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Journal of Biomedical Optics

Depth-dependent autofluorescence photobleaching using 325, 473, 633, and 785 nm of porcine ear skin ex vivo
Author(s): Johannes Schleusener; Jürgen Lademann; Maxim E. Darvin
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Paper Abstract

Autofluorescence photobleaching describes the decrease of fluorescence intensity of endogenous fluorophores in biological tissue upon light irradiation. The origin of autofluorescence photobleaching is not fully understood. In the skin, the spatial distribution of various endogenous fluorophores varies within the skin layers. Most endogenous fluorophores are excited in the ultraviolet and short visible wavelength range, and only a few, such as porphyrins (red) and melanin (near-infrared), are excited at longer wavelengths. The excitation wavelength- and depth-dependent irradiation of skin will therefore excite different fluorophores, which will likely influence the photobleaching characteristics. The autofluorescence photobleaching of porcine ear skin has been measured ex vivo using 325, 473, 633, and 785 nm excitation at different skin depths from the surface to the dermis at 150 μ m . Confocal Raman microscopes were used to achieve sufficient spatial resolution of the measurements. The autofluorescence area under the curve was measured for 21 consecutive acquisitions of 15 s. In all cases, the photobleaching follows a two-exponential decay function approximated by nonlinear regression. The results show that photobleaching can be applied to improve the signal-to-noise ratio in Raman spectroscopy for all of the applied excitation wavelengths and skin depths.

Paper Details

Date Published: 5 January 2017
PDF: 9 pages
J. Biomed. Opt. 22(9) 091503 doi: 10.1117/1.JBO.22.9.091503
Published in: Journal of Biomedical Optics Volume 22, Issue 9
Show Author Affiliations
Johannes Schleusener, Charité Universitätsmedizin Berlin (Germany)
Jürgen Lademann, Charité Universitätsmedizin Berlin (Germany)
Maxim E. Darvin, Charité Universitätsmedizin Berlin (Germany)

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