Optical tweezers: where physics meets biology Nov 13, 2008 Joost
van Mameren explains how quantitative force measurements by
optical tweezers can unravel the mechanical properties of
biological molecules. First demonstrated over 20 years ago,
optical tweezers have become an established tool in research
fields ranging from biophysics to cell biology. As their name
suggests, optical tweezers use beams of light to hold and
manipulate microscopically small objects such as biological
molecules or even living cells. They are formed when a laser
beam is tightly focussed to a tiny region in space using a
microscope objective as a lens. This region becomes an optical
trap that can hold small objects in 3D. Optical tweezers can
also make accurate measurements of the tiny, sub-picoNewton
forces exerted on the trapped objects. This allows researchers
to study the diffusion dynamics (or Brownian motion) of an
object in a solvent — a property that can play a key role in the
function of many biological molecules. Optical tw