Beyond the Bragg peak: hyperthermal heavy ion damage to DNA components

Area of Science:

• Radiation chemistry
• Biophysics
• Materials science

Background:

• DNA damage is a critical concern in radiation biology and medicine.
• Understanding the fundamental mechanisms of DNA damage is essential for predicting biological outcomes.
• Heavy ion impacts are increasingly used in cancer therapy and space exploration.

Purpose of the Study:

• To investigate the molecular mechanisms of DNA damage induced by hyperthermal heavy ion impacts.
• To identify the primary targets and pathways of nucleoside and DNA damage.
• To assess the spatial extent and complexity of damage beyond the initial impact zone.

Main Methods:

• Exposure of DNA building blocks (nucleosides) to hyperthermal heavy ions (0.25-1.75 eV/amu).
• Analysis of molecular fragments and damage pathways using mass spectrometry and computational modeling.
• Extrapolation of nucleoside damage to DNA strand break complexity.

Main Results:

• Observed destruction of nucleosides, bases, and sugars by heavy ion impact.
• Identified base loss, sugar loss, and complete disintegration as key nucleoside damage pathways.
• Sugar damage was predominant, leading to complex DNA strand breaks.
• Damage extends beyond the Bragg peak and involves secondary particles.

Conclusions:

• Heavy ion impacts cause significant molecular damage to DNA constituents.
• The dominant sugar damage pathway results in complex DNA strand breaks.
• Radiation damage from heavy ions can be extensive, affecting areas beyond direct impact and involving secondary particle interactions.