AFM biomechanics

Experimental biomechanics allows testing the mechanical stability of single molecules, cells, and tissues. Atomic Force Microscope (AFM) is one of the main tools in this research and works perfectly in tandem with steered molecular dynamics.

It enabled us to explore DNA mechanics under a previously untested high stretching force regime, up to 1.8 nN of the possible limit of the sugar-phosphate backbone. We observed that if the double helix is prohibited from rotation, a transition is displayed as a small plateau in force vs. distance plot during stretching and relaxation at stretching forces approaching 1 nN. This transition was absent when molecules with rotational freedom were stretched, showing thus that the underlying mechanism was directly connected with molecule linking number conservation.