Potential controlling highly-efficient catalysis of wheat-like silver particles for electrochemiluminescence immunosensor labeled by nano-Pt@Ru and multi-sites biotin/streptavidin affinity

Abstract

The potential controlling silver catalysis for Ru(bpy)₃²⁺ electrochemiluminescence (ECL) signal at a special potential −0.4∼1.25 V was newly developed as the new ECL signal amplification strategy for ultrasensitive protein detection. Firstly, the wheat-like deposited silver (DpAg) particles were modified on the bare glass carbon electrode (GCE) surface by cyclic voltammetry deposition to capture the primary antibodies and then bind the antigen analytes. Secondly, as a sandwich immunoreaction format, the secondary antibodies conjugated with the Ru(bpy)₃²⁺-doped Pt (Pt@Ru) nanoparticles by the multi-sites biotin/streptavidin (SA) affinity can be captured onto the electrode surface to generate ECL signal. In the proposed Ru(bpy)₃²⁺ ECL system without any co-reactant, the detected ECL signal was amplified due to following multiple amplification strategies: (1) the ECL catalysis for Ru(bpy)₃²⁺ was performed by electro-inducing the DpAg particles to generate Ag⁺ ion and controlled by the special potential. The catalyzer Ag⁺ was produced near the electrode surface and reproduced by cyclic potential scan, which improved the catalytic efficiency. (2) The amount of the ECL signal probes linked to secondary antibodies were amplified by the adsorption of Pt nanoparticles and the multiple sites bridge linkage of biotin/SA. These new multiple signal amplification strategies made the proposed ECL immunosensor achieve ultrasensitive detection for model protein human IgG with a detection limit down to 3 pg mL⁻¹, which can be further extended to the detection of disease biomarkers.