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- Albèr, Cathrine, et al.
(författare)
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Effects of water gradients and use of urea on skin ultrastructure evaluated by confocal Raman microspectroscopy
- 2013
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier. - 0005-2736 .- 1879-2642 .- 0006-3002. ; 1828:11, s. 2470-2478
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Tidskriftsartikel (refereegranskat)abstract
- The rather thin outermost layer of the mammalian skin, stratum corneum (SC), is a complex biomembrane which separates the water rich inside of the body from the dry outside. The skin surface can be exposed to rather extreme variations in ambient conditions (e.g. water activity, temperature and pH), with potential effects on the barrier function. Increased understanding of how the barrier is affected by such changes is highly relevant for regulation of transdermal uptake of exogenous chemicals. In the present study we investigate the effect of hydration and the use of a well-known humectant, urea, on skin barrier ultrastructure by means of confocal Raman microspectroscopy. We also perform dynamic vapor sorption (DVS) microbalance measurements to examine the water uptake capacity of SC pretreated with urea. Based on novel Raman images, constructed from 2D spectral maps, we can distinguish large water inclusions within the skin membrane exceeding the size of fully hydrated corneocytes. We show that these inclusions contain water with spectral properties similar to that of bulk water. The results furthermore show that the ambient water activity has an important impact on the formation of these water inclusions as well as on the hydration profile across the membrane. Urea significantly increases the water uptake when present in skin, as compared to skin without urea, and it promotes formation of larger water inclusions in the tissue. The results confirm that urea can be used as a humectant to increase skin hydration.
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- Albèr, Cathrine, et al.
(författare)
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Spatial imaging and evaluation of humectants impact on stratum corneum hydration with confocal Raman microscpectroscopy
- 2012
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Ingår i: International Journal of Cosmetic Science. - : John Wiley & Sons. - 0142-5463 .- 1468-2494. ; :34, s. 359-359
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Objective: Confocal Raman microspectroscopy (CRM) enables non-invasive depth-scanning of biological tissues. The technique has been used to obtain information about the molecular composition of the skin, tracking of externally applied compounds and to determine molecular concentration profiles. The objective of this study is to use CRM in order to evaluate the changes in stratum corneum hydration when applying polyethylene glycol and the humectants urea and glycerol, and thereby also varying the external chemical potential of water. In the present study we also utilize the advantages of CRM to create novel spatial high- resolution Raman images of stratum corneum. Methodology: Excised porcine skin membranes (500 nm in thickness) were equilibrated from the surface with phosphate buffered saline (PBS) together with different types of humectants using Franz cells. The Raman measurements were performed with a WITec alpha300 system (Ulm, Germany) equipped with a 532 nm laser. The change in stratum corneum hydration after treatment with different humectants was determined from the relative intensity of the water and protein spectra. Raman images were created along a cross section by integrating the Raman intensities for specific vibrational modes. Results and conclusions: The results show that the hydration profiles of stratum corneum correlates well with the gradient in water chemical potential created by the applied humectants, i.e. low molecular weight humectants enable increased hydration of stratum corneum compared to a high molecular weight, non-penetrating polyethylene glycol. In addition the novel results from the Raman imaging experiments illustrates that it is possible to distinguish between water rich domains and the extracellular lipid rich domains along a cross section of the intact skin membrane.
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- Ali, Abdullah, 1985-, et al.
(författare)
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Relationship between sensorial and physical characteristics of topical creams : A comparative study on effects of excipients
- 2022
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Ingår i: International Journal of Pharmaceutics. - : Elsevier B.V.. - 0378-5173 .- 1873-3476. ; 613
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Tidskriftsartikel (refereegranskat)abstract
- Rising consumer demands for safer, more natural, and sustainable topical products have led to increased interest in finding alternative excipients, while retaining functionality and cosmetic appeal. Particle-stabilized Pickering creams have emerged as possible alternatives to replace traditional surfactant-stabilized creams and are thus one of the focuses in this study. The aim of this paper was to study relationships between sensorial characteristics and physical properties to understand how different excipients affect these aspects, comparing one starch particle–stabilized and three surfactant-stabilized formulations. A human panel was used to evaluate sensorial perception, while physical properties were deduced by rheology and tactile friction, together with in vivo and ex vivo skin hydration measurements. The results show that sensorial attributes related to the application phase can be predicted with rheology, while afterfeel attributes can be predicted with tactile friction studies. Differences in rheological and sensory properties among surfactant-based creams could mainly be attributed to the type of emollients used, presence of thickeners and surfactant composition. Differences between surfactant-based creams and a Pickering cream were more evident in relation to the afterfeel perception. Presence of starch particles in the residual film on skin results in high tactile friction and low perception of residual coating, stickiness, greasiness, and slipperiness in sensorial afterfeel. © 2021 The Authors
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