Enhancing the applied force and range of axial optical tweezers

Axial optical tweezers provide a natural geometry for performing biomechanical assays, such as rupture force measurements of protein binding. Axial traps, however, are typically weaker than their lateral counterparts and require high laser power to maintain a well-calibrated, linear restoring force....

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Main Authors: Zheng Zhang, Joshua N. Milstein
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Biophysical Reports
Online Access:http://www.sciencedirect.com/science/article/pii/S2667074725000242
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author Zheng Zhang
Joshua N. Milstein
author_facet Zheng Zhang
Joshua N. Milstein
author_sort Zheng Zhang
collection DOAJ
description Axial optical tweezers provide a natural geometry for performing biomechanical assays, such as rupture force measurements of protein binding. Axial traps, however, are typically weaker than their lateral counterparts and require high laser power to maintain a well-calibrated, linear restoring force. Here, we show how to extend the spatial range over which well-calibrated forces can be applied by considering aberration effects and extend the range of applied forces by accounting for the nonlinear response that appears when an optically trapped bead is moved far from the trap center. These refinements to the force calibration can be used to apply higher axial forces at reduced laser powers deeper into a sample. To illustrate the method, we reproduce both the linear extension regime and the overstretching transition observed in double-stranded DNA at significantly reduced laser powers.
format Article
id doaj-art-a15aaf58c65c4f6e87eed5f2c7eb7a35
institution Kabale University
issn 2667-0747
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publishDate 2025-09-01
publisher Elsevier
record_format Article
series Biophysical Reports
spelling doaj-art-a15aaf58c65c4f6e87eed5f2c7eb7a352025-08-20T03:30:07ZengElsevierBiophysical Reports2667-07472025-09-015310021910.1016/j.bpr.2025.100219Enhancing the applied force and range of axial optical tweezersZheng Zhang0Joshua N. Milstein1University of Toronto, Department of Physics, Toronto, Ontario, Canada; University of Toronto Mississauga, Department of Chemical and Physical Sciences, Mississauga, Ontario, CanadaUniversity of Toronto Mississauga, Department of Chemical and Physical Sciences, Mississauga, Ontario, Canada; Corresponding authorAxial optical tweezers provide a natural geometry for performing biomechanical assays, such as rupture force measurements of protein binding. Axial traps, however, are typically weaker than their lateral counterparts and require high laser power to maintain a well-calibrated, linear restoring force. Here, we show how to extend the spatial range over which well-calibrated forces can be applied by considering aberration effects and extend the range of applied forces by accounting for the nonlinear response that appears when an optically trapped bead is moved far from the trap center. These refinements to the force calibration can be used to apply higher axial forces at reduced laser powers deeper into a sample. To illustrate the method, we reproduce both the linear extension regime and the overstretching transition observed in double-stranded DNA at significantly reduced laser powers.http://www.sciencedirect.com/science/article/pii/S2667074725000242
spellingShingle Zheng Zhang
Joshua N. Milstein
Enhancing the applied force and range of axial optical tweezers
Biophysical Reports
title Enhancing the applied force and range of axial optical tweezers
title_full Enhancing the applied force and range of axial optical tweezers
title_fullStr Enhancing the applied force and range of axial optical tweezers
title_full_unstemmed Enhancing the applied force and range of axial optical tweezers
title_short Enhancing the applied force and range of axial optical tweezers
title_sort enhancing the applied force and range of axial optical tweezers
url http://www.sciencedirect.com/science/article/pii/S2667074725000242
work_keys_str_mv AT zhengzhang enhancingtheappliedforceandrangeofaxialopticaltweezers
AT joshuanmilstein enhancingtheappliedforceandrangeofaxialopticaltweezers