Bioanalytical determination of cardiac troponin T

Abstract

Currently, there is a great strain on health services owing to the growing elderly population. Consequently, there is a need for rapid, quantitative analytical sensors and sensing systems, which can empower patients to manage their own health. The concentration of cardiac troponin T (cTnT) in the bloodstream has been linked to heart muscle damage, so cTnT levels can be used as a highly sensitive and specific marker of myocardial necrosis, thereby being useful in the diagnosis of subacute myocardial infarction (heart attack). At present, clinical analyses are generally carried out using high-cost complex instrumentation, so the development of portable systems that are able to detect this biomarker with high sensitivity and selectivity is crucial. This work aimed to develop a rapid, quantitative point-of-care system for the detection of myocardial infarction. The combination of immunoassays with either electrochemical or chemiluminescence (CL) detection can deliver simple, sensitive, and selective techniques required for the detection of the cTnT biomarker. As a result, these detection methods were selected. A heterogeneous immunoassay was employed with an antibody modified with a ferrocenecarboxaldehyde label (Fc). The anti-cTnT-Fc was immobilised by an N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide/N-hydroxysulfosuccinimide (EDC/sulfo-NHS) linker onto the surface of an indium tin oxide (ITO) and Screen-Printed Electrode (SPE) electrodes, which were modified to obtain a phenylamine group on the surface. A rapid and sensitive detection technique of cTnT was developed using ITO electrodes with luminol chemiluminescence (CL) immunoassays with the limit of detection (LOD) of 26.07 pg mL-1. With cyclic voltammetry (CV) detection, the LOD values were decreased at 0.5 pg mL-1. Moreover, electroimmunoassay including square wave voltammetry (SWV) and cyclic voltammetry (CV) detection using SPE electrodes, where SWV performed best with a LOD 16.73 pg mL-1. However, in comparison with conventional clinical methods, the calibration curves for the cTnT analyte using CL and electrochemical techniques showed a very low concentration of LOD and high correlation coefficient, indicating that these techniques provide high sensitivity and selectivity, particularly in comparison to conventional clinical methods.