Ionic liquids make DNA rigid

TL;DR

This study reveals that increasing ionic liquid concentration significantly enhances the rigidity of dsDNA, contrasting with traditional salt effects, and provides insights into DNA stability in ionic liquids through simulations and theoretical models.

Contribution

First systematic investigation of dsDNA mechanical properties in ionic liquids using molecular dynamics and theoretical models, highlighting concentration-dependent rigidity.

Findings

dsDNA in 50 wt% ILs has lower persistence length than in 80 wt% ILs

Both persistence length and stretch modulus increase with IL concentration

Results support elastic theory predictions, unlike in monovalent salt

Abstract

Persistence length of dsDNA is known to decrease with increase in ionic concentration of the solution. In contrast to this, here we show that persistence length of dsDNA increases dramatically as a function of ionic liquid (IL) concentration. Using all atomic explicit solvent molecular dynamics simulations and theoretical models we present, for the first time, a systematic study to determine the mechanical properties of dsDNA in various hydrated ionic liquids at different concentrations. We find that dsDNA in 50 wt% ILs have lower persistence length and stretch modulus in comparison to 80 wt% ILs. We further observe that both persistence length and stretch modulus of dsDNA increase as we increase the ILs concentration. Present trend of stretch modulus and persistence length of dsDNA with ILs concentration supports the predictions of the macroscopic elastic theory, in contrast to the behavior exhibited by dsDNA in monovalent salt. Our study further suggests the preferable ILs that can be used for maintaining DNA stability during long-term storage.