AI Article Synopsis
- The study investigates how 4-thiothymidine (S4-TdR) behaves when exposed to UVA light, particularly its ability to generate reactive singlet oxygen when combined with molecular oxygen.
- Spectroscopic measurements revealed a process where S4-TdR transitions from higher energy states (S2) to lower energy states (S1) and then generates a triplet state (T1), which is responsible for its photochemical activity.
- The research found a high efficiency for the interaction between S1 and T1 states, and confirmed that this process leads to creating singlet oxygen with potential therapeutic applications.
Article Abstract
Excited-state dynamics of 4-thiothymidine (S4-TdR) and its photosensitization to molecular oxygen in solution with UVA irradiation were investigated. Absorption and emission spectra measurements revealed that UVA photolysis of S4-TdR gives rise to a population of T1(pipi*), following S2(pipi*) --> S1(npi*) internal conversion. In transient absorption measurement, the 355 nm laser photolysis gave broad absorption (380-600 nm) bands of triplet S4-TdR. The time-resolved thermal lensing (TRTL) signal of S4-TdR containing the thermal component due to decay of triplet S4-TdR was clearly observed by the 355 nm laser excitation. The quantum yield for S1 --> T1 intersystem crossing was estimated to be unity by a triplet quenching experiment with potassium iodide. In the presence of molecular oxygen, the photosensitization from triplet S4-TdR gave rise to singlet oxygen O2 (1Deltag) with a quantum yield of 0.50. Therapeutic implications of such singlet oxygen formation are discussed.
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| http://dx.doi.org/10.1021/jp0678094 | DOI Listing |
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Triplet formation of 4-thiothymidine and its photosensitization to oxygen studied by time-resolved thermal lensing technique.
J Phys Chem B
May 2007
Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan.
Article Synopsis
- The study investigates how 4-thiothymidine (S4-TdR) behaves when exposed to UVA light, particularly its ability to generate reactive singlet oxygen when combined with molecular oxygen.
- Spectroscopic measurements revealed a process where S4-TdR transitions from higher energy states (S2) to lower energy states (S1) and then generates a triplet state (T1), which is responsible for its photochemical activity.
- The research found a high efficiency for the interaction between S1 and T1 states, and confirmed that this process leads to creating singlet oxygen with potential therapeutic applications.
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