A separation-free amperometric immunosensor for vitellogenin based on screen-printed carbon arrays modified with a conductive polymer

A disposable amperometric immunosensor was studied for the rapid detection of carp (Carassius auratus) Vitellogenin (Vtg). The sensor was fabricated based on screen-printed carbon arrays (SPCAs) containing eight carbon working and an integrated carbon counter electrodes. To construct the sensor, a conducting polymer (poly-terthiophene carboxylic acid) was electropolymerized on the surface of working electrodes and the polymer-coated SPCAs was characterized by SEM. Horseradish peroxidase (HRP) and a monoclonal antibody (anti-Vtg) specific to carp Vtg were covalently attached onto the polymer modified SPCAs. The immobilization of HRP and anti-Vtg onto the polymer-coated SPCAs was examined using cyclic voltammetry and quartz crystal microbalance studies. In order to detect the amount of Vtg, glucose oxidase (GOx)-labelled Vtg bound to the sensor surface under competition with the Vtg analyte was quantified amperometrically using glucose as a substrate. The performance of the eight sensors in arrays was evaluated by obtaining the calibration plots for Vtg. The sensor arrays exhibit a linear range of the Vtg concentration from 0.25 to 7.8 ng/ml and the detection limit was determined to be 0.09 ng/ml. Furthermore, the performance of the immunosensor for the determination of Vtg was evaluated by a standard addition method performed in fish serum samples.