Ratiometric electrochemical sensor based on metal-organic framework and nanosilver as response signals for cTnI detection

The concentration of cardiac troponin I (cTnI) serves as a well-established biomarker of myocardial injury. In this work, a ratiometric electrochemical aptasensor utilizing Zirconium-metal organic framework (UiO-66) and AgNPs as electrochemical signaling tags were developed for the ultrasensitive detection of cardiac troponin I (cTnI). Upon specific binding between cTnI and the aptamer, probe 1 (P1) dissociated from the aptamer, resulting in a decreased UiO-66 signal. Meanwhile, signal amplification mediated by terminal deoxynucleotide transferase (TdT) provided a substantial quantity of active sites for surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization, leading to a massive amount of silver nano-particles deposited on the electrode surfaces with enhanced silver ion signals. The concentration range of cTnI was determined to be 1 × 10⁻³–1 × 10² ng mL⁻¹, with a detection limit as low as 20.53 fg mL⁻¹. Notably, the ratiometric sensor performed well in detecting cTnI in serum samples from patients, indicating clinical application potential. Importantly, the aptasensor exhibited excellent performance in detecting cTnI in human serum samples, highlighting its strong potential for clinical application.