CHED 396 |
| Deoxyribonucleic Acid (DNA) is the genetic material of living organisms; environmental factors such as ultraviolet (UV) exposure from sunlight can cause DNA photodamage leading to molecular lesions linked to skin cancer. Researchers have investigated the structure and aromaticity of DNA and RNA nitrogenous bases to understand the underlying causes of this photodamage. Our research is centered in studying synthetic DNA oligonucleotides and monomers of DNA bases using ultrafast spectroscopy to gain a greater understanding of energy transfer within the genetic material. It is well known that the absorption of a photon of 266nm light by a nucleic acid polymer leads to excited states. However, the relationship of the location of excitation and where UV photodamage occurs in DNA has not been resolved as the energy carried by the absorbed photon of light may migrate from the base where it was absorbed to where damage or deactivation occurs. In addition, the very short lifetime of the excited state has precluded direct spectroscopic studies of oligonucleotides up until recently. However, with the pump-dispersed probe transient absorption apparatus at USC and the capability to screen small volumes of DNA bases and/or oligonucleotides using a wire-guided jet, we have been successful in collecting insightful data on nucleic acids. The <50 fs instrument response of our system has opened the possibility to probe and monitor the singlet state for energy migration in oligonucleotides. Our presentation will show that the electronic energy relaxation mechanisms are complex in the different individual bases A and T. However, the mechanism of deactivation is similar between monomer bases and their single stranded oligomers (poly-A and poly-T). |
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Undergraduate Research Poster Session: Chemical Education
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |