Enhanced Electrochemiluminescence of Ru (bpy)32+ -Doped Silica Nanoparticles by Chitosan/Nafion shell @ Carbon Nanotube Core Modified Electrode.

Although the Ru (bpy)32+ -doped silica nanoparticles have been widely explored as the labeling tags for electrochemiluminescence (ECL) sensing different targets, the poor electrical conductive property of the silica nano-matrix greatly limits their ECL sensitivity. Thus, the novel scheme to overcome this drawback on Ru (bpy)32+ -doped silica nanoparticles ECL is desirable. Herein, a new scheme for this purpose was developed based on electrochemically depositing nanoscale chitosan hydrogel layer on carbon nanotube (CNT) surface to form chitosan hydrogel shell @ CNT core na-nocomposites. In this case, the nanoscale chitosan hydrogel layer only forms on the CNT surface due to the superior electrocatalytic effect of CNT on the H+ reducing compared with the basic glass carbon electrode. Due to both the super-hydrophilic property and polyelectrolyte feature of nanoscale chitosan hydrogel on CNT surface, the chemical affinity as well as the electric conductive between Ru (bpy)32+ -doped silica nanoparticles and CNT were obviously enhanced, and then the ECL effectivity of Ru (bpy)32+ inside silica nanoparticles was improved. Furthermore, based on the discriminating interaction of this Ru (bpy)32+ -doped silica nanoparticles towards both ssDNA probes and ssDNA probe/miRNA complex, as well as the specific adsorption effect of these nanoparticles on nanoscale chitosan shell @ Nafion/CNT core modified glass carbon electrode, a highly sensitive ECL method for miRNA determination was developed and successfully used to detect miRNA in the human serum samples.