An electrochemical immunosensor for adiponectin using reduced graphene oxide-carboxymethylcellulose hybrid as electrode scaffold

Reduced graphene oxide-carboxymethylcellulose hybrid (CMC-rGO) was used for the development of a novel electrochemical immunosensor for the determination of adiponectin (APN) cytokine. The hybrid material was synthesized by covalent binding of oxidized CMC to GO layers followed by chemical reduction with sodium borohydride. A sandwich-type immunoassay was employed involving the commercial metal-complexes based polymer Mix & Go™ for the stable and oriented immobilization of anti-APN capture antibody. Biotinylated-anti-APN and HRP-Strept were used for the assay configuration. The APN quantification was performed by amperometry at −200 mV using the hydrogen peroxide/hydroquinone enzyme substrate/mediator system. A sigmoidal calibration plot for APN in the 0.1-50 μg/mL range, with a linear portion in the 0.5-10.0 μg/mL APN concentration range was obtained. The calculated limit of detection (3sb/m) was 61 ng/mL APN. The usefulness of the immunosensor was evaluated by analyzing human serum from hypercholesterolemia or diabetes patients.