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Proceedings Paper

UV-A fluorescence of sunscreens and possible energy transfer to skin components
Author(s): Rajagopal Krishnan; Craig A Elmets; Thomas M. Nordlund
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Paper Abstract

Photophysical studies of UV-B sunscreens showed a measurable UV-A emission from padimate O (2-ethylhexyl-4-(dimethylamino)benzoate). Since recent studies associate UV-A to skin cancer induction pathways, as well as skin aging, we studied the effect of padimate O emission when applied to skin. After application of padimate O to skin the emission spectrum of skin showed a large increase in the intensity of 470 nm peak. The 470 nm emission in skin arises from a skin component, possibly collagen, which absorbs at about 360 nm, where padimate O emits. The excitation spectra of skin with padimate O measured at an emission wavelength of 468 nm show a peak at 310 nm with a broad shoulder at about 350 nm to 370 nm, which increased in intensity with time. However, the excitation spectrum of skin with octyl salicylate (another UV-B emitting sunscreen) did not show such a shoulder or increase in intensity. Thus, we attribute the presence of a shoulder in the excitation spectrum of skin and the increase in its intensity as evidence for energy transfer from padimate O to collagen. The transfer mechanism is not clear.

Paper Details

Date Published: 8 February 2008
PDF: 9 pages
Proc. SPIE 6842, Photonic Therapeutics and Diagnostics IV, 684208 (8 February 2008); doi: 10.1117/12.758693
Show Author Affiliations
Rajagopal Krishnan, Univ. of Alabama at Birmingham (United States)
Univ. of California, San Francisco (United States)
Craig A Elmets, Univ. of Alabama at Birmingham (United States)
Thomas M. Nordlund, Univ. of Alabama at Birmingham (United States)

Published in SPIE Proceedings Vol. 6842:
Photonic Therapeutics and Diagnostics IV
Kenton W. Gregory M.D.; Reza S. Malek M.D.; Nikiforos Kollias; Brian Jet-Fei Wong M.D.; Henry Hirschberg M.D.; Justus F. R. Ilgner M.D.; Steen J. Madsen; Guillermo J. Tearney M.D.; Bernard Choi; Haishan Zeng, Editor(s)

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