Force Spectroscopy with a Small Dithering of AFM Tip: A Method of Direct and Continuous Measurement of the Spring Constant of Single Molecules and Molecular Complexes

Author :Lilia A. Chtcheglova, George T. Shubeita, Sergey K. Sekatskii, and Giovanni Dietler
Publication :Biophysical Journal
Volume :86
Pages :1177-1184
Year :2004

A new method of direct and continuous measurement of the spring constant of single molecule or molecular
complex is elaborated. To that end the standard force spectroscopy technique with functionalized tips and samples is combined
with a small dithering of the tip. The change of the dithering amplitude as a function of the pulling force is measured to extract
the spring constant of the complex. The potentialities of this method are illustrated for the experiments with single bovine serum
albumin’its polyclonal antibody (Ab-BSA) and fibrinogen’fibrinogen complexes.