Mo2C combined with carbon material nanosphere as an electrochemiluminescence super-enhancer and antibody label for ultrasensitive detection of cardiac troponin I

Abstract To sensitively detect cardiac troponin I (cTnI), a novel electrochemiluminescence (ECL) immunosensor was constructed on the basis of the core-shell Mo2C combined with carbon material (Mo2C@C) nanosphere as an ECL super-enhancer and a label of secondary antibody (Ab2). Mo2C@C nanosphere with excellent conductivity and high chemical stability could increase the ECL intensity of the tris-(2,2′-bipyridine)ruthenium (Ru(bpy)32+). Mo2C@C/polyethylenimine (Mo2C@C/PEI) firmly anchored Ab2 by covalent bonding. Otherwise, amino-modified multiwall carbon nanotubes@nafion (MWCNTs-NH2@N) composite film, as substrate material, could connect with the Ru(bpy)32+ by ion exchange and immobilize primary antibodies (Ab1) by amide bond. In addition, the boron nitride quantum dots (BNQDs) were utilized as the co-reactant, which were synthesized by using low-cost material melamine as a nitrogen source. Under optimal experimental conditions, the proposed ECL immunosensor possessed a low detection limit of 0.03 pg/mL (S/N = 3) and a wide linear range from 0.1 pg/mL to 50 ng/mL. The ultrasensitive ECL immunosensor had excellent stability, outstanding specificity and great reproducibility. It was also used to detect cTnI in human serum with satisfactory results.