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Novitom explains why and how looking at intercellular lipids in the stratum corneum, in an article published in Cosmetic Testing News.
The barrier function of the stratum corneum (SC) is intrinsically linked to the organisation of its intercellular lipids. Characterising and monitoring this organisation is therefore essential for understanding and quantifying the effects of cosmetic products and treatments on skin barrier integrity.
The physiological lipid matrix, composed primarily of ceramides, free fatty acids and cholesterol, is arranged into complex lamellar structures aligned parallel to the corneocyte surface. Within these lipid layers, highly ordered crystalline domains coexist with less organised amorphous regions.
Assessing the molecular organisation of SC lipids following treatment provides valuable insights into a product’s ability to penetrate the skin, reinforce barrier function, improve skin nutrition, or modify the physical properties of the stratum corneum.
Several analytical techniques are routinely used to investigate SC lipids, including differential scanning calorimetry (DSC), Raman spectroscopy and transmission electron microscopy (TEM).
To obtain a more comprehensive understanding of lipid architecture at the molecular level, X-ray diffraction technique is required.
Following application of a commercially available cosmetic cream, consumers reported smoother and softer skin. X-ray microdiffraction analysis helped explain the molecular basis of this sensory perception.
Measurements revealed that the regular lamellar organisation of intercellular lipids was significantly disrupted at the outer surface of the stratum corneum, where the cream was applied. In contrast, lipid organisation remained largely unchanged in deeper regions closer to the epidermis.
This localised disruption of surface lipid organisation may contribute to the perceived softening effect, potentially by facilitating the desquamation process while preserving the integrity of the deeper barrier structure.
Conclusion
By combining synchrotron-based X-ray microdiffraction with micrometre-scale spatial resolution, Novitom provides an advanced analytical platform for investigating the molecular organisation of the stratum corneum and the mechanisms by which cosmetic products interact with skin lipids.
The technology offers a unique opportunity to bridge formulation science, efficacy evaluation and claim substantiation through direct measurement of structural changes within the skin barrier.
X-ray diffraction provides detailed information on:
As these parameters exhibit relatively low inter-individual variability, they represent robust biomarkers of skin barrier quality and are particularly valuable for monitoring structural changes induced by cosmetic products and treatments.
To enhance the relevance of X-ray diffraction for cosmetic research, Novitom has developed proprietary measurement protocols based on the exceptional capabilities of synchrotron X-ray sources.
This approach enables:
Beyond structural characterisation, X-ray microdiffraction provides mechanistic insights into how cosmetic products interact with the skin barrier.
The technique can:
Such information is highly valuable for understanding formulation performance and supporting mechanism-based product development.
X-ray microdiffraction offers formulators a powerful tool for rational formulation optimisation by providing direct evidence of how ingredients and finished products interact with the skin barrier at the molecular level.
In parallel, the resulting data can support scientifically substantiated marketing claims related to barrier reinforcement, nourishment, repair and skin conditioning.
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