DNA‐Encoded Gold‐Gold Wettability for Programmable Plasmonic Engineering

Controlling the deposition and diffusion of adsorbed atoms (adatoms) on the surface of a solid material is vital for engineering the shape and function of nanocrystals. Here, we report the use of single-stranded DNA (oligo-adenine, oligo-A) to encode the wettability of gold seeds by homogeneous gold adatoms to synthesize highly tunable plasmonic nanostructures. We find that the oligo-A attachment transforms the nanocrystal growth mode from the classical Frank-van der Merwe to the Volmer-Weber island growth. Finely tuning the oligo-A density can continuously change the gold-gold contact angle (theta) from 35.1 +/- 3.6 degrees to 125.3 +/- 8.0 degrees. We further demonstrate the versatility of this strategy for engineering nanoparticles with different curvature and dimensions. With this unconventional growth mode, we synthesize a sub-nanometer plasmonic cavity with a geometrical singularity when theta>90 degrees. Superfocusing of light in this nanocavity produces a near-infrared intraparticle plasmonic coupling, which paves the way to surface engineering of single-particle plasmonic devices.