction. It was found that antibodies raised to a carbazole dimer monolayer could increase the charge movement across that monolayer surface. Antibody fragments were taken from a specific anti-carbazole antibody fragment library and combined with an antibody fragment directed to the hormone estrone 3 glucuronide (E3G), the target antigen to form a bispecific antibody fragment. The device utilised these specific antibody fragments and incorporated them on the top plate of a capillary fill format as the immuno-assay components. The immuno-reaction utilised a competition assay. Free E3G analyte in the sample displaced the bispecific antibody fragment from the immuno-surface leaving it free to bind the carbazole monolayer surface. There the binding was detected using amperometric or coulometric methods. By combining all there element it was possible to develop a sensitive immuno-assay that could detect E3G in a reproducible calibrated fashion down to 10 ng/ml.
authors.affiliation: Unilever Research Colworth, Colworth House, Sharnbrook, Bedford MK44 1LQ, UK. robert.porter@unilever.com
authors.forename: R
authors.initials: R
authors.lastname: Porter
authors.forename: P
authors.initials: P
authors.lastname: van der Logt
authors.forename: S
authors.initials: S
authors.lastname: Howell
authors.forename: M
authors.initials: M
authors.lastname: Kyröläinen-Reay
authors.forename: A
authors.initials: A
authors.lastname: Badley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018033:Antibodies, Bispecific / Q000235:genetics; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D002161:Camelids, New World; D002227:Carbazoles / Q000276:immunology; D004563:Electrochemistry; D004566:Electrodes; D004582:Electronics, Medical; D004797:Enzyme-Linked Immunosorbent Assay; D004970:Estrone / Q000031:analogs & derivatives* / Q000032:analysis / Q000276:immunology; D007118:Immunoassay / Q000379:methods* / Q000706:statistics & numerical data; D007128:Immunoglobulin Fragments / Q000235:genetics; D008969:Molecular Sequence Data; D012680:Sensitivity and Specificity
chemical_list: D018033:Antibodies, Bispecific; D002227:Carbazoles; D007128:Immunoglobulin Fragments; C015856:estrone-3-glucuronide; D004970:Estrone