Nanostructured Iron Oxide Platform for Impedimetric Cholesterol Detection

A nanostructured iron oxide (NanoFe(3)O(4), particle size ca. 25 nm and roughness ca. 2:1 nm) film deposited onto a hydrolyzed indium-tin-oxide (ITO) coated glass plate has been used to immobilize cholesterol oxidase (ChOx) to fabricate an impedimetric cholesterol sensor. Electrochemical studies reveal that surface charged Fe3O4 nanoparticles provide better conformation for ChOx loading resulting in enhanced electron transfer between ChOx and the electrode. Impedimetric response studies of the ChOx/NanoFe(3)O(4)/ITO bioelectrode exhibit improved linearity (2.5-400 mg/dL), low detection limit (0.25 mg/dL), fast response time (25 s), high sensitivity (86 Omega/mg dL(-1)/cm(-2)) and a low value of the Michaelis-Menten constant (K-m 0.8 mg/dL) with a regression coefficient of 0.997.