Precise size control of hydrophobic gold nanoparticles in the 2-5 nm range.

We report a seed-mediated synthesis strategy to control the size of gold nanoparticles at the atomic scale in the 2-5 nm size range. Starting from 2 nm seeds, a regrowth in organic solvent with a designed amount of precursor can achieve in a predictive fashion a precise mean size with a 0.3 nm resolution.