Description du projet
Un regard plus approfondi sur la structure de la mélanine
La mélanine est à l’origine de la pigmentation des cellules et c’est à elle que l’on doit la coloration de nos cheveux, de notre peau et de nos yeux. Aussi caractérisée comme hétérogène, très colorée et insoluble, la mélanine protège notre peau du soleil. Son analogue synthétique, la polydopamine, a suscité un vif intérêt dans la communauté des matériaux. Ses fonctions ne sont toutefois pas pleinement comprises en raison de sa structure polymère hétérogène. Dans ce contexte, le projet Mel.Photo.Protect financé par l’UE, comblera cette lacune dans les connaissances en expliquant la structure de la mélanine et sa fonction photoprotectrice générale grâce à la chimie computationnelle. Les résultats mettront également en lumière le rôle pathogène possible de la chimio-excitation de la mélanine et permettront de dégager de nouveaux principes pour la conception de matériaux fonctionnels à base de polydopamine.
Objectif
Melanin is the deeply coloured, insoluble and heterogenous biopolymer of animal skin, hair and eyes responsible for protection against harmful light action. It also has a pathogenic role as a generator of reactive oxygen species and possibly through chemiexcitation, and its polydopamine synthetic analogue has raised great interest in the materials community. In spite of these multiple points of interest, the details of melanin structure and its main photoprotecting function are still largely unknown, mostly due to the heterogeneous polymer structure. Closing this gap is an urgent challenge, and our proposal aims at doing that with the methods of computational chemistry. Based on the widely accepted hierarchical structure model for melanin, in WP1 we will generate a library of aggregates made of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) oligomers with different connectivity and redox state (diol, semiquinone and quinone forms). In WP2 we will simulate the absorption spectra of the aggregates and compare them with the experimental melanin spectrum, which starts at the near IR and increases monotonically into the UV. In WP3 we will simulate the excited-state decay mechanisms for the different aggregates in order to explain melanin's lack of fluorescence, which is indicative of fast decay responsible for its photoprotecting function. The results of our project will provide a new view on the photoprotecting function of melanin based on a systematic consideration of its heterogeneous structure, and they will allow us to assess what specific aggregates are responsible for the different functional characteristics. They will help us to assess the possible pathogenic role of melanin chemiexcitation, and provide new principles for design of PDA-based functional materials.
Champ scientifique
Programme(s)
Régime de financement
MSCA-IF-EF-ST - Standard EFCoordinateur
17004 Girona
Espagne