title: Analysis of Human and Porcine Skin in vivo/ex vivo for Penetration of Selected Oils by Confocal Raman Microscopy.
abstract: BACKGROUND
  The subject of oil penetration into the skin is controversially discussed in the scientific literature.
  
  
  METHODS
  Confocal Raman microscopy was used for analyzing oil penetration into the skin. The following methods were applied in the study: methods based on tracking specific peaks (method 1), the nonrestricted multiple least square fit (method 2), analyzing the lipid-to-keratin peak ratio using the perpendicular drop-down cutoff procedure (method 3), and the Gaussian function-based deconvolution procedure (method 4).
  
  
  RESULTS
  The results obtained using methods 1, 2 and 4 show that the investigated oils do not penetrate deeper than 11 µm into human and porcine skin. Petrolatum has a prominent swelling effect on the stratum corneum (32% in vivo, 28% ex vivo), while the other oils exhibit no significant swelling effect. By using method 3, the penetration profile of oils, and especially of petrolatum, into the skin was interpreted incorrectly for various reasons that are addressed herein below.
  
  
  CONCLUSIONS
  Predominantly remaining in the uppermost corneocyte layers of the stratum corneum, topically applied oils do not reach the viable cells of the stratum spinosum. To exclude any possible mistakes when using the lipid-keratin Raman peak (2,820-3,030 cm-1), the penetration analysis should be performed using the Gaussian function-based deconvolution procedure.
authors.affiliation: Center of Experimental and Applied Cutaneous Physiology, Department of Dermatology, Venereology and Allergology, Charitx00E9; - Universitx00E4;tsmedizin Berlin, Berlin, Germany.
authors.forename: ChunSik
authors.initials: C
authors.lastname: Choe
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
authors.forename: Maxim E
authors.initials: ME
authors.lastname: Darvin
mesh_terms: D000328:Adult; D000818:Animals; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009821:Oils / Q000493:pharmacokinetics*; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D013059:Spectrum Analysis, Raman; D013552:Swine; D055815:Young Adult
chemical_list: D009821:Oils