Effect of intense, ultrashort laser pulses on DNA plasmids in their native state: strand breakages induced by {\it in-situ} electrons and radicals

TL;DR

This study investigates how intense, ultrashort laser pulses cause DNA strand breaks in plasmids through in-situ generated electrons and radicals, highlighting the roles of radicals and scavengers in DNA damage.

Contribution

It demonstrates that ultrashort laser pulses induce DNA damage via in-situ electrons and radicals, with radicals being the primary cause, and shows how scavengers can inhibit this damage.

Findings

Ultrashort laser pulses induce DNA strand breaks in plasmids.

Radicals, especially OH radicals, are primary agents of damage.

Scavengers reduce DNA damage by neutralizing radicals.

Abstract

Single strand breaks are induced in DNA plasmids, pBR322 and pUC19, in aqueous media exposed to strong fields generated using ultrashort laser pulses (820 nm wavelength, 45 fs pulse duration, 1 kHz repetition rate) at intensities of 1-12 TW cm$^{-2}$. The strong fields generate, {\it in situ}, electrons and radicals that induce transformation of supercoiled DNA into relaxed DNA, the extent of which is quantified. Introduction of electron and radical scavengers inhibits DNA damage; results indicate that OH radicals are the primary (but not sole) cause of DNA damage.