Following aptamer-thrombin binding by force measurements

The rupture forces between an aptamer (1)-functionalized AFM tip and a thrombin-modified Au surface are analyzed. The rupture force for a single aptamer/thrombin complex is determined as ̃4.45 pN. The analysis of the system reveals that the rupture forces correspond to the melting of the G-quadruplex structure of the aptamer bound to the thrombin. This melting of the G-quadruplex leads to the dissociation of the aptamer/thrombin complex. © 2006 American Chemical Society.