The use of UV resonance Raman spectroscopy in the analysis of ionizing radiation-induced damage in DNA




Shaw, Conor Patrick

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Raman spectroscopy is a form of vibrational spectroscopy that is capable of probing biological samples at a molecular level. In this work it was used in the analysis of ionizing radiation-induced damage in DNA. Spectra of both simple, short-stranded DNA oligomers (SS-DNA) and the more complicated calf-thymus DNA (CT-DNA) were acquired before and after irradiation to a variety of doses from 0 to ~2000 Gy. In a technique known as ultraviolet resonance Raman spectroscopy (UVRRS), three UV wavelengths of 248, 257 and 264 nm were utilized in order to selectively enhance contributions from different molecular groups within the samples. Assignment of the spectral peaks was aided by the literature, as well as through analysis of UVRR spectra of short strands of the individual DNA bases obtained at each of the three incident UV wavelengths. Difference spectra between the irradiated and unirradiated samples were calculated and the samples exposed to ~2000 Gy showed significant radiation-induced features. Intensity increases of spectral peaks, observed primarily in the CT-DNA, indicated unstacking of the DNA bases and disruption of Watson-Crick hydrogen bonds, while intensity decreases of spectral peaks, observed only in the SS-DNA, indicated both base damage and the loss of structural integrity of the DNA molecule. The high molecular specificity of UVRRS allowed for precise identification of the specific bonds affected by the radiation, and the use of the varying incident wavelengths allowed for the observation of damage to moieties that would otherwise have been excluded. The use of UVRRS shows promise in the study of radiation-induced damage to DNA and would be well suited for extension to the study of more complicated biological systems.



radiation, DNA, radiation damage, DNA damage, Raman, spectroscopy, resonance, ultraviolet, base stacking