ESR study of hair and melanin-keratin mixtures - the effects of temperature and light
| Autor: | Gerard Lang, Andre Deflandre, René Arnaud, Gilles Perbet |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
chemistry.chemical_classification
Aging Direct excitation integumentary system business.industry Radical Pharmaceutical Science Dermatology Photochemistry Lambda Light effect Melanin Wavelength Colloid and Surface Chemistry Optics chemistry Chemistry (miscellaneous) Absorption band Drug Discovery Keratin sense organs business |
| Zdroj: | International journal of cosmetic science. 6(2) |
| ISSN: | 0142-5463 |
| Popis: | Synopsis The ESR spectrum of hair presents a symmetrical absorption band with the same characteristics as pure melanin (g= 2.0030; deltaH= 5 G). Between 250 degrees K and 490 degrees K, the intensity of the signal increases as for pure melanin. This variation may be explained by a change in the moisture content of hair as function of the temperature. Below 250 degrees K, in a frozen medium, melanin-water interactions remain constant and the number of radicals is no longer a function of temperature. Under exposure to light of hair, melanin-derived radicals were formed. Stable and short-lived radicals were observed at lambda > 345 nm; only unstable radicals were formed at lambda > 450 nm. At shorter wavelengths (lambda > 280 nm), a new asymmetric signal (g= 2.0065H= 20 G) appeared on UV exposure of black, grey or white hair; this signal was attributed to radicals formed in the direct excitation of keratin amino acids. |
| Databáze: | OpenAIRE |
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