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

TL;DR

This study demonstrates that intense ultrashort laser pulses generate in-situ electrons which induce single strand breaks in DNA plasmids, with damage mitigated by scavengers, highlighting a laser-induced electron damage mechanism.

Contribution

It reveals a novel mechanism where ultrashort laser pulses cause DNA damage via in-situ electron generation, advancing understanding of laser-DNA interactions.

Findings

Laser pulses induce DNA strand breaks in aqueous media.

Electron and radical scavengers reduce DNA damage.

In-situ generated electrons cause transformation of supercoiled DNA.

Abstract

Single strand breaks are induced in DNA plasmids, pBR322 and pUC19, in aqueous media by intense ultrashort laser pulses (820 nm wavelength, 45 fs pulse duration, 1 kHz repetition rate) at intensities of 1-12 TW cm$^{-2}$. The intense laser radiation generates, {\it in situ}, electrons that induce transformation of supercoiled DNA into relaxed DNA. The extent of electron-mediated relaxation of DNA structure is quantified. Introduction of electron and radical scavengers inhibits DNA damage.