Bifunctional nanostructure of magnetic core luminescent shell and its application as solid-state electrochemiluminescence sensor material.

Bifunctional nanoarchitecture has been developed by combining the magnetic iron oxide and the luminescent Ru(bpy)32+ encapsulated in silica. First, the iron oxide nanoparticles were synthesized and coated with silica, which was used to isolate the magnetic nanoparticles from the outer-shell encapsulated Ru(bpy)32+ to prevent luminescence quenching. Then onto this core an outer shell of silica containing encapsulated Ru(bpy)32+ was grown through the Stöber method. Highly luminescent Ru(bpy)32+ serves as a luminescent marker, while magnetic Fe3O4 nanoparticles allow external manipulation by a magnetic field. Since Ru(bpy)32+ is a typical electrochemiluminescence (ECL) reagent and it could still maintain such property when encapsulated in the bifunctional nanoparticle, we explored the feasibility of applying the as-prepared nanostructure to fabricating an ECL sensor; such method is simple and effective. We applied the prepared ECL sensor not only to the typical Ru(bpy)32+ co-reactant tripropylamine (TPA), but also to the practically important polyamines. Consequently, the ECL sensor shows a wide linear range, high sensitivity, and good stability.