New antibodies immobilization system into a graphite–polysulfone membrane for amperometric immunosensors

Polysulfone membrane is used for the first time for the preparation of electrochemical immunosensors. A disposable immunosensor based on a porous conductor polymer graphite–polysulfone–electrode has been developed using a phase inversion technique for the determination of anti-rabbit IgG (anti-RIgG) as a model analyte. To construct the sensor, a conductor membrane was deposited on the surface of working graphite–epoxy composite (GEC) electrode. The membrane was characterized by SEM. This sensor was based on the competitive assay between free and labeled anti-RIgG for the available binding sites of immobilized rabbit IgG (RIgG). Incubation parameters were optimized in this work. The immunological reaction was detected using an enzymatic-labeling procedure (HRP enzyme) combined with the amperometric detection using H2O2 as substrate and hydroquinone as mediator. This sensor shows stability during a week and a good reproducibility. The current was monitored amperometrically at −0.1 V versus SCE and this method showed a linear range of the anti-RIgG from 1 to 6 μg/ml. The detection limit was determined to be 0.77 μg/ml.