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 similar to 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 mu A/(mg dL cm(2)) 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). (C) 2008 Published by Elsevier B.V.