Experimental test of Sinai's model in DNA unzipping
Cathelijne ter Burg1, Paolo Rissone2, Marc Rico-Pasto2, Felix Ritort2,3, Kay Jörg Wiese1
1CNRS-Laboratoire de Physique de
l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Universités, Université Paris-Diderot, Sorbonne Paris Cité
24 rue Lhomond, 75005 Paris, France
2Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Carrer de Martí i Franquès 1, 08028 Barcelona, Spain
3Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028 Barcelona, Spain
Abstract
The experimental measurement of correlation functions and critical exponents in disordered systems is key to testing renormalization group (RG) predictions. We mechanically unzip single DNA hairpins
with optical tweezers, an experimental realization of the diffusive motion of a particle in a one-dimensional random force field, known as the Sinai model. We measure the unzipping forces $F_w$ as a function of the trap position $w$ in equilibrium, and calculate the force correlator $\Delta_m(w)$, its amplitude, and correlation length, finding agreement with theoretical predictions. We study the universal scaling properties by varying the trap strength $m^2$. Fluctuations of the position of the base pair at the unzipping junction $u$ scale as $u \sim m^{-\zeta}$, with a roughness exponent $ \zeta=1.34\pm0.06$, in agreement with the analytical prediction $\zeta = \frac{4}{3}$. Our study provides a single-molecule test of the functional RG approach for disordered elastic systems in equilibrium.
arXiv:2210.00777 [pdf]
Phys. Rev. Lett. 130 (2023) 208401[pdf]
Copyright (C)
by Kay Wiese. Last edited May 17, 2023.