Electrostatic multilayer deposition of a gold-dendrimer nanocomposite

Poly(amidoamine) (PAMAM) dendrimers can be used as a polymeric template/sta bilizer/reservoir to prepare stable gold-dendrimer nanocomposites by reduci ng PAMAM-tetrachloroaurate polysalts using hydrazine. In the gold-dendrimer nanocomposite, the presence of elemental gold is indicated by its characte ristic plasmon absorption peak at 529 nm in aqueous solution and is visuali zed by transmission electron microscopy (TEM) equipped with energy-dispersi ve X-ray spectroscopy (EDXS). Electrostatic layer-by-layer assembly of the gold-dendrimer nanocomposite using poly(sodium 4-styrenesulfonate) (PSS) as the oppositely charged polyelectrolyte leading to nanoscale uniform multil ayers of gold-dendrimer nanoclusters is reported. UV-vis absorption spectra from the consecutive multilayers indicated that each bilayer growth is reg ular, even though a 20 nm absorption bathochromic shift takes place in the film. TEM of PSS/gold-dendrimer nanocomposite film demonstrates that gold n anoparticles (5-20 nm) appear as aggregates within a gold-dendrimer nanocom posite monolayer, an observation borne out by crystalline gold electron dif fraction patterns obtained from PSS/gold-dendrimer nanocomposite. Atomic fo rce microscopy (AFM) of PSS/gold-dendrimer nanocomposite film indicates tha t the nanoclusters are arrayed with high uniformity at the nanometer scale.