UV degradation of deoxyribonucleic acid

AC electrical characterisation and insight to charge transfer mechanisms in DNA molecular wires through temperature and UV effects

“…With regard to the response of the impedance of the DNA molecular wire to UV light irradiation, our results showed notable change on the electrical conductivity of DNA. These results are supported by some work in the literature, particularly the works of Gomes et al who had also reported loss of conductivity in calf thymus DNA after longer periods of irradiation and a selective shift of loss tangent after each irradiation periods [42,43]. They had used FTIR techniques to identify the changes in chemical bonds after UV light exposure, where they specifically detected an increase in the peak area ratio of thymine groups and other known molecules after UV irradiation suggesting stretching of chemical bonds at the phosphate groups and base pairs.…”

“…They had used FTIR techniques to identify the changes in chemical bonds after UV light exposure, where they specifically detected an increase in the peak area ratio of thymine groups and other known molecules after UV irradiation suggesting stretching of chemical bonds at the phosphate groups and base pairs. Further, through IR spectra www.ietdl.org measurements in DNA cast thin films and analysing the infrared peaks after UV exposure, Gomes et al had shown that the absorbance associated with symmetric PO 2 -stretching of backbone vibrations decreases with UV irradiation time indicating damage to this group [42,43]. These conclusions are consistent with our reported results where UV irradiation caused increase in impedance, both at lower frequencies (where tunnelling CT mechanism through phosphate backbone dominates) and higher frequencies (where charge hopping through base-pairs is dominant).…”

DNA damage induced by carbon ions (C3+) beam accessed by independent component analysis of infrared spectra

“…This is confirmed with the creation of C  O bonds, increase of 1632 cm 1 peak. Similar behavior has been observed during ultraviolet (UV) irradiation of DNA samples (Gomes et al 2009), results which have also been corroborated by vacuum ultraviolet (VUV) circular dichroism on aqueous sugar solutions which suggested the presence of a weak band at 188 nm associated with the p-p * transition of the C  O chromophore in the sugar open-chain (Brondsted-Nielsen et al 2005). The negative peaks at 1301, 1253 and 1119 cm 1 are associated to PO 4 2 groups' fragmentation.…”

“…Three main regions can be observed in these spectra, namely: 1800-1500 cm 1 , 1500-1200 cm 1 and 1200-900 cm 1 . These regions contain a number of absorbance peaks that can be associated with DNA molecular vibrations (Lindqvist et al 2000, Banyay et al 2003, Gault et al 2005, Gomes et al 2009, 2012 as follows:…”

Effect of magnesium ions on the structure of DNA thin films: an infrared spectroscopy study

“…The former vibrations, commonly considered to originate in guanine bases (C6=O6) and thymine bases (C2=O2), are centred at 1704 cm −1 , while vibrations in thymine bases (C4=O4) are centred at 1661 cm −1 . The latter vibrations, considered to originate in adenine bases (C8=N7), are centred at 1608 cm −1 , and those originating in the cytosine bases (C4=N3) and guanine bases (C8=N7) are centred at 1487 cm −1 ( 13 , 15 , 42 , 43 ). The most prominent phosphate and sugar stretching vibrations are asymmetric and symmetric PO 2 stretching modes at 1234 and at 1089 cm −1 , respectively, sugar-phosphate stretching bands at 1069 and at 893 cm −1 , and deoxyribose stretching mode at 966 cm −1 .…”