Controlled Plasmon Resonance of Gold Nanoparticles Self-Assembled with PAMAM Dendrimers

Self-assembly of optically active gold nanoparticles with varying generations of poly(amidoamine) (PAMAM) dendrimers provides aggregates with controlled interparticle spacing, as determined using small-angle X-ray scattering (SAXS). This structural control provides a method for systematically shifting the surface plasmon resonance (SPR) of the particles, based on the decrease in dipolar coupling with increased interparticle distance. Through choice of dendrimer generation, we were able to tune interparticle spacing over a 2.1 nm range, resulting in an 84 nm shift in the SPR. This modulation demonstrates the feasibility of using dendrimer assembly to tune the optical properties of materials.