Imperatore, Riccardo (2015) DESIGN AND DEVELOPMENT OF NANOSTRUCTURED FORMULATIONS FOR COSMECEUTIC APPLICATIONS. [Tesi di dottorato]

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Abstract

Nowadays the care of the exterior appearance and the purchase of cosmetic products that preserve the health and human well being, satisfying the relationship health = well being = beauty, are covering an increasingly important role. In this context, the present PhD project, developed in collaboration with Eurosocap srl company, world leader in the production of hair extensions, is aimed at the design and the development of highly innovative trichological formulations for cosmeceutic applications. In the first part of this work, the interest is focused on the optimization of formulations based on the use of new components, safe for the health of customers and more eco-friendly. Several cosmetic formulations for hair care were prepared. In these formulations main components are surfactants, molecules that spontaneously self-organize into a variety of nanostructures, from micelles to vesicles. Other important components in cosmetic formulations are preservatives whose function is to avoid the product degradation. Considering that the surfactants themselves present bacteriostatic effects, it was evaluated if preservatives are actually needed in trichological formulations. For this reason, a prototype of a shampoo and of a conditioner were formulated both without preservatives and with preservatives in order to underline microstructural differences and to obtain microbiological information, through respectively Electron Paramagnetic Resonanance (EPR) studies and a specific biological test, called Challeng test. The second part of this thesis concerns the evolution from cosmetic to cosmeceutic formulations. Cosmeceutic products are cosmetic-pharmaceuticals hybrids which can be applied topically as cosmetics but that contain physiologically active substances such as restructuring vitamins, growth factors, enzymes or antioxidants. In this project a particular attention is given to a powerful antioxidant, the resveratrol in order to contrast the damaging effects of oxidative stress on the hair structure. The aim is to insert this molecule, poorly soluble in water, into adeguate nano-vehicles so as to preserve the resveratrol efficacy, its stability and to allow the gradual release of this substance on the hair surface. Nano-vehicles, compatible with a typical hair formulation, are represented by catanionic vesicles, aggregates formed by an anionic and a cationic surfactant. In particular two surfactant very common in hair formulations were chosen: Sodium Dodecyl Sulfate (SDS) and Cetrimonium Chloride (CTAC). Catanionic vesicles obtained by mixing the two surfactant solutions at different molar ratios were characterized through Dynamic Light Scattering (DLS), Small Angle Neutron Scattering (SANS) and Electron Paramagnetic Resonance (EPR) measurements in order to describe the phase behavior for the catanionic mixture SDS-CTAC-water, both in the cationic rich-side and in the anionic rich-side. Then, UV measurements were executed so as to evaluate resveratrol solubility in CTAC, SDS and in catanionic vesicles solutions and spectrofluorimetry analyses were carried out to obtain information about the chemical environment in which the antioxidant is located. Finally, EPR studies were performed in order to evaluate the ability of resveratrol as radical scavenger in surfactants aggregates. Overall, this thesis represents an attempt to build a reliable scientific and technological basis for the development of cosmeceutic formulations for hair care.

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