title: A graphene-based electrochemical competitive immunosensor for the sensitive detection of okadaic acid in shellfish.
abstract: A novel graphene-based voltammetric immunosensor for sensitive detection of okadaic acid (OA) was developed. A simple and efficient electrografting method was utilized to functionalize graphene-modified screen-printed carbon electrodes (GSPE) by the electrochemical reduction of in situ generated 4-carboxyphenyl diazonium salt in acidic aqueous solution. Next, the okadaic acid antibody was covalently immobilized on the carboxyphenyl modified graphene electrodes via carbodiimide chemistry. Square wave voltammetry (SWV) was used to investigate the stepwise assembly of the immunosensor. A competitive assay between OA and a fixed concentration of okadaic acid-ovalbumin conjugate (OA-OVA) for the immobilized antibodies was employed for the detection of okadaic acid. The decrease of the [Fe(CN)(6)](3-/4-) reduction peak current in the square wave voltammetry for various concentrations of okadaic acid was used for establishing the calibration curve. A linear relationship between the SWV peak current difference and OA concentration was obtained up to ~5000 ng L(-1). The developed immunosensor allowed a detection limit of 19 ng L(-1) of OA in PBS buffer. The matrix effect studied with spiked shellfish tissue extracts showed a good percentage of recovery and the method was also validated with certified reference mussel samples.
authors.affiliation: Institut national de la recherche scientifique, Centre - Energie, Matériaux et Télécommunications, 1650, Boul. Lionel Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: Shimaa
authors.initials: S
authors.lastname: Eissa
authors.forename: Mohammed
authors.initials: M
authors.lastname: Zourob
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques; D055664:Electrochemical Techniques; D004566:Electrodes; D005292:Ferricyanides / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D019319:Okadaic Acid / Q000032:analysis*; D010084:Oxidation-Reduction; D012758:Shellfish / Q000032:analysis
chemical_list: D055910:Antibodies, Immobilized; D005292:Ferricyanides; C007931:hexacyanoferrate III; D019319:Okadaic Acid; D006108:Graphite