Transmittance and Autofluorescence of Neonatal Rat Stratum Corneum: Nerolidol Increases the Dynamics and Partitioning of Protoporphyrin IX into Intercellular Membranes
In this work, we developed an experimental apparatus to directly measure transmittance and fluorescence in the stratum corneum (SC) ex vivo. The SC transmittance varied from ~6 to ~52 % in the wavelength range of 280–850 nm. For 260–300 nm excitation, the SC autofluorescence showed a strong emission band between 290 and 425 nm, which is associated with tryptophan, and another in the 600–670 nm range, which we attributed to a process involving resonance energy transfer to very hydrophobic keratin filaments. Weaker emission associated with less hydrophobic keratin filaments was also observed in the wavelength range of 350–480 nm. Protoporphyrin IX (PpIX) was incorporated into SC membranes, and its penetration was further increased by the addition of nerolidol to the treatment suspension. Both PpIX and the endogenous porphyrins showed fluorescence anisotropy consistent with their localization in SC membranes, and their molecular dynamics increased significantly in the presence of 1 % nerolidol. The emission and excitation spectra of PpIX and the endogenous SC porphyrins showed similar alterations during the photobleaching induced by 405-nm irradiation. This work also highlights the SC contribution to skin autofluorescence, which could be useful for fluorescence spectroscopy applications in the early diagnosis of skin diseases.
KeywordsNerolidol Fluorescence Stratum corneum PpIX
This work was supported by the Brazilian research funding agencies CNPq, FAPEG and CAPES. L. Alonso acknowledges CAPES for doctoral fellowship support. P. J. Gonçalves and A. Alonso gratefully acknowledge CNPq for research grants. The authors also thank Dr. Jesiel F. Carvalho, Dr. Renata M. Pereira and Dr. Lauro J. Q. Maia for their assistance with instruments.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
- 1.Borisova EG, Angelova LP, Pavlova EP (2014) Endogenous and exogenous fluorescence skin cancer diagnostics for clinical applications. IEEE J of Selected Topics in Quantum Electronics 20(2). doi: 10.1109/JSTQE.2013.2280503
- 24.Scheuplein RJ (1964) A survey of some fundamental aspects of the absorption and reflection of light by tissue. J Soc Cosmet Chem 15:111–122Google Scholar
- 36.Ibrahim H, Kasselouri A, You C, Maillard P, Rosilio V, Pansu R, Prognon P (2011) Meso-tetraphenyl porphyrin derivatives: the effect of structural modifications on binding to DMPC liposomes and albumin. J Photochem Photobiol A Chem 217:10–21. doi: 10.1016/j.jphotochem.2010.09.008 CrossRefGoogle Scholar
- 40.Moreira RA, Mendanha SA, Fernandes KS, Matos GG, Alonso L, Dorta ML, Alonso A (2014) Miltefosine increases lipid and protein dynamics in leishmania amazonensis membranes at concentrations similar to those needed for cytotoxicity activity. Antimicrob Agents Chemother 58(6):3021–3028CrossRefPubMedPubMedCentralGoogle Scholar