Luminescent images of single gold nanoparticles and their labeling on silica beads.

Luminescent Au nanoparticles were synthesized in a modified Brust method (average diameters of metal core = 1.6 nm). The fluorescence images were measured using scanning confocal microscopy and validated as compared with organic fluorophores. The metal particles were functionalized with succinimidyl ester terminated ligands and bound as fluorophores on surface-aminated silica beads to mimic labeling of biological functionalities. The labeled silica beads were shown to display bright signals and good photostability. Our results indicate that the luminescent metal nanoparticles can be employed as the probes to label the biological functionalities in developing molecule imaging agents.