Enhanced luminescence of phenyl-phenanthridine dye on aggregated small silver nanoparticles

Tiopronin-coated silver particles (average diameters of core = 1.6 nm) were prepared by a modified Brust method, and the ligands on the metal core were partially displaced by (2-mercapto-propionylamino) acetic acid-2,5-dioxo-pyrrolidin-1-ylester through ligand exchanges. The particles were bound on amine-pendent polymer backbones by condensation to generate compact aggregates of particles. The aggregated particles displayed a plasmon absorbance rising at 440 nm. Luminescence was enhanced to about 2 times with increasing the plasmon rising by the particle aggregation upon excitation at 400 nm when the polymer was labeled by 3,8-diamino-6-phenyl-phenanthridine.