Poil | EPFL Graph Search

vignette|Follicule pileux. vignette|Description de la structure interne d'un cheveu (vu en coupe). vignette|Certains hommes, et plus rarement des femmes, ont une pilosité abondante dans le dos, le cou et sur les membres. Le poil est à la fois une production filiforme de l'épiderme et l'un des plus petits organes, couvrant partiellement ou intégralement la surface de nombreux êtres vivants végétaux et animaux. Parmi les vertébrés, les poils sont caractéristiques des mammifères, tout en étant présents aussi bien chez les arthropodes (ex : mygales) que chez les annélides (ex : polychètes). Il existe divers appellations des formations pileuses. Chez les animaux et en particulier les vertébrés, lorsque la couverture pileuse de la peau est complète, on parle de pelage (la fourrure comprenant à la fois les poils et la peau). Chez l'humain, la pilosité couvrant le crâne en dehors du visage est appelée chevelure, celle couvrant la mâchoire et le cou (lorsque les poils ne sont pas du duvet) es

Bioinspired Selective Surface Deposition of Fragrance Delivery Systems

Kemal Arda Günay

The perception of pleasantness in many of the consumer goods is provided by volatile chemical compounds called fragrances. While the volatility of fragrances is essential to provide a pleasant olfactory response, it presents at the same time a technological problem, such that their premature evaporation and degradation may occur prior to the application during the storage. Another crucial aspect that affects the performance of the consumer goods is the deposition of these delivery systems to the target of interest. The potential strategies to improve the deposition of fragrance delivery systems are much less explored compared to their preparation and predominantly based on the physiochemical optimization of the surface/interface properties, such as hydrophobicity and charge of the existing delivery systems. However, the extent of depositions achieved using these strategies are typically modest. Phage display is an in vitro evolutionary selection technique that is widely used to identify substrate selective short peptide ligands. Although it has been predominantly used to isolate biomolecule binding ligands, its scope has been expanded in the last decade and it has also found use to identify hard and soft material binders. From this aspect, phage display may also provide short peptide ligands that can bind to i. e. cotton and hair surfaces under laundry and hair wash conditions. These ligands can be considered as a tool to improve the deposition of any fragrance delivery system upon their chemical incorporation via orthogonal functional groups. This Thesis aims to explore the feasibility of phage display identified peptides to selectively deposit fragrance delivery systems on cotton fabric and human hair surfaces and it can be subdivided into 4 Chapters. Chapter 1 provides a summary for the identification and characterization of soft matter binding peptides via phage display. Herein, soft matter will be subdivided into three general classes: synthetic polymers, small organic molecules and natural polymers. Chapter 2 proposes a general synthetic method for the preparation of water soluble peptide-polymer conjugates that proceeds at mild conditions without the requirement of peptide protecting groups. Chapter 3 describes the preparation of fragrance delivery systems that can selectively deposit onto cotton fabric under laundry wash conditions. The Chapter will first show the identification of cotton fabric binding peptides via phage display experiments. In the next steps, the strongest cotton binding peptide will be incorporated into two different model fragrance delivery systems that are based on linear polymers and nanoparticles. Chapter 4 applies the general strategy described in Chapter 3 to a more challenging task: Selectively depositing fragrance delivery systems onto hair under shampoo conditions. First, the feasibility of phage display to identify hair binding peptides under shampoo conditions will be demonstrated. Subsequently, two of the peptide-polymer conjugates described in Chapter 2 will be used as a model for hair targeting fragrance delivery systems. In the final section, the influence of the stringency of the shampoo conditions as well as the steric hindrance in the peptide terminal domains to the deposition of these peptides onto hair will be assessed.

EPFL2016

Acquisition et recalage informatique d'images confocales de tissus denses

Nicolas Fête

Analysis of the 3D structure of a biological sample is an important step to model cell and tissue dynamics. As a model system, we set up to determine the number of nuclei in a follicular papilla using confocal imaging and 3D computer reconstruction. The follicular papilla is a small mesenchymal ovalshape structure localized at the basis of the hair follicle that is particularly important for hair follicle morphogenesis, and the size of which varies during hair growth. However, little is known on the influence of the hair cycle on the number of cells in a follicular papilla. Fgf5 -/- mice have long hairs (angora phenotype) due to an extended hair cycle, and small dermal papilla. There are several hypotheses to explain the latter observation : there are less cells in Fgf5 -/- dermal papilla than in wild type papilla mutant papilla produces less extra cellular matrix than wild type papilla it is a combination of both To discriminate between these hypotheses, dermal papilla were microdissected from vibrissal follicles occupying the same position on the mystacial pad of same age Fgf5 -/- and wild type mice. Nuclei were stained with a fluorescent dye and the papilla examined under a confocal microscope. Because of dermal papilla thickness, two stacks of images were acquired for each sample (recto and verso acquisitions), registrated using especially implemented computer science program and analyzed. This whole process turned out to be far more complex and cumbersome than anticipated. First, we had to design a special setup in order to be able to make two side scans of samples, second the acquisition time of two stacks of images to cover the entire dermal papilla was rather long, third repositioning and analysis of the images were complex. Nonetheless, the number of nuclei in a dermal papilla was determined with precision. Analysis of dermal papilla obtained at different time of the hair cycle is ongoing. Our work paves the way to the analysis of other biological structures important during skin morphogenesis or regeneration, i.e. the ectodermal placodes. An important lesson of our work is that there is no straightforward imaging and computer science approach when it comes to the biology of complex structures and that the technology needs to be customized to the biological question.

EPFL2008

Selective Peptide-Mediated Enhanced Deposition of Polymer Fragrance Delivery Systems on Human Hair

Kemal Arda Günay, Harm-Anton Klok

The deposition of fragrance delivery systems onto human hair from a shampoo formulation is a challenging task, as the primary function of shampoo is to cleanse the hair by removing primarily hydrophobic moieties. In this work, to tackle this challenge, phage-display-identified peptides that can bind to human hair under shampooing conditions are first identified and subsequently used to enhance the deposition of model fragrance delivery systems. These delivery systems are based on either poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) copolymers as a representative for polymeric profragrances or polyurethane/polyurea-type core-shell microcapsules as a model physical fragrance carrier. The incorporation of a hair-binding peptide enhanced the deposition of PHPMA copolymers by a factor of 3.5-5.0 depending on the extent of peptide incorporation, whereas 10 wt % surface functionalization of microcapsules with the peptide led to a 20-fold increase in their deposition. In a final experiment, treatment of the hair samples under realistic application conditions with the peptide-functionalized microcapsules resulted in an increase in fragrance release from the hair surfaces.

2017