Chitin is a natural sugar-like polysaccharide found in crab and shrimp shells that is formed by glucosamine and N-acetyl glucosamine linked in a glycoside structure (see Figure 1).1, 2 Its natural rod-like and positively charged alpha-nanocrystalline structure can be separated from the raw material chitin into a 240 nm x 5 nm x 7 nm nanofibrillar form. These nanocrystals exhibit an exceptionally high surface area, up to 400 m2/g, and demonstrate relevant biological significance because they are able to activate fibroblast proliferation and cytokine production, favoring giant cell migration, macrophage activation and neovascularization.
Due to their molecular conformation and chemical-physical activity, chitin nanofibrils (CN) are capable of establishing ionic bonds with water, similar to yaluronic acid (YA). In addition, they are capable of forming complexes with active ingredients for delivery to different sites in a controlled-release manner, depending on the vehicle selected.3
Functional skin care ingredients generally are delivered topically to the epidermis or dermis via the outer layer of the skin.4-7 To this purpose, one naturally derived, industrially obtained CN8 was examined for its delivery and active benefits.9-12 Having the same backbone as YA, CN is strongly hydrophilic and is therefore capable of attracting and binding molecules of water. It also forms stable ionic bonds with glycosaminoglycans (GAGs), which are negatively charged at the sulfate location, in addition to combining with various hydro- and lipid-soluble active ingredients commonly used in cosmetics.
These properties and the fact that CN is a strongly charged compound suggest its use both for local and global activity in lipid bilayer membranes, or in the GAG-rich extracellular matrix—including the outmost layer of the stratum corneum (SC), the whole SC, the lipid lamellae, the corneocytes within the SC, and the viable epidermis and dermis, as well as structural entities such as hair follicle, sebaceous or eccrine glands, or specific cell types such as melanocytes, langerhans or mast cells.
CN could thus be targeted to ameliorate permeability at different skin levels to provide variable cosmetic efficacy (see Figure 2). However, the penetration depth of CN and/or CN-complexes depends on the specific bonds formed both with the cellular components and the ingredients selected.
In vivo: To verify the cosmetic efficacy of CN, both in vitro and in vivo studies, published elsewhere,9,12-17 were conducted to examine the ability of CN to increase the penetration and efficacy of active compounds through the SC and thereby the viable skin. The polyglucoside was found to be capable of activating the proliferation of keratinocytes at the epidermal level as well as fibroblasts at the dermal level, regulating not only collagen synthesis but also the activity of cytokines and macrophages. As a consequence, it was demonstrated to play a fundamental role in the process of tissue granulation.18
In addition, in a double blind in vivo study of 40 women—30 suffering from photoaged and dry skin versus a control group of 10—skin hydration, as measured by the 3C System method,19 increased by approximately 35% over the control with CN alone and 60% when active compounds were added to the CN (see Figure 3). In addition, the surface skin lipids were shown to increase by approximately 17% over the control when using CN alone, and 75% when the same active compounds were added (see Figure 4).
At the same time, TEWL in the skin decreased by approximately 50% using CN alone and 72% using CN with active ingredients. Lipid peroxides were also reduced by 35% using CN alone and 66% when incorporating actives (see Figure 5). Interestingly, a chromameter also showed CN to provide whitening activity as it strongly decreased the appearance of age spots on skin hyperpigmentation (see Figure 6).
In vitro: In vitro studies on fibroblast cultures demonstrated that CN is capable of increasing fibroblast proliferation and collagen production. Moreover, it is generally known that irradiation causes a drastic, dose-dependent reduction of ATP; however, as irradiated keratinocyte cultures verified, CN may increase ATP production. Furthermore, the deficit of ATP causes a consequent increase in free radical production and subsequent lack of water, which can induce precocious cell apoptosis.
For all these reasons—i.e., the increased ATP and collagen production at cellular levels, the in vivo improvement of skin hydration and superficial skin lipids, and the simultaneous reduction of TEWL, lipid peroxides and skin hyperpigmentations—CN and CN complexes, may be used both as a delivery agent and an active compound for antiaging skin care (see Figure 7).
The described studies1-18 showed how CN may increase the efficacy of active ingredients13, 14 by positively affecting the partition coefficient between formulations and the skin when employed in different emulsions; i.e., micro- or nano-sized, or micellar or lamellar in nature.15-16 In addition, the prevalent amino groups of CN embedded in water form hydrogen and ionic bonds with different molecules, which also contributes to the stability of the final suspension (see Figure 8).20 In water solution, the CN complexes reorganize themselves spontaneously into larger crystal-like complexes that are capable of emulsifying different classes of lipids.
It is well-known that in order to increase the efficacy and bio-availability of active ingredients applied to skin, variables such as the interaction between the vehicle and active ingredient, the capacity of the vehicle to produce changes in skin structure, and the droplet size of the vehicle must be critically controlled. Nano-emulsions (niosomes, etosomes, etc.), for example, ensure closer contact with the SC and therefore increase the amount of active that reaches the desired site of action. In relation, CN appears to create a monolayer of lipidic film on the SC, thereby increasing the skin penetration of active compounds and reducing excessive water evaporation, in turn increasing skin hydration.20
Moreover, when directly in contact with the SC, the emulsified CN is hydrolyzed by skin enzymes and transformed into dimeric and/or tetrameric units. These oligomeric units can penetrate skin layers. As previously noted, the formulation design, ingredients selected, CN and CN complexes used, and the manufacturing process are important factors contributing to skin penetration17, 20 and these factors will be explored in more depth in a future article. Thus the authors conclude that CN used alone or in combination may find interesting applications to lead to a new generation of antiaging and wound healing products.
CN provides interesting cosmetic delivery properties and allows for the formation of particular chemical bonds and connections between water, actives and the cells of both the SC and viable skin. These bonds appear to be mediated by a group of noncovalent attractions (i.e., ionic and hydrogen bonds) that are individually quite weak but whose energies can combine to create an effective force between two or more separate molecules. Thus, according to the current data and hypotheses,20 once delivered to skin, CN may have different fates. Partially or totally hydrolyzed CN may be used as monomer sub-unit to construct giant polymeric macromolecules, such as large polysaccharides; or, it may act as an energy source and be broken down and transformed into small molecules in a maze of intracellular metabolic pathways. It should be noted that both glucosamine and acetyl glucosamine are fundamental ingredients of the body not only for cartilage and bone metabolism, but also for the synthesis and metabolism of glycosaminoglycans.21 In addition, CN is a sugar-like compound that is edible and can thus be considered safe.
In conclusion, since CN easily bonds to water and other molecules to penetrate various skin layers, it could be useful as a skin carrier as well as an active component since it activates the proliferation of keratinocytes and fibroblasts.13-18 For a clearer understanding of this interesting molecule, further studies are necessary; however, current results suggest its use to slow premature skin aging and to ameliorate general well-being. Discovering other properties of this interesting nano-crystal will be a challenge for the future.
Send e-mail to pierfrancesco.morganti@ mavicosmetics.it.
- RAA Muzzarelli, M Mattioli-Belmonte, A Pugnaloni and G Biagini, in Chitin and Chitinases, P Jollés and RAA Muzzarelli, eds., Birkhaüser Verlag Basel: Swizterland (1999) pp 251-264
- RAA Muzzarelli and C Muzzarelli, in Chitin and Chitosan: Opportunities and Challenges, PK Dutta, ed., SSM International Publication: Contai, India (2005) pp 129-146
- P Morganti, Where nutriceuticals meet cosmeceuticals, J Appl Cosmetol 25 111-120 (2007)
- P Morganti, Y Li and G Morganti, Nano-structured products: Technology and future, J Appl Cosmetol 25 161-178 (2007)
- P Morganti, G Morganti, RAA Muzzarelli and C Muzzarelli, Chitin nanofibrils: A natural compound for innovative Cosmeceuticals. Cosm & Toil 122(4) 81-88 (2007)
- P Morganti and G Morganti, Nanotechnology and wellness, SÖFW 133(5) 22-27 (2007)
- G Biagini Et al, Cutaneous absorption of nanostructured chitin associated with natural synergistic molecules (lutein), J Apppl Cosmetol 26 69-80 (2008)
- International Patent PCT/IB2005/053576, assisgned to Mavi Sud, Italy (2005)
- RAA Muzzarelli et al, Chitin nanofibrils/chitosan glycolate composites as wound medicaments, Carbohydrate Polymers 70(3) 274-284 (2007)
- P Morganti, Applied nanotechnology in cosmetics and functional food, Eucocosmetics 2 12-15 (2007)
- P Morganti and G Morganti, Fabricating a good treatment, SP&C 85-86 (April 2007)
- P Morganti et al, Chitin-nanofibrils: A new active cosmetic carrier, J of Appl Cosmetol 26 105-128 (2008)
- P Morganti and G Morganti, Chitin nanofibrils for advanced cosmeceuticals, Clinics in Dermatol 26 334-340 (2008)
- P Morganti et al, Nanoscience the challenging cosmetics healthy food and biotextiles, SÖFW 135(4) 2-7 (2009)
- P Morganti, RAA Muzzarelli and C Muzzarelli, Multifunctional use of innovative chitin nanofibrils for skin care, J Appl Cosmetol 24 105-114 (2006)
- JW Wiechers, Science and Application of Skin Delivery Systems. Allured Business Media: Carol Stream, IL, USA (2008)
- P Morganti, G Morganti, G Fabrizi and A Cardillo, A new sun to rejuvenate the skin, J Appl Cosmetol 26 159-166 (2008)
- P Mezzana, Clinical efficacy of a new chitin nanofibrils-based gel in wound healing, Acta Chirurgiae Plasticae 50(3) 81-84 (2009)
- A Cardillo and P Morganti, Fast and noninvasive method for assessing skin hydration, J Appl Cosmetol 12 11-16 (1994)
- P Morganti, Chemical-physical activity of chitin nanofibrils to stabilize cosmetic emulsion and increase skin penetration, J Appl Cosmetol (2009) in press
- K Kazel and OZ Domen, Effects of hexosamine derivates and uronic acid derivates on glycosaminoglycan metabolism, Pharmacol 5 337-345 (1971)