We described the use of silica nanoparticles as building blocks for the immobilization of electrogenerated chemiluminescence (ECL) reagent Ru(bpy)3" and the fabrication of layer-by-layer assembly film by alternating the deposition of the Ru(bpy)3 2'-doped silica nanoparticles and Au nanoparticles. UV-vis absorption spectroscopy, scanning electron microscopy (SEM), cyclic voltarnmetry and ECL were used to characterize the uniform growth of the multilayer film. Since Ru(bpy)3 21 could still maintain its ECL property when doped into the silica nanoparticles, the as-prepared multilayer film could be used as an effective ECL sensor, and the sensor showed high sensitivity and good stability. (c) 2008 Elsevier Ltd. All rights reserved.