Enhanced fluorescence from dye molecules by Au nanoparticles on asymmetric double-stranded DNA and mechanism

Gold nanoparticles (NPs) prepared on asymmetric DNA double helical structures show some twinning structures and sharp corners because of the low processing temperature. The distance between individual NPs varies between 2 and 4 nm, and these NPs form clusters with a size of ∼40 nm. The DNA structures also provide docking sites for the fluorescent dye. The dependence of the fluorescence enhancement on the distance between the NPs and dye molecules is investigated. The maximum enhancement factor is 5.8 when the distance between the dye and Au NP surface is 3.4 nm and the results are consistent with theoretical simulation.