Confocal Raman spectroscopy: Noninvasive in vivo investigation of human skin on a molecular level

For more than 20 years now confocal Raman spectroscopy is used to measure molecular concentration profiles in vivo in the human skin. With a depth resolution down to 3 µm the epidermis and upper dermis can be directly assessed and the molecular composition of a wide range of skin components and externally applied molecules be quantified.

Measurements can be performed on almost every region of the body surface, as on the extremities, the trunk, but also on areas more difficult to reach, as scalp, axillae, lips and inside of the mouth.

In the first decade of the 21st century the research focused on the chemical composition of the epidermis. Water distribution in the stratum corneum, the content and composition of natural moisturization factors (NMF) and skin lipids, where important topics.

In the last decade a new important field of application occurred, the quantitative penetration and permeation of externally applied components and actives.

In this presentation an overview on the methodology is given, with examples of water and NMF measurements. To explain the approach of quantitative measurement of skin penetration and permeation in vivo, results of caffeine penetration are presented. Simple solutions in water with and without a penetration enhancer were investigated. With the Raman technology the permeation rate of caffeine into the stratum corneum as well as the depletion rate into the living epidermis could be quantitatively measured.

Conférence proposée par Canal U, plus d’info sur le site de Canal U

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