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2012-11-07

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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/53339

Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis

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ABSTRACT Dual-trap optical tweezers are often used in high-resolution measurements in single-molecule biophysics. Such measurements can be hindered by the presence of extraneous noise sources, the most prominent of which is the coupling of fluctuations along different spatial directions, which may affect any optical tweezers setup. In this article, we analyze, both from the theoretical and the experimental points of view, the most common source for these couplings in dual-trap optical-tweezers setups: the misalignment of traps and tether. We give criteria to distinguish different kinds of misalignment, to estimate their quantitative relevance and to include them in the data analysis. The experimental data is obtained in a, to our knowledge, novel dual-trap optical-tweezers setup that directly measures forces. In the case in which misalignment is negligible, we provide a method to measure the stiffness of traps and tether based on variance analysis. This method can be seen as a calibration technique valid beyond the linear trap region. Our analysis is then employed to measure the persistence length of dsDNA tethers of three different lengths spanning two orders of magnitude. The effective persistence length of such tethers is shown to decrease with the contour length, in accordance with previous studies.

Related resource

http://dx.doi.org/10.1016/j.bpj.2012.09.022

Subject

Biofísica, ADN, Polímers, Elasticitat, Aparells i instruments científics, Molècules, Espectroscòpia

Subject (English)

Biophysics, DNA, Polymers, Elasticity, Scientific apparatus and instruments, Molecules, Spectrum analysis

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Articles publicats en revistes (Física de la Matèria Condensada)

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RIBEZZI-CRIVELLARI, M. and RITORT FARRAN, Fèlix. Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis. Biophysical Journal. 2012. Vol. 103, num. 9, pags. 1919-1928. ISSN 0006-3495. [consulted: 7 of October of 2026]. Available at: https://hdl.handle.net/2445/53339

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