Quantum Efficiency Modification of Organic Fluorophores Using Gold Nanoparticles on DNA Origami Scaffolds

We used DNA origami as a platform to coassemble a 20 nm gold nanoparticle (AuNP) and an organic fluorophore (TAMRA) and studied the distance-dependent plasmonic interactions between the particle and the dye using steady state fluorescence and lifetime measurements. Greater fluorescence quenching was found at smaller dye-particle distances, which was accompanied by an enhancement of the decay rate. We also fabricated 20 and 30 nm AuNP homodimers using DNA origami scaffolds and positioned a Cy3 fluorophore between the AuNPs in both assemblies. For each particle size, three different interparticle distances were investigated. Up to 50% enhancement of the Cy3 fluorescence quantum efficiency was observed for the dye between the 30 nm AuNPs. These results are in good agreement with the theoretical simulations.