Biosensing based upon molecular confinement in metallic nanocavity arrays

摘要

We study enhancement of fluorescence of molecular species bound within metallic nanocavities. These nanos-tructures possess a number of desirable properties for real-time microarrays, such as localization of excitation light within the nanocavities, strong isolation from fluorescence produced by unbound species, and an apparent increase in fluorescence yield for bound species. Experimental measurements show a nearly a factor of 2 increase in excitation intensity within the nanocavities, and factor of 6 increase in yield. A simple electromangetic model of a dipole within a nanocavity shows an increase in radiative output consistent with our yield estimates and also verifies the strong fluorescence isolation from species lying outside the nanocavity.