Electrochemical cardiac troponin I immunosensor based on nitrogen and boron-doped graphene quantum dots electrode platform and Ce-doped SnO2/SnS2 signal amplification

The detection of acute myocardial infarction directly depends on the concentration of the cardiac troponin I (CTnI) in human blood plasma. In this study, the sensitive, selective, and fast sandwich-type electrochemical CTnI immunosensor was developed by using nitrogen and boron-dopped graphene quantum dots -as electrode platform and two-dimensional Ce-dopped SnO2/SnS2 (Ce–SnO2/SnS2) as signal amplification. In preparation of electrochemical CTnI immunosensor, the coordinated covalent bond between capture antibody (anti-CTnI-Ab1) and nitrogen and boron-dopped graphene quantum dots as electrode platform led to immobilization of anti-CTnI-Ab1, and the strong esterification between the secondary antibody (anti-CTnI-Ab2) and thioglycolic acid-modified Ce–SnO2/SnS2 resulted in anti-CTnI-Ab2 conjugation. Finally, the resultant electrochemical CTnI immunosensor was formed via antigen-antibody interaction. High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, UV–Vis spectroscopy and Raman spectroscopy, as well as some electrochemical characterization techniques, including cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy were used to characterize the prepared immunosensor. The detection limit of CTnI in plasma samples was calculated as 2.00 fg mL−1, making it an effective tool for acute myocardial infarction testing.