Polyelectrolyte-based electrochemiluminescence enhancement for Ru(bpy)32+ loaded by SiO2 nanoparticle carrier and its high sensitive immunoassay

• Preparation of strong ECL nanoparticles PAA–Ru@SiO2/[PAA⋯Ru&Nafion⋯Ru].
• Ion-pair macromolecule PAA–Ru formed to greatly increase the doping amount.
• PAA&Nafion membrane increased the amount of ion-exchanged Ru(bpy)32+.
• PAA&Nafion membrane enhanced the ability of electron transfer.
• Realized antibody labeling and established a high-sensitive immunoassay.

In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy)32+, which were loaded by the carrier of SiO2 nanoparticle. There were two kinds of Ru(bpy)32+ for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA–Ru(bpy)32+. The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy)32+. The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy)32+. At the same time, ECL intensity of the doped-inside Ru(bpy)32+ was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy)32+ and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL−1 (R2 = 0.9912). The detection limit could be as low as 0.11 pg mL−1 (signal-to-noise ratio = 3).

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