The relationship between interfacial bonding and radiation damage in adsorbed DNA

Area of Science:

• Surface science
• Radiation chemistry
• Molecular biology

Background:

• Understanding DNA-surface interactions is crucial for nanotechnology and biosensing.
• Radiation damage mechanisms at the molecular level are not fully understood.
• The influence of substrate binding on DNA's radiation sensitivity requires investigation.

Purpose of the Study:

• To compare radiation damage in thiolated and unthiolated DNA adsorbed on gold.
• To elucidate the mechanisms behind radiation-induced DNA damage.
• To correlate molecular structure and electronic properties with radiation sensitivity.

Main Methods:

• X-ray photoelectron spectroscopy (XP) to analyze elemental composition changes.
• Time-dependent spectral analysis to quantify damage kinetics.
• X-ray absorption spectroscopy to probe electronic structure.
• Kinetic modeling to determine damage parameters.

Main Results:

• Both DNA configurations protrude from the gold surface at ~45 degrees.
• Radiation damage primarily involves phosphodiester bond cleavage and COH desorption.
• Thiolated DNA exhibits significantly higher radiation-induced damage.
• Lower electron population in the N-C=N LUMO of thiolated DNA enhances low-energy electron capture.

Conclusions:

• Covalent thiolation of DNA on gold increases its susceptibility to radiation damage.
• Charge transfer dynamics between the gold substrate and DNA influence radiation sensitivity.
• The N-C=N LUMO plays a critical role in mediating radiation damage pathways.