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Influence of Microwave Power on EPR Signal of Melanin Radical and Copper(II) Ions in DOPA-Melanin Complexes

100%
Najder-Kozdrowska L., Pilawa B., Więckowski A., Buszman E., Wrześniok D.
Acta Physica Polonica A
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2013
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vol. 124
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issue 1
112-114
EN
Electron paramagnetic resonance spectroscopy EPR was used for examination of microwave saturation in DOPA-melanin complexes with kanamycin and Cu(II) ions. The fast spin-lattice relaxation processes take place in system of paramagnetic metal ions. EPR signal of melanin radical saturated with growing of microwave power used during measurements. After adding Cu(II) ions a shortening of relaxation time is observed for EPR signal of melanin radical.
2
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Effect of pH on Paramagnetic Centers in Cladosporium cladosporioides Melanin

86%
Pilawa B., Buszman E., Gondzik A., Wilczyński S., Zdybel M., Witoszyńska T., Wilczok T.
Acta Physica Polonica A
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2005
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vol. 108
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issue 1
147-150
EN
Paramagnetic centers in melanin existing in pigmented soil fungi Cladosporium cladosporioides cultured at acidic (4, 5, 6), neutral (7), and alkaline (8) pH were studied by EPR method. o-semiquinone free radicals (g: 2.0032-2.0040) concentration in melanin biopolymer increased for pH from 4 to 6, decreased at pH 7, and reached the maximum value at pH 8. It may be expected that melanin free radicals reactions with small molecules (metal ions, drugs) are the most effective at pH between 6 and 8. Slow spin-lattice relaxation processes exist in the all studied melanin samples.
3
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Triplet States in DOPA-Melanin and in Its Complexes with Kanamycin and Copper Cu(II) Ions

86%
Najder-Kozdrowska L., Pilawa B., Buszman E., Więckowski A., Świątkowska L., Wrześniok D., Wojtowicz W.
Acta Physica Polonica A
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2010
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vol. 118
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issue 4
613-618
EN
The mono- and biradical forms of DOPA-melanin (DOPA-eumelanin) were studied by EPR spectroscopy in 100-300 K temperature range. The existence of triplet states in DOPA-melanin was proved. The analysis of EPR spectra has shown that in DOPA-melanin and its complexes with kanamycin and Cu^{2+} ions, two kinds of paramagnetic centres exist. The first of them are in doublet ground state with spin S = 1/2 and they obey the Curie law. The paramagnetic centres of the second group are in thermally excited triplet state with spin S = 1 and in this case the Curie law is not fulfilled.
4
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Paramagnetic Centers in DOPA-Melanin-Dihydrostreptomycin Complexes

86%
Buszman E., Pilawa B., Zdybel M., Wrześniok D., Grzegorczyk A., Wilczok T.
Acta Physica Polonica A
|
2005
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vol. 108
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issue 2
353-356
EN
DOPA-melanin-dihydrostreptomycin complexes with drug concentrations 1×10^{-4}-1×10^{-2} M were examined by the use of electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). Dihydrostreptomycin was chosen for studies, because this aminoglycoside antibiotic causes strong toxic effects in organism. It was stated that dihydrostreptomycin generates o-semiquinone free radicals with g=2.0038 in melanin. Free radicals formation increases with increase in the antibiotic concentration. Changes of EPR lines with microwave powers pointed out that slow spin-lattice relaxation processes exist in DOPA-melanin and in its complexes with dihydrostreptomycin. The measured EPR lines were homogeneously broadened.
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