Ultrabright Eu-Doped Plasmonic Ag@SiO2 Nanostructures: Time-gated Bioprobes with Single Particle Sensitivity and Negligible Background

Eu chelate-doped plasmonic silver-core-silica-shell nanocomposites show greatly increased fluorescence enhancement factors of up to 145 at high excitation intensities, due to significantly increased radiative rates in samples with metal cores. They offer exceptionally high signal intensity, sufficient for single particle detection and compatibility with time-gated imaging offering nearly background-free conditions. A bioassay application is also presented.