Optical characterization of supported gold nanoparticles for plasmonic biosensors

Gold nanoparticles (AuNP) continue rising a strong interest for research and especially in the field of biosensors as attested by growing number of publications. One reason is that AuNP exhibit an optical response dominated by the localised surface plasmon resonance (LSPR) that is highly sensitive to the molecular environment. This paper describes the preparation of monodisperse supported AuNP and their characterization by optical UV-visible spectroscopy. It is shown how the surface density of AuNP can be extracted from the spectra, using a complementary check against AFM images. An example of a plasmonic biosensor capable of the specific recognition of avidin is presented.