title: Direct measurement of torque in an optical trap and its application to double-strand DNA.
abstract: We present a method that offers the possibility to directly apply and measure torque on particles in an optical trap. It can be used to rotationally manipulate biopolymers attached to appropriate particles. A flat object is trapped and oriented in the focus of a linearly polarized laser light. The direction and power of the orientational trap are controlled by the polarization state of the light. As a demonstration of the capabilities of the method, we examined the torsional stiffness of dsDNA (lambda-DNA) in its linear torsional regime by directly measuring the torque generated by the molecule.
authors.affiliation: Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, 6726 Szeged, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Oroszi
authors.forename: Péter
authors.initials: P
authors.lastname: Galajda
authors.forename: Huba
authors.initials: H
authors.lastname: Kirei
authors.forename: Sándor
authors.initials: S
authors.lastname: Bottka
authors.forename: Pál
authors.initials: P
authors.lastname: Ormos
mesh_terms: D004247:DNA / Q000737:chemistry*; D055095:Optics and Photonics; D013997:Time Factors; D019415:Torque
chemical_list: D004247:DNA