Immunosensor for rapid detection of human cardiac troponin I, a biomarker for myocardial infarction

Abstract

A rapid detection approach based on quench-release for cardiac troponin I (cTnI), a biomarker of myocardial infarction, was developed. To ensure detection accuracy, a rabbit monoclonal antibody, RabMG4C80A (G4), that binds specifically to cTnI was used. The antigen-binding fragment of G4 was prepared and labeled with fluorescent dyes to produce a fluorescent immunosensor G4 Q-body that can be used for cTnI detection. Using this method, an assay could be completed in as little as 5 min, enabling rapid diagnosis following myocardial infarction and providing a timely basis for patient treatment. A dose–response curve of the G4 Q-body for cTnI detection was obtained from the fluorescence spectra, from which the concentration of cTnI in the sample was determined. The limits of detection and concentration for 50% of maximal effect of the assay were found to be below 10 pM and 3.8 nM, respectively, of cTnI. The optimal detection range was 10 pM–1000 nM. After the occurrence of acute myocardial infarction, the cTnI concentration rose to 2 nM in 1 h and persisted for 6–8 days at around 20 nM; the detection range of the assay therefore covered the clinically relevant range of cTnI during myocardial infarction. This is the first Q-body based on rabbit monoclonal antibodies, and it is expected to contribute to the rapid diagnosis and precise treatment of myocardial infarction.