Optical Methods for Measurements of Skin Penetration

Gotter, B.; Faubel, W.; Neubert, Reinhard H.H.

doi:10.1159/000131081

Cited by 40 publications

(28 citation statements)

References 64 publications

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“…[5] In skin research, numerous applications of infrared spectroscopy [6][7][8] and fluorescence microscopy [9][10][11] indicated the potential of noninvasive techniques for substance follow-up in human skin. Recently, confocal Raman microscopy (CRM) came in the center of interest in pharmaceutical research in general, [12,13] and skin research in particular.…”

Section: Introductionmentioning

confidence: 99%

Accessing Raman spectral variability in human stratum corneum for quantitative in vitro depth profiling

Franzen

Windbergs

2013

J Raman Spectroscopy

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The opportunity of label-free and non-destructive detection of substances inside human skin by confocal Raman microscopy represents a novel approach for investigating drug penetration and permeation. Several studies already introduced confocal Raman microscopy for depth profiling in skin; however, the reported results show high deviations. Thus, analysis of the spectral variability of human skin itself is a necessary prerequisite for systematic quantitative investigations of drug penetration and permeation by confocal Raman microscopy.In our work, we acquired Raman depth profiles from excised human skin samples after abdominal plastic surgery and investigated the absolute intensity fluctuation of four major skin derived Raman peaks. The results prove the expected high variability in spectral intensity, but we could not detect dissimilarities between different skin donors. A detailed analysis of the major endogenous skin components revealed differences in spatial distribution which consequently affects their individual applicability as reference peaks for relative depth profiling. Furthermore, we discovered an increase in signal variability in deeper stratum corneum layers, which has to be considered in future substance depth profiling investigations. In addition, we discovered an exponential decay of the Raman signal for all major skin components accounting for signal attenuation inside biological tissue. Based on this mathematical description, quantitative follow-up of substances in human skin can be realized. All in all, the results of this study elucidate the necessity of substantial understanding of endogenous spectral characteristics inside human skin as essential prerequisite for rational depth profiling of substances in human skin.

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Section: Introductionmentioning

confidence: 99%

Accessing Raman spectral variability in human stratum corneum for quantitative in vitro depth profiling

Franzen

Windbergs

2013

J Raman Spectroscopy

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“…F inhomogeneity = A homogeneous /A inhomogeneous (1) A completely homogeneous distribution corresponds to a factor of inhomogeneity of 1. Higher F inhomogeneity values describe a more inhomogeneous distribution of the applied products on the skin.…”

Section: Definition Of a Factor Of Inhomogeneitymentioning

confidence: 99%

“…Optical spectroscopy can be a valuable tool to obtain qualitative and quantitative information on substances utilizing an appropriate absorption band [1][2][3] . A linear relationship exists between the spectroscopically measured absorbance and the concentrations of the absorbing species distributed homogeneously in the investigated system (Lambert-Beer law).…”

Section: Introductionmentioning

confidence: 99%

Quantification of the Inhomogeneous Distribution of Topically Applied Substances by Optical Spectroscopy: Definition of a Factor of Inhomogeneity

Weigmann

Schanzer²,

Vergou³

et al. 2012

Skin Pharmacol Physiol

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The inhomogeneous distribution of topically applied substances due to decisive differences in the skin structure (furrows and wrinkles) affects the efficacy of cosmetic products, in particular sunscreens. The combination of tape stripping and optical spectroscopy results in absorption data, which reflect ex vivo the inhomogeneity of the in vivo distribution of topically applied substances. Based on these data, a factor of inhomogeneity is defined describing the individual distribution of formulations on the skin surface of volunteers. Thus, the influence of different skin surface structures and the influence of different formulations on the distribution of the topically applied substances can be determined. Analyzing the inhomogeneity data on 6 volunteers (5 sunscreens per volunteer), it was found that the influence on the distribution of sunscreens caused by the formulation was higher than the inhomogeneity originating from the differences in the skin surface structure of the volunteers. The method is well suited to characterize, for example, sunscreens and antiaging creams in the process of development, as well as for the evaluation of the final products.

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“…This problem was studied and described by many groups (36)(37)(38)(39)(40)(41)(42)(43)(44), and a recent study by Xiao et al, using multilayered systems constituted with polymers films with refractive indexes close to those of the human skin, showed that the error in the measurement led to an underestimation of the depth value of 15-20% (45). Therefore, all depth values deduced from Raman measurements should be theoretically corrected by applying a 15-20% factor.…”

Section: Confocal Raman Microscope Studiesmentioning

confidence: 99%

Ingredients Tracking of Cosmetic Formulations in the Skin: A Confocal Raman Microscopy Investigation

et al. 2011

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Optical Methods for Measurements of Skin Penetration

Cited by 40 publications

References 64 publications

Accessing Raman spectral variability in human stratum corneum for quantitative in vitro depth profiling

Accessing Raman spectral variability in human stratum corneum for quantitative in vitro depth profiling

Quantification of the Inhomogeneous Distribution of Topically Applied Substances by Optical Spectroscopy: Definition of a Factor of Inhomogeneity

Ingredients Tracking of Cosmetic Formulations in the Skin: A Confocal Raman Microscopy Investigation

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