NOVEL ANALYTICAL STUDY FOR REACTION INTERMEDIATES IN THE PRIMARY RADIATION INTERACTION OF DNA USING A SYNCHROTRON...

Area of Science:

• Atomic and Molecular Physics
• Biophysics
• Spectroscopy

Background:

• Understanding DNA damage mechanisms is crucial for radiation biology and medicine.
• Current methods for studying DNA damage intermediates can be destructive.
• Soft X-ray synchrotron radiation offers a unique tool for probing molecular processes.

Purpose of the Study:

• To develop a novel, non-destructive spectroscopy for identifying molecular processes that induce DNA lesions.
• To analyze reaction intermediates in DNA damage induction and self-organized restoration pathways.
• To investigate the luminescence response of aqueous nucleotides to soft X-ray excitation.

Main Methods:

• Utilized a liquid micro-jet technique to introduce aqueous nucleotide samples into a vacuum chamber.
• Measured UV-visible luminescence (X-ray induced luminescence - XIL) as a function of soft X-ray energy (nitrogen to oxygen K-edge region).
• Analyzed XIL intensities and spectra to understand the interaction of soft X-rays with nucleotides.

Main Results:

• Observed significantly enhanced XIL intensities for nucleotide solutions in the soft X-ray region (410-530 eV).
• Attributed this enhancement to K-shell excitation/ionization of nitrogen atoms in nucleobases.
• Found that XIL spectra did not show X-ray absorption near-edge structure (XANES) signatures, indicating luminescence quantum yield is measured.
• Provided the first evidence of luminescence resulting from X-ray absorption in aqueous nucleotides.

Conclusions:

• X-ray induced luminescence (XIL) spectroscopy is a viable non-destructive method for studying DNA damage.
• The K-shell excitation of nitrogen in nucleobases plays a key role in XIL.
• This technique offers a new pathway to investigate the fundamental processes of radiation-induced DNA damage and repair.