Single-molecule stochastic resonance

TL;DR

This study experimentally demonstrates stochastic resonance in single DNA hairpins using optical tweezers, showing how noise can enhance the detection of molecular transitions and optimizing response at specific frequencies.

Contribution

First experimental observation of stochastic resonance in single-molecule DNA hairpins under oscillating force, analyzing how various conditions affect SR quantifiers.

Findings

Signal-to-noise ratio peaks at resonance frequency.

SR enhances detection of low SNR conformational transitions.

SR quantifiers depend on trap stiffness and handle length.

Abstract

Stochastic resonance (SR) is a well known phenomenon in dynamical systems. It consists of the amplification and optimization of the response of a system assisted by stochastic noise. Here we carry out the first experimental study of SR in single DNA hairpins which exhibit cooperatively folding/unfolding transitions under the action of an applied oscillating mechanical force with optical tweezers. By varying the frequency of the force oscillation, we investigated the folding/unfolding kinetics of DNA hairpins in a periodically driven bistable free-energy potential. We measured several SR quantifiers under varied conditions of the experimental setup such as trap stiffness and length of the molecular handles used for single-molecule manipulation. We find that the signal-to-noise ratio (SNR) of the spectral density of measured fluctuations in molecular extension of the DNA hairpins is a good quantifier of the SR. The frequency dependence of the SNR exhibits a peak at a frequency value given by the resonance matching condition. Finally, we carried out experiments in short hairpins that show how SR might be useful to enhance the detection of conformational molecular transitions of low SNR.