Iron oxide nanoparticles–chitosan composite based glucose biosensor

Iron oxide (Fe 3O 4) 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–Fe 3O 4 nanocomposite film via physical adsorption. The size of the Fe 3O 4 nanoparticles estimated using X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) has been found to be ∼22 nm. The CH–Fe 3O 4 nanocomposite film and GOx/CH–Fe 3O 4/ITO bioelectrode have been characterized using UV–visible and Fourier transform infrared (FTIR) spectroscopic and scanning electron microscopy (SEM) techniques, respectively. This GOx/CH–Fe 3O 4/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 cm 2) and shelf life of about 8 weeks under refrigerated conditions. The value of Michaelis–Menten ( K m) constant obtained as 0.141 mM indicates high affinity of immobilized GOx towards the substrate (glucose).