Innovation in Thermalism: An Example in Beira Interior Region of Portugal
11.3 Skin Structure and Challenges for Dermocosmetic Formulations Development Based on Thermal Water
11.3.1 Nanobiotechnology and Cosmetics Formulations
A Review
Nanobiotechnology is the science of manipulating atoms and molecules on a nanoscale (Raj et al. 2012 ), the application of which has developed tremendously in recent years (Mihranyan et al. 2012 ) although it was implemented very early in the cosmetics sector. Between 2000 and 2010, L’Oreal SA (France) was the fi rst cosmetic company in the ranking of world-wide companies with nanotechnology- related patents and very early on fi rst applied nanobiotechnology in cosmetics.
Lancôme launched a cream with nanocapsules of pure vitamin E to combat ageing
of the skin (Mihranyan et al. 2012 ; Raj et al. 2012 ) and, in 1986, Dior presented Capture® antiageing cream, the fi rst liposomal cosmetic product (Müller et al. 2002 ).
Almost all the major cosmetic companies, such as Mustela, Artdeco, Nivea, Avon, The Body Shop, Revlon, Chanel, Skinceuticals, Estée Lauder, Shiseido, Garnier, and Boticario, are examples of entrepreneuring companies in this sector that have products based on nanobiotechnology (Mihranyan et al. 2012 ; Raj et al. 2012 ).
The vast infl uence of nanobiotechnology in the cosmetics industry is due to the improvement of cosmetics properties achieved by nanocarriers related to the improvement of delivery, bioavailability and targeting of active principles to skin, with higher performance than the conventional products and without causing irrita- tion. These vehicles are extensively researched and the result is the promotion of many advantages of nanobiotechnology over traditional formulations (Mihranyan et al. 2012 ; Padamwar and Pokharkar 2006 ), because they:
(i) target specifi c, controlled release and optimisation of the availability of cos- metic agents with higher periods of permanence of active substances on the skin;
(ii) improve the stability of various cosmetic ingredients not stable or sensitive to temperature, pH, light or oxidation, like unsaturated fatty acids, vitamins, or antioxidants, by encapsulation within the nanocarriers;
(iii) enhance penetration of certain ingredients, such as vitamins and other antioxidants;
(iv) reduce the amount of agents and additives in products;
(v) improve shelf life and hence greater product effi cacy;
(vi) increase the effi cacy and tolerance of UV fi lters on the skin surface;
(vii) make the product more aesthetically pleasing (e.g. in mineral sunscreens, making the particles of the active mineral smaller allows them to be applied without leaving a noticeable white cast).
Many biodegradable and biocompatible materials (synthetic and natural) are used for the development of vehicular systems. The main advantages of using biodegradable polymers over non-biodegradable polymers in cosmetics applica- tions is that they are generally non-reactive when in contact with the human body and can be broken down or metabolized and removed from the body via normal metabolic pathways, avoiding possible side effects, due to their properties of biocompatibility and biodegradability (Ammala 2013 ).
Polymers are some of the most common materials in encapsulation carriers for delivery systems in dermatology and cosmetology. They are derived from natural polymers, particularly modifi ed polysaccharides, such as starch and chitosan, as well as natural or synthetic lipids and phospholipids, like phosphatidylcholine, and polyesters based on polylactide, polyglycolide and their copolymers (Mihranyan et al. 2012 ). Based on these materials, and taking into account their specifi c physico- chemical properties, the principal nanocarriers in cosmetics development are nano- emulsions and liposomes as well as polymeric and solid lipid nanoparticles.
11.3.1.1 Liposomes
Liposomes are a well-known and frequently used vesicular delivery system of active substances in drugs and cosmetics alike. These concentric bilayered vesicles of phospholipids can fuse with other bilayers such as the cell membrane, which pro- motes release of its contents, making them useful for cosmetic delivery applications to enhance the penetration of active principles through the skin (Raj et al. 2012 ).
Liposomes measure between 20 nm and a few μm in diameter and, due to their hydrophilic core, they can encapsulate, amongst other substances, water-soluble agents and retain a small amount of liposoluble substances in the space between the bilayer membranes (Greßler et al. 2010 ).
11.3.1.2 Nanoemulsions
Nanoemulsions are very fi ne emulsions of oil in water with a dispersion of droplets that measure approximately 50–1,000 nm. These transparent and fragile droplets have a single layer of phospholipids surrounding an oily liquid core. Their smaller particle size provides higher stability and better suitability to carry active ingredi- ents, mainly liposoluble agents, greatly increasing the product shelf life; they also have good sensorial properties (merging textures), specifi c biophysical properties (especially hydrating power) and penetrate and/or permeate the skin more deeply, probably due to their fl exibility and affi nity to stratum corneum (Greßler et al. 2010 ; Gupta et al. 2013 ; Patravale and Mandawgade 2008 ; Raj et al. 2012 ).
11.3.1.3 Nanoparticles Systems
Polymeric Nanoparticles
Polymeric nanoparticulate systems include nanocapsules and nanospheres with diameters of less than 1 μm (Guterres et al. 2007 ) that are used not only to make substances more compatible but also to protect from oxidation and to reduce the odor and control the release of the active substances. They are structurally stable due to their rigid matrix and are able to maintain their structure for long periods of time when topically applied. Since they are mostly retained in the stratum corneum, they also improve the release of active principles through the skin (Gupta et al. 2013 ).
Nanocapsules differ from nanospheres because of the encapsulation mechanisms of the bioactive molecules in their matrix, which can be entrapped, dispersed, dissolved within or adsorbed. Nanocapsules are vesicular reservoir-type systems due to the presence of oil, whereas nanospheres form a matrix system provided by the polymeric chains (Guterres et al. 2007 ). Polymer composition for both is identi- cal and includes biodegradable synthetic polymers, like polyamides, cross-linked polysiloxanes or modifi ed natural products such as gelatin and albumin (Patravale and Mandawgade 2008 ).
Solid Lipid Nanoparticles
Solid lipid nanoparticles (SLN) are the new generation of nanoparticulate active substance vehicles developed at the beginning of the 1990s as an alternative to emulsions, liposomes and polymeric nanoparticles (Pardeike et al. 2009 ). Produced without solvents, SLN are formed by a matrix of lipids which are physiologically well tolerated biodegradable raw materials that have a higher affi nity to stratum corneum and consequently enhanced bioavailability and protection against chemi- cal degradation (Guterres et al. 2007 ; Pople and Singh 2006 ). SLN appear promis- ing not only as a drug carrier system, particularly for lipophilic agents, but also for large scale production and sterilization. Nevertheless, they present some disadvan- tages such as low drug-loading capacities and physical instability during storage or administration due to the complexity of the physical state of the lipid (Guterres et al.
2007 ). In recent years use of SLN for the topical application of vitamin A, E or coenzyme Q10 has been investigated for site-specifi c and controlled rate of delivery through intact skin (Mihranyan et al. 2012 ; Pople and Singh 2006 ).
One of most important characteristics of some of this nanocarrier is its capacity for loading hydrophilic components. This capacity may be the key for encapsulation of thermal water.