High‐Density Gold Nanoparticles Supported on a [Ru(bpy) 3 ] 2+ ‐Doped Silica/Fe 3 O 4 Nanocomposite: Facile Preparation, Magnetically Induced Immobilization, and Applications in ECL Detection

A large‐scale process combined sonication with self‐assembly techniques for the preparation of high‐density gold nanoparticles supported on a [Ru(bpy) 3 ] 2+ ‐doped silica/Fe 3 O 4 nanocomposite (GNRSF) is provided. The obtained hybrid nanomaterials containing Fe 3 O 4 spheres have high saturation magnetization, which leads to their effective immobilization on the surface of an ITO electrode through simple manipulation by an external magnetic field (without the need of a special immobilization apparatus). Furthermore, this hybrid nanomaterial film exhibits a good and very stable electrochemiluminescence (ECL) behavior, which gives a linear response for tripropylamine (TPA) concentrations between 5 μ M and 0.21 m M , with a detection limit in the micromolar range. The sensitivity of this ECL sensor can be easily controlled by the amount of [Ru(bpy) 3 ] 2+ immobilized on the hybrid nanomaterials (that is, varying the amount of [Ru(bpy) 3 ] 2+ during GNRSF synthesis).