Conference Contribution Details
RE Imhof and P Xiao
Invited Lecture: Skin Forum 12th Annual Meeting, Frankfurt, March 2011.
Diffusion barriers are everywhere, from cell membranes to sausage skins. The focus in this talk is the skin barrier formed by the stratum corneum (SC), which protects us from dehydration and poisoning. Given its vital role, it is important to be able to measure its properties, both to assess damage and to develop methods for modifying it.
As with everything in biology, the SC barrier function is not simple. Even in its unmodified, clean, healthy state, it varies from person to person, site to site, time to time etc. Apply a chemical and the barrier function changes because of chemical interactions and physical (occlusion, swelling) changes. And of course, different chemicals and formulations affect the barrier in different ways.
The use of TEWL to measure SC barrier function relies on the discovery of Hancock et al  that water can resch the skin surface by diffusion through the epidermis. I will review this approach for both in-vivo and in-vitro applications. In addition, there are a number of techniques that give information about the barrier via concentration depth-profiles and Fick’s first law of diffusion. In this category are the non-invasive optical techniques of Opto-thermal Transient Emission Radiometry (OTTER) and Confocal Raman Spectroscopy.
More invasive but a lot simpler and cheaper is the technique of tape stripping. This also yields concentration depth-profiles in combination with techniques that measure what has been removed and/or what remains behind. One source of uncertainty with this approach is the non uniformity of the stripping process. In this context, I plan to present a new approach to map such non-uniformities using a contacting silicon array sensor.
|||Hancock, W, Whitehouse, AGR & Haldane, JS (1929). The loss of water and salt through the skin and the corresponding physiological adjustments. Proc. Roy. Soc. B, 105: 43-59.|
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