Influence of Functional Bio-Based Coatings Including Chitin Nanofibrils or Polyphenols on Mechanical Properties of Paper Tissues

The paper tissue industry is a constantly evolving sector that supplies markets that require products with different specific properties. In order to meet the demand of functional properties, ensuring a green approach at the same time, research on bio-coatings has been very active in recent decades. The attention dedicated to research on functional properties has not been given to the study of the morphological and mechanical properties of the final products. This paper studied the effect of two representative bio-based coatings on paper tissue. Coatings based on chitin nanofibrils or polyphenols were sprayed on paper tissues to provide them, respectively, with antibacterial and antioxidant activity. The chemical structure of the obtained samples was preliminarily compared by ATR-FTIR before and after their application. Coatings were applied on paper tissues and, after drying, their homogeneity was investigated by ATR-FTIR on different surface areas. Antimicrobial and antioxidant properties were found for chitin nanofibrils- and polyphenols-treated paper tissues, respectively. The mechanical properties of treated and untreated paper tissues were studied, considering as a reference the same tissue paper sample treated only with water. Different mechanical tests were performed on tissues, including penetration, tensile, and tearing tests in two perpendicular directions, to consider the anisotropy of the produced tissues for industrial applications. The morphology of uncoated and coated paper tissues was analysed by field emission scanning electron microscopy. Results from mechanical properties evidenced a correlation between morphological and mechanical changes. The addition of polyphenols resulted in a reduction in mechanical resistance, while the addition of chitin enhanced this property. This study evidenced the different effects produced by two novel coatings on paper tissues for personal care in terms of properties and structure.This research was funded by the Bio-Based Industries Joint Undertaking under the European Union Horizon 2020 research program (BBI-H2020), ECOFUNCO project, grant number G.A 837863

Nouveaux hydrogels à base de polysaccharide obtenus par voie biomimétique ou par photoréticulation.

In the framework of an eco-responsible context and to take advantage of biocompatibility, notably in cosmetic and biomedical applications, we have developed new hydrogels based on neutral and anionic polysaccharides using two original routes. The first approach is biomimetic and consists of mimicking a natural development of hydrogels that is found in certain plants for which an enzyme, laccase, allows to create crosslinks by dimerization of phenolic compounds, in occurrence of ferulic acid (FA) present on arabinoxylans mucilage of cereal seeds for example. Thus, our work consisted in grafting ferulic acid via two different chemical ways that means imidazole and carbodiimide respectively for neutral or anionic polysaccharides. We functionalized three polysaccharides: pullulan or PUL (neutral model), carboxymethylpullulane or CMP (model anionic) and hyaluronic acid or HA (anionic of interest) with grafting rates of between 2 and 25%. The physicochemical study in diluted and semi-diluted regimes evidenced an associative behavior due to the amphiphilic character of the functionalized polysaccharides. The crosslinking in the presence of laccase, followed in situ thanks to rheology, has been successfully performed on the various envisaged systems with possible controls of kinetics, the final mechanical properties or the swelling of the hydrogels as a function of the neutral or charged nature of the polysaccharides, the degree of substitution in FA, the polymer concentration or the enzymatic activity. The synthesized derivatives have generally demonstrated interesting biological activities (antioxidant and cytocompatibility). The second approach is based on the possible photocrosslinking of polysaccharides (PUL, CMP and HA) functionalized by the grafting of mono or polyunsaturated fatty amine/acid (oleylamine, oleic acid and linoleic acid) via imidazole chemistry. If pullulan grafted with 2% of linoleic acid was found to be water-insoluble due to its neutral character, all other derivatives (i.e. anionic ones) with grafting rates of 3 and 10% showed good solubility in water. The physicochemical studies show a very strong associative character of these amphiphilic derivatives with the formation of physical gels in semi-diluted regime. Photocrosslinking has been demonstrated in situ thanks to rheology/UV irradiation in the presence of a Darocur 1173® photoinitiator. The preliminary results according to this photocrosslinking approach thus open interesting perspectives.Dans un contexte de démarche écoresponsable et pour répondre aux exigences de biocompatibilité notamment dans les applications cosmétiques et biomédicales, nous avons développé de nouveaux hydrogels à base de polysaccharides neutres et anioniques en utilisant deux voies originales. La 1ère approche est biomimétique et a consisté à mimer un phénomène d’élaboration naturelle d’hydrogels que l’on retrouve chez certains végétaux pour lesquels une enzyme, la laccase, permet de créer des liens de réticulation par dimérisation des composés phénoliques (en l’occurrence de l’acide férulique FA) présents sur les arabinoxylanes des mucilages des graines de céréales par exemple. Notre travail a ainsi consisté à greffer de l’acide férulique via deux chimies différentes de type imidazole et carbodiimide respectivement pour des polysaccharides neutres ou anioniques. Nous avons ainsi fonctionnalisé trois polysaccharides : le pullulane ou PUL (neutre modèle), le carboxyméthylpullulane ou CMP (anionique modèle) et l’acide hyaluronique ou HA (anionique d’intérêt). Des taux de greffage compris entre 2 et 25% ont été obtenus. L’étude physicochimique en régimes dilué et semi-dilué a permis de mettre en évidence un comportement associatif lié au caractère amphiphile des polysaccharides fonctionnalisés. La réticulation en présence de laccase, suivie in situ en rhéologie, a été réalisée avec succès sur les différents systèmes envisagés avec des contrôles possibles de la cinétique, des propriétés mécaniques finales ou encore du gonflement des hydrogels en fonction du caractère neutre ou chargé des polysaccharides, du degré de substitution en acide férulique, de la concentration en polymère ou de l’activité enzymatique fixée. Les dérivés synthétisés ont globalement démontré des activités biologiques (antioxydante et cytocompatible) intéressantes. La deuxième approche repose sur la photoréticulation possible de polysaccharides (PUL, CMP et HA) fonctionnalisés par le greffage d’amine/acide gras mono ou polyinsaturé (oleylamine, acide oléique et linoléique) via la chimie des imidazoles. Si le pullulane modifié par l’acide linoléique à 2% s’est avéré non hydrosoluble en raison de son caractère neutre, tous les autres dérivés avec des taux de greffages de 3 et 10% ont démontré une bonne solubilité dans l’eau. Les études physicochimiques mettent en évidence un très fort caractère associatif de ces dérivés amphiphiles avec la formation de gels physiques en régime semi-dilué. La photoréticulation a été démontrée en rhéologie sous irradiation UV in situ en présence d’un photoamorceur de type Darocur 1173®. Les résultats préliminaires obtenus selon cette approche en photoréticulation ouvrent ainsi des perspectives intéressantes

New hydrogels based on polysaccharide obtained by biomimetics or UV crosslinking

Dans un contexte de démarche écoresponsable et pour répondre aux exigences de biocompatibilité notamment dans les applications cosmétiques et biomédicales, nous avons développé de nouveaux hydrogels à base de polysaccharides neutres et anioniques en utilisant deux voies originales. La 1ère approche est biomimétique et a consisté à mimer un phénomène d’élaboration naturelle d’hydrogels que l’on retrouve chez certains végétaux pour lesquels une enzyme, la laccase, permet de créer des liens de réticulation par dimérisation des composés phénoliques (en l’occurrence de l’acide férulique FA) présents sur les arabinoxylanes des mucilages des graines de céréales par exemple. Notre travail a ainsi consisté à greffer de l’acide férulique via deux chimies différentes de type imidazole et carbodiimide respectivement pour des polysaccharides neutres ou anioniques. Nous avons ainsi fonctionnalisé trois polysaccharides : le pullulane ou PUL (neutre modèle), le carboxyméthylpullulane ou CMP (anionique modèle) et l’acide hyaluronique ou HA (anionique d’intérêt). Des taux de greffage compris entre 2 et 25% ont été obtenus. L’étude physicochimique en régimes dilué et semi-dilué a permis de mettre en évidence un comportement associatif lié au caractère amphiphile des polysaccharides fonctionnalisés. La réticulation en présence de laccase, suivie in situ en rhéologie, a été réalisée avec succès sur les différents systèmes envisagés avec des contrôles possibles de la cinétique, des propriétés mécaniques finales ou encore du gonflement des hydrogels en fonction du caractère neutre ou chargé des polysaccharides, du degré de substitution en acide férulique, de la concentration en polymère ou de l’activité enzymatique fixée. Les dérivés synthétisés ont globalement démontré des activités biologiques (antioxydante et cytocompatible) intéressantes. La deuxième approche repose sur la photoréticulation possible de polysaccharides (PUL, CMP et HA) fonctionnalisés par le greffage d’amine/acide gras mono ou polyinsaturé (oleylamine, acide oléique et linoléique) via la chimie des imidazoles. Si le pullulane modifié par l’acide linoléique à 2% s’est avéré non hydrosoluble en raison de son caractère neutre, tous les autres dérivés avec des taux de greffages de 3 et 10% ont démontré une bonne solubilité dans l’eau. Les études physicochimiques mettent en évidence un très fort caractère associatif de ces dérivés amphiphiles avec la formation de gels physiques en régime semi-dilué. La photoréticulation a été démontrée en rhéologie sous irradiation UV in situ en présence d’un photoamorceur de type Darocur 1173®. Les résultats préliminaires obtenus selon cette approche en photoréticulation ouvrent ainsi des perspectives intéressantes.In the framework of an eco-responsible context and to take advantage of biocompatibility, notably in cosmetic and biomedical applications, we have developed new hydrogels based on neutral and anionic polysaccharides using two original routes. The first approach is biomimetic and consists of mimicking a natural development of hydrogels that is found in certain plants for which an enzyme, laccase, allows to create crosslinks by dimerization of phenolic compounds, in occurrence of ferulic acid (FA) present on arabinoxylans mucilage of cereal seeds for example. Thus, our work consisted in grafting ferulic acid via two different chemical ways that means imidazole and carbodiimide respectively for neutral or anionic polysaccharides. We functionalized three polysaccharides: pullulan or PUL (neutral model), carboxymethylpullulane or CMP (model anionic) and hyaluronic acid or HA (anionic of interest) with grafting rates of between 2 and 25%. The physicochemical study in diluted and semi-diluted regimes evidenced an associative behavior due to the amphiphilic character of the functionalized polysaccharides. The crosslinking in the presence of laccase, followed in situ thanks to rheology, has been successfully performed on the various envisaged systems with possible controls of kinetics, the final mechanical properties or the swelling of the hydrogels as a function of the neutral or charged nature of the polysaccharides, the degree of substitution in FA, the polymer concentration or the enzymatic activity. The synthesized derivatives have generally demonstrated interesting biological activities (antioxidant and cytocompatibility). The second approach is based on the possible photocrosslinking of polysaccharides (PUL, CMP and HA) functionalized by the grafting of mono or polyunsaturated fatty amine/acid (oleylamine, oleic acid and linoleic acid) via imidazole chemistry. If pullulan grafted with 2% of linoleic acid was found to be water-insoluble due to its neutral character, all other derivatives (i.e. anionic ones) with grafting rates of 3 and 10% showed good solubility in water. The physicochemical studies show a very strong associative character of these amphiphilic derivatives with the formation of physical gels in semi-diluted regime. Photocrosslinking has been demonstrated in situ thanks to rheology/UV irradiation in the presence of a Darocur 1173® photoinitiator. The preliminary results according to this photocrosslinking approach thus open interesting perspectives

Hydrogels Based on Polysaccharides Grafted Ferulic Acid: A Biomimetic Approach

International audienc

Enzymatic cross-linking of carboxymethylpullulan grafted with ferulic acid

International audienc

Biomimetic hydrogel by enzymatic crosslinking of pullulan grafted with ferulic acid

International audienc

Antimicrobial and Gas Barrier Crustaceans and Fungal Chitin-Based Coatings on Biodegradable Bioplastic Films

Chitin nanofibrils (CN) can be obtained from crustaceans and fungal sources and can be used for preparing coatings for bioplastic films, that are fundamental for developing a safe and sustainable biodegradable food packaging. Coatings with different concentrations of CN from shrimps were applied on different bioplastic substrates, like Poly (butylene succinate-co-adipate)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PBSA/PHBV) blend, Polybutylene succinate (PBS), and Polybutylene adipate terephthalate/Poly(lactic acid) (PBAT/PLA) blend, but the adhesion to the substrates was scarce. On the contrary, the fungal-based CN showed a better adhesion. Additionally, it was found that the use of an additive based on oligomeric lactic acid was useful to prepare a coating with an improved adhesion to bioplastics. The gas barrier properties to oxygen and water vapour of coated and un-coated films were measured, revealing an improvement of these properties thanks to applied coatings, especially towards the oxygen. Antimicrobial properties and biodegradation capacity were also evaluated revealing an antibacterial effect of the coatings that did not significantly interfere with their biodegradability. The results are discussed and interpreted considering the correlation between composition and macromolecular structures with the observed functional properties