Electrochemical Sandwich-Type Aptasensor Based on the Multifunctional Catechol-Loaded Au/MIL-53(Fe) for Detection of Cardiac Troponin I

Accurate detection of irreversible acute myocardial infarction (AMI) is always a challenge in clinical emergencies, and its early diagnosis can increase the patient's chance of surviving. Herein, an electrochemical aptasensor with excellent sensitivity and accuracy was developed for the detection of cardiac troponin I (cTnI). This aptasensor is prepared using sandwiching the cTnI biomarker between the magnetic nanoparticles/Tro6 aptamer (MNPs/Tro6) and multifunctional catechol-(CC)-loaded Tro4/Au/MIL-53(Fe)-based nanocomposite [Tro4/CC/Au/MIL-53(Fe)]. The CC/Au/MIL-53(Fe) provides high electrocatalysis toward electro-oxidation of hydrazine, numerous active sites as the signal amplifier and Tro4 aptamer carrier, on the one hand, and the MNPs, which provide the high complex media's signal-to-noise ratio (S/N), on the other hand. Analysis of the electrochemical impedance spectroscopy data revealed that the double layer capacitance (surface roughness effect) contributed to the CC/Au/MIL-53(Fe)'s increased activity in part but that the intrinsic activity was mostly responsible (synergistic effect). The optimized sandwich-type aptasensor by a face-centered central composite design allows for the detection of cTnI (0.5 pg mL–1) with a broad dynamic range (2 pg mL–1 to 150 ng mL–1), addressing the clinical necessity of AMI diagnosis as well as exceptional selectivity among different biomarkers. The recommended method was effectively used to assess cTnI in AMI patient plasma, above 90% clinical sensitivity, highlighting the capability of the platform for bioanalysis in real-world samples.