The Use of Ultraviolet Resonance Raman Spectroscopy in the Analysis of Ionizing-Radiation-Induced Damage in DNA

Abstract

Ultraviolet resonance Raman spectroscopy (UVRRS) was used to determine damage done in both calf-thymus DNA (CT-DNA) and a short stranded DNA oligomer (SS-DNA) due to ionizing radiation from a medical ⁶⁰Co radiation therapy unit used in the treatment of cancer. Spectra were acquired at incident UV wavelengths of 248, 257, and 264 nm in order to utilize the differences in UVRR cross-sections of the bases with wavelength. Through the analysis of difference spectra between irradiated and unirradiated DNA at each of the incident UV wavelengths, damage to CT- and SS-DNA was observed and identified. Significant radiation-induced increases in the difference spectra of the CT-DNA indicated disruption of the stable, stacked structure of its bases, as well as the disruption of Watson–Crick hydrogen bonds between the base pairs. Base unstacking was not as evident in the SS-DNA, while radiation-induced spectral decreases suggest disruption of the structure of the nucleotides. As demonstrated, UVRRS has the ability to highlight contributions from specific moieties with the use of varying incident UV wavelengths, thus enhancing the already information-rich content of the Raman spectra.