Gold Nanorod DNA Origami Antennas for 3 Orders of Magnitude Fluorescence Enhancement in NIR.

DNA origami has taken a leading position in organizing materials at the nanoscale for various applications such as manipulation of light by exploiting plasmonic nanoparticles. We here present the arrangement of gold nanorods in a plasmonic nanoantenna dimer enabling up to 1600-fold fluorescence enhancement of a conventional near-infrared (NIR) dye positioned at the plasmonic hotspot between the nanorods. Transmission electron microscopy, dark-field spectroscopy, and fluorescence analysis together with numerical simulations give us insights on the heterogeneity of the observed enhancement values. The size of our hotspot region is ∼12 nm, granted by using the recently introduced design of NAnoantenna with Cleared HotSpot (NACHOS), which provides enough space for placing of tailored bioassays. Additionally, the possibility to synthesize nanoantennas in solution might allow for production upscaling.