Preparation of particles for cosmetic applications in human hair

• Author(s): Fernandes, Bruno Pacheco
• Date: 2012
• Persistent ID: https://hdl.handle.net/1822/23114
• Origin: RepositóriUM - Universidade do Minho
• Document Type: Master thesis
• Language: English
• Contributor(s): Universidade do Minho; Paulo, Artur Cavaco; Silva, Raquel

Description

Nanoparticles (NPs) have a huge interest for transdermal applications, demonstrating their ability to be trapped in the hair follicles (HFs) where they release the entrapped compounds. For hair cosmetics, this discovery is particularly important as it can improve the treatment of several hair follicle related disorders/diseases. Therefore, the aim of this work was to obtain NPs of Poly (Lactic Acid) (PLA-NPs) for topical delivery of drugs at the level of the HFs. Further, these particles may be used for cosmetic applications in human hair. The effect of several parameters was examined, in order to establish an improved nanoprecipitation protocol for the preparation of suitable PLA carriers for follicular targeting. Thus, the application of mechanical stirring or ultrasound, the use of Acetone/Ethanol (50/50, v/v) as the solvent phase and the addition of 0.6% (w/w) of Pluronic F68 to the formulation showed the best compromise between the desired properties (monodispersed populations of particles with a mean size of ≈150 nm were obtained, the ζ-potential was less than -18 mV and particles exhibited a spherical shape with smooth surface) and the yield of nanoparticles (≈90% was showed for particles produced with agitation and ≈70% when ultrasound was employed). After the encapsulation of model compounds, no significant changes were found in the properties of particles and the entrapment efficiency was above 80%. Nevertheless, the use of sonication promoted higher loading efficiencies. In turn, the release kinetics of PLA nanoparticles indicated an anomalous dye transport mechanism (diffusion and polymer degradation) for Nile Red (lipophilic) and a Fickian diffusion of first order for FITC (hydrophilic). Furthermore, the release from particles produced with agitation was slightly faster than from particles produced with sonication. Finally, fluorescence microscopy on porcine skin cryosections showed that the produced PLA-NPs can effectively transport lipophilic and hydrophilic compounds into the HFs, with fluorochromes reaching a maximal depth corresponding to the full follicles length after 24h. In conclusion, the modified nanoprecipitation protocol presented in this study allows the preparation of PLA nanocarriers with potential for hair follicle therapy and the yields obtained are acceptable for industrial purposes.