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Ultrafast spectroscopy study of DNA photophysics after proflavine intercalation
Jie Zhou1, Xueli Wang1, Menghui Jia1
1State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.
Abstract:
Proflavine (PF), an acridine DNA intercalating agent, has been widespread applied as an anti-microbial and topical antiseptic agent due to its ability to suppress DNA replication. On the other hand, various studies show that PF intercalation to DNA can increase photogenotoxicity and has potential chances to induce carcinomas of skin appendages. However, the effects of PF intercalation on the photophysical and photochemical properties of DNA have not been sufficiently explored. In this study, the excited state dynamics of the PF intercalated d(GC)9 • d(GC)9 and d(AT)9 • d(AT)9 DNA duplex are investigated in an aqueous buffer solution. Under 267 nm excitation, we observed ultrafast charge transfer (CT) between PF and d(GC)9 • d(GC)9 duplex, generating a CT state with an order of magnitude longer lifetime compared to that of the intrinsic excited state reported for the d(GC)9 • d(GC)9 duplex. In contrast, no excited state interaction was detected between PF and d(AT)9 • d(AT)9. Nevertheless, a localized triplet state with a lifetime over 5 µs was identified in the PF-d(AT)9 • d(AT)9 duplex.
Insights
Proflavine (PF) DNA intercalation alters excited state dynamics. PF forms a long-lived charge transfer state with GC-rich DNA but induces a localized triplet state in AT-rich DNA.
Area of Science:
- Photochemistry
- Molecular Biophysics
- DNA Interactions
Background:
- Proflavine (PF) is an antimicrobial DNA intercalator.
- PF's DNA intercalation may increase photogenotoxicity and skin cancer risk.
- The photophysical effects of PF on DNA remain underexplored.
Purpose of the Study:
- Investigate the excited state dynamics of PF intercalated into GC-rich and AT-rich DNA duplexes.
- Elucidate the photophysical consequences of Proflavine-DNA interactions.
Main Methods:
- Ultrafast spectroscopy was used to study excited state dynamics.
- Proflavine (PF) was intercalated into d(GC)9•d(GC)9 and d(AT)9•d(AT)9 DNA duplexes.
- Experiments were conducted in aqueous buffer solutions.
Main Results:
- Excited state charge transfer (CT) was observed between PF and d(GC)9•d(GC)9, forming a long-lived CT state.
- No excited state interaction was detected between PF and d(AT)9•d(AT)9.
- A localized triplet state with a lifetime exceeding 5 µs was identified in the PF-d(AT)9•d(AT)9 duplex.
Conclusions:
- Proflavine's excited state dynamics are sequence-dependent.
- PF interaction with GC-rich DNA leads to significant charge transfer.
- PF interaction with AT-rich DNA results in a long-lived localized triplet state.
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