Immunologically Controlled Biofuel Cell as a Self-Powered Biosensor for Antibiotic Residue Determination

A biofuel cell consisting of a self-powered sulfonamide immunosensor as biocathode and a cellobiose dehydrogenase (CDH)-based bioanode was developed for the determination of sulfonamide antibiotics in milk. A graphite-rod electrode was modified with proteinG for the immobilization of selective capture antibodies. A direct competitive immunoassay with a horseradish-peroxidase-labeled analog of the antibiotic and the 2,2-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) diammonium salt-mediated reduction of H2O2 allows quantification of antibiotic residues. CDH was co-immobilized with a toluidine-blue-modified redox polymer on a graphite electrode for the biocatalytic oxidation of lactose in milk. An open-circuit voltage of 676mV and a maximal power density of 6.9 mu Wcm(-2) were obtained. The power densities measured at 550mV (vs. the anode) as a function of antibiotic concentration in milk samples allowed the construction of a calibration curve with a detection limit for sulfapyridine as low as 2.4ngmL(-1).