title: Single beam optical tweezers setup with backscattered light detection for three-dimensional measurements on DNA and nanopores.
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.
authors.affiliation: Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld Institute for Biophysics and NanoScience (BINAS), Bielefeld University, Bielefeld, Germany. andy.sischka@physik.uni-bielefeld.de
authors.forename: Andy
authors.initials: A
authors.lastname: Sischka
authors.forename: Christoph
authors.initials: C
authors.lastname: Kleimann
authors.forename: Wiebke
authors.initials: W
authors.lastname: Hachmann
authors.forename: Marcus M
authors.initials: MM
authors.lastname: Schäfer
authors.forename: Ina
authors.initials: I
authors.lastname: Seuffert
authors.forename: Katja
authors.initials: K
authors.lastname: Tönsing
authors.forename: Dario
authors.initials: D
authors.lastname: Anselmetti
mesh_terms: D010582:Bacteriophage lambda / Q000737:chemistry*; D004279:DNA, Viral / Q000737:chemistry*; D007259:Infrared Rays; D007834:Lasers; D016062:Porosity
chemical_list: D004279:DNA, Viral