title: Comparison of Brownian-dynamics-based estimates of polymer tension with direct force measurements.
abstract: With the aid of brownian dynamics models, it is possible to estimate polymer tension by monitoring polymers' transverse thermal fluctuations. To assess the precision of the approach, brownian dynamics-based tension estimates were compared with the force applied to rhodamine-phalloidin labeled actin filaments bound to polymer beads and suspended between two optical traps. The transverse thermal fluctuations of each filament were monitored with a CCD camera, and the images were analyzed to obtain the filament's transverse displacement variance as a function of position along the filament, the filament's tension, and the camera's exposure time. A linear Brownian dynamics model was used to estimate the filament's tension. The estimated force was compared and agreed within 30% (when the tension <0.1 pN ) and 70% (when the tension <1 pN ) with the applied trap force. In addition, the paper presents concise asymptotic expressions for the mechanical compliance of a system consisting of a filament attached tangentially to bead handles (dumbbell system). The techniques described here can be used for noncontact estimates of polymers' and fibers' tension.
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Towne Building, 220 S. 33rd St., Philadelphia, Pennsylvania 19104-6315, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Arsenault
authors.forename: Prashant K
authors.initials: PK
authors.lastname: Purohit
authors.forename: Yale E
authors.initials: YE
authors.lastname: Goldman
authors.forename: Henry
authors.initials: H
authors.lastname: Shuman
authors.forename: Haim H
authors.initials: HH
authors.lastname: Bau
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D001696:Biomechanical Phenomena; D055595:Mechanical Phenomena; D008954:Models, Biological; D009068:Movement; D052898:Optical Tweezers; D011108:Polymers / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D011108:Polymers