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Human glabrous skin contains crystallized urea dendriform structures in the stratum corneum which affect the hydration levels

  • Glabrous skin is hair-free skin with a high density of sweat glands, which is found on the palms, and soles of mammalians, covered with a thick stratum corneum. Dry hands are often an occupational problem which deserves attention from dermatologists. Urea is found in the skin as a component of the natural moisturizing factor and of sweat. We report the discovery of dendrimer structures of crystalized urea in the stratum corneum of palmar glabrous skin using laser scanning microscopy. The chemical and structural nature of the urea crystallites was investigated in vivo by non-invasive techniques. The relation of crystallization to skin hydration was explored. We analysed the index finger, small finger and tenar palmar area of 18 study participants using non-invasive optical methods, such as laser scanning microscopy, Raman microspectroscopy and two-photon tomography. Skin hydration was measured using corneometry. Crystalline urea structures were found in the stratum corneum of about two-thirds of the participants. Participants with a higher density of crystallized urea structures exhibited a lower skin hydration. The chemical nature and the crystalline structure of the urea were confirmed by Raman microspectroscopy and by second harmonic generated signals in two-photon tomography. The presence of urea dendrimer crystals in the glabrous skin seems to reduce the water binding capacity leading to dry hands. These findings highlight a new direction in understanding the mechanisms leading to dry hands and open opportunities for the development of better moisturizers and hand disinfection products and for diagnostic of dry skin.

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Document Type:Article
Author:Victor Hugo Pacagnelli InfanteORCiD, Roland BennewitzORCiD, Marius KrögerORCiD, Martina C. MeinkeORCiD, Maxim E. DarvinORCiD
Parent Title (English):Experimental Dermatology
First Page:986
Last Page:995
Year of first Publication:2023
Release Date:2023/07/19
Tag:glabrous skin; laser scanning microscopy; skin hydration; stratum corneum; urea
Impact:03.600 (2022)
Funding Information:Volkswagen Foundation
Groups:Interaktive Oberflächen
DDC classes:600 Technik, Medizin, angewandte Wissenschaften / 610 Medizin, Gesundheit
Open Access:Open Access
Signature:INM 2023/054
Licence (German):License LogoCreative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International