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Updated: Jul 3, 2026
Stretching Short Sequences of DNA with Constant Force Axial Optical Tweezers
Published on: October 13, 2011
Single beam optical tweezers setup with backscattered light detection for three-dimensional measurements on DNA and
Andy Sischka1, Christoph Kleimann, Wiebke Hachmann
1Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld Institute for Biophysics and NanoScience (BINAS), Bielefeld University, Bielefeld, Germany. andy.sischka@physik.uni-bielefeld.de
Abstract:
We introduce a versatile and high precision three-dimensional optical tweezers setup with minimal optical interference to measure small forces and manipulate single molecules in the vicinity of a weak reflective surface. Our tweezers system integrates an inverted optical microscope with a single IR-laser beam that is spatially filtered in an appropriate way to allow force measurements in three dimensions with remarkably high precision when operated in backscattered light detection mode. The setup was tested by overstretching a lambda-DNA in x and z directions (perpendicular and along the optical axis), and by manipulating individual lambda-DNA molecules in the vicinity of a nanopore that allowed quantitative single molecule threading experiments with minimal optical interference.
