Interaction of highly charged rigid polymer in monovalent salt*

Charged polymers such as DNA bear important biological functions and have useful applications as a nanomaterial. Experiments of these polyelectrolytes are often performed in aqueous salt solutions. Using an empirical ion potential that reproduces pair correlations from all atom molecular dynamics (MD) simulations, we study ion distributions and DNA-DNA interactions by coarse-grained MD simulations with explicit salt ions. We focus on high concentration regimes, and found that at concentrations greater than 2M, both the ion distribution profile and the potential of mean force between DNAs becomes non-monotonic and has attractive wells. These results are in good agreement with our liquid state theory predictions. Furthermore, the importance of detailed DNA structure will be discussed using all atom MD simulation of DNAs. Our study can help interpret experimental results and help control the phase behavior of charged polymer using salts.