Electrochemical ultrasensitive detection of cardiac troponin I using covalent organic frameworks for signal amplification.

The accurate and rapid detection of cardiac troponin I (cTnI) at an early stage can prevent people from getting acute myocardial infarction to a great extent. Here, an ultrasensitive sandwich-type electrochemical immunosensor for the quantitative detection of cTnI is designed based on a novel signal amplification strategy. Gold nanoparticles (Au NPs) doped covalent organic frameworks (COFs) and electron mediator toluidine blue (TB-Au-COFs) behave as labels for achieving signal amplification. Note that polypyrrole modified titanium dioxide nanoparticles (TiO-PPy) with a high electronic conductivity and a large specific surface area can promote the performance of the immunosensor. For the immobilization of primary antibodies, Au NPs decorated TiO-PPy (TiO-PPy-Au) is used as the substrate material to improve electron transfer. The proposed method exhibits a linear range from 0.5 pg mL to 10.0 ng mL and a low detection limit of 0.17 pg mL (S/N = 3). The immunosensor exhibits good stability, acceptable reproducibility and accuracy, indicating potential applications in clinical diagnostics.