Force measurements on single molecular contacts through evanescent wave microscopy.
We introduce a new method to apply controlled forces on single molecules. The motion of a micron-sized bead attached to a solid surface through a single molecular contact is tracked by evanescent wave microscopy as a force is exerted through a flow. We report measurements of the streptavidin-biotin bond rupture force obtained with this technique. We also obtain detailed measurements of the balance of forces involved in detaching an adhering bead with a flow. A small lateral force translates into a much bigger normal force on the attachment point. This effect is relevant for the interpretation of common cell adhesion assays.
Zocchi
G
G
Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA. zocchi@physics.ucla.edu
D001685:Biological Factors / Q000737:chemistry; D001710:Biotin / Q000737:chemistry*; D015815:Cell Adhesion Molecules / Q000737:chemistry; D008853:Microscopy / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods; D019809:Streptavidin / Q000737:chemistry*
D001685:Biological Factors; D015815:Cell Adhesion Molecules; D001710:Biotin; D019809:Streptavidin