Electrochemical biosensors to detect cardiac troponin I with heart failure using nanocomposites of Poly(β-Cyclodextrin)-graphene quantum dots on modified glassy carbon electrode: Fabrication and characterizations

Rapid and precise quantification of cardiac troponin I (cTnI) is critical for early diagnosis of cardiac events; this study introduces a novel electrochemical aptasensor leveraging a graphene quantum dots/poly(β-cyclodextrin) nanocomposite for sensitive and selective detection of cTnI in serum samples. The aptasensor was fabricated by immobilization 5’-amine modified troponin I aptamer on electrodeposited nanocomposite of graphene quantum dots and poly(β-cyclodextrin) on glassy carbon electrode (apt/pβ-CD/GQD/GCE). To prevent non-specific binding, the aptamer-modified electrode was treated with 6-mercaptohexanol (MCH). The structural and morphological analyses indicated to successful electrodeposition of pβ-CD/GQD on the glassy carbon electrode (GCE) surface. Electrochemical analyses using electrochemical impedance spectroscopy (EIS) techniques, cyclic voltammetry (CV), and differential pulse voltammetry (DPV) indicated a sensitive and selective performance of the aptasensor with a wide linear detection range from 10 -5 ng.mL -1 to 10 -3 ng.mL -1 and a low limit of detection (2.03 fg.mL -1 ). The sensor showed excellent reproducibility with a relative standard deviation (RSD) of 3.79% for repeated measurements and retained over 94% of its initial response after 55 days, demonstrating outstanding stability. This detection range covers ultra-low to clinically relevant concentrations of cTnI, enabling early diagnosis of cardiac events—particularly important since basal cTnI levels in healthy individuals typically fall below 0.04 ng.mL -1 . The aptasensor was validated using serum samples from a healthy individual, achieving recoveries between 90% and 99% with low RSD (3.42% to 4.66%); future work will explore its application to pathological samples. The low-cost and easy-to-fabricate aptasensor provides a favorable alternative for valid and precise cTnI quantification, potentially enhancing the efficiency of early diagnosis of cardiac disease and coronary heart disease.