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.