Emission Behavior of Fluorescently Labeled Silver Nanoshell: Enhanced Self-Quenching by Metal Nanostructure

摘要

Labeled silica beads with an average diameter of 100 nm were synthesized by incorporating with 20–600 μM Ru(bpy)3²⁺ complexes. Silver shells were deposited on the beads layer-by-layer with the shell thickness of 5–50 nm. The emission band became narrower and the intensity was enhanced depending on the shell thickness. Self-quenching of the probe was observed at high concentration. Poisson statistics were employed to analyze self-quenching of the fluorophores. The estimated quenching distance was extended from 6 to 16 nm with shell growth from 0 to 50 nm. Moreover, the silver shells were also labeled with Rhodamine 6G. Fluorescence enhancement and reduced lifetime were also observed for silver-silica shell containing R6G. We found that by adjustment of probe concentration and silver shell thickness, a Ru(bpy)3²⁺-labeled particle could be 600 times brighter than an isolated Ru(bpy)3²⁺ molecule. We expect labeled metal core–shell structures can become useful probes for high sensitivity and/or single particle assay.