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Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials

100%
Adamczyk J., Ramos P., Pilawa B.
Nukleonika
|
2015
|
vol. 60
|
issue 3
449-453
EN
Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very first and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g) and synthetic (~1019 spin/g) dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp) of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp): 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.
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Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

88%
Zdybel M., Pilawa B., Buszman E., Wrzesniok D., Krzyminiewski R., Kruczynski Z.
Polish Journal of Medical Physics And Engineering
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2011
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vol. 17
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issue 2
85-94
EN
Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanin's paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.
3
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Zastosowanie spektroskopii EPR w badaniach jakościowych i ilościowych centrów paramagnetycznych melanin

51%
Chodurek E., Barbara B.
Annales Academiae Medicae Silesiensis
|
2022
|
issue 76
21-30
EN
Electron paramagnetic resonance (EPR) spectroscopy is a method useful in biology and medicine to examine paramagnetic substances, their role in disease processes and therapy. The aim of this review work is to present the physical foundations of EPR spectroscopy and to review the applications of the EPR method for the qualitative and quantitative research on paramagnetic centers in melanin. The possibilities of EPR spectroscopy and experimental procedures applied to determine the types of paramagnetic centers existing in synthetic melanin and in melanin biopolymers are discussed. A useful spectroscopic parameter to determine the type of paramagnetic centers is the spectroscopic cleavage coefficient g, which depends on the location of the unpaired electron in the molecule. o-Semiquinone free radicals with spin S = 1/2 and biradicals with spin S = 1, exist in melanin. Free radicals and biradicals can be distinguished spectroscopically by analysing the influence of temperature on the integral intensity of EPR lines. The concentration of paramagnetic centers in melanin is proportional to the intensity of the integral EPR spectrum. The influence of paramagnetic and diamagnetic metal ions, and oxygen on the concentration of paramagnetic centers in melanin is presented. The publications on the influence of medicinal substances on the concentration of paramagnetic centers in tumor cells were reviewed. The usefulness of EPR spectroscopy in identifying melanin in biological samples, among others, cancer cells, bacteria, and fungi, is presented.
PL
Spektroskopia elektronowego rezonansu paramagnetycznego (electron paramagnetic resonance – EPR) jest metodą przydatną w biologii i medycynie do badania substancji paramagnetycznych, ich roli w procesach chorobowych oraz terapii. Celem pracy jest przedstawienie podstaw fizycznych spektroskopii EPR oraz dokonanie przeglądu zastosowań metody EPR do badań jakościowych i ilościowych centrów paramagnetycznych melanin. Omówiono możliwości spektroskopii EPR i procedury eksperymentalne stosowane do wyznaczenia rodzajów centrów paramagnetycznych występujących w melaninach syntetycznych oraz w biopolimerach melaninowych. Parametrem spektroskopowym przydatnym do określenia rodzaju centrów paramagnetycznych jest współczynnik rozszczepienia spektroskopowego g, który zależy od lokalizacji niesparowanego elektronu w cząsteczce. W melaninach występują o-semichinonowe wolne rodniki o spinie S = 1/2 oraz birodniki o spinie S = 1. Wolne rodniki i birodniki można odróżnić spektroskopowo poprzez analizy wpływu temperatury pomiaru na intensywność integralną linii EPR. Koncentracja centrów paramagnetycznych w melaninie jest proporcjonalna do intensywności integralnej widma EPR. Przedstawiono wpływ paramagnetycznych i dia-magnetycznych jonów metali oraz tlenu na koncentrację centrów paramagnetycznych w melaninie. Dokonano przeglądu publikacji dotyczących wpływu substancji leczniczych na koncentrację centrów paramagnetycznych w melaninie. Przedstawiono przydatność spektroskopii EPR w identyfikowaniu melaniny w próbkach biologicznych, m.in. komór-kach nowotworowych, bakteriach i grzybach.
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