Impedance immunosensor for bovine interleukin-4 using an electrode modified with reduced graphene oxide and chitosan

We have developed an impedimetric immunosensor for the determination of bovine interleukin-4, a cytokine involved in the immune response to certain parasites and the development of some bovine diseases. Monoclonal antibody against bovine interleukin-4 was immobilized on a glassy carbon electrode modified with reduced graphene oxide and chitosan. Transmission electron microscopy, static contact angle measurement, and electrochemical impedimetry are used to characterize the immunosensor. The nanocomposite possesses a high surface area that is well suited for the immobilization of antibody. The relative increase in impedance on exposure of the sensor to solutions containing bovine interleukin-4 is linearly proportional to its logarithmic concentration in the 0.1 to 50 ng mL−1 and the detection limit is 80 pg mL−1. The immunosensor is selective, well reproducible, and acceptably stable. It presents a useful tool for further studies on the role of this cytokine in the immunology and pathogenesis of bovine diseases.