Tunable synthesis of poly(ethylene imine)–gold nanoparticle clusters

The reaction of tetrachloroauric acid in DMF with poly(ethylene imine) (PEI) as a reducing agent yields spherical nanoparticles. Depending on the reaction conditions single gold nanoparticles or gold-PEI clusters with tunable size up to 200 nm in diameter were obtained which could serve as potential building blocks for metamaterials.