Measuring DNA damage created by a gaseous flux of hydroxyl radicals and plasma-activated microdroplets delivered from a remote plasma operating at atmospheric pressure

Abstract

Non-thermal plasma generates reactive molecules that damage DNA in a controlled manner, potentially revolutionising targeted cancer therapies by delivering hydroxyl radical doses while sparing healthy tissue This research explores hydroxyl radical (•OH) interactions with linear genomic DNA exposed to bubbled effluent from a remote RF helium plasma (atmospheric air-excluded). Experiments varied plasma-liquid distances from 50–120 mm. At 50 mm, near-complete DNA fragmentation occurred within 480 s.

Plasma chemistry simulations using open-source ZDPlasKin code quantified species densities at plasma exit and their evolution with distance, enabling flux conversion at the liquid surface. A MATLAB plasma - liquid reaction chemistry model investigated fragmentation dynamics from direct •OH hits, using input fluxes to determine plasma species reactions with liquid and net •OH flux, confirming •OH as the dominant reactive species alongside primary H₂O₂ output. Fragmentation dynamics were quantified using agarose gel electrophoresis (AGE) with custom fluorescence intensity profile analysis. This revealed •OH driven damage rates far exceeding typical plasma - liquid studies, sustained to 120 mm via plasma-activated droplets. Direct comparisons with existing plasma - DNA studies remain limited due to differences in DNA form and experimental focus. However, tentative comparisons with radiolysis, UV photolysis, and Fenton •OH generation suggest this remote plasma is more effective.

Plasma-activated microscale droplets collected post-exposure markedly increased fragmentation versus plasma alone, extending reactivity for potential tube transport and in vivo plasma treatment via minimally invasive surgery.

Date of Award	Feb 2026
Original language	English
Sponsors	Department for the Economy
Supervisor	Paul Maguire (Supervisor) & Davide Mariotti (Supervisor)