Dual-Wavelength Ratiometric Electrochemiluminescence Immunosensor for Cardiac Troponin I Detection.

Ratiometric electrochemiluminescence (ECL) has attracted special focus in biological analysis field because it could eliminate the environmental interference to gain precise measurement. Herein, a dual-wavelength ratiometric ECL biosensor was designed for detection of cardiac troponin I (cTnI), where (4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium(II) (Ru(dcbpy)32+) and Au nanoparticles loaded graphene oxide/polyethyleneimine (GPRu-Au) nanomaterial acts as an acceptor, and Au nanoparticles modified graphitic phase carbon nitride nanosheets composite (Au-CNN) acts as donor. Au-CNN shows high and steady ECL signal centered at 455 nm, which is well matched with the adsorption of GPRu-Au, thereby a high efficient electrochemiluminescent resonance energy transfer (ECL-RET) sensing platform is designed. AuNPs facilitate the immobilization of antibody on the nanomaterials through Au-N bond. The high surface area of graphene oxide/polyethyleneimine allows a large number of Ru(dcbpy)32+ to be loaded, which immensely amplify the ECL signal. This sensing platform exhibits outstanding analytical performance toward cTnI with a detection limit of 3.94 fg/mL (S/N=3). The high reliability, selectivity and sensitivity of this ratiometric ECL biosensor provides a versatile sensing platform for the bioanalysis.