Electrochemical/colorimetric dual-mode sensing strategy for cardiac troponin I detection based on zirconium nitride functionalized covalent organic frameworks

Cardiac troponin I (cTnI) is a gold-standard marker for the detection of acute myocardial infarction (AMI). Accurate and timely detection of cTnI is particularly important for AMI diagnosis and therapy. Herein, based on the dual-capacity (electro-catalysis and catalytic degradation) of PtPd@ZrN@COF to toluidine blue (TB), we developed novel electrochemical and enzyme-linked immunosorbent assay (ELISA) methods for ultrasensitive detection of cTnI. In the electrochemical sensor, polyaniline-coated cerium oxide loaded with gold nanoparticles (Au@PANI@CeO2) were used as a substrate platform for immobilizing antibodies (Ab1), and PtPd@ZrN@COF loaded with the affinity peptide (Pep) of cTnI and TB (Pep/TB/PtPd@ZrN@COF) was the probe material for signal amplification of the sensor. Using the ‘peptide-cTnI-Ab1′ sandwich biosensor, we successfully detected cTnI in a concentration range of 0.00001–50 ng·mL−1 with an ultralow detection limit (LOD) of 3.3 fg·mL−1. In addition, a sandwich ELISA was constructed by 96-well plate using Pep/PtPd@ZrN@COF as the probe molecule for cTnI detection, showing a detection range of 0.00001–5 ng·mL−1 and a LOD of 3.3 fg·mL−1. Both detection methods presented excellent accuracy, selectivity, reproducibility, and stability, providing a potential application in clinical diagnosis of AMI.