Redox molecule based SERS sensors

NICOLAS G. TOGNALLI; PABLO SCODELLER; VICTORIA FLEXER; RAFAEL SZAMOCKI; ALEJANDRA RICCI; MARIO TAGLIAZUCCHI; ERNESTO J. CALVO; ALEJANDRO FAINSTEIN

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Año: 2009 p. 7412 - 7423

1463-9076

We describe a general framework to design nanobiosensors based on a wired enzyme coupled to aredox molecule and integrated with SERS Au core–shell nanoparticles and ordered nanocavities.The response of the proposed sensor is based on the different electronic resonant Raman behaviorof the oxidized or reduced electronic states of the molecular wire, and on the surface plasmonamplification induced by the tailored metallic substrate. The nanobiosensors can be interrogatedremotely through the resonant Raman scattering intensity recovery or spectral variation of theredox molecule, an Os-complex, when the latter varies its oxidation state. Alternatively, we showthrough two-color spectro-electrochemistry that Raman scattering is also finely sensitive tooxidation state changes of flavin, a biomimetic system that mimics the active center of manyflavoprotein enzymes. We show that multiple sample spectroscopic ellipsometry gives access to thespectral dependence of the optical constants of single redox-molecule layers, and through it to theelectronic resonances of the system. All the components for selective molecular recognition andfor the generation of an optical amplified signal, are self-contained in the proposed biosensor. Asproof of concept a compact SERS sensor responsive to glucose with millimolar concentration insolution is demonstrated.