Chitosan–iron oxide nanobiocomposite based immunosensor for ochratoxin-A

The rabbit immunoglobulin antibodies (IgGs) have been immobilized onto nanobiocomposite film of chitosan (CH)–iron oxide (Fe3O4) nanoparticles prepared onto indium–tin oxide (ITO) electrode for detection of ochratoxin-A (OTA). Excellent film forming ability and availability of –NH2 group in CH and affinity of surface charged Fe3O4 nanoparticles for oxygen support the immobilization of IgGs. Differential pulse voltammettry (DPV) studies indicate that Fe3O4 nanoparticles provide increased electroactive surface area for loading of IgGs and improved electron transport between IgGs and electrode. IgGs/CH–Fe3O4 nanobiocomposite/ITO immunoelectrode exhibits improved characteristics such as low detection limit (0.5 ng dL−1), fast response time (18 s) and high sensitivity (36 μA/ng dL−1 cm−2) with respect to IgGs/CH/ITO immunoelectrode.