An aqueous suspension of gold nanoparticles of sizes from 20 to 90 nm can be conjugated with mercaptosuccinic acid and exposed to a second phase of toluene containing an electrostatic coupler. tetraoctylammonium bromide, to organize the gold particles at the interface between water and toluene. The particles have an amphiphilic character similarly to Janus beads The thus formed membrane can be transferred to a solid surface to yield centimeter-sized densely packed particle layers We show that by changing the coupler concentration, the particle distances can be tailored, which modifies the optical properties. (C) 2010 Elsevier Inc All rights reserved