An electrochemical thrombin aptasensor based on the use of graphite-like C₃N₄ modified with silver nanoparticles

An electrochemical aptasensor for thrombin is introduced that makes use of a nanohybrid composed of silver nanoparticles and graphite-like carbon nitride (Ag-g-C₃N₄). The material has a large surface and good biocompatibility. AgNPs are modified directly on the surface of g-C₃N₄ via chemical reduction. A glass carbon electrode (GCE) modified with Ag-g-C₃N₄ can immobilize a large number of amino-terminated thrombin binding aptamers (NH₂-TBA) through strong Ag-N bonds. The electrochemical impedance signal of the aptasensor increases in the presence of thrombin. Under the optimal conditions and by using [Fe(CN)₆]^3-/4- as an electrochemical probe, the aptasensor shows a wide linear range of 100 fM - 20 nM with a lower detection limit of 38 fM. The method was applied to the determination of thrombin in spiked human plasma and the recoveries fluctuated from 97.2% to 103%. Graphical abstractSchematic representation of an electrochemical aptasensor using graphite-like carbon nitride (C₃N₄) modified with silver nanoparticles as electrode substrate for thrombin (TB) detection.