Bio-quantum dots for electrochemical sensing of cardiac biomarkers of acute myocardial infarction

Cellulose nanofibers (CNFs) are utilized as a biotemplate for facile fabrication of quantum dots via a one-step method. The structural integrity of quantum dots with radical active sites and probable conjugation sites with reactive groups was comprehensively studied using optical absorbance, NMR, PL, FTIR, Raman, XPS, and UPS analyses. Acute myocardial infarction (AMI) is detected by electrochemical biosensing of a cardiac biomarker using a troponin protein family sensing molecule. Cardiac troponin I (cTnI) conjugated with graphene quantum dots (GQDs) was used as a biomimetic receptor for immunosensing of cTnI with a detection limit of 29 pM. The cTnI-based biosensor enables selective sensing in the presence of various interferents. Calibration and validation of the cTnI sensor platform were demonstrated in a PBS medium with successful implementation of a point-of-care indium tin oxide (ITO) electrode for measurement. For the proof-of-concept, a GQD-modified flexible ITO electrode was administered for electrochemical sensing of cTnI at a low sample concentration and showed promising results for cardiovascular diagnosis.