EPR PERSISTENCE MEASUREMENTS OF UV-INDUCED MELANIN FREE RADICALS IN WHOLE SKIN |
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| Authors: | Bernard Collins Theodore O Poehler Wayne A Bryden |
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| Institution: | Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA;The Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723, USA |
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| Abstract: | Electron paramagnetic resonance is used to detect the formation of free radicals caused by exposure to ultraviolet radiation in chemically untreated rabbit skin. A fast jump in EPR signal level, occurring over a few seconds, is observed immediately after a skin sample is exposed to UV. This is followed by a slower increase toward an elevated steady-state signal over a period of hours as the skin is continuously exposed to a UV light source. Upon cessation of UV light exposure, EPR signal levels undergo an abrupt drop followed by a slower decay toward natural levels. Elevated free radical concentrations following UV exposure are found to persist for several hours in whole skin. These results are consistent with time-resolved EPR measurements of photoinduced radicals in various natural melanins. |
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