Preparation and characterization of dendrimer-gold colloid nanocomposites.

Au colloids in the 2-3-nm size regime were prepared by in situ reduction of HAuCl(4) in the presence of poly(amidoamine) dendrimers. The dendrimers encapsulate the colloids, imparting stability to the aqueous colloidal solutions. The nanocomposite materials can be isolated by precipitation. The dendrimer generation used in the synthesis controls the size of the resultant colloids:  lower-generation dendrimers give rise to larger colloids. The materials were characterized by infrared and UV-vis spectroscopy and transmission electron microscopy.