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

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.

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

Solution self-assembly of hybrid block copolymers containing poly(ethylene glycol) and amphiphilic peptide sequences

Harm-Anton Klok, Harald Nuhn

The self-assembly in aqueous solution of hybrid block copolymers consisting of amphiphilic ?-strand peptide sequences flanked by one or two PEG chains was investigated by means of circular dichroism spectroscopy, small-angle X-ray scattering, and transmission electron microscopy. In comparison with the native peptide sequence, it was found that the peptide secondary structure was stabilized against pH variation in the di- and tri-block copolymers with PEG. Small-angle X-ray scattering indicated the presence of fibrillar structures, the dimensions of which are comparable to the estimated width of a ?-strand (with terminal PEG chains in the case of the copolymers). Transmission electron microscopy on selectively stained and dried specimens shows directly the presence of fibrils. It is proposed that these fibrils result from the hierarchical self-assembly of peptide ?-strands into helical tapes, which then stack into fibrils. © 2005 American Chemical Society.

2005

Switch-peptides: controlling biological function and self-assembly of amyloid ß-derived peptides using enzyme-triggered acyl migrations

Sonia Dos Santos

Conformational transitions of peptides and proteins have recently moved to the center of interest in various domains of research at the interface of chemistry, biology, and medicine due to their implication in an increasing number of diseases in which the pathogenesis is causally linked to the misfolding of a protein. For example, the amyloid β protein linked to Alzheimer's disease undergoes various conformational transitions, eventually leading to the formation of self-associating β-sheets, which in turn give rise to insoluble, fibrillar aggregates. Consequently, studies of such proteins are hampered by problems of solubility and often yield contradictory results. With the aim of surmounting these difficulties in the study of conformational transitions of peptides and proteins, a novel tool based on the concept of "Switch-Peptides" enabling the in situ induction of peptide folding will be elaborated in the present thesis. As shown in the Scheme, N(Y)-protected switch-peptides serve as stable, self-contained precursor molecules, in which folding and self-assembly is blocked by the presence of Ser or Thr derived switch-elements S, dissecting the regular peptide backbone by an ester and a flexible C-C bond. Removal of the protecting group Y triggers a spontaneous acyl migration that restores the native polypeptide chain ("statu nascendi") setting off the folding process. The body of work presented herein consists of two main themes: With the goal of developing a system amenable to physiological conditions, the introduction and evaluation of different, enzymatically cleavable Y groups was conceived. For proof of concept, the biologically active peptides angiotensin and neuropeptide Y were used, allowing the study of the impact of the S-element on their biological activities. Investigations of the analogue [Thr]5-Ang II containing a pH-triggered switch (Y = H+) reveal that the acyl migrations are very fast, exhibiting half-lives of less than one minute. With the introduction of enzymatically labile Y groups, specifically an Arg-Pro dipeptide (cleavable by dipeptidyl aminopeptidase) or the amino acid pGlu (cleavable by pyroglutamate aminopeptidase), rates of conversion ranging from minutes to hours are observed as monitored by HPLC, NMR and CD. Problems of steric interference associated with the action of enzymes such as esterases and penicillin amidase were overcome by developing linkers of different structural features. D-aminopeptidase (Y = D-Ala) was shown to extend the rates of enzymatic cleavage to half-lives of several days. The enzymes studied display high specificity for the switch-peptide substrates and a quantitative conversion from the Soff to the Son state. We took advantage of the affinity of Ang II and NPY for their respective receptors (AT2 and Y1) to show that their switch-peptide analogs are inactive in the Soff state where as after enzymatically triggered acyl migration, the peptides display high receptor affinity (IC50 = 45 nM for Ang II and IC50 = 5 nM for NPY). In the case of NPY, a conformational transition from a random coil to an α-helix as bioactive conformation is observed by CD. The second part of the work is dedicated to conformational transitions of type random coil → β-sheet in different model peptides or peptides derived from Aβ(1-42). All peptides studied show high potential for self-association and subsequent precipitation. However, in the Soff state, the switch-peptides display a high degree of stability and strongly enhanced aqueous solubility. After enzymatic triggering of the acyl migration, a conformational transition to a β-sheet accompanied by the formation of fibrils and spontaneous precipitation are observed by CD and EM studies. Based on the elaborated systems, the introduction of several orthogonal S-elements in Aβ derived peptides was realized. The incorporation of two different S-elements into the Aβ(1-42) sequence was found to greatly facilitate the normally difficult synthesis, and enabled the study of the influence of the individual peptide segments on the overall folding process. It was shown for the first time that the hexamer Aβ(37-42) is essential for the formation of β-sheets and subsequent fibrillization. As a final aspect, the elaboration of switch-peptides exhibiting β-breaking properties was investigated. Preliminary results indicate that one of the designed switch-peptides substantially slows down the formation of fibrils, representing a significant step in the development of therapeutically relevant compounds for the treatment of Alzheimer's disease. In conclusion, the elaborated methodologies allow for a general application of the switch concept as diagnostic tool in the study of fibrillogenesis.