Gold and silver nanoparticle multilayer films were used for the development of a plasmonic sensor, applied to detect surface binding of organic and/or biological molecules. The sensitivity to binding events is related to energetic shifts of the surface plasmon resonance on the film. When applied as a bulk sensor (sensitivity to changes on refractive index of the medium in contact with the metal surface), the sensitivity was found to be ca. 220 ± 33 nm RIU-1 for gold and ca. 140 ± 10 nm RIU-1 for silver nanoparticles. The systems were also found efficient as surface biosensors (sensitivity to changes on the effective refractive index due to adsorptions on the metal surface) detecting the surface binding of biotin-streptavidin protein system. The main advantage of the plasmonic biosensor developed in this work is the use of a very simple and low cost methodology when compared to fancier approaches, such as the ones using focused ion beam and surface relief gratings, although presenting similar sensitivity, and allowing, as for these cases, real-time measurements.
SPR; gold nanoparticles; silver nanoparticles; biosensor; protein
