Dynamic force spectroscopy of single chainlike molecules using the frequency-modulation technique with constant-excitation

Abstract

To measure forces acting on a chainlike molecule in liquid, we introduce a dynamic approach based on the frequency-modulation technique with constant-excitation. In difference to the classical approach where the force is recorded as a conventional force versus distance curve in a static measurement, we are able to detect simultaneously the conservative force as well as the energy dissipation during the elongation of a chainlike molecule. We apply this technique to dextran monomers and demonstrate the agreement of the experimental force curves with a “single-click” model.