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Published on: July 6, 2016
Charge separation in acridine- and phenothiazine-modified DNA
Kiyohiko Kawai1, Yasuko Osakada, Mamoru Fujitsuka
1The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan. kiyohiko@sanken.osaka-u.ac.jp
The Journal of Physical Chemistry. B
|January 30, 2008
Summary
Researchers engineered DNA with specific molecules to create a long-lasting charge-separated state using visible light. This advancement in DNA optoelectronics enhances charge separation efficiency by using a base pair spacer to prevent rapid recombination.
Area of Science:
- Molecular-scale optoelectronics
- Nanotechnology
- Biophysics
Background:
- DNA's potential for optoelectronics and sensors is limited by fast charge recombination.
- Efficient generation of long-lived charge-separated states in DNA is crucial for applications.
- Acridine (Acr+) and phenothiazine (Ptz) are key components for photosensitization and charge trapping.
Purpose of the Study:
- To understand the mechanism of charge separation in DNA for generating long-lived states.
- To improve the quantum yield (Phi) of charge-separated states in modified DNA.
- To investigate the role of intervening base pairs in controlling charge recombination rates.
Main Methods:
- Synthesis of protonated Acr+- and Ptz-modified DNA.
- Investigation of charge injection dynamics using steady-state fluorescence and lifetime measurements.
- Assessment of quantum yield and charge-separated state lifetime via nanosecond laser flash photolysis.
Main Results:
- A long-lived, charge-separated state was successfully generated in modified DNA upon visible light irradiation.
- The highest quantum yield (Phi) was observed in DNA with a single adenine-thymine (A-T) base pair spacer between Acr+ and guanine (G).
- The A-T spacer effectively slowed charge recombination by preventing contact ion pair formation.
Conclusions:
- Strategic placement of redox-inactive intervening base pairs can refine DNA charge separation processes.
- Using an A-T base pair as a spacer between a photosensitizer and the oxidized nucleobase significantly reduces charge recombination.
- This approach enhances the lifetime and efficiency of charge-separated states in DNA for nanotechnology applications.
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