EP4412623A1 - Chitosan-based swelling gel - Google Patents

Abstract

The present invention relates to the field of compositions comprising a polymer bearing a chelating group capable of chelating one or more metals, and to the various uses thereof. In particular, the present invention relates to compositions comprising a copolysaccharide carrying a chelating group, which compositions may be in the form of a gel, as well as to the threads obtained from this gel.

Description

Description

Title: Chitosan-based swelling gel

Technical area

The present invention falls within the field of compositions comprising a polymer carrying a chelating group which can chelate one or more metals, and their various uses. In particular, the present invention relates to compositions which may be in the form of a gel, comprising a polysaccharide carrying a chelating group, as well as the yarns obtained from these gels.

Prior technique

[0002] Polysaccharides are polymers derived from plant, fungal, animal or bacterial biomass. These polymers have very varied physicochemical properties and can be shaped for a wide range of biomedical applications because they are often resorbable, biocompatible or even bioactive. The chemical modification of polysaccharides makes it possible to adapt their physicochemical properties, in particular their solubility in an aqueous medium at pH close to neutrality. Their functionalization by highly specific chelating agents also allows specific applications in the biomedical field. For example, after grafting these motifs onto the structure of polysaccharides, the polymer could be used in the composition of a detoxifying biomedical device to purify living organisms of pathogenic metals as part of maintaining homeostasis.

The maintenance of the homeostasis of the internal environment of the organism, that is to say of all the liquids or biological fluids of the organism, is necessary for the proper functioning of the latter. In many pathologies, systemic or local dysregulations of metal homeostasis have been demonstrated. Chelation therapies aimed at reducing the concentration of metal ions have already been used for many years in cases of acute poisoning. Thus, a number of chelating agents are already accepted in humans, each associated with a particular group of metals (G. Crisponi et al., Coordination Chemistry Reviews, 2015).

[0004] More and more scientific studies are highlighting the important role that metals could have in a number of neurological disorders, in particular iron, but also copper, zinc, manganese and even aluminum and lead (EJ McAllum et al., J. Mol. Neurosci., 2016). [0005] Thus, there are already medical devices that can be used for capturing metals. Nevertheless, it is always beneficial to improve the results obtained to date, in particular to reduce the side effects of said treatments.

[0006] Furthermore, it is also desirable to have a variety of shapes for medical devices, for example a single or multi-strand yarn which can be woven or knitted in the form of a textile and makes it possible to obtain a medical device of the dressing or parietal implant. A wire alone can also be advantageous in the event that the implantation must be combined with a minimally invasive strategy. The supply of a wire to capture metal cations to locally restore metal homeostasis when there is an accumulation of metals in the body would therefore be particularly interesting.

[0007] Thus, one object of the invention is to provide a composition that can chelate one or more metals. Another object of the invention is to provide a wire which can chelate one or more metals. Another object of the invention is to provide a yarn having good mechanical properties, and which can thus be woven or knitted in the form of a textile.

Summary

[0008] The invention relates firstly to a composition comprising: a. At least one chitosan A, and b. At least one random copolysaccharide B with a weight-average molecular mass of between 100 kDa and 1000 kDa of formula I:

Formula I in which:

- each Rc independently represents a group comprising a chelating agent,

- each Z independently represents a binder which may be a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more heteroatoms, preferably chosen among nitrogen, oxygen, sulfur and atoms of the halogen family,

- x is between 0.01 and 0.5,

- y is between 0.05 and 0.5,

- the y/x ratio being greater than 0.2, preferably greater than 1,

- the sum x + y being greater than 0.1, and less than 10% of the groups comprising a chelating agent of the Rc type being chelated by a cation of a transition element chosen from among the elements of block d or f, and c . possibly water.

[0009] The presence of an Rc-type chelating group in the copolysaccharide B enables this composition to capture one or more metals effectively, and in particular to capture metal cations. In addition, the use of chitosan A and polysaccharide B, which is produced from chitosan, makes it possible to obtain a composition that has interesting properties. Indeed, this composition can be biodegradable, biocompatible and bioabsorbable. The use of such a composition making it possible to chelate metals therefore has many possible applications at the medical level.

[0010] In addition, it is possible to form a yarn from this composition, in particular by extrusion of the composition. This wire has good mechanical properties and can be shaped. It is possible to braid the threads, for example to form a textile material (knit or fabric) capable of capturing metals.

[0011] Furthermore, surprisingly, the inventors demonstrated that this composition could swell on contact with a biological fluid in significant proportions. This swelling promotes the diffusion and capture of the metal species to be captured, and therefore improves the efficiency of the material.

The invention also relates to a yarn comprising a gel or a lyophilisate of the composition according to the invention.

The invention also relates to a textile material comprising yarns according to the invention.

The invention also relates to a medical device comprising the composition according to the invention, the medical device preferably being a dressing, an implant or a dermal filler.

The invention also relates to the composition according to the invention for its use for the capture of at least one metal, preferably for its use for the capture of at least one metal in the treatment or prevention of endometriosis, fungal infections, bacterial infections, chronic wounds, neurodegenerative diseases, nervous system damage, hemochromatosis, Wilson's disease or lead poisoning.

The invention also relates to a method for preparing a composition according to the invention, comprising the following steps:

1) dispersion of chitosan A and random polysaccharide B with a weight-average molecular mass of between 100 kDa and 1000 kDa of formula I in water,

2) addition of an acid, preferably acetic acid,

3) mixing then centrifugation of the solution obtained to recover a solution comprising the composition of the invention,

4) optionally, treatment of the solution obtained in step 3 in a basic aqueous bath to obtain the composition in the form of a gel, and

5) optionally, washing, drying and/or sterilization of the gel obtained in step 4, preferably by autoclave.

Brief description of the drawings

[0017] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the appended drawings, in which:

Fig. 1

[0018] [Fig. 1] shows a photo of the hydrogels in disk form obtained according to Example 4, top left: composition 9 according to the invention (HG-5-5), bottom left: composition 12 according to the invention (HG -8-8), bottom right: composition 10 according to the invention (HG-5-10), top right: composition 11 according to the invention (HG-5-15).

Fig. 2

[0019] [Fig. 2] shows a photo of the hydrogels in the form of a cylinder obtained according to example 4. This is the comparative composition 2 (Ref-HG-8-0).

Fig. 3

[0020] [Fig. 3] shows a photo of the hydrogels in the form of a cylinder obtained according to example 4. This is composition 10 according to the invention (HG-5-10).

Fig. 4

[0021] [Fig. 4] shows an optical microscope photo of a thread having a knot according to example 5. [0022] [Fig. 5] shows a photo under an optical microscope of a braiding of two threads according to example 5.

Fig. 6

[0023] [Fig. 6] shows a photo of the dried gel according to Example 6.

Fig. 7

[0024] [Fig. 7] shows a photo of the swollen gel according to example 6.

Fig. 8

[0025] [Fig. 8] shows an optical microscope photo of a wire that has been half immersed in water according to example 6.

Fig. 9

[0026] [Fig. 9] shows an optical microscope photo of a wire according to example 6, of which a drop of water has been deposited on only one portion.

Fig. 10

[0027] [Fig. 10] shows a photo of the formation of a gel according to example 12, after injection of composition 23 according to the invention (IS-1,7-3,3) in 10 mM PBS.

[0028]

Fig. 11

[0029] [Fig. 1 1] shows MRI images (7.1T) of a gel formed just after injection (day 0) and after 15 days and 30 days according to example 14.

Fig. 12

[0030] [Fig. 12] shows MRI images (7.1 T) of the gel formed just after injection according to example 14.

Definition

[0031] In the present disclosure, all % and ppm are indicated by weight, unless otherwise indicated.

[0032] Unless otherwise indicated, all the viscosities referred to in this presentation correspond to a magnitude of dynamic viscosity at 25° C. called "Newtonian", that is to say the dynamic viscosity which is measured, in such a way known per se, with a rheometer at a sufficiently low shear rate gradient for the measured viscosity to be independent of the rate gradient. Within the meaning of the present disclosure, by “chitosan” is meant a natural polymer of the co-polysaccharide type, consisting of a random distribution (random copolysaccharide) or not (block or block copolysaccharides) of D-glucosamine ( GIcN) and N-acetyl-D-glucosamine (GIcNAc), or even exclusively D-glucosamine, linked by type 0(1 ->4) glycosidic bonds. Chitosan is not very present in the native state in the biomass, it is mainly obtained by chemical modification of chitin, of which it is a derivative. Chitin has a structural role, it is mainly found in certain fungi of which it constitutes the cell wall (Basidiomycetes ex: agariscus campestris, agariscus bisporus, Ascomycetes, Zygomycetes, and Deuteromycetes), but it also forms the exoskeleton of arthropods (crustaceans, insects) especially in shrimp or crab and the endoskeleton of cephalopods such as squid or cuttlefish. The transition from chitin to chitosan takes place by deacetylation, that is to say by alkaline hydrolysis of the acetyl groups to generate primary amine groups. Chitosan is a biodegradable and biocompatible polymer, exhibiting bacteriostatic and fungistatic properties.

By "gel" is meant a non-fluid polymer network which is swollen by a solvent. The polymer network is a network made up of cross-linked polymer chains. The interactions responsible for polymer crosslinking can be physical or chemical. Advantageously, in the context of the invention, the gels consist exclusively of chitosan A, of copolysaccharide B, and, optionally, of water and/or of an active pharmaceutical ingredient.

By "hydrogel" is meant a viscoelastic material comprising at least 60% by mass of water, and preferably at least 80% by mass of water. The hydrogel according to the invention contains, in general, from 0.1% to 40% and preferably from 0.5 to 20% by mass of the mixture of chitosan A and copolysaccharide B.

[0036] In the context of the invention, the hydrogel is said to be physical, because the interactions responsible for the inter-chain cross-linking giving its cohesion to the hydrogel are of the physical type, and are in particular hydrogen bonds and/or hydrophobic interactions, as opposed to a so-called chemical hydrogel (also called cross-linked hydrogel), in which the inter-chain interactions are of the covalent bond type. No chemical crosslinking agent is present in a purely physical hydrogel. Advantageously, in the context of the invention, the physical hydrogels consist exclusively of water, chitosan A, copolysaccharide B, and optionally an active pharmaceutical ingredient, and preferably contain more than 80% ( m/m) of water. In particular, such hydrogels contain neither collagen, neither polycaprolactone nor toxic chemical cross-linking agent (such as glutaraldehyde, formaldehyde, epichlorohydrin, etc.). Having a physical hydrogel has advantages because a chemical hydrogel is poorly resorbable due to the stability of the covalent bonds, whereas the physical hydrogel of chitosan A and copolysaccharide B according to the present invention is resorbable in a physiological medium, especially in slightly acidic conditions.

By "xerogel" is meant a material obtained by drying, in particular drying of a hydrogel, comprising less than 60% by mass of water, preferably less than 50% by mass of water and more preferentially, less than 20% water. The xerogel according to the invention contains, in general, at least 40% by mass of the mixture of chitosan A and of copolysaccharide B, preferably between 40 and 100%, preferentially between 50 and 99.9% of the mixture, and more preferentially between 80 and 99.5% of the mixture.

[0038] By "airgel", we mean a material structurally similar to a hydrogel but whose water has been replaced by gas by a process avoiding the impact of the capillary forces of the solvent on the material (cf. Mike Robitzer, Laurent David, Cyrille Rochas, Francesco Di Renzo and Françoise Quignard Nanostructure of calcium alginate aerogels obtained from multistep solvent exchange route, Langmuir 2008, 24, 12547-12552, and Mike Robitzer, Laurent David, Cyrille Rochas, Francesco Di Renzo and Françoise Quignard, Supercritically -dried alginate aerogels retain the fibrillar structure of the hydrogels, Macromol. Symp. 2008, 273, 80-84).

In the context of the invention, the mass-average molar masses Mw of chitosan A and of copolysaccharide B are determined by steric exclusion chromatography, the experimental conditions of which are described in the publication “Physico-chemical studies of the gelation of chitosan in a hydroalcoholic medium” A. MONTEMBAULT, C. VITON, A. DOMARD, Biomaterials, 26(8), 933-943, 2005.

[0040] The degree of acetylation (DA) of chitosan A and copolysaccharide B is determined using the proton NMR technique, following Hirai's methodology (A. HIRAI, H ODANI, A. NAKAJIMA, Polymer Bulletin , 26(1), 87-94, 1991).

In the context of the invention, the degree of crystallinity represents the proportion of material found in the crystalline state. For polysaccharides it is often determined by X-ray diffraction (Alexander, LE, 'X-ray Diffraction Methods in Polymer Science', Wiley-Interscience, New York, 1969, p. 137) because many polysaccharides degrade at lower temperatures at the melting temperature of the crystalline phase, which does not allow the use of differential scanning calorimetry. It is therefore this method which is to be considered within the scope of the invention. Other spectroscopic methods are possible but must be adapted in each case (Infra-Red Spectrometry with Fourier Transform, Raman Spectroscopy). The determination of the density by a gradient column makes it possible in principle to calculate the degree of crystallinity knowing the density of the amorphous phase and the crystalline phase of the polymer, but many polysaccharides can swell and absorb the solvents used for the gradient columns density, which again limits the use of this method.

In the context of the invention, the size of the crystallites can be determined by studying the width of the diffraction peaks obtained by the powder method, using the Laue-Scherrer relationship (Alexander, L. E., ' X-ray Diffraction Methods in Polymer Science', Wiley-interscience, New York, 1969, p. 137).

Description of embodiments

The invention relates firstly to a composition comprising: a. At least one chitosan A, and b. At least one random copolysaccharide B with a weight-average molecular mass of between 100 kDa and 1000 kDa of formula I:

Formula I in which:

- each Rc independently represents a group comprising a chelating agent,

- each Z independently represents a binder which may be a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more heteroatoms, preferably chosen among nitrogen, oxygen, sulfur and atoms of the halogen family,

- x is between 0.01 and 0.5,

- y is between 0.05 and 0.5,

- the y/x ratio being greater than 0.2, preferably greater than 1,

- the sum x + y being greater than 0.1, and less than 10% of the groups comprising a chelating agent of Rc type being chelated by a cation of a transition element chosen from the elements of block d and f, and c. possibly water.

According to one embodiment, the mass ratio between A and B (A:B) is between 2:1 and 1:10, preferably between 1:1 and 1:5.

This composition may also comprise at least one active pharmaceutical ingredient, preferably chosen from anticancer agents, antibacterial agents, antifungal agents, anti-inflammatories, messenger RNAs, proteins and antigens.

By active pharmaceutical ingredient is meant any compound having a therapeutic or preventive effect. The fact that this composition has good swelling properties makes it possible to effectively capture and then release the active pharmaceutical ingredients. It is in fact possible to bring the composition into contact with the active pharmaceutical ingredient, for example with a solution comprising the active pharmaceutical ingredient, and the composition then captures this ingredient. Then, this ingredient can be salted out, for example by immersing the composition in another medium. This advantageously occurs when the composition is in the form of a gel.

The composition can be in several forms: aqueous solution, lyophilizate or gel.

According to one embodiment, the composition is an aqueous solution, preferably comprising at least 10 g/L, preferably at least 50 g/L, of the mixture of chitosan A and copolysaccharide B. When the composition is under In the form of an aqueous solution, the composition may be injectable. The concentration of the mixture of chitosan A and of copolysaccharide B can be between 10 g/L and 500 g/L, preferably between 40 g/L and 160 g/L.

The aqueous solution may have a Newtonian viscosity between 0.1 and 50,000 Pa.s, preferably between 50 and 25,000 Pa.s, and more preferably between 100 and 10,000 Pa.s.

The aqueous solution is a gellable solution. It can gel when brought into contact with a coagulation bath at basic pH. The gelation takes place at basic pH after neutralization of the initially protonated amines (NH ₂ ) (NH ₃ ⁺ ) present in the solution. The state of entanglement of the chains resulting from the high initial viscosity is fixed by the formation of interchain interaction sites (crystallites, hydrophobic interactions, interactions by hydrogen bonds) and thus ensures obtaining a stable physical hydrogel and sufficient mechanical properties to be manipulated or stretched. The resulting hydrogels are reversible by acid solution treatment and dissociate from chemical hydrogels where gelation is provided by the formation of irreversible covalent chemical bonds. They can be dried and rehydrated reversibly. The solution can also be lyophilized.

The composition can also be in the form of a lyophilizate or a gel, preferably in the form of a hydrogel, a xerogel or an airgel.

The hydrogel according to the invention may contain from 0.1% to 40% and preferably from 0.5 to 20% by mass of the mixture of chitosan A and copolysaccharide B.

The xerogel according to the invention may contain at least 40% by weight of the mixture of chitosan A and copolysaccharide B, preferably between 40 and 100%, preferably between 50 and 99.9% of the mixture, and more preferably between 80 and 99.5% of the mixture. When the composition is in the form of a xerogel, the xerogel may result from the at least partial drying of a hydrogel.

The xerogel, when in contact with an aqueous medium or a biological tissue for a period of at least 1 hour, swells to form a hydrogel, said hydrogel having a volume at least 2 times greater , preferably at least 5 times greater than the volume of reference xerogel before contact with the aqueous medium or the biological tissue. The swelling can be quantified by measuring the mass of the initial xerogel and the mass of the resulting hydrogel.

A biological tissue is a set of differentiated or undifferentiated cells, organized according to a characteristic architecture, in association with a network of natural macromolecules or extracellular matrix (ECM) and contributing to exert the same function. The cellular tissue is naturally hydrated, which allows the xerogel to swell.

The hydrogel obtained by rehydrating a xerogel can then be dried again to reform a xerogel. It is possible to carry out several drying-inflating cycles with this composition.

The gels according to the invention have good mechanical properties. It is thus possible to make threads thereof, for example by extruding the composition according to the invention through a die in a coagulation bath. These threads can then be used to prepare a textile material. The wire may have a diameter of between 50 μm and 700 μm, preferably between 80 μm and 500 μm. The composition according to the invention, and in particular the threads and/or the textile materials, can be used in medical devices, thanks to their good properties of swelling and metal uptake. Advantageously, the threads and/or the textile materials can be degraded by the organism or explanted to eliminate the chelated metals.

The medical device in question is preferably a dressing, an implant or a dermal filler. According to one embodiment, the medical device comprises a yarn and/or a textile material according to the invention.

[0060] In the case of a dermal filler, this can be in the form of a thread, preferably said thread being in the form of a xerogel which can swell on contact with an aqueous medium or a biological tissue to form a hydrogel. The dermal filler can also be a solution according to the invention which can then be injected.

[0061] The good metal-capturing properties of the composition make it possible to use it for the capture of at least one metal in the treatment or prevention of endometriosis, fungal infections, bacterial infections, chronic wounds ( bedsores, diabetic wounds) neurodegenerative diseases (Parkinson's disease, Alzheimer's disease, etc.), hemochromatosis, Wilson's disease, or lead poisoning. The metal is preferably a metal cation. According to one embodiment, the metal belongs to the group consisting of copper, iron, lead, zinc, aluminum, gadolinium and manganese and more preferably, to the group consisting of copper, iron and Lead.

The invention also relates to the use of the composition according to the invention for capturing at least one metal, optionally for the treatment or prevention of a disease.

The invention also relates to a method for treating or preventing endometriosis, fungal infections, bacterial infections, chronic wounds (bedsores, diabetic wounds), neurodegenerative diseases (Parkinson's disease, Alzheimer's disease, ...), hemochromatosis, Wilson's disease, or lead poisoning, said method comprising the use of the composition according to the invention for the capture of at least one metal.

Process for preparing the composition

The invention also relates to a method for preparing a composition according to the invention comprising the following steps:

1 ) dispersion of chitosan A and random copolysaccharide B of molecular mass weight average of between 100kDa and 1000kDa of formula I in water,

2) addition of an acid, preferably acetic acid,

3) mixing and then centrifuging the solution obtained to recover a solution comprising the composition,

4) optionally, treatment of the solution obtained in step 3 in a basic aqueous bath to obtain the composition in the form of a gel, and

5) optionally, washing, drying and/or sterilization of the gel obtained in step 4, preferably by autoclave.

Preferably, the acid is added in stoichiometric proportion with respect to the non-functionalized primary amine type functions of the chitosan A and of the copolysaccharide B. The acid is preferably organic.

The solution comprising the composition preferably has a viscosity of between 0.1 and 50,000 Pa.s.

The basic aqueous bath in step 4 is a coagulation bath which allows the solution to gel. This coagulation bath is preferably an alkaline solution, for example of sodium hydroxide, ammonia or potash, at a concentration which can be between 0.5 and 10 M, preferably between 1 and 5 M. The coagulation bath can also be a coagulation chamber where alkaline vapors are used, such as ammonia vapors.

To obtain a yarn, it is possible, during step 4, to extrude the composition according to the invention through a die (or extrusion cone). The extrudate is then introduced into the coagulation bath. It is also possible to extrude the composition directly into the coagulation bath.

[0069] Step 5 can comprise one or more washing steps, the washing being able to be carried out with water or with a buffer.

Step 5 can also include one or more solvent exchange steps, for example to replace the water with ethanol.

[0071] Step 5 may comprise one or more drying steps. The drying in step 5 can be carried out in the open air, at ambient temperature, or at a temperature comprised between 30 and 250°C, for example in hot air at a temperature comprised between 100 and 200°C. According to one embodiment, the drying is carried out after exchange of water with ethanol by successive baths gradually concentrated in alcohol, then after exchange of ethanol with liquid CO ₂ in a pressurized enclosure, then after expansion in medium supercritical CO ₂ , which makes it possible to form an airgel. Any sterilization technique well known to those skilled in the art may be used, in particular steam sterilization by autoclave, gamma or beta irradiation.

Chitosan A

The composition according to the invention comprises a chitosan A.

The composition may have;

- a level of crystallinity reduced to chitosan A of at least 10% relative to the total dry mass of the composition, and

- a chitosan A crystallite size of less than 20 nm.

The level of crystallinity reduced to chitosan A can be between 10 and 25%. The crystallites of chitosan A play the role of physical cross-linking nodes essential to the constitution of a gel. The size of the crystallites can for example be between 1 and 20 nm.

Advantageously, chitosan A has an average molecular weight Mw of between 100 kg/mol and 1000 kg/mol, preferably between 200 kg/mol and 700 kg/mol.

According to a preferred embodiment, chitosan A has a degree of acetylation x of less than 40%, preferably less than 10%, for example between 0% and 10%.

Copolysaccharide B

The composition comprises a random copolysaccharide B with a weight-average molecular mass of between 100 kDa and 1000 kDa of formula I.

It is understood that, in formula I above, several Rc groups may be present in the polysaccharide. These Rc groups can be identical to or different from each other. They are all independently chosen from the groups carrying a chelating agent. The same applies to the Z binders: several Z binders may be present, and they may be identical or different from each other.

The copolysaccharide B can be of formula II:

Formula II in which:

- Rci and RC ₂ are different, and are groups containing a chelating agent, - Zi and Z ₂ , which are identical or different, are binders which may be a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more several heteroatoms, preferably chosen from nitrogen, oxygen, sulfur and atoms of the halogen family,

- x is between 0.01 and 0.5, preferably between 0.01 and 0.1, and preferably between 0.05 and 0.1,

- y is between 0.01 and 0.5, preferably between 0.05 and 0.2,

- z is between 0 and 0.2, and less than 10% of the groups comprising a chelating agent of Rc1 and Rc2 type being chelated by a cation of a transition element chosen from among the elements of block d and f.

The term Rc-type group means the Rc groups in the polysaccharide of formula I, and the Rci and Rc ₂ groups, when the Rc ₂ group is present, in the polysaccharide of formula II.

According to one embodiment, less than 10% of the groups of Rc type, preferably less than 5%, are chelated by a cation, in particular a metal cation. The fact that the Rc-type groups are in free form allows good uptake of metals. Copolysaccharide B also exhibits high hydrophilicity, which induces good swelling properties.

In accordance with the invention, the groups Rc, Rci and Rc ₂ are chelating agents. In other words, the groups Rc, Rci and Rc ₂ make it possible to chelate one or more metals by forming a complex.

Each of the groups Rc, Rci and Rc ₂ can contain one or more coordination sites. Preferably, the coordination site is a nitrogen or oxygen atom. Advantageously, each of the groups Rc, Rci and Rc ₂ comprises between 4 and 8 coordination sites, more advantageously between 6 and 8 coordination sites and even more advantageously each of the groups Rc, Rci and Rc ₂ comprises 8 coordinating sites.

The term coordination site means a single function capable of binding to a metal. For example, an amine function represents a coordination site by the formation of a dative bond between the nitrogen atom and the metal and a hydroxamic acid function also represents a coordination site by the formation of a dative bond between the oxygen of the carbonyl unit and by a covalent bond with the oxygen of the dioxide unit the coordination site thus forming a five-membered ring.

In one embodiment of the invention, for the polysaccharide of formula I, each Rc group is independently chosen from the group consisting of DOTA (1,4,7,10-tetraazacyclododecane-N,N',N ”,N'”-teracetic acid), NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid), NODAGA (1,4,7-triazacyclononane-1-glutaric-4,7-diacetic acid ), DOTAGA (2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acid), DOTAM (1,4,7,10-tetrakis(carbamoylmethyl) -1,4,7,10 tetraazacyclododecane), NOTAM (1,4,7-tetrakis(carbamoylmethyl)-1,4,7-triazacyclononane), DOTP (1,4,7,10-tetraazacyclododecane 1,4,7, 10-tetrakis(methylene phosphonate), NOTP (1,4,7-tetrakis(methylene phosphonate)-1,4,7-triazacyclononane), TETA (1,4,8,1 1-tetraazacyclotetradecane-N,N' acid, N”,N'”-teraacetic acid), TETAM (1 ,4,8,1 1 - tetraazacyclotetradecane-N,N',N”,N'”-tetrakis(carbamoyl methyl), DTPA (diethylene triaminopentaacetic acid) and DFO (deferoxamine), preferably from the group consisting of DOTAGA, DFO, DOTAM and DTPA and more preferably the Rc group is DOTAGA.

In one embodiment of the invention, for the polysaccharide of formula II, Rci and RC ₂ are independently chosen from the group consisting of DOTA, NOTA, NODAGA, DOTAGA, DOTAM, NOTAM, DOTP, NOTP, TETA, TETAM, DTPA and DFO, preferably from the group consisting of DOTAGA, DFO, DOTAM and DTPA.

According to one embodiment, for the polysaccharide of formula II, the Rci group is DOTAGA, and preferably, z=0.

According to one embodiment, for the polysaccharide of formula II, the Rci group is DOTAGA and the Rc ₂ group is DFO

The term “Z-type binder” means the Z binders in the polysaccharide of formula I, and the Zi and Z ₂ binders, when the Z ₂ binder is present, in the polysaccharide of formula II.

The choice of binders Z, Zi and Z ₂ in formulas I and II essentially depends on the Rc, Rci and Rc ₂ groups and on the metal to be chelated. Indeed, for steric reasons in particular, the Rc, Rci and Rc ₂ groups may be more or less close to the 6-membered ring of the nitrogen of the glucosamine unit.

Preferably, in formula I, each Z is independently a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more heteroatoms, preferably chosen from nitrogen, oxygen, sulfur and atoms of the halogen family.

According to one embodiment, in formula I, each Z is independently selected from the group consisting of: a bond, a linear or branched alkyl chain comprising between 1 and 12 carbon atoms, and a linear or branched alkenyl chain comprising between 2 and 12 carbon atoms, said alkyl and alkenyl chains possibly being interrupted by one or more C ₆ -Cio aryl groups, and/or by one or more heteroatoms or groups selected from the group consisting of -O-, - S-, -C(O)-, -NR'-, -C(O)NR'-, -NR'-C(O)-, -NR'-C(O)-NR'-, -NR' -C(O)-O-, -OC(O)NR', -C(S)NR'-, -NR'-C(S)-, -NR'-C(S)-NR' said alkyl chains and alkenyl which may be substituted by one or more groups selected from the group consisting of halogen, -OR', -COOR', -SR', -NR' ₂ , each R' is independently H or C 1 -C ₆ alkyl .

Advantageously, in formula I, each Z is independently selected from the group consisting of: a bond and a linear or branched alkyl chain comprising between 1 and 12 carbon atoms, said alkyl chain possibly being interrupted by one or more groups C ₆ -Cio aryl, and/or by one or more heteroatoms or groups selected from the group consisting of -O-, -S-, -C(O)-, -NR'-, -C(O)NR' -, -NR'-C(O)-, -C(S)NR'-, -NR'-C(S)-, -NR'-C(S)-NR', each R' is independently H or a Ci-C ₆ alkyl,

In a particular embodiment, each Z is an alkyl chain comprising between 1 and 12 carbon atoms.

In another particular embodiment, each Z is a polyethylene glycol (PEG) segment.

Preferably, in formula II, Zi and Z ₂ are independently a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more heteroatoms, preferably chosen from nitrogen, oxygen, sulfur and atoms of the halogen family.

According to one embodiment, in formula II, Zi and Z ₂ are independently selected from the group consisting of: a bond, a linear or branched alkyl chain comprising between 1 and 12 carbon atoms, and a linear alkenyl chain or branched containing between 2 and 12 carbon atoms, said alkyl and alkenyl chains possibly being interrupted by one or more C ₆ -Cio aryl groups, and/or by one or more heteroatoms or groups selected from the group consisting of -O-, -S-, -C(O)-, -NR'-, -C(O)NR '-, -NR'-C(O)-, -NR'-C(O)-NR'-, -NR'-C(O)-O-, -OC(O)NR', -C(S )NR'-, -NR'-C(S)-, -NR'-C(S)-NR', said alkyl and alkenyl chains possibly being substituted by one or more groups selected from the group consisting of halogens, -OR ', -COOR', -SR', -NR' ₂ , each R' is independently H or C 1 -C ₆ alkyl.

Advantageously, in formula II, Zi and Z ₂ are independently selected from the group consisting of: a bond and a linear or branched alkyl chain comprising between 1 and 12 carbon atoms, said alkyl chain possibly being interrupted by one or several C ₆ -Cio aryl groups, and/or by one or more heteroatoms or groups selected from the group consisting of -O-, -S-, -C(O)-, -NR'-, -C(O) NR'-, -NR'-C(O)-, -C(S)NR'-, -NR'-C(S)-, -NR'-C(S)-NR', each R' is independently H or a Ci-C ₆ alkyl,

In a particular embodiment Zi and/or Z ₂ is an alkyl chain comprising between 1 and 12 carbon atoms.

In another particular embodiment, Zi and/or Z ₂ is a polyethylene glycol (PEG).

According to the invention, z is between 0 and 0.2. In other words, the C-type units can be exclusively units comprising as binder Zi and as group carrying a chelating agent Rci.

The polysaccharide according to the invention has a weight-average molecular mass of between 100 kDa and 1000 kDa, advantageously, the weight-average molecular mass of the polysaccharide according to the invention is between 200 kDa and 750 kDa, more advantageously between 250 kDa and 500 kDa and even more advantageously between 300 kDa and 400 kDa.

According to one embodiment, the copolysaccharide B is chosen from the following polysaccharides:

- copolysaccharide of formula II where y = 0.15, Rci is DOTAGA and Zi is a bond;

- copolysaccharide of formula II where 0.05 <z <0.06, Rci is DOTAGA and Zi is a bond, and Rc ₂ is DFO and Z ₂ is selected from the group consisting of: a bond and a linear or branched alkyl chain comprising between 1 and 12 carbon atoms, said alkyl chain possibly being interrupted by one or more C ₆ -Cio aryl groups, and/or by one or more heteroatoms or groups selected from the group consisting of -O-, -S- , -C(O)-, -NR'-, -C(O)NR'-, -NR'-C(O)-, -C(S)NR'-, -NR'-C(S)- , - NR'-C(S)-NR', each R' is independently H or C1- _C6 alkyl,

The copolysaccharide B can be obtained according to a process comprising the following three successive steps:

Step 1: solubilization of a chitosan in an acid solution at a pH between 4 and 5;

Step 2: partial acetylation of the amine functions of the chitosan dissolved in step 1 (formation of acetylated units);

Step 3: functionalization of at least some of the amine functions still present at the end of step 2 (formation of units comprising the Rc group).

[0106] Stage 3 can be subdivided into several sub-stages, in particular when the binder Z is a hydrocarbon chain as defined previously.

In the embodiments where the binder Z is a hydrocarbon chain as defined above, step 3 may include a sub-step 3-1 consisting in grafting said hydrocarbon chain onto at least some of the amine functions still present at the end of step 2, then a sub-step 3-2 consisting in the grafting of the Rc group on said hydrocarbon chain. Alternatively, step 3 does not include a sub-step. In this alternative, said hydrocarbon chain is coupled with the Rc group prior to step 3, said step 3 is then carried out with a molecule comprising the Rc group and said hydrocarbon chain.

[0108] Alternatively, the copolysaccharide B can be obtained from a chitosan having the desired acetylation rate, thus, in this embodiment the acetylated units are already present and do not need to be formed. . In this embodiment, the process for obtaining copolysaccharide B comprises at least the following two successive steps:

Step 1b: solubilization of a partially acetylated chitosan in an acid solution at a pH between 4 and 5;

Step 2b: functionalization of at least some of the amine functions of said partially acetylated chitosan dissolved in step 1b (formation of units comprising the Rc group).

In the same way as previously for said step 3, said step 2b can be subdivided into several sub-steps, in particular when the binder Z is a hydrocarbon chain as defined above. In the embodiments where the binder Z is a hydrocarbon chain as defined above, step 2b may comprise a sub-step 2b-1 consisting in linking said hydrocarbon chain on at least part of the amine functions, then a under step 2b-2 consisting in the grafting of the Rc group on said hydrocarbon chain. Alternatively, step 2b does not include a sub-step. In this alternative, said hydrocarbon chain is coupled with the Rc group prior to step 2b, said step 2b is then carried out with a molecule comprising the Rc group and said hydrocarbon chain.

Examples

Materials and methods

Several chitosan A and copolysaccharides B were used to prepare the compositions according to the invention. Table 1 summarizes the compounds used. The syntheses of compounds B1 and B2 are presented respectively in examples 1 and 2.

[0112] [Table 1]

The degree of acetylation (DA) of compounds B1 and B2 is obtained as follows: The 1 H NMR spectra of the products to be analyzed are obtained using an Avance III HD 400 MHz NanoBay spectrometer from Bruker . The phase is corrected manually using the water peak located at 4.7 ppm. The integration of the peaks is done manually by integrating the bulk of the peaks between 4.1 and 2.9 ppm and by integrating the peak at 2.00 ppm between 2.02 and 1.90 ppm. The percentage DA is directly obtained by normalizing the integration of the peak mass to 200. The degree of substitution in DOTAGA (DS) is obtained as follows: Different samples of the product to be analyzed are obtained by redispersion of the freeze-dried product in an acetate buffer (0.1 M acetic acid and 0.1 M ammonium acetate ) to obtain a final mass concentration of polymer of 0.1%. Different volumes of a copper nitrate solution are added in order to obtain copper concentrations in each sample ranging from 0 to 1 mM, then each sample is stirred. The absorbance of the resulting solutions is then measured using a Varian Cary® 50 UV-Visible spectrophotometer. The determination of the DS is carried out by plotting the absorbance at 295 nm (maximum of absorption of DOTA-GA) in function of the copper concentration, the break corresponding to the quantity of DOTAGA for 1 g of product.

The purity of compounds B1 and B2 is checked as follows: The HPLC-SEC-UV chromatograms of the products to be analyzed were recorded on samples at a mass concentration of polymer of 1% with a Shimadzu Prominence HPLC system. The SEC column used is a PolySep-GFC-P 4000 column and an acetate buffer is used as eluent (0.1 M acetic acid and 0.1 M ammonium acetate). The operating temperature is 30°C and the absorption wavelength is 295 nm. The eluent flow rate is 0.8 mL/min. The purity of the product is checked by integration of the peak of free DOTA-GA on the integration of the peak of chitosan grafted with DOTA-GA.

Example 1 - Synthesis of MEX-CD2 (B1)

The chitosan precursor of the polysaccharide MEX-CD2 (B1) is of medical quality and of animal origin. The average molar masses by weight and number (respectively M _w = 2.583.10 ⁵ g/mol, M _n = 1.323.10 ⁵ g/mol) were determined by size exclusion chromatography coupled with refractive index measurements and multi-angle laser light scattering. The degree of acetylation (proportion of N-acetyl-D-glucosamine unit) of such crude chitosan was determined by 1H NMR spectroscopy by Hirai's method (Asako Hirai et al., Determination of degree of deacetylation of chitosan by 1 H NMR spectroscopy, Polymer Bulletin, 1991, 26, 87-94) and is estimated at 6 ± 0.5%.

60 g of chitosan are introduced into a 10 L reactor with 4 L of ultrapure water and 50 mL of acetic acid, then the mixture is placed under mechanical stirring at 500 RPM. After complete dissolution of the chitosan (3 h), 4 L of 1,2-propanediol are added to the medium and the mixture is kept under stirring until homogenization (2 h). 120g of DOTA-GA anhydride are then introduced and the mixture is kept under shaking overnight until completely dissolved. The synthesis product is then purified by tangential filtration using the Sartoflow® Advanced device with a Sartocon® Slice PESU cassette (polyethersulfone membranes; cut-off threshold: 100 kDa; filtration area: 0.1 m ² ) according to a model of diafiltration-concentration against 200L of a 0.1 M acetic acid solution then 200L of a 5 mM acetic acid solution. Purification is followed by size exclusion chromatography coupled with a UV detector until less than 5% of free DOTA-GA is obtained. The product is then freeze-dried and the degree of acetylation (DA) and the degree of substitution (DS) are determined respectively by ¹ H NMR and by the copper chelation method described above. Purity was checked by HPLC as mentioned above.

Example 2 - Synthesis of MEX-CDDFO1 (B2)

The precursor chitosan of the polysaccharide MEX-CDDFO1 (B2) is identical to that described in Example 1 (M _w = 2.583.10 ⁵ g/mol, M _n = 1.323.10 ⁵ g/mol, DA=6±0 .5%).

60 g of chitosan, 4 L of ultra-pure water and 45 mL of glacial acetic acid are introduced into a 10 L reactor and stirred for 16 hours at a pH of 4.5 ± 0.5. 1.2 L of propane-1,2-diol are added to the solution and stirring is maintained for 1 hour. A solution composed of 14 mL of acetic anhydride dissolved in 600 mL of propane-1,2-diol is then added slowly over 30 min, the reaction medium is kept under stirring for 4 h. 120 g of DOTA-GA anhydride are then weighed and added to the reactor, then 2 L of propane-1,2-diol are added and stirring is maintained for 16 h. At the end of the reaction, the solution is purified by tangential filtration using a 100 kDa membrane. The synthesis product is then purified by tangential filtration in the same way as described in Example 1, against 200 L of a 0.1 M acetic acid solution then 200 L of ultrapure water. Purification is followed by size exclusion chromatography coupled with a UV detector until less than 5% of free DOTA-GA is obtained. The product is then freeze-dried at a concentration of 7 g/L and the degree of acetylation (DA) and the degree of substitution (DS) are determined respectively by ¹ H NMR and by the copper chelation method described above.

A volume of 720 mL of purified chitosan-DOTAGA at a concentration of 7 g/L is introduced into a 2 L flask. This solution (pH between 6 and 6.5) is supplemented with ultra-high water. pure to reach a total volume of 900 mL. In parallel, 143.1 mg of p-NCS-Bz-DFO are weighed and dissolved in 100 mL of DMSO. This solution is then added dropwise to the chitosan-DOTAGA solution. The solution is kept under stirring and heated at 40° C. overnight. 500 mL of this solution are diluted to 5 L with ultrapure water then reconcentrated to 1 L by cross-flow filtration using the Sartoflow® Smart device with two Sartocon® Slice PESU cassettes (polyethersulfone membranes; cut-off threshold: 100 kDa; surface of filtration: 0.02 m ² ). Filtration is continued at constant concentration against 4L of ultrapure water then the solution is reconcentrated to 500 mL.

The HPLC-SEC-UV analysis of the product makes it possible to confirm the grafting of the DFO and the elimination of the residual p-NCS-Bz-DFO. The comparison of the HPLC-SEC-UV analyzes of chitosan-DOTAGA and chitosan-DOTAGA-DFO shows an increase in the absorption of the polymer peak (around 7 min) when the p-NCS-Bz-DFO is grafted.

In the case of MEX-CDDFO1 (B2), the copper chelation method was applied to the product before functionalization with DFO and made it possible to determine a DS in DOTAGA of 8.6%. A method analogous to that of copper chelation made it possible to determine the DS in DFO. Increasing concentrations of iron (III) are added to a solution of MEX-CDDFO1 (B2) at 0.1 g/L in an acetate buffer at pH 4.5 (0.1 M ammonium acetate and 0.1 M acetic acid ). The absorption measured at 425 nm (λmax of the [Fe(n ⁶ -DFO)] complex) is then plotted as a function of the iron concentration and the iron concentration corresponding to the slope break makes it possible to obtain the DS. This method makes it possible to estimate the DS of MEX-CDDFO1 (B2) at 0.7%.

¹ H NMR analysis of the intermediate product (N-DOTAGA chitosan) according to the method described above made it possible to determine a DA of 26%. The 1H NMR analysis of MEX-CDDFO1 (B2) reveals the presence of a peak at 7.3 ppm characteristic of the protons of a substituted benzene. The NMR spectrum of the product also shows peaks that are identical between 1.1 and 1.7 ppm to those of deferoxamine mesylate alone, which confirms the effective grafting of DFO onto the N-DOTAGA chitosan after purification.

Example 3 - Synthesis of MEX-CDFO (B3)

The chitosan precursor of the MEX-CDFO polysaccharide is identical to that described in Example 1 (Mw=2.583.105 g/mol, Mn=1.323.105 g/mol, DA=6±0.5%). For 2.5 g of chitosan, 170 mL of ultra-pure water and 2.25 mL of glacial acetic acid are introduced into a 1 L reactor and placed with stirring until the chitosan is completely dissolved. 50 mL of propane-1,2-diol are added to the solution. A solution composed of 785 μL of acetic anhydride dissolved in 25 mL of propane-1,2-diol is then added slowly, the reaction medium is kept under stirring for 4 h. 40 mL of ultra-pure water and 43 mL of a 1 M NaOH solution are added to obtain a solution between pH 5.5 and 6.5. A volume of 75 mL of propane-1,2-diol and 35 mL of DMSO are added. Simultaneously 576 mg of p-NCS- Bz-DFO are weighed and dissolved in 57.6 mL of DMSO. This solution is added at a rate of 150 µL/min. During the addition of DFO, 3.1 mL of 1 M HCl is also added at a rate of 8 µL/min. The solution is kept under stirring and heated at 40° C. overnight. 250 mL of this solution are diluted by 5 in 0.1 M acetic acid then it is reconcentrated to 500 mL by tangential filtration using the Sartoflow® Smart device with two Sartocon® Slice PESU cassettes (polyethersulfone membranes; cutoff: 100 kDa; filtration area: 0.02 m ² ). Filtration is continued at constant concentration against 5 L of acetic acid and 2.5 L of ultrapure water then the solution is reconcentrated to 250 mL.

In the case of MEX-CDFO (B3), the iron chelation method explained previously is also used for the purpose of estimating the DS. This method makes it possible to estimate the DS of MEXCDFO (B3) at 3%.

The 1 H NMR analysis makes it possible to confirm the grafting of the DFO and the DS thanks to the characteristic peaks of the DFO. According to the NMR spectrum, the DS is equal to 2.9%. Also it is possible to determine the DA with this same spectrum. The DA to find is 41%.

Example 4 - Compositions according to the invention (Aqueous solutions)

Different compositions according to the invention have been prepared. A non-functionalized chitosan A of low DA which can be 250 kDa or 650 kDa is mixed with a copolysaccharide B according to a ratio o/% where a is the mass concentration of chitosan A and 0 the mass concentration of copolysaccharide B in the formulation considered (Table 2). Different quantities of chitosan A (a) and copolysaccharide B (P) in freeze-dried form are introduced into a 50 mL reactor and are redispersed with gentle stirring in an adequate volume of water. Acetic acid is added in stoichiometric proportion with respect to the non-functionalized primary amine functions present in the medium. The mixture is left under agitation until complete solubilization of the product.

By way of example, the preparation of composition 10 according to the invention (HG-5-10) takes place as follows: 3.0 g of B1 (MEX-CD2) and 1.5 g of chitosan A1 are dispersed in 28.93 mL of ultrapure water and 1.07 mL of ultrapure acetic acid are added with mechanical stirring at 100 RPM in a 50 mL reactor. The mixture is left stirring for 24 hours until complete dissolution and homogenization of the medium.

The various compositions and their preparations are presented in Table 2.

[0130] [Table 2]

The solution obtained is recovered and introduced into a suitable fluid dispenser, then centrifuged at 4000 RPM for 10 minutes to obtain a solution without air bubbles comprising the composition. The Newtonian viscosities of each solution were determined using an AR200 rheometer from TA Instruments. Each solution obtained was also tested to see if it is possible to produce a gel and/or a thread. The results are presented below (Table 3).

[0132] [Table 3]

These results show that, unlike the composition according to the invention, when the composition comprises only the copolysaccharide B, it is not possible to gel the solution or to produce threads. However, the addition of a copolysaccharide B to a chitosan A makes it possible to obtain a gellable solution and, in certain cases, to lower the viscosity of the resulting solution (cf. comparative compositions 2 and 3 and composition 9, and comparative composition 4 and composition 13), which contributes to better workability of the solution and allows better spinning.

Example 5 - Compositions according to the invention (Gels)

Several hydrogels were obtained by gelation of solutions obtained in Example 3. Gelation of the solution occurs after immersion in a 3 mol/L sodium hydroxide bath. The hydrogels obtained according to the invention are characterized as physical hydrogels where gelation takes place at basic pH after neutralization of the initially protonated amines (NH ₂ ) (NH ₃ ⁺ ) present in the solution. The state of entanglement of the chains resulting from the high initial viscosity is fixed by the formation of the nodes of interchain physical interactions and thus ensures the obtaining of a stable physical hydrogel and of sufficient mechanical properties to be manipulated or stretched. The resulting hydrogels are reversible by acid solution treatment and dissociate from chemical hydrogels where gelation is provided by the formation of irreversible covalent chemical bonds. They can be dried and rehydrated reversibly.

[0135] Obtaining hydroqels in disk form

After centrifugation, compositions 9 to 12 according to the invention are introduced into a PVC mold whose dimensions are either 0=1 cm and h=2 mm or 0=3 cm and h=2.5 mm. After the solution has spread evenly, the mold containing the solution is introduced into a bath of sodium hydroxide (NaOH) at 3 mol/L for 1 hour 30 minutes. The hydrogel disc thus formed is removed from the mold and placed in a water bath for 30 minutes. The disc is then rinsed a second time in another bath of ultrapure water for 30 minutes. The hydrogel is then rinsed in a phosphate buffer at pH=7.4 for 24 hours. It is then introduced with phosphate buffer into a glass bottle and sterilized for 20 minutes at 121°C in an autoclave. The hydrogels obtained in the form of a disc are presented in FIG.

[0137] Obtaining hydroqel in the form of a cylinder

After centrifugation, comparative composition 2 and composition 10 according to the invention are connected to a compressed air system (Nordson Ultimus™) allowing the solution to be extruded. A 5 mm diameter extrusion tube is fitted to the dispenser's syringe and the solution is extruded directly into a 3 mol/L soda bath. The extrusion pressure is adapted to the initial viscosity of the precursor solution and is between 1 and 3 bars. The hydrogel thus formed is left immersed in the sodium hydroxide bath for 1 hour 30 minutes. The cylinder is removed and placed in an ultrapure water bath for 30 minutes. The tube is then rinsed a second time in another bath of ultrapure water for 30 minutes. The hydrogel is then rinsed in a phosphate buffer at pH 7.4 for 24 hours. It is finally introduced with phosphate buffer into a glass bottle and sterilized for 20 minutes at 121°C in an autoclave. The hydrogels obtained in the form of a cylinder are presented in figures 2 and 3.

The hydrogel obtained from chitosan A alone has an opaque white appearance and is relatively rigid to handle. The more the hydrogel is loaded with copolysaccharide B, the more the latter appears transparent with a less pronounced Tyndall effect reflecting a better homogeneity of the structure at the microscopic scale.

Example 6 - Compositions according to the invention (Yarns)

Yarns comprising the composition according to the invention are obtained in the following way: some of the solutions obtained in Example 3 are introduced into a suitable fluid dispenser (or doser), then centrifuged. The fluid dispenser containing the solution is then connected to a compressed air system. An extrusion cone which can be 254 μm, 406 μm, or 584 μm is fitted to the dispenser then the solution is extruded under a constant pressure which can range from 150 kPa to 400 kPa in a bath of concentrated sodium hydroxide at 3 mol/ I. The hydrogel obtained is neutralized in two water baths and then dried at a temperature which can range from 100° C. to 200° C. using a thermo-regulated air blower. The dry yarn is collected and wound into spools. By way of example, the preparation of yarn from composition 10 according to the invention takes place as follows: 3.0 g of copolysaccharide B1 and 1.5 g of chitosan A1 are dispersed in 28, 93 mL of ultra-pure water and 1.07 mL of ultra-pure acetic acid with gentle mechanical stirring at 100 RPM in a 50 mL reactor. The mixture is left stirring for 24 hours until complete dissolution and homogenization of the medium. The solution obtained is recovered and introduced into a suitable fluid dispenser, then centrifuged at 4000 RPM for 10 minutes. The fluid dispenser containing the solution is then connected to a compressed air system and a 406 µm extrusion cone is fitted to the system. A constant pressure of 200 kPa is delivered until complete extrusion of the starting solution. The solution is extruded directly into a 3 mol/L sodium hydroxide bath and gelled directly to form a hydrogel. The hydrogel obtained in the form of a fine cylinder is drawn into a coil circuit and is successively neutralized in two ultrapure water baths each containing 5L of water. The hydrogel is then dried under hot air at 150° C. using a thermoregulated air blower. The yarn obtained after drying is wound on a spool located at the end of the spinning circuit. The yarn obtained is shown in Figures 4 and 5. These figures show that it is possible to tie knots and braid several yarns together.

The mean diameter of the wires was determined under an optical microscope by measuring different portions of the wire. On average, 5 portions of the wire were studied in order to establish an average diameter as representative as possible of the entire structure. The linear density of the different yarns was also determined by weighing different lengths of yarn on a precision balance. The mechanical properties of the yarns obtained were determined by tensile tests using a Shimadzu Autograph AG-X plus system. On average, five tensile tests are carried out on each wire in order to check the repeatability of each measurement. The results are shown in Table 4.

[0143] [Table 4]

These results show that the threads according to the invention have satisfactory mechanical properties comparable to those of threads of chitosan A alone. In particular, the yarns according to the invention have mechanical properties suitable for shaping the yarns by braiding several yarns or by weaving or knitting.

Example 7 - Study of the swelling of threads and gels according to the invention

The gels and yarns according to the invention described in the preceding sections all have unique swelling capacities in the presence of aqueous fluids. First, the capacity and the drying and swelling kinetics of the gels were determined according to the initial formulation. After neutralization of the pH of the hydrogels by successive rinsing, the gel is left in the open air for 1 week until complete drying in xerogel. The mass of the hydrogel was measured on a precision balance before drying and at regular time intervals during drying. The drying kinetics of the hydrogels are listed in Table 6. Since chitosan A is more hydrophobic than copolysaccharides B, the drying rate is slower when the quantity of copolysaccharide B contained in the gel is high. Thus, freezing reference chitosan A alone (comparative composition 2) reaches a stable mass after 30 hours, composition 9 according to the invention (HG-5-5) after 52 hours, composition 12 according to the invention (HG- 8-8) after 72 hours, and compositions 10 and 11 according to the invention (HG-5-10 and HG-5-15) after 144 hours.

[0146] [Table 5]

The xerogels were then immersed in ultrapure water for 48 hours until the gels were completely hydrated. The mass of each gel was precisely measured before hydration and at regular time intervals during the swelling test. The swelling kinetics of the gels are transcribed in Table 6. In the same way as for the drying step, the hydrophobicity of the reference gel based on chitosan A alone leads to limited rehydration of the gel. Thus a low maximum swelling of the gel obtained from comparative composition 2 (Ref HG-8-0), of the order of twice its initial volume, is observed after 6 hours. On the other hand, a strong increase in the swelling capacity of the gels according to the invention is observed, depending on the quantity of copolysaccharide B present in the formulation, going up to more than 22 times its initial volume for the composition 1 1 according to the invention (HG-5-15) after 30 hours.

The gels before and after hydration are presented in FIGS. 6 and 7 (composition 11 according to the invention).

[0149] [Table 6]

The swelling capacity of the threads according to the invention was also evaluated during their rehydration by immersion in an ultrapure water bath. In the same way as for bulk hydrogels, threads according to the invention were cut and then immersed in ultrapure water for 15 minutes. The initial mass of each thread, as well as the mass of the thread at regular time intervals, was measured using a precision balance. The swelling kinetics for the yarns are transcribed in Table 7. A slight difference in swelling is noted for a given formulation as a function of the diameter of the initial yarn. With an identical formulation, the swelling values obtained from the yarns are relatively similar to those obtained with the hydrogels. In the same way as for the hydrogels, the reference yarn based on chitosan A (comparative composition 2, Ref HG-8-0) exhibits a slight maximum swelling of the order of 2 times its initial volume after 15 minutes . The yarn obtained with composition 11 according to the invention (HG-5-15) containing the most copolysaccharide B has a swelling capacity equivalent to the hydrogel of the same formulation, up to 21 times its initial volume after 15 minutes of immersion. Unlike hydrogels, the rehydration observed with threads is very rapid and results from a much higher surface area to volume ratio for threads than for bulk hydrogels. A microscopic observation of the yarn swelling phenomenon was also carried out by immersing part of a yarn obtained with composition 11 according to the invention (HG-5-15) in ultrapure water for 5 minutes. In the same way, the influence of a drop of water deposited on a portion of wire was observed. The wires are shown in figure 8 and 9.

These results show us that the compositions according to the invention have a much higher swelling capacity than the yarns with only chitosan A.

[0152] [Table 7]

An experiment was conducted on a hydrogel disk according to the invention to evaluate the influence of several drying-inflation cycles on the hydration and dehydration capacities of the hydrogel. A solution of composition 11 according to the invention (HG-5-15) was formulated and then gelled in a mold of dimension 0=3cm and h=2.5mm to obtain a hydrogel in the form of a disc whose mass was measured precisely to the precision balance. The hydrogel is then rinsed as described above, then left to dry for 1 week and weighed. The xerogel is then again hydrated and weighed after complete hydration and then again dried for a week. After a week the gel is weighed and then again immersed in water for 5 days. The values obtained over several cycles are transcribed in Table 8.

[0154] [Table 8]

[0155] A small loss of mass linked to the reduction in the swelling and drying capacities of the gel seems to occur gradually over the cycles of hydration and dehydration, but remains very limited. Similarly, a limited loss of 14% in swelling capacities is observed after two complete cycles of hydration and dehydration spanning a total of two weeks.

Example 8 - Study of the metal extraction capacity of the wires according to the invention

The lead, copper, cadmium and iron extraction capacity of certain wires according to the invention was evaluated precisely by ICP-MS analysis after immersion of the wires in dilute solutions of metals. First, an experience was carried out on a metal solution containing three metal cations (Cu ²⁺ , Pb ²⁺ , Cd ²⁺ ). 10 mL of metal solutions composed of the three metals Cu, Pb and Cd at 0 ppb, 10 ppb and 100 ppb respectively were prepared in pure water from a reference solution of each metal at 500 ppb. In parallel, a 1 mg wire is weighed precisely on the precision balance and this piece is then cut into four pieces of identical lengths and masses (m = 0.25 mg). The four pieces of wire are then immersed in each metal solution. After a period of 4 hours, 1 day, 2 days and 1 week respectively, a piece of yarn is removed and then dried in an oven for 24 hours at 40°C. The samples dry at 4 hours, 1 day and 2 days are then analyzed using an ICP-MS Nexion 2000 spectrophotometer from Perkin-Elmer without prior mineralization and after simple solubilization of the dry thread in 1 mL of a solution of nitric acid (HNO ₃ ) at 10% wt. The samples at 1 week are, for their part, recovered then introduced into a Teflon container with 2 mL of HNO ₃ at 69% wt. and 1 mL of ultrapure water for digestion in a Multiwave 5000 microwave from Anton Paar for 30 minutes at 200°C. The mineralized product is then analyzed by ICP-MS. The results obtained on the yarn obtained with composition 12 according to the invention (HG-8-8) are presented in Table 9.

[0157] [Table 9] The yarn used for this experiment is obtained with composition 12 according to the invention (HG-8-8) and therefore consists of 50% by weight of chitosan A and 50% by weight of copolysaccharide B. The yarn has been immersed in a metal solution of 10,000 times its own volume and is capable of efficiently extracting copper, lead and cadmium by concentrating the metals more than 1000 times in its volume compared to the surrounding solution. The wire is also capable of effectively extracting the three metals for dilute metal solutions of the order of ten ppb.

A metal extraction study was also conducted in a biological medium on reconstituted and heavily hemolyzed pig blood in order to assess the iron extraction capacity of the wires. 10 mL of a solution of haemolyzed pig blood are prepared by redispersion at 10 g/L of the dried blood powder in ultrapure water. In parallel, a 1 mg wire is weighed precisely on the precision balance and this piece is then cut into four pieces of identical lengths and masses (m=0.25 mg). The four pieces of wire are then immersed in the reconstituted pig's blood solution. After a period of 1 hour, 2 hours, 4 hours and 24 hours respectively, a piece of yarn is removed and then rinsed in 60mL of ultrapure water for 1 minute before being dried in an oven for 24 hours at 40°C. . The dry threads are then recovered and introduced into a Teflon container with 2mL of HNOs at 69% wt. and 1 mL of ultrapure water for digestion in a Multiwave 5000 microwave from Anton Paar for 30 minutes at 200°C. The mineralized product is then analyzed by ICP-MS. The results obtained on three wires are presented in Table 10.

[0160] [Table 10]

After one hour of immersion, the three wires are capable of extracting iron from the medium. However, the addition of copolysaccharide B in the composition makes it possible to increase the chelation capacities of the wire with respect to iron after one hour and significantly after 2 hours. This increase is particularly significant when the composition according to the invention comprises 2 chelating agents of different Rc type.

The iron extraction capacity according to the invention against different iron (III) chelators (citrate, NTA, Deferiprone) was precisely evaluated by ICP-MS analysis after immersion of the xerogel pellets in iron solutions. (2 ppm iron) containing iron chelators in proportions to have one iron cation per complex (11 citrate/1 iron; 1.1 NTA/1 iron; 4 Deferiprone/1 iron). The solutions are buffered at pH 7.4 with 0.1 M PBS for the solutions having citrate or deferiprone, for the solutions having NTA the buffer used is 0.05 M Tris HCl. A xerogel pellet of known mass was immersed in a volume of 20 ml of metallic solution for a period of 24 hours in the case of the experiment with deferiprone and 90 hours for the experiments with NTA and citrate. The control pellets were immersed in the buffer solution (PBS or Tris-HCl) for a time corresponding to the experiment considered. Samples were taken from the solutions at t: 0 and t: final. These samples are then analyzed using an ICP-MS Nexion 2000 spectrophotometer from Perkin-Elmer. The gel pellets are recovered and mineralized in a Multiwave 5000 microwave from Anton Paar according to the method presented previously. Thus the resulting solutions are analyzed by ICP-MS. The results obtained for inventions 10, 16, 17, 15, 18 of respective compositions HG-5-10; HG-5-9.5-0.5; HG-5-9.2-0.8; HG-5-9-1; HG-5-8-2 are shown in Table 11.

[Table 11 ] comprising iron chelates having relatively low complexation constants such as citrate or NTA. In the case where the pellets are faced with a strong iron complexing agent as is the case with deferiprone, only the gels comprising DFO are capable of extracting iron, which corresponds to inventions 16, 17, 15, 18 Invention 18 (HG-5-8-2) having the most MEX-CDFO (B3) polymer in its composition has the best iron extracting capacity compared to deferiprone.

Another metal extraction study was conducted in a biological medium on bovine plasma in order to evaluate the iron extraction capacity of the pellets under conditions closer to reality. For inventions 10, 16, 17, 15 and 18, a pellet was weighed and introduced into 20 mL of bovine plasma for 24 hours. The t:0 plasma is analyzed by ICP-MS. The pellets are mineralized and analyzed by ICP-MS according to the method explained above. The results obtained for inventions 10, 16, 17, 15, 18 of respective compositions HG-5-10; HG-5-9.5-0.5; HG-5-9.2-0.8;

HG-5-9-1; HG-5-8-2 are shown in Table 12.

[Table 12] After 24 hours, the 3 gels are able to extract part of the iron from the plasma. Example 9 - Studies of the release capacity of threads and hydrogels according to the invention

The loading capacity of the yarn with the substance of interest and their controlled release into another solution or another medium have been demonstrated. First, the possibility of loading and releasing the thread with a substance was evaluated using a fluorescent molecule. 10 mL of a 25 mg/L fluorescein solution is prepared by dissolving fluorescein in ultrapure water. A 4 mg thread is then cut and weighed on a precision balance before being immersed in the fluorescein solution for 10 minutes. The threads are then removed from the solution and dried in an oven at 40° C. for 2 hours then at ambient temperature for 3 days. The wire is then immersed in 20 mL of ultrapure water and a sample of 2 mL of this solution is taken after 0, 1, 2, 5, 10, 15, 30, 45 minutes and after 15 hours and is analyzed using a Cary Eclipse fluorescence spectrometer from Agilent (Table 11).

[0166] [Table 13]

The loading and release capacities of the substance of interest of three thread formulations were studied using fluorescein by analysis of the fluorescence of the solution after release. The three threads release fluorescein 1 minute after immersion of the charged dry thread in ultrapure water. Comparative formulation 2 (HG-8-0) composed solely of chitosan A releases very little fluorescein. The addition of copolysaccharide B in the yarn composition allows to increase the release capacity of the threads, this is particularly true the more the composition is loaded with copolysaccharide B

An identical experiment was carried out, this time loading the threads with miconazole, which is an imidazole antifungal molecule commonly used in various medical devices (topical spray, creams, lotions, etc.) to cure the fungal infections. 100 mL of a 0.1 g/L miconazole solution is prepared by dissolving miconazole in ultrapure water. A thread obtained from composition 10 according to the invention (HG-5-10) of 0.9 mg (10 cm) is then cut and weighed on a precision balance before being immersed in the miconazole solution for 10 minutes . The threads are then removed from the solution and hung on a glass rod to dry for 3 hours at room temperature. The wire is then immersed directly in 3 mL of ultrapure water contained in a plastic spectrophotometer cuvette and an analysis of the medium is carried out at regular time intervals by fluorescence analysis using a Cary Eclipse fluorescence spectrometer from Agilent (Table 12).

[0169] [Table 14]

The same experiment was carried out by loading the threads with penicillin, which is an antibiotic. 100 mL of a penicillin solution at 0.1 g/L is prepared by dissolving the penicillin in ultrapure water. A thread obtained from composition 10 according to the invention (HG-5-10) of 0.9 mg (10 cm) is then cut and weighed on a precision balance before being immersed in the penicillin solution for 5 minutes. The threads are then removed from the solution and hung on a glass rod to dry for 3 hours at room temperature. The wire is then immersed in 10 mL of ultrapure water and samples are taken after 1 h, 2 h and 22 h. THE samples are then analyzed by UV-visible absorbance using a

Varian Cary 50 UV-Vis spectrophotometer from Agilent (Table 13).

[0171] [Table 15]

These results show that the compositions according to the invention can be loaded with active pharmaceutical ingredient, and can also release them.

Example 10 - Preliminary study of the composition of a gelling injectable solution

Several solutions were prepared in the same way as described in example 4 but this time the quantity of acetic acid is added so as to obtain a homogeneous mixture where the acid is lacking with respect to the functions unfunctionalized amines. Briefly, different amounts of chitosan A1 and compound B1 are added to a reactor with milli-Q water and acetic acid. The mixture is left stirring for at least one hour at 100 RPM. The solution is then collected and introduced into a fluid dispenser and then centrifuged at 4000 RPM for 10 minutes to remove the remaining air bubbles. The pH and osmolarity of each formulation were measured with a Mettler Toledo SevenCompact S210 pH meter and a Camlab Loser Micro MCD200 Plus osmometer respectively. The different compositions and their preparations are shown in Table 16.

[Table 16]

The pH values obtained on the aqueous solutions of MEX-CD2 without addition of acid are relatively low. This is explained by the prior presence of acetic acid in the MEX-CD2 lyophilisate to ensure its solubility during the purification step. The acetic acid contained in the MEX-CD2 lyophilisate is also osmotically active and contributes to an increase in osmolarity. The viscosity of each solution was measured using a HAAKE RheoStress 600 rheometer equipped with a C35/ ²⁰ Ti L plane cone geometry. The values of the Newtonian viscosities are presented in Table 15. It is noted that the viscosity directly depends on the total polymer concentration, the lower the concentration, the lower the viscosity. In the same way, at an equal total polymer concentration, a larger mass fraction of MEX-CD2 contributes to reducing the viscosity.

The injectability of each composition was precisely measured using a Shimadzu AG-X plus force machine. Each solution was introduced into a BD Hylok™ 1 mL pre-fillable glass syringe fitted with a Sterican 27G needle (0.4x12 mm). Injectability was determined as the force in Newtons required to eject the solution at a constant piston velocity of 1 mm/s. The injectability of the system mainly depends on the viscosity of the solution and therefore depends on the total polymer concentration and to a lesser extent on the mass fraction of MEX-CD2 in the composition considered. Thus, the solutions are readily injectable at 3% (w/w), moderately injectable at 5% (w/w), difficult to inject at 7% (w/w), and non-injectable at 10% (w/w) ( T. E. Robinson et al., Filling the Gap: A Correlation between Objective and Subjective Measures of Injectability, Adv. Healthc. Mater., vol. 9, no 5, p. 1901521 , 2020).

[Table 17]

Example 11 - Determination of the mass fraction of MEX-CD2 suitable for a gelling solution for injection

This example makes it possible to demonstrate the impact of the mass fraction of MEX-CD2 on the final formulation. Therefore, 5% (w/v) solutions were produced with different mass fractions of MEX-CD2 ranging from 0% to 100% MEX-CD2. Each of these formulations was sterilized for 20 minutes at 121°C in an autoclave to assess the impact of this process on the rheological properties of the system. For each of these formulations, the pH, osmolarity, viscosity and injectability were determined and are presented in Table 18.

[Table 18]

These formulations were produced by adding acetic acid in stoichiometric proportions with the free amines of the two polymers; the residual amount of acetic acid present in the MEX-CD2 lyophilisate was not considered. This explains why the pH decreases almost linearly with the quantity of MEX-CD2 added to the composition and therefore with the mass fraction of MEX-CD2 of the formulation considered. The Newtonian viscosity measured on these solutions before and after sterilization decreases linearly as a function of the mass fraction of MEX-CD2. The injectability follows the same trend and therefore demonstrates that the greater the amount of MEX- CD2 is important in the formulation considered, the more the latter is simple to inject. The 5% (w/v) formulated samples are all moderately injectable at 27G with ejection forces ranging from 19 N for a 100% MEX-CD2 formulation to 38 N for a standard 100% chitosan formulation. The impact of sterilization on the viscosity of the formulation strongly depends on the mass fraction of MEX-CD2. Thus, the formulations comprising a mass fraction of MEX-CD2 greater than or equal to 67% see their viscosities little or not affected during the sterilization of the mixture.

Example 12 - Injectability and gelation of an injectable gelling solution MEX-CD2-I

This example aims to precisely determine the physico-chemical and rheological properties of two formulations of MEX-CD2-I (gelling injectable solution) selected from the results of the preceding examples. Thus the formulations at 5% (w/w) with a mass fraction of MEX-CD2 equal to 67% and 100% respectively were studied more precisely. The 67% MEX-CD2 formulation was synthesized at two slightly different pHs to assess the impact of pH on the rheological properties of the formulation. Each of these two formulations was also prepared at 10% (w/w) in order to envisage a mixture of these more concentrated precursor solutions with molecules of interest according to a 1:1 ratio. Each of these formulations was sterilized for 20 minutes at 121°C in an autoclave to study the impact of sterilization on their properties. For each of these formulations, pH, osmolarity and viscosity were measured and are shown in Table 19. For the 5% (w/w) formulations, injectability was also determined using different needles.

[Table 19]

The injectability of the formulations mainly depends on the Newtonian viscosity of the solution, the internal radius of the needle and, to a lesser extent, the length of the needle used. For a formulation at 5% (w/w) with a mass fraction of MEX-CD2 of 67%, it is observed that a reduction in the pH generates a significant increase in the injectability after sterilization of the mixture. This is in agreement with the observation made on the viscosity of the system. The 5% (w/w) formulation with 100% MEX-CD2 is easier to inject than the 67% MEX-CD2/CTS formulation, regardless of the needle used. Finally, whatever the formulation considered, the system does not seem to be manually injected with a 30 G needle. The two formulations can be injected manually by a practitioner with a 27 G needle or less.

The IS-1,7-3,3 and IS-0-5 compositions are capable of gelling spontaneously by immersion in a physiological medium having a pH greater than 6.2 and an osmolarity greater than 285 mOsm/L [Fig .10]. To evaluate the rheological properties of the gel formed, 2 mL of the composition IS-1,7-3,3 are introduced into a mold under disc shape 25 mm in diameter. The mold is immersed in 20 mL of 10 mM PBS and left for 2 hours. The storage modulus (G') and the loss modulus (G") of the formed hydrogel were recorded on an ARES rheometer from TA Instruments using a 25 mm plane/plane geometry. Before the measurement, the deviation The apparatus is zeroed with the mold empty. A sweep with a constant strain of 1% and a frequency of 10 Hz was performed on the formed hydrogel after placing the mold containing the hydrogel on the geometry. hydrogel begins to form spontaneously after immersion in PBS and a progressive gelation front can be observed. The gel obtained has values of G' and G" greater than 10 ² Pa for a high oscillation frequency, which corresponds to a very flexible gel. Moreover, the value of G' is higher than that of G" which means that the resulting material is indeed closer to a gel than to a solution. G' and G" decrease with frequency which seems to put in evidence of a significant relaxation phenomenon (flow/relaxation/chain mobility, viscoelastic effect) due to a weakly cross-linked gel.

Example 13 - In-vivo tolerance study of the implantation in the peritoneal cavity of a xerogel HG-5-10

A xerogel (h=1.5 mm and 0=10 mm) in the form of a pellet was obtained by partial drying of a gel comprising the composition HG-5-10 prepared as described in example 4. This xerogel has was implanted into the peritoneum of 10 male C57BI/6 mice to assess the biocompatibility and tolerance of the implant. Parameters assessed in this study include lifetime observations and measurements (including morbidity/mortality, clinical signs, body weight, food consumption), hematology before and after treatment, and blood chemistry and organ weights after treatment and autopsy. Half of the mice were sacrificed on D7 and the other half on D56.

Under the experimental conditions adopted, xerogel HG-5-10 administered as an implantable medical device in the peritoneum, in C57BI/6 male mice, did not induce systemic signs of toxicity. In this study, no death, significant change in body weight or haematological change was induced by the implant at D7 and D56 in mice. Intra-abdominal implantation of xerogel HG-5-10 did not cause microscopic changes in the liver or changes in liver weight.

Example 14 - In-vivo MRI study of the degradability of the gelling injectable solution IS-1,7-3,3 by subcutaneous administration

About 300 μl of the IS-1,7-3,3 formulation loaded with 305 ppm of Gd (precomplexed on MEX-CD2) were injected subcutaneously into the back of BALB/c mice in good condition. health using a 22G syringe. MRI images, in Figure 11, of the gel implanted in mice were acquired for 1 month after implantation at 7.1 T on a Bruker Avance Neo 300 MHz spectrometer equipped with a micro-2.5 micro-imaging probe at room temperature (RT=21 ^° C.). Signal intensities in liver, kidney and spleen were also monitored.

In FIG. 12, the T ₂ w images were acquired using a standard RARE sequence (Rapid Acquisition with Refocated Echoes) with the following parameters: TR = 4000 ms, TE = 24 ms, RARE factor = 16, number of means = 4, FOV = 30 mm, slice thickness = 1 mm, matrix size 128x 128. Ti w images were acquired using a standard MSME (multi spin multi echo) sequence with the following parameters: TR = 400 ms, TE = 3.3 ms, number of averages = 6, FOV = 30 mm, slice thickness = 1 mm, die size 128x 128. Ti values were measured using a Saturation sequence Recovery Spin Echo (TE = 3.8 ms, 10 variable TR ranging from 50 to 5000 ms, FOV = 30 mm, slice thickness = 1 mm, array size 128 x 128) and analyzed using the equation Saturation Recovery Ti. The size of the gel formed was measured by manual drawing of the ROI in the MRI images.

As listed in Table 20, the volume occupied by the formed gel decreased to approximately 50% of the initial volume in 30 days of monitoring, while the Ti measured in the same area increased approximately 6 times. . From day 15 after implantation, implant heterogeneity began to increase due to cell infiltration. This infiltration is demonstrated by the increase in the standard deviations in Ti measured from day 15 to day 30. The starting volumes of the implants in the 3 mice were respectively 304, 348 and 216 mm ³ . Tiw signal intensities in liver, kidney and spleen did not increase over the time range studied.

[Table 20]

Claims

Claims [Claim 1] A composition comprising: a. At least one chitosan A, and b. At least one random copolysaccharide B with a weight-average molecular mass of between 100kDa and 1000kDa of formula I: Formula I in which: - each Rc independently represents a group comprising a chelating agent, - each Z independently represents a binder which may be a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more heteroatoms, preferably chosen among nitrogen, oxygen, sulfur and atoms of the halogen family, - x is between 0.01 and 0.5, - y is between 0.05 and 0.5, - the y/x ratio being greater than 0.2, preferably greater than 1, - the sum x + y being greater than 0.1, and less than 10% of the groups comprising a chelating agent of Rc type being chelated by a cation of a transition element chosen from among the elements of block d and f, and c . possibly water. [Claim 2] Composition according to Claim 1, characterized in that it has: - a level of crystallinity reduced to chitosan A of at least 10% relative to the total dry mass of the composition, and - a chitosan A crystallite size of less than 20 nm. [Claim 3] Composition according to one of the preceding claims, characterized in that the mass ratio between A and B (A:B) is between 2:1 and 1:10, preferably between 1:1 and 1:5 . [Claim 4] Composition according to one of the preceding claims, characterized in that chitosan A has an average molecular weight M _w of between 100 kg/mol and 1000 kg/mol, preferably between 200 kg/mol and 700 kg/mol. soft. [Claim 5] Composition according to one of the preceding claims, characterized in that chitosan A has a degree of acetylation x of less than 40%, preferably less than 10%, for example between 0% and 10%. [Claim 6] Composition according to one of the preceding claims, characterized in that the random copolysaccharide B with a weight-average molecular mass of between 100 kDa and OOkDa of formula I is of formula II: Formula II in which: - Rci and RC ₂ are different, and are groups containing a chelating agent, - Zi and Z ₂ , which are identical or different, are binders which may be a single bond or a hydrocarbon chain comprising between 1 and 12 carbon atoms, said chain possibly being linear or branched and possibly comprising one or more unsaturations and possibly comprising one or more several heteroatoms, preferably chosen from nitrogen, oxygen, sulfur and atoms of the halogen family, - x is between 0.01 and 0.5, preferably between 0.01 and 0.1, and preferably between 0.05 and 0.1, - y is between 0.01 and 0.5, preferably between 0.05 and 0.2, - z is between 0 and 0.2, and less than 10% of the groups comprising a chelating agent of the Rc1 and Rc2 type being chelated by a cation of a transition element chosen from the elements of block d and f. [Claim 7] Composition according to one of the preceding claims, characterized in that it additionally comprises at least one active pharmaceutical ingredient, preferably chosen from anticancer agents, antibacterials, antifungals, antiinflammatories, messenger RNAs , proteins, and antigens. [Claim 8] Composition according to one of the preceding claims, characterized in that it is an aqueous solution, preferably comprising at least 10 g/L of the mixture of chitosan A and polysaccharide B. [Claim 9] Composition according to one of Claims 1 to 7, characterized in that it is in the form of a lyophilisate or of a gel, preferably in the form of a hydrogel, a xerogel or an airgel. [Claim 10] Composition according to Claim 9, characterized in that it is in the form of a xerogel, the said xerogel being derived from the at least partial drying of a hydrogel. [Claim 11] Composition in the form of a xerogel according to claim 10, characterized in that in contact with an aqueous medium or a biological tissue for a period of at least 1 hour, it swells to form a hydrogel, said hydrogel having a volume at least 2 times greater, preferably at least 5 times greater, than the volume of reference xerogel before contact with the aqueous medium or the biological tissue. [Claim 12] Wire characterized in that it comprises a gel or a lyophilisate of the composition according to Claim 9. [Claim 13] Textile material characterized in that it comprises yarns according to claim 12. [Claim 14] Medical device characterized in that it comprises the composition according to one of claims 1 to 1 1, the medical device preferably being a dressing, an implant or a dermal filler. [Claim 15] Medical device according to claim 14, characterized in that it is a dermal filler in the form of a thread, said thread preferably being in the form of a xerogel which can swell on contact with a medium aqueous or biological tissue to form a hydrogel. [Claim 16] Composition according to one of Claims 1 to 11 for its use for the capture of at least one metal, preferably for its use for the capture of at least one metal in the treatment or prevention of endometriosis, fungal infections, bacterial infections, chronic wounds, neurodegenerative diseases, nervous system damage, hemochromatosis, Wilson's disease or lead poisoning. [Claim 17] Process for the preparation of a composition according to one of Claims 1 to 7, comprising the following steps: 1) dispersion of chitosan A and random polysaccharide B with a weight-average molecular mass of between 100 kDa and 1000 kDa of formula I in water, 2) addition of an acid, preferably acetic acid, 3) mixing then centrifugation of the solution obtained to recover a solution comprising the composition according to one of claims 1 to 7, 4) optionally, treatment of the solution obtained in step 3 in a basic aqueous bath to obtain the composition in the form of a gel, and 5) optionally, washing, drying and/or sterilization of the gel obtained in step 4, preferably by autoclave.