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%.