Emollient structure and chemical functionality effects on the biomechanical function of human stratum corneum / C. Berkey in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 42, N° 6 (12/2020)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 42, N° 6 (12/2020) . - p. 605-614 Titre : Emollient structure and chemical functionality effects on the biomechanical function of human stratum corneum Type de document : document électronique Auteurs : C. Berkey, Auteur ; D. Kanno, Auteur ; Annette Mehling, Auteur ; J.-P. Koch, Auteur ; W. Eisfeld, Auteur ; M. Dierker, Auteur ; M. Bhattacharya, Auteur ; Reinhold H. Dauskardt, Auteur Année de publication : 2020 Article en page(s) : p. 605-614 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Biomécanique Caractérisation Cosmétiques Couche cornée Dermo-cosmétologie Emollients Fourier, Spectroscopie infrarouge à transformée de Peau -- analyse Peau -- Soins et hygiène Pénétration (physique) Index. décimale : 668.5 Parfums et cosmétiques Résumé : - Objective : Cosmetic emollients are widely used in skincare formulations due to their ability to 'soften' the skin and modulate formulation spreadability. Though emollients are commonly used, little is known about their effects on the biomechanical barrier properties of human stratum corneum (SC), which play a critical role in consumer perception of formulation efficacy. Accordingly, our objective was to provide new insights with a study involving fourteen cosmetic emollient molecules with widely varying structures, molecular weights, SC diffusivities, topological polar surface areas (TPSAs), viscosities and chemical functionalities. - Methods : Mechanical stress in the SC was measured in vitro using a substrate curvature measurement technique. Stress development due to SC drying was measured before and after topical treatment with cosmetic emollients. Emollient diffusivity and alterations to lipid content in SC after treatment were measured via ATR-FTIR spectroscopy. The maximum penetration volume of emollient in SC was characterized to elucidate mechanisms underlying emollient effects on stress. - Results : The application of all cosmetic emollients caused a reduction in SC mechanical stress under dehydrating conditions, and a linear correlation was discovered between emollient penetration volume and the degree of stress reduction. These molecules also induced increases in stress equilibration rate, signalling changes to SC transport kinetics. Stress equilibration rate increases linearly correlated with decreasing intensity of the νCH2 band, indicating a previously unknown interaction between cosmetic emollients and SC lipids. Stress and penetration volume results were rationalized in terms of a multi-parameter model including emollient molecular weight, diffusivity, TPSA and viscosity. - Conclusion : We provide a new rational basis for understanding the effects of cosmetic emollient choice on biomechanical properties affecting SC barrier function and consumer perception. We demonstrate for the first time that emollients very likely reduce SC mechanical stress through their ability to take up volume when penetrating the SC, and how molecular weight, SC diffusivity, TPSA and viscosity are predictive of this ability. As cosmetic formulations continue to evolve to meet the needs of customers, emollient molecules can be selected that not only contribute to formulation texture and/or spreadability but that also leverage this novel connection between emollient penetration and SC biomechanics. Note de contenu : - Stratum corneum preparation - Emollient treatments - Drying stress substrate curvature - Penetration volume measurements - ATR-FTIR spectroscopy - Table 1 : Names and relevant physical properties of emollients - Table 2 : Drying stress, penetration volume and diffusivity measurements of SC treated with emollients DOI : https://doi.org/10.1111/ics.12656 En ligne : https://drive.google.com/file/d/1iqy3w2otbjm-FJAy68hPKAWIkLGWpBIb/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35427 [article]

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Screening sunscreens : protecting the biomechanical barrier function of skin from solar ultraviolet radiation damage / C. Berkey in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 39, N° 3 (06/2017)

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 39, N° 3 (06/2017) . - p. 269-274 Titre : Screening sunscreens : protecting the biomechanical barrier function of skin from solar ultraviolet radiation damage Type de document : texte imprimé Auteurs : C. Berkey, Auteur ; K. Biniek, Auteur ; Reinhold H. Dauskardt, Auteur Année de publication : 2017 Article en page(s) : p. 269-274 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Barrière cutanée Etude in vitro Etude in vivo Peau -- Effets du rayonnement solaire Peau -- Physiologie Photoprotection Produits antisolaires Index. décimale : 668.5 Parfums et cosmétiques Résumé : OBJECTIF : Solar ultraviolet (UV) radiation is ubiquitous in human life and well known to cause skin damage that can lead to harmful conditions such as erythema. Although sunscreen is a popular form of protection for some of these conditions, it is unclear whether sunscreen can maintain the mechanical barrier properties of skin. The objective of this study was to determine whether in vitro thin-film mechanical analysis techniques adapted for biological tissue are able to characterize the efficacy of commonly used UV inhibitors and commercial sunscreens to protect the biomechanical barrier properties of stratum corneum (SC) from UV exposure. METHODS : The biomechanical properties of SC samples were as sayed through measurements of the SC's drying stress profile and delamination energy. The drying stresses within SC were characterized from the curvature of a borosilicate glass substrate onto which SC had been adhered. Delamination energies were characterized using a double-cantilever beam (DCB) cohesion testing method. Successive DCB specimens were prepared from previously separated specimens by adhering new substrates onto each side of the already tested specimen to probe delamination energies deeper into the SC. These properties of the SC were measured before and after UV exposure, both with and without sunscreens applied, to determine the role of sunscreen in preserving the barrier function of SC. RESULTS : The drying stress in SC starts increasing sooner and rises to a higher plateau stress value after UVA exposure as compared to non-UV-exposed control specimens. For specimens that had sunscreen applied, the UVA-exposed and non-UV-exposed SC had similar drying stress profiles. Additionally, specimens exposed to UVB without protection from sunscreen exhibited significantly lower delamination energies than non-UV-exposed controls. With commercial sunscreen applied, the delamination energy for UV-exposed and non-UV-exposed tissue was consistent, even up to large doses of UVB. CONCLUSION : In vitro thin-film mechanical analysis techniques can readily characterize the effects of SC's exposure to UV radiation. The methods used in this study demonstrated commercial sunscreens were able to preserve the biomechanical properties of SC during UV exposure, thus indicating the barrier function of SC was also maintained. Note de contenu : - Stratum corneum preparation - UV exposure and sunscreens - Drying stress measurements - Dual-cantilever beam testing DOI : 10.1111/ics.12370 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28624 [article]

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