Lethal DNA damage caused by ion-induced shock waves in cells

Area of Science:

• * Biophysics
• * Radiation Biology
• * Materials Science

Background:

• * Understanding ion-induced radiation damage is vital for radiotherapy and space radiation protection.
• * The multiscale approach (MSA) predicts nanoscale shock waves from high linear energy transfer (LET) ions.
• * High-LET ions (e.g., carbon and heavier) deposit significant energy, causing complex biological effects.

Purpose of the Study:

• * To investigate the dominant mechanism of complex DNA damage induced by high-LET ion irradiation.
• * To quantify DNA damage caused by projectile-ion-induced shock waves using molecular dynamics simulations.
• * To integrate shock-wave-induced thermomechanical stress into the MSA for radiation damage assessment.

Main Methods:

• * Reactive molecular dynamics simulations of DNA in water exposed to projectile ions.
• * Evaluation of DNA strand breaks as a function of bond dissociation energy and ion proximity.
• * Consideration of five projectile ions (carbon, oxygen, silicon, argon, iron) at Bragg peak energies.

Main Results:

• * Argon and iron ions induce multiple DNA bond breakages in a 20 base pair DNA segment.
• * Shock-wave-induced thermomechanical stress is identified as the dominant mechanism for complex DNA damage at high LET.
• * A single high-LET ion can cause lethal, complex DNA damage via shock waves.

Conclusions:

• * The shock-wave-induced thermomechanical stress mechanism explains the "overkill" effect in ion beam radiotherapy.
• * Experimental evidence supports the ion-induced shock-wave effect as a key radiation damage mechanism.
• * This research advances the understanding of ion radiation damage for improved therapeutic and protective strategies.