Bioapplication of plasmonic nanosheet

In this paper, we present our recent progress to fabricate "plasmonic silver nanosheet" for highly sensitive biosensing devices. Uniformly sized silver nanoparticles (d = 4.8 nm ±0.1 nm) are deposited on the substrate as a homogeneous nanosheet composed of two dimensional crystalline domains, in which the distance between silver cores is accurately controlled by the thickness of the capping organic molecules (myristate, alkanethiols). The silver nanosheet exhibits a significant shift of plasmon absorption band to the longer wavelength (ca. 50 nm) from the position in dispersion solution, while the peak width was rather reduced (sharpened) as an evidence of homogeneous coupling of local plasmons. We also found the unique coupling between propagating surface plasmon on gold thin film and localized surface plasmon on silver nanosheet. This flexible, transferable nanosheet, which can trap and transport bulk light at nano-interface, promises new application in the field of bio- and organic devices.