FEATURE COSMETICS
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topography of the skin. A light beam is reflected by skin’s surface, and the interference of the light is measured according to a reference light beam, and a 3D representation of the top of the skin is generated. ‘The surface of the skin is composed of
many micro-folds, and this micro-relief of the skin is largely responsible for the optical properties of the skin. Therefore, the image differs with the changing depth and width of the folds,’ Peno-Mazzarino explained. Many cosmetic products try to modify the
surface aspect of the skin, Peno-Mazzarino added, such as ‘soft focus’ or ‘filling’ creams that aim to reduce the depth of the micro-relief and make the skin smoother. ‘We take measurements before the
product has been applied, and then anywhere between five minutes and a few days after application. We can then compare the roughness of the skin and the width and depth of the micro-folds before and after treatment,’ said Peno-Mazzarino. With the ex-vivo model, the experiment can be maintained for 10 to 12 days. These types of products that target the
appearance of the skin’s surface tend to have much more immediate effects, which represents a new type of development of cosmetics, Peno-Mazzarino added. Nanoscale topography and Raman are
just two of many techniques used by BIO- EC and other cosmetics labs to provide companies with accurate information about the safety and efficacy of their products. However, when it comes to testing on human volunteers it becomes more challenging, as this requires tests that are not only minimally invasive, but robust. ‘Many existing techniques are not
suitable for use on volunteers because they are too invasive or damaging. We have a lot of techniques that could be very accurate and can go deep, but are destructive.
Image showing immunostaining of LEKTI (large multidomain serine protease inhibitor) in fluorescence microscopy carried out by the BIO-EC Laboratory
“If a light interferometer could be used on volunteers it could be a real advance”
Raman spectroscopy or IR spectroscopy can sometimes be destructive or invasive. Micro-tomography x-ray… is very accurate; it can go very deep into the skin, but we cannot expose the volunteers to x-ray frequently, it is just not possible,’ Peno- Mazzarino said. ‘The light interferometer… is very
sensitive to external vibrations, so it cannot be used in clinical evaluation on volunteers. We cannot put the arm or the face under the light of the interferometer because there are a lot of vibrations. If a light interferometer could be used on volunteers it could be a real advance because there is a lack of techniques for clinical evaluation,’ he continued. ‘So if there were to be an accurate,
non-invasive technique that allows you to go deep within the skin it could be a real advance.’
Destructive but effective When being invasive doesn’t matter, more aggressive techniques can be used to gain even more useful insights into the performance of cosmetics. As part of a collaboration between several
High resolution multivariate image of a skin cross section showing the different constituents of epidermis, obtained using Horiba’s equipment
22 Electro Optics May 2017
research and commercial organisations in France, state-of-the-art equipment and services are being made available to
companies in a bid to structure research and support France’s status as leaders in cosmetics development. The Cosmetomics innovation platform
involves partners such as BIO-EC, Polytec, the University of Cergy-Pontoise, ISIPCA (a school for post-graduate studies in perfume and cosmetics products) and Soleil, a synchrotron facility near Paris. With the particle accelerometer provided
by Soleil, x-ray micro-tomography can be carried out on a hair follicle, to measure all of the components of the hair, such as the sebum-producing, or sebaceous, glands. ‘It is useful because a lot of cosmetics
products aim to reduce the amount of sebum produced. With x-ray micro- tomography we can measure the volume of this gland… it is very invasive, but very useful,’ said Peno-Mazzarino. ‘A lot of big companies use these kinds
of technologies. But the Cosmetomics platform allows smaller companies and research labs to access this equipment. ‘I think this is the future of research in cosmetics because a lot of these technologies cannot be acquired by a standard research lab,’ he concluded. EO
References
[1] Essendoubi, M., Gobinet, C., Reynaud, R., Angiboust, J F., Manfait M, Piot O., 2016. Human skin penetration of hyaluronic acid of different molecular weights as probed by Raman spectroscopy. Skin Res Technol. 22(1) pp. 55-62
@electrooptics |
www.electrooptics.com
O. Piot and M. Manfait, Faculty of Pharmacy, University of Reims Champagne Ardenne, France
BIO-EC Laboratory
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