For 20 years, aptamers have been raising an increasing interest for biosensor applications as replacements for antibodies, due to their high stability and low cost. The main objective of this Ph.D. thesis is to show the great capacities of an aptamer biochip that combines the advantages of aptamer probes associated with a SPRi (Surface Plasomn Resonance imaging) detection to monitor, in real-time and in a label-free manner, molecular interactions occurring on the surface of the biochip. Two aptamers selected against the thrombin protein (APT1 = 5′- GGT-TGG-TGT-GGT-TGG -3′ and APT2 = 5′-AGT-CCG-TGG-TAG-GGG-AGG-TTG-GGG-TGA-CT-3′) were chosen as models for our study. This choice led to the exploration of different lines of research. First, both aptamers were used independently to develop a kinetic biosensor with remarkable performances for the quantification of thrombin. This tool served to determine independently, and compare, both the solution- and surface-phase affinities of the trombin-APT2 interaction. But more than a simple and effective biosensor, this kind of biochip represents a true platform to study the protein and its interactions within complex structures, such as the sandwich-like architecture with APT1 and APT2, or its interactions with other factors of the coagulation cascade (inhibition of thrombin by antithrombin III and heparin cofactor II, conversion of prothrombin into thrombin by the prothrombinase complex).
