CTnI diagnosis in myocardial infarction using G-quadruplex selective Ir(Ⅲ) complex as effective electrochemiluminescence probe

In this work, strong electrochemiluminescence (ECL) emission was achieved by using one type of the G-quadruplex selective iridium (III) complex as an efficient ECL signal probe. Based on the typical sandwich immunoreaction between the cardiac troponin-I antigen (cTnI) and its corresponding antibody, iridium (III) complex was introduced according to its specific interaction with G-quadruplex DNA that modified on the surface of negatively charged gold nanoparticles ((-)AuNPs), inducing an increased ECL signal, which was proportional to cTnI concentration. Based on of this, quantitative detection of cTnI could be realized in the range of 5.0 fg/mL-100 ng/mL, with a detection limit of 1.67 fg/mL. Moreover, the proposed immunosensor was successfully applied for the diagnosis of cTnI in human serums from healthy individuals and acute myocardial infarction (AMI) patients, suggesting a great potential application value in the early diagnosis of AMI.