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Development of an immunosensor for the determination of rabbit IgG using streptavidin modified screen-printed carbon
María Díaz-González1, David Hernández-Santos, María Begoña González-García
1Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, Asturias, 33006 Oviedo, Spain.
Voltammetric enzyme immunosensors based on the employment of streptavidin modified screen-printed carbon electrodes (SPCEs) for the detection of rabbit IgG, as a model analyte, were described. Alkaline phosphatase (AP) and 3-indoxyl phosphate (3-IP) were used as the enzymatic label and substrate, respectively. The adsorption of streptavidin was performed by deposition of a drop of a streptavidin solution overnight at 4 degrees C on the pre-oxidized surface of the SPCEs. The analytical characteristics of these sensors were evaluated using biotin conjugated to AP. The immunosensor devices were based on a specific reaction of rabbit IgG with its biotinylated antibodies, which were immobilised on the modified screen-printed carbon electrodes through the streptavidin:biotin reaction. The immunosensors were used for a direct determination of AP labelled rabbit IgG, and for free rabbit IgG detection using a sequential competitive immunoassay. A calibration curve in the range of 5 x 10(-11) to 1 x 10(-9)M of rabbit IgG was obtained with a estimated detection limit of 5 x 10(-11)M (7.0ng/ml). These immunosensors were stable for 5 months if they were stored at 4 degrees C.
Voltammetric enzyme immunosensors based on the employment of streptavidin modified screen-printed carbon electrodes (SPCEs) for the detection of rabbit IgG, as a model analyte, were described. Alkaline phosphatase (AP) and 3-indoxyl phosphate (3-IP) were used as the enzymatic label and substrate, respectively. The adsorption of streptavidin was performed by deposition of a drop of a streptavidin solution overnight at 4 degrees C on the pre-oxidized surface of the SPCEs. The analytical characteristics of these sensors were evaluated using biotin conjugated to AP. The immunosensor devices were based on a specific reaction of rabbit IgG with its biotinylated antibodies, which were immobilised on the modified screen-printed carbon electrodes through the streptavidin:biotin reaction. The immunosensors were used for a direct determination of AP labelled rabbit IgG, and for free rabbit IgG detection using a sequential competitive immunoassay. A calibration curve in the range of 5 x 10(-11) to 1 x 10(-9)M of rabbit IgG was obtained with a estimated detection limit of 5 x 10(-11)M (7.0ng/ml). These immunosensors were stable for 5 months if they were stored at 4 degrees C.
