“Interfaces.” The unifying thread of the 10th Scientific Symposium organised by LVMH Recherche Parfums & Cosmétiques opened the door to a multitude of approaches, whether anthropological, biological, chemical or even historical. At the end, cosmetology emerged as a comprehensive science.
Indeed, the notion of interface can be applied to many areas, starting, of course, by the skin itself. “Skin is the final destination of the cosmetic products. It is our interface with the world: an interface of colour, a visible protective interface and a support of our contact with others. The everyday life of skin is governed by biological and physicochemical interfaces, exchanges with light or other sources of stress,” explains Frédéric Bonté, Director of Scientific Communication at LVMH Recherche.
Skin as a communication interfaceProfessor Nina G. Jablonski, Head of Department of Anthropology at the Pennsylvania State University, explained that human skin is unique among mammals because its lack of functional body hair, its high density of sweat glands, its range of natural colours, and its ability to be deliberated decorated for social purposes. “Humans are highly visual animals, and it is likely that we have been decorating our naked skin for nearly the entire history of our species. Reconstruction of the details of this history is difficult, but archaeological evidence indicates that humans have probably been decorating their skin with mineral pigments for at least 80,000 years.”
Skin therefore appears as a social communication tool, including the colour that we intend it to get through tanning or, on the contrary, through bleaching agents.
Skin as a protection and reception interface
For his part, Desmond Tobin, Professor of Cell Biology and Director of the Centre for Skin Sciences (CSS) at the University of Bradford, says human skin is “strategically located at the interface of the internal and noxious external environments.” It “plays a significant role in sensing and responding to light of all types,” he adds. Generally speaking, human beings are looking for sun light and are avoiding it too: the need it, but it can become dangerous. As per the latter, the effects of UV radiations have been extensively documented, however, according to Pr. Tobin, other types of light also deserve more scientific attention.
For instance, approximately 33% of the sunlight impacting on human skin is represented by infra red light and its impact on skin ageing has been demonstrated recently. The incidence of visible light is also of current research interest. At this level, recent findings are quite surprising, as photosentive proteins, rhodopsin and opsin, once considered as specific of rod cells of the eye’s retina, have been detected in human epidermis.
According to Desmond Tobin, skin appears as a giant photoprotector organ, as well as a giant photoreceptor, which is sensitive to all kinds of lights that may have noticeable negative or positive health effects.
If the understanding of the skin’s structure and biology made huge progress over the latest years, it is also because of the progress in microscopy techniques. Emmanuelle Noblesse, Responsible of the Life Imaging Platform, Biology and Cutaneaous Obhjectivation Department at LVMH Recherche, explained the role of imaging in the demonstration of the various biological mechanisms that occur in cutaneous tissues.
Cosmetic products are made of interfaces
Beyond the role of skin, LVMH Recherche intended to show that the concept of interfaces was also applicable to cosmetic products, being either skin care, make-up or fragrances, both as complex molecular systems and as consumer goods that need to make sense in the mind of consumers.
Dr. Johann W. Wiechers hence presented a method for characterising emulsion structures, in order to better understand the surfactants’ behaviours at the interfaces between water and oil phases. Recently, this theory was transformed into a computer programme that can be used by formulators, with the aim of better understanding the behaviour of a surfactant system and thus decrease the number of operations required to get a desired emulsion.
Then, Sylvie Hénon, Professor of Physic at the University Paris Diderot, explained that the products used in cosmetology are mostly derived from divided media (suspensions, emulsions, and foams are composed of solid particles, liquid droplets or gas bubbles dispersed in a liquid) and their properties are largely dictated by the extent of the interface between the dispersed phase and the dispersion medium. However creation of an interface requires free energy, the cost to which is known as surface tension. Surfactant molecules reduce the surface tension and are one of the strategies that allow to stabilize suspensions and emulsions.
Finally, in a very different field, Germain Gazano, Marketing and Consumer Intelligence Director at LVMH Recherche, described the various methods that are used to dissect consumer perceptions regarding the products they are proposed; methods that are based on the analysis of their verbal responses, in other words, the semantics interface.
The impressive evolution of cosmetics’ efficacy, presentation and methods of application is based on a set of innovations that require a broad spectrum of scientific knowledge, on which LVMH Recherche gave a wondering overview in a one-day symposium.