Synthèse de matériaux multifonctionnels basés sur les carbohydrates pour le développement de l’énergie durable, la santé et l’environnement
Profil recherché : Titulaire d’un Master en chimie organique ou en chimie des matériaux. Connaissances indispensables en caractérisation de molécules (RMN, spectrscopie, etc.). 1) Gout pour l’expérimentation 2) Travail en équipe 3) Rigueur et soin expérimental et dans le traitement des données 4) Maîtrise de l'anglais lu, écrit et parlé 5) Aptitudes rédactionnelles et orales français/anglais
Synthèse de matériaux fonctionnels basés sur les carbohydrates pour le développement de l’énergie durable, la santé et l’environnement
Profil recherché : Titulaire d’un Master en chimie organique ou en chimie des matériaux. Connaissances indispensables en caractérisation de molécules (RMN, spectrscopie, etc.). 1) Gout pour l’expérimentation 2) Travail en équipe 3) Rigueur et soin expérimental et dans le traitement des données 4) Maîtrise de l'anglais lu, écrit et parlé 5) Aptitudes rédactionnelles et orales français/anglais
Synthèse d’électrodes organiques auto-assemblées stabilisées : Externalisation des fonctions redox pour le stockage de l’énergie
Profil recherché : Etre titulaire d’un doctorat en chimie organique, capable de réaliser les synthèses au laboratoire, purifier et caractériser les nouveaux composés. Il est nécessaire d’être autonome sur la prospection la bibliographie afin d’émettre des propositions en équipe. De bonnes capacités d’organisation, de restitution et de communication sont demandées.
Le LG2A est un laboratoire de recherche universitaire dont les activités de recherche sont centrées autour de la glycochimie et des agroressources. Dans le cadre d’investissements, le laboratoire va s’équiper d’un analyseur de mousse (foamscan analyser) et d’un goniomètre (mesure d’angle de contact). Un poste d’IE sera affecté à ces équipements. L’IE s’impliquera dans les travaux de recherche et plus particulièrement sur les molécules/matériaux organiques de synthèse pouvant présenter des propriétés moussantes, des propriétés de surface telle que l’hydrophilie, la lipophilie. L’analyseur dynamique de mousses permettra de mesurer la moussabilité de liquides, la stabilité des mousses et leur hauteur. Le goniomètre permettra de mesurer l’angle de contact et l’angle de décrochage « roll-off » sur des surfaces hydrophobes. L’IE recruté(e) travaillera en étroite collaboration avec l’ensemble des chercheurs et personnels affectés à ce projet mais aussi avec des laboratoires, institutions ou PME locales avec lesquels nous avons noué des liens forts.
Chercheur récompensé : Jamal EL-ABID
Encadrement : Dr. Vincent CHAGNAULT et Prof. José KOVENSKY
Résumé vulgarisé: Les oligosaccharides sulfatés sont de petites molécules importantes dans divers processus biologiques. Leur efficacité dépend beaucoup du nombre de groupes sulfate qu'ils contiennent et de leur répartition le long de la molécule. Cependant, il est difficile de fabriquer ces molécules, ce qui limite leur utilisation.
C'est pourquoi il est essentiel de rechercher des alternatives. Par exemple, nous avons développé une nouvelle méthode pour créer des molécules similaires aux oligosaccharides sulfatés en remplaçant les groupes sulfate par des groupes sulfonate plus stables en utilisant une méthode plus éco-compatible.
Nous avons ensuite testé ces nouvelles molécules pour voir comment elles interagissent avec certaines protéines et comment elles affectent l'inflammation. Il s'est avéré que l'une de ces molécules est plus efficace pour activer une protéine impliquée dans l'inflammation que son équivalent sulfaté. De plus, une autre molécule s'est révélée être un inhibiteur prometteur d'une enzyme liée à la coagulation sanguine.
En résumé, notre travail vise à créer des molécules similaires aux oligosaccharides sulfatés et à explorer leurs applications potentielles dans le domaine de la biologie et de la santé.
Ballout, N.; Boullier, A.; Darwiche, W.; Ait-Mohand, K.; Trécherel, E.; Gallégo, T.; Gomila, C.; Yaker, L.; Gennero, I.; Kovensky, J.; Ausseil, J.; Toumieux, S.
Bone fracture healing is a complex biological process involving four phases coordinated over time: hematoma formation, granulation tissue formation, bony callus formation, and bone remodelling. Bone fractures represent a significant health problem, particularly among the elderly population and patients with comorbidities. Therapeutic strategies proposed to treat such fractures include the use of autografts, allografts, and tissue engineering strategies. It has been shown that bone morphogenetic protein 2 (BMP-2) has a therapeutic potential to enhance fracture healing. Despite the clinical efficacy of BMP-2 in osteoinduction and bone repair, adverse side effects and complications have been reported. Therefore, in this in vitro study, we propose the use of a disaccharide compound (DP2) to improve the mineralisation process. We first evaluated the effect of DP2 on primary human osteoblasts (HOb), and then investigated the mechanisms involved. Our findings showed that (i) DP2 improved osteoblast differentiation by inducing alkaline phosphatase activity, osteopontin, and osteocalcin expression; (ii) DP2 induced earlier in vitro mineralisation in HOb cells compared to BMP-2 mainly by earlier activation of Runx2; and (iii) DP2 is internalized in HOb cells and activates the protein kinase C signalling pathway. Consequently, DP2 is a potential therapeutical candidate molecule for bone fracture repair.
Die, R. C.; Fanté, B.; Ambeu-Loko, N. C. M.; Hiebel, M. A.; Vallin, A.; Suzenet, F.; Chagnault, V.
Pyrimidine derivatives are an important class of compounds in medicinal chemistry. In this study, a series of 6-aryl4-oxo-1,4-dihydropyrimidine-5-carbonitrile derivatives were synthesized using a multicomponent reaction, followed by S-alkylation with different halogenated derivatives, and then evaluated for their antibacterial activities. Ciprofloxacin was used as the reference antibiotic. The prepared compounds were characterized by 1H, 13C NMR, FTIR spectroscopy, and LC-and HR-MS spectrometry. All compounds were screened in vitro against Pseudomonas aeruginosa and Escherichia coli (Gram-negative bacteria), as well as Staphylococcus aureus and Enterococcus faecalis (Gram-positive bacteria). The results showed that S-alkylation is beneficial in improving the antibacterial activity of the thiouracil derivatives offering a few compounds with antibacterial activity against Gram-positive bacteria.
Bonnet, V.; Clodic, G.; Sonnendecker, C.; Zimmermann, W.; Przybylski, C.
Cyclic oligosaccharides are well known to interact with various metals, able to form supramolecular complexes with distinct sizes and shapes. However, the presence of various isomers in a sample, including positional isomers and conformers, can significantly impact molecular recognition, encapsulation ability and chemical reactivity. Therefore, it is crucial to have tools for deep samples probing and correlation establishments. The emerging ion mobility mass spectrometry (IM-MS) has the advantages to be rapid and sensitive, but is still in its infancy for the investigation of supramolecular assemblies. In the herein study, it was demonstrated that IM-MS is suitable to discriminate several isomers of cyclodextrins (CD)-metals complexes, used as cyclic oligosaccharide models. In this sense, we investigated branched 6-O-α-glucosyl- or 6-O-α-maltosyl-β-cyclodextrins (G1-β-CD and G2-β-CD) and their purely cyclic isomers: CD8 (γ-CD) and CD9 (δ-CD). The corresponding collision cross section (CCS) values were deducted for the main positive singly and doubly charged species. Experimental CCS values were matched with models obtained from molecular modelling. The high mobility resolving power and resolution enabled discrimination of positional isomers, identification of various conformers and accurate relative content estimation. These results represent a milestone in the identification of carbohydrate conformers that cannot be easily reached by other approaches.
Ndour, M.; Bonnet, J.-P.; Cavalaglio, S.; Lombard, T.; Safran, J.; Pau-Roblot, C.; Bonnet, V.
Pectin is a polysaccharide frequently found in large amounts in the peel and seeds of many fruits and therefore represents very common food industry waste. In this study, we investigate demethylated citrus and apple pectins with a methylation degree ranging from 76% to 3%, as polymer binders for silicon-based anodes of lithium-ion batteries. Both chemical and enzymatic pectin demethylations were considered. First, the usual aggressive saponification reaction was carried out leading to 24% and 28% methylesterified pectins from citrus and apple, respectively, but leading at the same time to unavoidable strong pectin depolymerization, as shown by SEC studies. In a second approach, the methylesterase enzyme was used to catalyze citrus pectin demethylation leading to a similar methylesterification degree (24%) but drastically minimizing polymer chain degradation. Our best-demethylated pectin was compared with the standard polymer binder for Li-ion batteries i.e. carboxymethyl cellulose (CMC) inside a composite silicon anode for their effect on silicon electrochemical capacity retention. The 24% enzymatically demethylated citrus pectin achieved here a remarkable capacity of 2275 mA h g−1 after 49 cycles with a load of 1.6 mg cm−2 compared to 245 mA h g−1 measured for CMC. These demethylated pectins have a buffering effect on the silicon particles’ volume change during discharge/charge cycles. The increase of interactions between silicon and pectin, probably due to the presence of numerous carboxylic acid functions in this demethylated pectin, is hypothesized to be, at least partly, responsible for these enhanced electrochemical performances. In addition, the existing type of glycosidic linkage (α in pectins and β in CMC) can also be responsible for these enhanced results.
Funes, C. F.; Larach, A.; Besoain, X.; Serrano, D. D.; Hadad, C.; Pedreschi, R.; Van Nhien, A. N.; Fuentealba, C.
Postharvest avocado losses are mainly due to anthracnose disease caused by Colletotrichum gloeosporioides. Chemical fungicides are effective, but their negative effects on health and the environment have led to the search for sustainable alternatives such as biopolymer-based coatings and natural compounds. Therefore, chitin nanocrystals (NCChit) were extracted using a sustainable deep eutectic solvent (DES) and chemically modified into oxidized chitin nanocrystals (O-NCChit) or deacetylated chitin nanocrystals (D-NCChit) to modulate and increase the charge surface density and the dispersibility of the crystals. The modified NCChits were dispersed with silk fibroins (SF), essential oil (EO), melatonin (MT) and/or phenylalanine (Phe) to elaborate active coatings. Antioxidant and antifungal in vitro analyses showed that the O-NCChit/SF-based coating had the best performance. In addition, in vivo tests were carried out through the artificial inoculation of C. gloeosporioides on coated avocados. O-NCChit/SF/MT-based coatings reduced the severity of anthracnose by 45 %, the same effect as the chemical fungicide (Prochloraz®). Moreover, avocado quality parameters during cold storage and the shelf-life period were also evaluated, where nonsignificant differences were observed. Therefore, this study demonstrates the great potential of O-NCChit and SF in combination with active compounds for the control of anthracnose in ‘Hass’ avocados.