A method for the direct one-pot synthesis of amine-stabilized gold nanoparticles using 3-(trimethoxysilylpropyl)diethylenetriamine (TMSP dien) is described. The amine groups of this bifunctional molecule act as a stabilizer for gold nanoparticles as they form by reduction of HAuCl4. Highly stable gold nanoparticles with sizes tunable between 8 and 20 nm can be readily obtained. This method is quite simple to implement and environmentally benign as there is no need to add an external reducing reagent. The incorporated siloxy functionality was subsequently used to form a silica shell around the gold particle. (c) 2005 Elsevier Inc. All rights reserved.