Journal of Fluorescence

, Volume 10, Issue 3, pp 275–275

Fluorescence Studies of Melanin by Stepwise Two-Photon Femtosecond Laser Excitation

  • Klaus Teuchner
  • Jürgen Ehlert
  • Wolfgang Freyer
  • Dieter Leupold
  • Peter Altmeyer
  • Markus Stücker
  • Klaus Hoffmann
Article

DOI: 10.1023/A:1009453228102

Cite this article as:
Teuchner, K., Ehlert, J., Freyer, W. et al. Journal of Fluorescence (2000) 10: 275. doi:10.1023/A:1009453228102

Abstract

Fluorescence of synthetic melanin in the solvents H2O, KOH, ethylene glycol monomethyl ether, and dimethyl sulfoxide has been excited by two-photon absorption at 800 nm, using 120-fs pulses with photon flux densities of ≥1027 cm−2.S−1. Compared to the one-photon (400-nm)-induced fluorescence of melanin, the overall spectral shape is red-shifted and shows a strong environment sensitivity. The decay of the two-photon-induced fluorescence (TPF) of melanin is three-exponential, with a shortest main component of about 200 ps. The results of the TPF studies in line with the unique light absorption property of melanin of a monotonously decreasing absorption spectrum between the near UV-region and the near infrared region indicate that the TPF is realized via stepwise absorption of two 800-nm photons. In comparison to the simultaneous absorption of two photons, the stepwise process needs lower photon flux densities to get a sufficient population of the fluorescent level. This stepwise process offers new possibilities of selective excitation of melanin in skin tissue in a spectral region where there is no overlap with any absorption of another fluorescent tissue component. The first results with different samples of excised human skin tissue (healthy, nevus cell nevi, malignant melanoma) suggest that fluorescence excited in this way yields information on malignant transformation.

Melanin two-photon excited fluorescence femtosecond laser excitation malignant melanoma skin cancer diagnostics 

Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Klaus Teuchner
    • 1
  • Jürgen Ehlert
    • 2
  • Wolfgang Freyer
    • 2
  • Dieter Leupold
    • 2
  • Peter Altmeyer
    • 3
  • Markus Stücker
    • 3
  • Klaus Hoffmann
    • 3
  1. 1.Max-Born-Institut für Nichtlineare Optik und KurzzeitspektroskopieBerlinGermany
  2. 2.Max-Born-Institut für Nichtlineare Optik und KurzzeitspektroskopieBerlinGermany
  3. 3.Department of Dermatology, St. Josef HospitalRuhr-UniversityBochumGermany

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