Effects of atmospheric relative humidity on Stratum Corneum structure at the molecular level: ex vivo Raman spectroscopy analysis

Self Cite

Background: In vivo Raman spectroscopy is a powerful tool for real-time analysis and in situ evaluation of tissues such as the skin. The efficiency of this technique has been widely demonstrated as a label-free method for in vivo evaluation of the skin. The aim of this study is to gather information about inter- and intra-individual variations in the spectral descriptors of water content and structure, organization of the lipid barrier and structure of proteins in the stratum corneum (SC). Methods: In vivo SC measurements were performed on 17 female volunteers aged 20-30 years (phototypes I and II). For intra-individual variability, spectral collection was performed on 5 successive days per volunteer. Shapiro-Wilk and Cochran tests were applied to check the normality and the homoscedasticity of variances. ANOVA was then applied to evaluate intra- and intergroup variability. Results: ANOVA was performed on the spectral descriptors of water content and structure, organization of the lipid barrier and secondary structure of proteins in the SC. No significant intra- and interday variability was observed for all volunteers. Despite the low value of the total relative standard deviation, a highly significant variation was observed between volunteers. Conclusion: Interindividual variability for Raman measurements is significant for a set of volunteers with normal nondiseased SC and close phototypes. This variability should be taken into consideration as a threshold for significant variance when working in vivo.

Section: Resultssupporting

confidence: 86%

In vivo Raman Microspectroscopy: Intra- and Intersubject Variability of Stratum Corneum Spectral Markers

Quatela¹,

Miloudi²,

Tfayli³

et al. 2016

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“…The changes of the lipid structure of the stratum corneum subsequent to interaction with water have already been described by different work groups [29,49,50]. Such lipid changes could also occur when the petrolatum is topically applied to the skin as this induces a swelling effect in the stratum corneum.…”

Section: Discussionmentioning

confidence: 93%

Analysis of Human and Porcine Skin in vivo/ex vivo for Penetration of Selected Oils by Confocal Raman Microscopy

Choe

Lademann

Darvin

2015

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. Conclusion: 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.

“…CRS can help gain a better understanding of moisturizers' mechanisms within the skin through the direct measurement of water content, distribution and SC swelling [35]. In addition, it has been recently demonstrated that CRS can differentiate between different water-binding states, including unbound, partially bound and primary bound water [68,69]. The water content in each binding state has been found to vary differently in function of external stimuli, such as humidity and mechanical stress and, remarkably, correlations with structural and organizational changes in lipids and proteins were highlighted [68,70].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, it has been recently demonstrated that CRS can differentiate between different water-binding states, including unbound, partially bound and primary bound water [68,69]. The water content in each binding state has been found to vary differently in function of external stimuli, such as humidity and mechanical stress and, remarkably, correlations with structural and organizational changes in lipids and proteins were highlighted [68,70]. This demonstrates the potential of CRS to study the correlation of the skin barrier and hydration status in function of different stimuli.…”

Section: Discussionmentioning

confidence: 99%

“…lasers, detectors, confocal optics) to obtain high-quality spectra, as well as by specific software ‘know-how' to process and extract the information of interest [84] (e.g. deconvolution methods in case of overlapping spectral bands [22,68]). As a consequence, current state-of-the-art in vivo Raman applications are complex, expensive and relatively bulky, needing trained personnel for their use and not yet allowing measurements on recessed body parts [24,84,85].…”

Section: Discussionmentioning

confidence: 99%

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Microspectroscopic Confocal Raman and Macroscopic Biophysical Measurements in the in vivo Assessment of the Skin Barrier: Perspective for Dermatology and Cosmetic Sciences

Falcone

Uzunbajakava²,

Varghese

et al. 2015

Skin barrier function, confined to the stratum corneum, is traditionally evaluated using established, noninvasive biophysical methods like transepidermal water loss, capacitance and conductance. However, these methods neither measure skin molecular composition nor its structure, hindering the actual causes of skin barrier change or impairment. At the same time, confocal Raman microspectroscopy (CRS) can directly measure skin molecular composition and structure and has proven itself to be a powerful technique for biomolecular analysis. The aims of this literature review were to evaluate noninvasive biophysical methods in view of CRS and to outline a direction towards more specific and informative skin measurement methods. We address this by investigating, for the first time, the relation between in vivo assessment of the skin barrier using indirect biophysical methods and the actual skin composition and structure as given by CRS, and emphasize the high potential of CRS for dermatology and cosmetic sciences. CRS acceptance in these fields will require close collaboration between dermatologists, skin scientists and spectroscopy experts towards simplifying the technology and creating robust, rapid, easy-to-use and less expensive CRS applications.