2026-04-13T02:25:10Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/533392025-12-04T20:46:35Zcom_2072_1057col_2072_478822col_2072_478917

00925njm 22002777a 4500 dc Ribezzi-Crivellari, M. author Ritort Farran, Fèlix author 2014-04-08T10:16:55Z 2014-04-08T10:16:55Z 2012-11-07 2014-04-08T10:16:55Z 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. Biofísica ADN Polímers Elasticitat Aparells i instruments científics Molècules Espectroscòpia Biophysics DNA Polymers Elasticity Scientific apparatus and instruments Molecules Spectrum analysis Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis