Tunable fluorescence from patterned silver nano-island arrays for sensitive sub-cell imaging

Surface-enhanced fluorescence, a burgeoning technique in biological detection, provides largely enhanced fluorescence signal by exciting localized surfaces plasmons resonance with fluorescent dyes. Nanostructure and surroundings brings great impact on the emission signal, however, insufficient physics about the process limits further improvement on the nanostructure design. In this study, optical properties of Rhodamin-6G molecules on patterned silver nano-island arrays are tailored by precisely controlling the distance between the dyes and silver arrays. The fluorescence signal depends on the distance and the largest enhancement of 10 folds is achieved when the distance is 10 nm. The results are theoretically corroborated by finite difference time domain simulation and applied to cytoskeleton fluorescence imaging using phalloidin–fluorescein isothiocyanate. Our study provides insights into the physical mechanisms associated with the fluorescence enhancement and quenching, and our experiments suggest potential applications to high-sensitivity sub-cell imaging.