Rational utilization of Fe(III)-2-amino terephthalic acid MOF as a bifunctional nanocarrier of dopamine and aptamer for constructing ultrasensitive sandwich biosensor of cardiac Troponin I

The development of highly sensitive and specific method for the detection of cardiac troponin I (cTnI) is of great importance for the early diagnosis and prognosis of myocardial injury. Herein, a sandwich signal-on biosensor for cTnI has been developed through antibody-cTnI-aptamer sandwiched structure using a metal-organic framework (MOF) of Fe(III)-2-amino terephthalic acid (Fe-ATA) as a bifunctional nanocarrier for the loading of signal molecule of dopamine and recognition element of aptamer. The cTnI antibody was first immobilized on electro synthesized gold nanoparticles (AuNPs) modified electrode. Through the immunoreaction, the target cTnI was captured onto the electrode surface, followed by the binding of the Fe-ATA MOF via aptamer chemistry. Thanks to dual signal amplification that provided by high electroconductivity of AuNPs and the large surface area of Fe-ATA for loading numerous signal molecules, the biosensor presents an outperformed analytical performance for cTnI with a wide kinetic range from 10 fg mL−1 to 100 ng mL−1 and an ultralow detection limit of 0.92 fg mL−1. The spiked recovery assay shows that the proposed method is reliable for the detection of cTnI in actual human serum sample.