Excited quartet and doublet states in the complex of tetraphenylporphine zinc (II) and a nitroxide radical in solution: X- and W-band time-resolved EPR studies

2001 ◽  
Vol 21 (3-4) ◽  
pp. 483-493 ◽  
Author(s):  
J. Fujisawa ◽  
Y. Iwasaki ◽  
Y. Ohba ◽  
S. Yamauchi ◽  
N. Koga ◽  
...  
Keyword(s):  
Nitroxide Radical ◽  
Time Resolved ◽  
W Band

scholarly journals Photoreactivity of Hair Melanin from Different Skin Phototypes—Contribution of Melanin Subunits to the Pigments Photoreactive Properties

2021 ◽  
Vol 22 (9) ◽  
pp. 4465
Author(s):  
Krystian Mokrzynski ◽  
Shosuke Ito ◽  
Kazumasa Wakamatsu ◽  
Theodore G. Camenish ◽  
Tadeusz Sarna ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Singlet Oxygen ◽  
Near Infrared ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
W Band ◽  
Epr Oximetry ◽  
X Band ◽  
Hair Samples ◽  
Electron Paramagnetic

Photoreactivity of melanin has become a major focus of research due to the postulated involvement of the pigment in UVA-induced melanoma. However, most of the hitherto studies were carried out using synthetic melanin models. Thus, photoreactivity of natural melanins is yet to be systematically analyzed. Here, we examined the photoreactive properties of natural melanins isolated from hair samples obtained from donors of different skin phototypes (I, II, III, and V). X-band and W-band electron paramagnetic resonance (EPR) spectroscopy was used to examine the paramagnetic properties of the pigments. Alkaline hydrogen peroxide degradation and hydroiodic acid hydrolysis were used to determine the chemical composition of the melanins. EPR oximetry and spin trapping were used to examine the oxygen photoconsumption and photo-induced formation of superoxide anion, and time-resolved near infrared phosphorescence was employed to determine the singlet oxygen photogeneration by the melanins. The efficiency of superoxide and singlet oxygen photogeneration was related to the chemical composition of the studied melanins. Melanins from blond and chestnut hair (phototypes II and III) exhibited highest photoreactivity of all examined pigments. Moreover, melanins of these phototypes showed highest quantum efficiency of singlet oxygen photogeneration at 332 nm and 365 nm supporting the postulate of the pigment contribution in UVA-induced melanoma.

Time-Resolved X-, K-, and W-Band EPR of the Radical Pair State of Photosystem I in Comparison with in Bacterial Reaction Centers

1997 ◽  
Vol 101 (8) ◽  
pp. 1437-1443 ◽  
Author(s):  
A. van der Est ◽  
T. Prisner ◽  
R. Bittl ◽  
P. Fromme ◽  
W. Lubitz ◽  
...  
Keyword(s):  
Photosystem I ◽  
Radical Pair ◽  
Reaction Centers ◽  
Time Resolved ◽  
Bacterial Reaction Centers ◽  
W Band ◽  
Pair State

Magnetic-Field-Induced Orientation of Photosynthetic Reaction Centers As Revealed by Time-Resolved W-Band EPR of Spin-Correlated Radical Pairs

1999 ◽  
Vol 103 (49) ◽  
pp. 10733-10736 ◽  
Author(s):  
Thomas Berthold ◽  
Michael Bechtold ◽  
Ulrich Heinen ◽  
Gerhard Link ◽  
Oleg Poluektov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Reaction Centers ◽  
Photosynthetic Reaction Centers ◽  
Radical Pairs ◽  
Time Resolved ◽  
W Band
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