Electrochemiluminescence-Based Lateral Flow Assay for Detection of Cardiac Troponin T Using Aptamers Developed through a Modified SELEX Technique

Rapid and sensitive detection of cardiac troponin T (cTnT) through a portable device holds immense significance for the early diagnosis of acute myocardial infarction in point-of-care settings. Herein, an electrochemiluminescence-based lateral flow assay (LFA) on a microfluidic hybrid platform for cTnT detection was developed using an aptamer sandwich assay. Aptamers specific to cTnT were enriched from a library through a new centrifugal-systematic evolution of ligands by exponential enrichment (c-SELEX) technique. Two high-affinity aptamers, cT21 (Kd = 10.7 μM) and cT33 (Kd = 13.1 μM), with Kd values determined by isothermal titration calorimetry, were used respectively as capture and detection probes in the assay. In the assay, cT33 was labeled with Lumidot, while cT21 was immobilized on the LFA strip to capture the cTnT–cT33–Lumidot complex. The reaction solution containing luminol and cT33–Lumidot conjugate generated ECL signals under an applied potential of 1.4 V through an electrode pair screen printed on a nitrocellulose membrane of the device. The ECL intensity correlated linearly with the concentration of cTnT in the range of 100 pM to 10 nM and offered a limit of detection of 142.71 pM. This developed sensor exhibits high prospects for practical applications in diagnosing acute myocardial infarction in point-of-care settings.