LAYER-BY-LAYER SELF ASSEMBLED MULTILAYERS OF GLUCOSE OXIDASE AND OSMIUM POLYELECTROLYTE ON GOLD NANOPARTICLES: A NANOSENSOR RESPONSIVE TO GLUCOSE

P. SCODELLER, V. FLEXER, V. LELMINI, E.J CALVO, N. TOGNALLI , H. TROIANI, A. FAINSTEIN

Banff, Canada

Congreso; 58th Annual Meeting of the International Society of Electrochemistry; 2007

A reagentless suparmolecular "wired" enzyme biosensor was built on 20 nm Au nanoparticles Following the strategy of Hodak et. al on core-shell Au nanoparticles derivatizedwith mercapto propanesulfonate (MPS) were covered by successive layers ofoppositely charged polyelectrolyte and glucose oxidase. Enzyme glucose oxidaseand the molecular wire osmium pyridine-bipyridine-chloro complex covalently bond tolinear poly(allylamine) are integrated in a novel nanometric biosensor.The layer-by-layer self-assernbled multilayers were characterized by uv-visible spectroscopy.high resolution transmission electron microscopy (TEM), electrochemicaltechniques and Resonant Raman spectroscopy of the osmiumn complexWhen the modified Au-NPs terminated in PAH-Os(+) and thus carrying an excesspositive charge were adsorbed onto MPS primed Au, the osmium sites could beoxidized and reduced and the redox charge integrated from the cyclic voltammetry.Upon addition of glucose, a catalytic wave was apparent due to the redox-enzymecatalysis mediated by the osmium polymer and GOx wrapped around the NPsUV-visible spectra showed a small shift in the Au plasmon band at 530 nm due to thechange in dielectric constant and important changes of the absorption peaks of thePAH-0s and GOx in the UV region. The Resonant Raman spectrum of the Os(II)complex with excitation at 514 nm (10 mW) was characteristic of the Os complex, while the RR effect is lost upon oxidation to Os(III) with soybean Peroxidaseand H202. But addition of glucose restores the Resonant Raman signal by formation of Os( II) via enzymatic reduction with glucose. However, the recovery of the Ramansignal due to the recovery of Os(I1) sites is only a small fraction of the original value inexcellent agreement with electrochemical evidence.Therefore, a nanobiosensor hasbeen built and proved effective to detect glucose either by electrochemical or by opticalreading.