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See detailChitosan-based biomaterials for tissue engineering
Croisier, Florence ULg; Jérôme, Christine ULg

in European Polymer Journal (2013), 49(4), 780-792

Derived from chitin, chitosan is a unique biopolymer that exhibits outstanding properties, beside biocompatibility and biodegradability. Most of these peculiar properties arise from the presence of ... [more ▼]

Derived from chitin, chitosan is a unique biopolymer that exhibits outstanding properties, beside biocompatibility and biodegradability. Most of these peculiar properties arise from the presence of primary amines along the chitosan backbone. As a consequence, this polysaccharide is a relevant candidate in the field of biomaterials, especially for tissue engineering. The current article highlights the preparation and properties of innovative chitosan-based biomaterials, with respect to their future applications. The use of chitosan in 3D-scaffolds – as gels and sponges – and in 2D-scaffolds – as films and fibers – is discussed, with a special focus on wound healing application. [less ▲]

Detailed reference viewed: 134 (27 ULg)
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See detailChitosan-based biomimetic scaffolds and methods for preparing the same
Filée, Patrice; Freichels, Astrid ULg; Jérôme, Christine ULg et al

Patent (2011)

The invention concerns chitosan biomimetic scaffolds and methods for modulating their intrinsic properties such as rigidity, elasticity, resistance to mechanical stress, porosity, biodegradation and ... [more ▼]

The invention concerns chitosan biomimetic scaffolds and methods for modulating their intrinsic properties such as rigidity, elasticity, resistance to mechanical stress, porosity, biodegradation and absorbance of exudates. Therefore, the present invention relates to a layered chitosan scaffold wherein said layered scaffold comprises at least two fused layers, wherein at least one of the fused layers comprises a chitosan nanofiber membrane and the other fused layer comprises a porous chitosan support layer. Moreover, the present invention provides a layered chitosan scaffold characterized by (i) a good adhesion between the porous and nanofiber layers, (ii) a tuneable porosity of the nanofiber layer by tuning the distance between the nanofibers, (iii) a stable nanofibers and porous morphology even when immersed in water or other solvents and a process for the preparation of such layered chitosan scaffold. Finally, the present invention provides the use of the layered electrospun chitosan scaffold of the invention or the layered electrospun chitosan scaffold produced by the process of the invention as a wound dressing, in tissue engineering or for biomedical applications. [less ▲]

Detailed reference viewed: 69 (5 ULg)
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See detailChitosan-based biomimetic scaffolds and methods for preparing the same
Filée, Patrick; Freichels, Astrid ULg; Jérôme, Christine ULg et al

Patent (2011)

The invention concerns chitosan-based biomimetic scaffolds and methods for modulating their intrinsic properties such as rigidity, elasticity, resistance to mechanical stress, porosity, biodegradation and ... [more ▼]

The invention concerns chitosan-based biomimetic scaffolds and methods for modulating their intrinsic properties such as rigidity, elasticity, resistance to mechanical stress, porosity, biodegradation and absorbance of exudates. Therefore, the present invention relates to a layered chitosan-based scaffold wherein said layered scaffold comprises at least two fused layers, wherein at least one layer consists of a chitosan nanofiber scaffold membrane and at least one of the other layers of a porous chitosan scaffold support layer. Moreover, the present invention provides a layered chitosan-based scaffold characterized by (i) a good adhesion between the porous and nanofiber layers, (ii) a tuneable porosity of the nanofiber layer by tuning the distance between the nanofibers, (iii) a stable nanofibers and porous morphology even when immersed in water or other solvents and a process for the preparation of such layered chitosan-based scaffold.Finally, the present invention provides the use of the layered electrospun chitosan-based scaffold of the invention or the layered electrospun chitosan-based scaffold produced by the process of the invention as a wound dressing, in tissue engineering or for biomedical applications. [less ▲]

Detailed reference viewed: 66 (12 ULg)
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See detailChitosan-based nanofibers for wound dressing
Aqil, Abdelhafid ULg; Tchemtchoua Tateu, Victor ULg; Colige, Alain ULg et al

Poster (2011, May 12)

Detailed reference viewed: 79 (10 ULg)
See detailChitosan-based nanofibers mats for tissue engineering
Aqil, Abdelhafid ULg; Croisier, Florence ULg; Colige, Alain ULg et al

Conference (2016, May)

Polymer hydrogels resemble the natural living tissue due to their high water content and soft consistency. They find many applications in the design and production of contact and intraocular lenses ... [more ▼]

Polymer hydrogels resemble the natural living tissue due to their high water content and soft consistency. They find many applications in the design and production of contact and intraocular lenses, biosensors membranes, matrices for repairing and regenerating a wide diversity of tissues and organs. Polysaccharides such as chitosan and hyaluronic acid based hydrogels have shown a great potential for biomedical and pharmaceutical applications, on account of their remarkable compatibility with physiological medium. Besides, it is degraded in a physiological environment into non-toxic products, which make them outstanding candidates for short- to medium-term applications, especially for tissue engineering. In this respect, the preparation of nanometric fibers mats based on this polysaccharide are highly interesting as such structure mimics the one of skin extracellular matrix. Such nanofibrous materials can be prepared by electrospinning (Figure 1). This technique uses a high voltage to create an electrically charged jet of polymer solution to obtain polymer fibers ranging from nanometers to a few microns in diameter. We thus have investigated strategies allowing to generate chitosan based nanofiber mats exhibiting a mechanical resistance strong enough to be easily handled while keeping the peculiar features of chitosan hydrogels favoring the interaction with cells and soft tissues to provide efficient tissue reconstruction. In a first strategy, polysaccharide-based nanofibers with a multilayered structure were prepared by combining electrospinning (ESP) and layer-by-layer (LBL) deposition techniques. Elastic nanofibers bearing charges at their surface were firstly prepared by electrospinning poly(ε-caprolactone) (PCL) with a polyelectrolyte precursor. After activation by adjusting the pH, the layer-by-layer deposition of chitosan and hyaluronic acid, can be used to coat the electrospun fibers. A multilayered structure is then achieved by alternating the deposition of the positively charged chitosan with the deposition of a negatively charged polyelectrolyte. These novel polysaccharide-coated PCL fiber mats remarkably combine the mechanical resistance typical of the core material (PCL) – particularly in the hydrated state –, with the surface properties of chitosan. Besides, crosslinked nanofibrous mats of chitosan and polyethylene oxide blends, were successfully prepared via electrospinning technique followed by heat mediated chemical crosslinking. This chemical cross-linking allows adjusting the mechanical resistance of the mats while preserving their biocompatibility. In both cases, the control of the nanofiber structure offered by the electrospinning technology, makes the developed processes very promising to precisely design biomaterials for tissue engineering. Preliminary cell culture tests corroborate the potential use of such systems in wound healing applications. [less ▲]

Detailed reference viewed: 228 (11 ULg)
See detailChitosan-based nanofibers with multilayered structure for wound healing application
Croisier, Florence ULg; Detrembleur, Christophe ULg; Jérôme, Christine ULg

Poster (2011, November 21)

Chitosan is a natural polymer that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This polysaccharide has shown a great potential for biomedical ... [more ▼]

Chitosan is a natural polymer that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This polysaccharide has shown a great potential for biomedical applications, on account of its remarkable compatibility with physiological medium and its biodegradability. In this respect, nanometric fibers are highly interesting as their assembly mimics the skin extracellular matrix structure. Such nanofibrous materials can be prepared by electrospinning (ESP) and can be used as scaffolds, a.o. to form a temporary, artificial extracellular matrix. In the present study, electrospinning technique was combined with layer-by-layer deposition method (LBL) – a well-known method for surface coating, based on electrostatic interactions – in order to prepare multilayered chitosan-based nanofibers for wound healing application. [less ▲]

Detailed reference viewed: 122 (10 ULg)
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See detailChitosan-based wound dressings produced by electrospinning
Croisier, Florence ULg; Sorlier, Pierre; Jérôme, Christine ULg

Poster (2010, September 07)

Detailed reference viewed: 31 (4 ULg)
See detailChitosan-based wound dressings produced by electrospinning
Croisier, Florence ULg; Sorlier, Pierre; Jérôme, Christine ULg

Poster (2011, April 29)

Detailed reference viewed: 35 (2 ULg)
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See detailChitosan-coated electrospun nanofibers with antibacterial activity
Croisier, Florence ULg; Sibret, Pierre ULg; Dupont-Gillain, Christine C. et al

in Journal of Materials Chemistry B (2015), 3(17), 3508-2517

Charged nanofibers were prepared by electrospinning (ESP) poly(ε-caprolactone) with a copolymer bearing carboxylic acid functions. The presence of these functions allowed exposing some negative charges on ... [more ▼]

Charged nanofibers were prepared by electrospinning (ESP) poly(ε-caprolactone) with a copolymer bearing carboxylic acid functions. The presence of these functions allowed exposing some negative charges on the fiber surface, by dipping the fibers in a phosphate buffer. A layer of chitosan, a polycation in acidic medium, was then deposited on the nanofiber surface, thanks to electrostatic attraction. Fibers were characterized at each step of the process and the influence of the copolymer architecture on chitosan deposition was discussed. The antibacterial activity of the resulting fibers was finally assessed. [less ▲]

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See detailChitosan-coated nanofibers for wound dressing
Croisier, Florence ULg; Colige, Alain ULg; Jérôme, Christine ULg

Conference (2015, March 23)

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See detailChitosan-g-lactide copolymers for fabrication of 3D scaffolds for tissue engineering
Demina, Tatiana; Zaytseva-Zotova, D.S.; Timashev, P.S. et al

in IOP Conference Series: Materials Science and Engineering (2015), 87

Detailed reference viewed: 10 (1 ULg)
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See detailChitosan/polyester copolymers prepared by solid-phase synthesis as promising biomaterials
Demina, T; Akopova, T; Tsoy, A et al

Conference (2011, May 05)

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See detailChitosan: a versatile platform for pharmaceutical applications
Riva, Raphaël ULg; Jérôme, Christine ULg

in Material Matters: Chemistry Driving Performance (2014), 9(3), 95-98

Detailed reference viewed: 46 (8 ULg)
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See detailLes chitosanes – nouveaux adjuvants pour la vaccination par voie muqueuse chez les animaux
Gogev, S.; Versali, Marie-France ULg; Thiry, Etienne ULg

in Annales de Médecine Vétérinaire (2003), 147(5, OCT-NOV), 343-350

The advantage of mucosal vaccination is the induction of an immune response at entry sites of pathogens. Because vaccines alone are poorly bioavailable after mucosal administration, they need to be co ... [more ▼]

The advantage of mucosal vaccination is the induction of an immune response at entry sites of pathogens. Because vaccines alone are poorly bioavailable after mucosal administration, they need to be co-administered with penetration enhancers, or adjuvants. Numerous studies have demonstrated that chitosans and their derivatives are safe and effective mucosal absorption enhancers of hydrophylic macromolecules such as peptides and proteins. Chitosan is a cationic polysaccharide derived from chitin present in the covering layer of arthropods and in the cell walls of many fungi. Association of vaccines to chitosans, their derivatives or some of their particulate systems, such as nano- and microparticles, has also shown to enhance antigen uptake by mucosal lymphoid tissues, thereby inducing mucosal and systemic immune responses against these antigens. Chitosan and its derivatives are promising adjuvants for mucosal vaccine delivery in animals. [less ▲]

Detailed reference viewed: 49 (4 ULg)
See detailChiuse poetiche e senso della fine. Spunti per una tipologia
Benzoni, Pietro ULg

Scientific conference (2003, November 20)

Detailed reference viewed: 4 (0 ULg)
See detailLes Chlamydia, clinique, épidémiologie et diagnostic
MELIN, Pierrette ULg

Conference (1982, October 28)

Detailed reference viewed: 13 (0 ULg)
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See detailChlamydomonas can play a role in the study of a heteroplasmic human mitochondrial mutation
Larosa, Véronique ULg; Coosemans, Nadine ULg; Bonnefoy, Nathalie et al

Scientific conference (2011)

Detailed reference viewed: 21 (3 ULg)
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See detailThe Chlamydomonas genome reveals the evolution of key animal and plant functions.
Merchant, Sabeeha S.; Prochnik, Simon E.; Vallon, Olivier et al

in Science (2007), 318(5848), 245-50

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the ... [more ▼]

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella. [less ▲]

Detailed reference viewed: 106 (18 ULg)
Peer Reviewed
See detailA Chlamydomonas mutant locked in anaerobiosis
Ghysels, Bart ULg; Matagne, René-Fernand ULg; Franck, Fabrice ULg

Conference (2011, May)

The soil dwelling microalga Chlamydomonas reinhardtii most likely encounters transient periods of anaerobiosis in its natural environment, for instance at night time or when photosynthesis is turned down ... [more ▼]

The soil dwelling microalga Chlamydomonas reinhardtii most likely encounters transient periods of anaerobiosis in its natural environment, for instance at night time or when photosynthesis is turned down in response to macronutrient limitation. Anoxic conditions trigger state I to state II transition in C.r. and the induction of a chloroplast hydrogenase., which ability to accept electrons from reduced Fd results in a transient light driven H2 evolution. We present evidence that hydrogenase induction and state transitions are required for the induction of photosynthesis in anaerobiosis and therefore critical for this alga in order to survive transient anaerobic periods in the dark. In an anaerobic metabolic context the induction of photosynthesis is severely slowed down. The highly reduced state of the NAD(P) pools and the absence of O2 as electron sink hamper light driven reoxydation of the intersystem electron carriers while CO2 assimilation by the Calvin cycle is inhibited by ATP deficiency. We have seen that gradual increase of hydrogenase activity during anaerobiosis restores a PSI acceptor pool and leads to a reduction of the induction lag of oxygenic photosynthesis. A mutant HydEF devoid of hydrogenase maturation genes typically shows 3 to 4 times longer lag phases that the WT. State transitions provide another mechanism by which photosynthetic electron transport can be unlocked in anaerobic conditions. A state II conformation is known to stimulate photo-phosphorylation, and may therefore restore Calvin cycle activity in an ATP depleted metabolic context. We observed that an anaerobically adapted stt7 mutant locked in state I is only able to induce oxygenic photosynthesis upon hydrogenase expression. We therefore constructed a double mutant Stt7HydEF impaired of state transition ability and hydrogenase activity and found it to have lost the capacity of inducing photosynthesis in anaerobic conditions. [less ▲]

Detailed reference viewed: 88 (6 ULg)