Force and torque measurements using magnetic micro beads for single molecule biophysics

Year: 2003

Authors: Romano G., Sacconi L., Capitanio M., Pavone F.S.

Autors Affiliation: European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence, Italy; INFM sez.Firenze, via Sansone 1, 50019 Sesto Fiorentino, Florence, Italy Department of Physics, University of Florence, via Sansone 1, 50019 Sesto Fiorentino, Florence, Italy

Abstract: Characterization of optical trapping with laser tweezers of super-paramagnetic beads has been performed for the first time. In particular, we have compared the force action in optical trapping on super-paramagnetic beads with respect to the polystyrene ones. Using a novel magneto-optical manipulator we have developed a direct rotation detection scheme for trapped beads characterized by a high sensitivity and fast time response. Finally a calibration procedure able to directly measure an applied external torque on the trapped bead is shown. This demonstrates the capability of this apparatus to perform direct torque measurement (torsional rigidity) on a single bio-molecule attached to a super-paramagnetic bead. (C) 2002 Elsevier Science B.V. All rights reserved.

Journal/Review: OPTICS COMMUNICATIONS

Volume: 215 (4-6)      Pages from: 323  to: 331

KeyWords: Optical tweezers; Magnetic tweezers; Interferometric detection; Single molecule biophysics; Torque and force measurements
DOI: 10.1016/S0030-4018(02)02247-2

Citations: 44
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