Electrostatic engineering of charge clouds around DNA inhibits strand breakages

Abstract

Femtosecond laser-induced damage to plasmid DNA in aqueous medium manifests itself as strand breaks arising from interactions with slow OH-radicals (and electrons) in the laser-induced plasma generated in water. Such strand breakages are found to be significantly inhibited upon addition of salts (in physiologically significant concentrations) to the aqueous medium. A simple model rationalizes our observations and suggests the feasibility of electrostatically “engineering” DNA's ion atmosphere so as to prevent damage-inducing free radicals accessing DNA strands. These findings may aid development of new strategies for cancer treatment.

Strong Strand Breaks in DNA Induced by Thermal Energy Particles and Their Electrostatic Inhibition by Na+ Nanostructures

“…Our observations may open opportunities of further exploitation in terms of using different salts to electrostatically engineer the propensity for protection against low-energy radiation. 33 Our results seem to offer indications that plasmainduced effects in biological systems may have wider utility than initially thought not only in studying the effects of very low-energy radiation damage but also to explore processes that inhibit radical-induced damage in living matter.…”

Thermal Energy Electrons and OH-Radicals Induce Strand Breaks in DNA in an Aqueous Environment: Some Salts Offer Protection Against Strand Breaks

“…Inhibition of strand breakages does not become more efficient as charge state alters from singly charged (K-ions) to triply charged (Al-ions). It, therefore, appears likely that a simple electrostatic picture of the type invoked in earlier studies 20,25 may be correct but somewhat incomplete. Our present results suggest that binding effects may come into play, specifically the location within the DNA structure at which binding of each of the alkali ions occurs.…”

“…In recent reports we have invoked an electrostatic model to rationalize observations that salts seem to inhibit strand breakages in DNA. 20,25 The alkali ions used in the present experiments all possess a rare gas electronic configuration and will, consequently, be weak complex formers. It would be expected that their interaction with phosphorus, nitrogen and oxygen within the DNA structure would predominantly be electrostatic in nature, scaling linearly with the ion charge.…”