Double-Conjugated Ru(bpy)32+ Complexes for Enhanced Electrochemiluminescence Immunoanalysis
A new method was established to construct a ultrasensitive electrochemiluminescence (ECL) immunosensor by using Ru@SiO2 (Ru(bpy)3 2+ doped silica) - doped Au (Ru@SiO2-Au) composite nanoparticles to label Ru-Ab2 (monoclonal α-fetoprotein (AFP) antibody labeled with Ru(bpy)32+). The primary antibody, anti-AFP was first immobilized on the multi-walled carbon nanotubes (MCNTs) modified with gold nanoparticles (MCNTs-Au) modified glassy carbon electrode due to the covalent conjugation, then the antigen and the Ru@SiO2-Au composite nanoparticles labeled Ru-Ab2 (Ru@SiO2-Au~Ru-Ab2)was conjugated successively to form a double-conjugated Ru(bpy)32+ sandwich-type immunocomplex through the specific interaction. Accordingly, through the ECL response of Ru@SiO2-Au~Ru-Ab2 and tripropylamine (TPA), a strong ECL signal was obtained and an amplification analysis of protein interaction was achieved. The present immunosensor performed high sensitivity and wide liner for detection α-fetoprotein (AFP) in the range of 0.05-80 ng mL−1 and the limit detection was 0.025 ng mL−1(defined as S/N=3). The morphologies of MCNTs, MCNTs-Au, Ru@SiO2 and Ru@SiO2-Au nanoparticles were characterized by using transmission electronic microscopy (TEM). The developed label and method is versatile, offers enhanced performances, and can be easily extended to other protein detection.
J. G. Hou et al., "Double-Conjugated Ru(bpy)32+ Complexes for Enhanced Electrochemiluminescence Immunoanalysis", Advanced Materials Research, Vol. 345, pp. 381-386, 2012