title: A glucose biosensor based on surface active maghemite nanoparticles.
abstract: A simple carbon paste (CP) electrode, modified with novel maghemite (γ-Fe2O3) nanoparticles, called SAMNs (surface active maghemite nanoparticles) and characterized by a mean diameter of about 10nm, has been developed. The electrode catalyzes the electro-reduction of hydrogen peroxide at low applied potentials (-0.1 V vs SCE). In order to improve the electrocatalytic properties of the modified electrode an ionic liquid, namely 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), was introduced. At -0.1 V, the sensitivity of the SAMN-BMIM-PF6-CP electrode was 206.51 nA μM(-1)cm(-2), with a detection limit (S/N=3) of 0.8 μM, in the 0-1.5mM H2O2 concentration range. Furthermore, glucose oxidase was immobilized on the surface of maghemite nanoparticles as a monomolecular layer, by a bridge constituted of rhodamine B isothiocyanate, leading to a fluorescent, magnetic drivable nanocatalyst, containing 10 ± 2 enzyme molecules per nanoparticle. The resulting enzyme electrode presents a linear calibration curve toward glucose in solution in the concentration range of 0-1.5mM glucose, characterized by a sensitivity of 45.85 nA μM(-1)cm(-2) and a detection limit (S/N=3) of 0.9 μM. The storage stability of the system was evaluated and a half-life of 2 months was calculated, if the electrode is stored at 4°C in buffer. The present work demonstrates the feasibility of these surface active maghemite nanoparticles as efficient hydrogen peroxide electro-catalyst, which can be easily coupled to hydrogen peroxide producing enzymes in order to develop oxidase based reagentless biosensor devices.
authors: Department of Comparative Biomedicine and Food Science, University of Padua, Italy.
authors: Davide
authors: D
authors: Baratella
authors: Massimiliano
authors: M
authors: Magro
authors: Giulietta
authors: G
authors: Sinigaglia
authors: Radek
authors: R
authors: Zboril
authors: Gabriella
authors: G
authors: Salviulo
authors: Fabio
authors: F
authors: Vianello
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004800:Enzymes, Immobilized; D005290:Ferric Compounds / Q000737:chemistry*; D005947:Glucose / Q000302:isolation & purification*; D005949:Glucose Oxidase / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D004800:Enzymes, Immobilized; D005290:Ferric Compounds; D052578:Ionic Liquids; C000499:ferric oxide; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D005947:Glucose