Iron oxide nanoparticles–chitosan composite based glucose biosensor

Iron oxide (Fe3O4) nanoparticles prepared using co-precipitation method have been dispersed in chitosan (CH) solution to fabricate nanocomposite film on indium–tin oxide (ITO) glass plate. Glucose oxidase (GOx) has been immobilized onto this CH–Fe3O4 nanocomposite film via physical adsorption. The size of the Fe3O4 nanoparticles estimated using X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) has been found to be ∼22 nm. The CH–Fe3O4 nanocomposite film and GOx/CH–Fe3O4/ITO bioelectrode have been characterized using UV–visible and Fourier transform infrared (FTIR) spectroscopic and scanning electron microscopy (SEM) techniques, respectively. This GOx/CH–Fe3O4/ITO nanocomposite bioelectrode has response time of 5 s, linearity as 10–400 mg dL−1 of glucose, sensitivity as 9.3 μA/(mg dL cm2) and shelf life of about 8 weeks under refrigerated conditions. The value of Michaelis–Menten (Km) constant obtained as 0.141 mM indicates high affinity of immobilized GOx towards the substrate (glucose).