la0617560_si_001.pdf (212.19 kB)
Phase Transfer of Large Gold Nanoparticles to Organic Solvents with Increased Stability
journal contribution
posted on 2007-01-30, 00:00 authored by Jeffrey M. McMahon, Steven R. EmoryIn this paper, we describe a new procedure to phase transfer large gold nanoparticles (diameters > 45 nm) from
aqueous solution to organic solvents. This is accomplished using a covalent amide coupling reaction that incorporates
dicyclohexylamine (DCHA) headgroups on the surface of mercaptoacetic acid (MAA) functionalized gold nanoparticles.
Gold nanoparticles are first synthesized in aqueous solution by the citrate-reduction method, and nanoparticle size
is controlled by the molar ratio of the reducing agent (sodium citrate) and the gold precursor (KAuCl4). MAA is then
adsorbed to the surface of the gold nanoparticles followed by an amide-coupling reaction to covalently attach DCHA
to the surface-immobilized MAA. The bulky dicyclohexyl groups entropically stabilize gold nanoparticles in organic
solvents. This procedure was used to reliably transfer gold nanoparticles with diameters between 45 and 100 nm from
aqueous solution to organic solvents such as dimethyl sulfoxide and chloroform.