Electrochemiluminescent detection of cardiac troponin I by using soybean peroxidase labeled-antibody as signal amplifier.

This work proposed an electrochemiluminescence (ECL) immunosensor for quantitative monitoring of cardiac troponin I (cTnI) in plasma with soybean peroxidase (SBP) labeled-antibody as signal amplifier. The ECL sandwich immunosensor was constructed by covalent binding anti-cTnI capture antibody (Ab1) to polyethylenimine-functionalized graphene matrix, which was obtained by a simple hydrothermal reaction between polyethylenimine (PEI) and graphene oxide (GO). After that, the SBP-labeled detection antibody (SBP-Ab2), synthesized by NaIO4 method, was immobilized on the surface of electrode through sandwich immunoreaction. The SBP on electrode surface displayed strong and stable ECL signal of luminol in the presence of H2O2, which could be used for cTnI detection with a concentration range of 5-30,000pg/mL and a detection limit of 3.3pg/mL. This proposed SBP-modified immunosensor displayed high sensitivity, selectivity and accuracy, and was expected not only to detect cTnI in practical human plasma sample but also to be used in other biomarkers detection.