EP1440114A1

EP1440114A1 - Material consisting of at least a biodegradable polymer and cyclodextrins

Info

Publication number: EP1440114A1
Application number: EP02781387A
Authority: EP
Inventors: Ruxandra Gref; Patrick Couvreur
Original assignee: Centre National de la Recherche Scientifique CNRS
Current assignee: Centre National de la Recherche Scientifique CNRS
Priority date: 2001-09-27
Filing date: 2002-09-27
Publication date: 2004-07-28
Also published as: JP2005503476A; CA2461421A1; US20050043481A1; FR2830017B1; WO2003027169A1; FR2830017A1

Abstract

The invention concerns a material consisting of at least a biodegradable polymer and a cyclic oligosaccharide, characterized in that at least one molecule of said oligosaccharide is grafted via a covalent bond to at least a molecule of said biodegradable polymer. The invention also concerns a method for preparing said material, the nanoparticles and microparticles derived from said material and uses thereof as biological vectors for active substances.

Description

MATERIAL COMPOSED OF AT LEAST ONE BIODEGRADABLE POLYMER AND

CYCLODEXTRIN

The present invention relates to new materials based on biodegradable polymers and cyclic oligosaccharides, preferably cyclodextrins, particles derived from these materials and their uses as biological vectors for active materials.

The present invention relates very particularly to the field of vectors of the nano- and microparticles type and their applications.

Commonly, the term "nanoparticles" includes nanospheres as well as nanocapsules. Nanocapsules are vesicular vectors formed by an oily cavity surrounded by a polymeric wall, and nanospheres are made up of a polymer matrix capable of encapsulating active ingredients. Generally, the active products are incorporated at the level of the nanoparticles either during the polymerization process of the monomers from which the nanoparticles are derived, or by adsorption on the surface of the nanoparticles already formed, or during the manufacture of the particles from the preformed polymers.

Different types of nano- and microparticles are already proposed in the literature. Conventionally, they are derived from a material obtained by direct polymerization of monomers (for example cyanoacrylates), by crosslinking, or else they are produced from preformed polymers: poly (lactic acid) (PLA), po! Y (glycolic acid) (PGA), poly (ε-caprolactone) (PCL), and their copolymers, such as for example poly (lactic acid-co-glycolic acid) (PLGA), etc.

More recently, a new type of material has been produced by catalytic polymerization of monomers (such as for example lactide or caprolactone) on cyclodextrins. Unfortunately, it is not possible to precisely control the chemical composition of this type of copolymer. Indeed, all the hydroxyl functions present on the cyclodextrins are capable of initiating the polymerization of the monomers. A very large number of polymer chains of variable sizes are thus formed deriving from the monomer, which on the one hand turns out to be uncontrollable and on the other hand has the effect of disturbing the complexing properties of the cyclodextrins. Consequently, obtaining this type of copolymer by direct polymerization of the monomers on the cyclodextrins does not make it possible to control the degrees of polymerization and of substitution and therefore to ensure good reproducibility of synthesis and to prepare homogeneous samples.

In conjunction with this problem of controlling the chemical composition of polymers, there is that of their weak encapsulation capacity. Indeed, the capacity loaded with active principles of nanoparticles is often limited. This drawback is more particularly encountered for the encapsulation of poorly water-soluble active ingredients since the conventional methods of manufacturing nano- or microparticles often use polymerization techniques in an aqueous medium.

Consequently, the materials currently available are not entirely satisfactory.

The first object of the present invention is precisely to propose a material making it possible to overcome these drawbacks.

Its second object relates to particles, preferably nanoparticles, obtained from such a material. The invention also aims in a third object, the use of these particles and in particular as biological vehicles.

More specifically, the first aspect of the invention relates to a material composed of at least one biodegradable polymer and of a cyclic oligosaccharide, characterized in that at least one molecule o of said oligosaccharide is grafted via a bond covalent to at least one molecule of said biodegradable polymer. In contrast to the materials mentioned above, the material developed according to the present invention has the first advantage of having a controlled structure and therefore of being able to be prepared in a reproducible manner. The biodegradable polymer used is in particular characterized in terms of molar mass.

More specifically, the claimed material is obtained by functionalization of the molecule of a biodegradable polymer with at least one molecule of cyclic oligosaccharide.

This functionalization is carried out by establishing a covalent bond between the two types of molecule. In this case, this covalent bond is biodegradable and preferably derives from the reaction between a carboxylic acid function and a hydroxyl function, leading to an ester function.

More preferably, this bond is derived from the reaction between a carboxylic function, optionally activated, present on the biodegradable polymer and a hydroxyl function present on the oligosaccharide. The preferred activated derivatives of the acid are either the N-hydroxysuccinimide ester, previously synthesized and isolated, or derivatives obtained "in situ" and not isolated from the reaction medium, for example that derived from carbonyidiimidazole (CDI) This reactive function preferably derives from the carboxylic function which can either be naturally present on the backbone of the biodegradable polymer or have been introduced there before at its backbone, so as to allow its subsequent coupling with a molecule of a cyclic oligosaccharide.

According to a preferred variant of the invention, the claimed material is composed of a copolymer in accordance with the invention which is grafted at the level of said biodegradable polymer to a second molecule of cyclic oligosaccharide, a second molecule of biodegradable polymer and / or a molecule distinct from said biodegradable polymer and from said cyclic oligosaccharide. In Figure 1 are shown schematically structures according to the invention.

According to a first variant of the invention, the biodegradable polymer molecule is grafted, preferably in the terminal position, by a biodegradable covalent bond, preferably of the ester type, to at least two cyclic oligosaccharide molecules, preferably of the cyclodextrin type. .

According to a second variant of the invention, the biodegradable polymer molecule is grafted by a biodegradable covalent bond, preferably of ester type, to at least one oligosaccharide molecule, preferably of cyclodextrin type and a molecule of a separate polymer , preferably poly (ethylene glycol).

This second variant consisting in fixing at the free end of the biodegradable polymer, a second molecule or macromolecule is particularly advantageous when it is desired to prevent any spontaneous self-encapsulation of the hydrophobic chain of said biodegradable polymer in the cavity of the oligosaccharide more particularly. a cyclodextrin. In this way, it ensures the availability of said cavity for any hydrophobic active principle. Whatever the variant considered, it can also be envisaged that the graft (s) carried by the biodegradable polymer molecule is also grafted by a biodegradable function, preferably of the ester type, to one or more other molecules of said biodegradable polymer, thus making it possible to obtain materials of very high molar mass (crosslinked).

The materials according to the invention have the second advantage of having satisfactory biodegradability due to the chemical nature of the polymers which constitute it.

For the purposes of the invention, the term “biodegradable” is intended to denote any polymer which dissolves or degrades in a period acceptable for the application for which it is intended, usually in in vivo therapy. Generally, this period must be less than 5 years and more preferably one year when a corresponding physiological solution is exposed with a pH of 6 to 8 and at a temperature between 25 ° C and 37 ° C. The biodegradable polymers according to the invention are or are derived from synthetic or natural biodegradable polymers.

Conventionally, the most widely used synthetic biodegradable polymers are polyesters: PLA, PGA, PCL, and their copolymers, such as for example PLGA. Indeed, their biodegradability and biocompatibility have been widely established. Other synthetic polymers are also being investigated. These are polyanhydrides, poly (alkylcyanoacrylates), polyorthoesters, polyphosphazenes, polyamino acids, polyamidoamines, polysiloxane, polyesters such as polyhydroxybutyrate or poly (malic acid), as well as their copolymers and derivatives. Natural biodegradable polymers (proteins such as albumin or gelatin, or polysaccharides such as alginate, dextran or chitosan) may also be suitable.

In this case, synthetic polymers are particularly interesting because their bioerosion is observed quickly. However, commercial polymers are not always suitable for being coupled with one or more oligosaccharides because they do not have the reactive group considered, more particularly the carboxylic acid group, especially in the case of linear biodegradable polyesters (PLA, PCL, etc.). .). Consequently, the coupling of these polymers with a cyclic oligosaccharide in accordance with the present invention involves a prior synthesis of the polymers having the required reactive groups, more particularly the carboxylic acid functions, while controlling the nature of the groups naturally present at the chain end . These are in particular the compounds thus obtained that it is intended to denote in the context of the present invention by the term derivatives of biodegradable polymers.

This is how the biodegradable polymer preferably corresponds to general formula I:

(R-,) - biodegradable polymer - (R ₂ ) _m (I)

in which :

- n and m represent independently of each other, either 0 or 1,

- Ri represents a Cι-C ₂ o alkyl group, a polymer different from the biodegradable polymer [for example poly (ethylene glycol) (PEG)], or a copolymer containing PEG blocks or ethylene oxide units, such as for example a Pluronic® polymer], a protected reactive function present on the polymer (eg BOC-NH-), a carboxylic function or a hydroxyl function and

- R ₂ represents a hydroxyl function or a carboxylic function.

Polyesters are especially preferred as biodegradable polymers according to the invention: poly (lactic acid) (PLA), poly (glycolic acid) (PGA), poly (ε-caprolactone) (PCL), and their copolymers, such as for example poly (lactic acid-co-glycolic acid) (PLGA), synthetic polymers such as polyanhydrides, poly (alkylcyanoacrylates), polyorthoesters, polyphosphazenes, polyamides (eg polycaprolactam), polyamino acids, polyamidoamines, poly (alkylene d-tartrate), polycarbonates , polysiloxane, polyesters such as polyhydroxybutyrate or polyhydroxyvalerate, or poly (malic acid), as well as the copolymers of these materials and their derivatives.

It is more preferably a polylactic, a polyester preferably of molecular weight less than 5000 g / mole and in particular of a polycaprolactone preferably having a molecular weight of between 2000 and 4000 g / mole.

The claimed material is also particularly advantageous for developing nanoparticles or microparticles having a high encapsulation capacity thanks to the presence within its structure of cyclic oligosaccharide molecules. Of course, the encapsulation rate is a function of the mass rate of cyclic oligosaccharide.

For the purposes of the present invention, the term “oligosaccharide” is intended to denote a cyclic chain of at most 15 and preferably at most 10 monosaccharide units joined by glycosidic bonds.

The cyclic oligosaccharide is preferably chosen from cyclodextrins which can be neutral or charged, native (cyclodextrins α, β, γ, δ, ε), branched or polymerized or else chemically modified for example by substitution of one or more hydroxyls by groups such as alkyls, aryls, arylalkyls, glycosyls, by etherification with alcohols or by esterification with aliphatic acids, as well as by grafting of polymeric links (eg polyethylene glycol). Among the above groups, more particularly preferred are hydroxypropyl, methyl and thiobutyl ether groups.

Of course, these modifications must concern few of the groups present on the cyclic oligosaccharides, so as to leave the vast majority of them free to then allow the coupling of the biodegradable polymers. Thus, cyclodextrins have already been described grafted with hydrophilic chains of the poly (ethylene glycol) type.

The presence of at least one molecule and preferably two molecules of cyclic oligosaccharides, in particular of cyclodextrins covalently linked to the hydrophobic polymer in the material according to the invention is particularly advantageous. It allows the active principle, intended to be transported using particles derived from the claimed material, to penetrate inside the polymer structure of said material and this whatever its nature, namely hydrophobic, amphiphilic and / or insoluble . This results in a significantly increased encapsulation yield due to the presence of the hydrophobic internal cavities of the cyclodextrins. These allow on the one hand to increase the charge in active principle, and on the other hand to access a better control of the release profile. According to an advantageous embodiment of the present invention, the claimed material has a mass content of cyclic oligosaccharide, preferably cyclodextrin, at least equal to 10% and advantageously between approximately 20 and 40%.

In addition to an advantageous behavior in terms of biodegradability and encapsulation capacity, the material according to the invention is also particularly advantageous in terms of bioadhesion and targeting properties for the particles which are derived therefrom at the level of organs and / or cells. .

As a representative of the material claimed, mention may more particularly be made of a copolymer having a biodegradable polymer backbone and at least two cyclodextrin grafts, optionally grafted with one or more biodegradable polymer molecules of chemical nature, whether or not distinct from those of the polymer constituting the skeleton of said material. The second variant of the invention relates to a material composed of molecules of biodegradable polymers grafted on the one hand to a molecule of a cyclic oligosaccharide, preferably of the cyclodextrin type, and on the other hand to a molecule of a biodegradable polymer distinct, is particularly interesting in this respect. According to this variant, it is in fact possible to envisage incorporating, at the level of the structure of the material, compounds intended to intervene in level of the release profile of the active materials to be released from the nanoparticles composed of said material.

One can also consider modifying the structure of the materials for example, by grafting by an ester bond to the biodegradable polymer molecule of one or more PEG chains. The particles thus covered with a crown of PEG manifest a prolonged circulation in the blood.

The copolymers constituting the claimed material can be in the form of di- or multi-block copolymers, have a structure of the linear, branched or crosslinked type.

Under the term "crosslinked", reference is made to polymers forming a three-dimensional network as opposed to simplified linear polymers. In the three-dimensional network, the chains are connected to each other by covalent or ionic bonds and become insoluble.

Diblock or multiblock copolymers can be obtained by varying the oligosaccharide / biodegradable polymer molar ratio during synthesis. The crosslinked structure copolymers can be obtained from biodegradable polymers comprising at least two reactive functions.

The second aspect of the present invention relates to a process for preparing the claimed material.

More specifically, this method comprises bringing together at least one molecule of a biodegradable polymer or one of its derivatives carrying at least one reactive function, with at least one molecule of a cyclic oligosaccharide, under suitable conditions to the formation of a covalent bond between the two types of molecules and in that said material is recovered. Advantageously, in the case of polycaprolactone, the claimed preparation process does not require the use of a catalyst like the conventional processes for direct polymerization of monomers on the backbones of oligo- or polysaccharides. This specificity of the claimed process is therefore particularly advantageous in terms of safety and biodegradability in the resulting material.

According to a preferred variant of the invention, the reactive function present on the biodegradable polymer is an activated carboxylic acid function. Preferably, the oligosaccharide, more preferably a cyclodextrin, and the suitably activated biodegradable polymer are brought into contact in a mass ratio varying from 2: 98 to 40: 60.

The ester bond between the cyclic oligosaccharides and the polyesters is carried out either by passing through an activated ester of the acid function (esterification with NHSl in the presence of dicyclohexylcarbodiimide (DCC)), which is then isolated, or by passing through a non-isolated intermediate ( activation with carbonyidiimidazole (CDI)). This esterification reaction falls within the competence of a person skilled in the art.

More preferably, the biodegradable polymers meet the definitions proposed above. In particular, they can be derived from molecules of biodegradable polymers, natural or synthetic, and which have been modified so as to be functionalized in accordance with the present invention.

A third aspect of the invention relates to particles made of a material according to the invention.

The claimed particles can have a size between 50 nm and 500 μm and preferably between 80 nm and 100 μm.

In fact, according to the preparation protocol used to prepare the particles from the claimed material, the size of the particles can be fixed. According to a preferred embodiment of the invention, the particles have a size between 1 and 1000 nm and are then called nanoparticles. Particles varying in size from 1 to several thousand microns refer to microparticles. The claimed nanoparticles or microparticles can be prepared according to methods already described in the literature, such as for example the solvent emulsion / evaporation technique [R. Gumy et al. "Development of biodegradable and injectable latices for controlled release of potent drugs" Drug Dev. Ind. Pharm., Vol 7, p. 1-25 1981)]; the nanoprecipitation technique using a water-miscible solvent (FR 2 608 988 and EP 274 691). There are also variants of these methods. For example, the so-called “double-emulsion” technique, which is advantageous for the encapsulation of hydrophilic active principles, consists in dissolving these in an aqueous phase, in forming an emulsion of the water / oil type with an organic phase containing the polymer. , then to form an emulsion of the water / oil / water type using a new aqueous phase containing a surfactant. After evaporation of the organic solvent, nano- or micro-spheres are recovered.

The material according to the present invention has the major advantage of having surfactant properties, due to its amphiphilic nature. These properties can therefore be exploited advantageously during the preparation of particles, for example, so as to avoid the use of surfactants, systematically used in the above-mentioned processes. Indeed, these are not always biocompatible and are difficult to remove at the end of the process.

Another advantage of the material according to the present invention is to offer the possibility of modulating the properties which are involved in the particle manufacturing process through the choice:

- the biodegradable polymer / oligosaccharide and / or mass ratio - molar masses (block sizes) of the biodegradable polymers and of the oligosaccharides considered.

It is thus possible to obtain water-soluble or water-insoluble copolymers, having hydrophilic-lipophilic balances spread over a wide range therefore making it possible to stabilize either water / oil or oil / water emulsions.

Similarly, one can envisage the formation of particles from mixtures of two or more types of materials according to the present invention. As a representative of the particles according to the invention, mention may more particularly be made of a material derived from a block of polycaprolactone or of poly (lactic acid) linked by an ester type bond to at least one and preferably to the minus two molecules of cyclodextrin.

As regards the particle structures obtainable from the material according to the invention and the abovementioned methods, they can be variable. A distinction is thus made between: a hydrophobic core-like structure in biodegradable polymer (which can encapsulate active principles) - hydrophilic ring in cyclic oligosaccharide, obtained either using one of the abovementioned processes, or by adsorption of the material according to l invention of preformed particles; - A structure of the particles according to which the matrix in biodegradable polymer contains aqueous inclusions which can be obtained by a process of “double emulsion” and adapted to the encapsulation of the hydrophilic active principles. Depending on the procedure chosen and the hydrophilic-lipophilic balance of the material, the cyclic oligosaccharide can be available either exclusively at the inclusions aqueous, either at the level of these inclusions and at the surface of the particles. Thus, certain encapsulated sensitive active principles (proteins, peptides, etc.) can be protected from interactions, often denaturing, with the hydrophobic biodegradable polymer and the organic solvent;

- a hydrophilic core type structure (cyclic oligosaccharide) - hydrophobic crown (biodegradable polymer), when the particles are produced from an oil in oil emulsion (for example, silicone-acetone oil) or water in oil in oil;

a micellar structure, obtained by the self-association of a material in accordance with the invention in the aqueous phase, and

- a so-called gel structure formed by crosslinking the oligosaccharides with biodegradable polymers comprising at least two reactive functions;

- a core / crown type structure with a PEG (or other hydrophilic polymer) crown and a mixed core of polyester and cyclic oligosaccharide.

In the case of the present invention, the particles preferably degrade over a period of between one hour and several weeks.

The particles according to the invention may contain an active substance. This substance can be hydrophilic, hydrophobic or amphiphilic in nature and biologically active.

As biological active materials, mention may more particularly be made of peptides, proteins, carbohydrates, nucleic acids, lipids, polysaccharides or their mixtures. They can also be synthetic or natural organic or inorganic molecules which, administered in vivo to an animal or to a patient, are capable of inducing a biological effect and / or manifesting therapeutic activity. It can thus be antigens, enzymes, hormones, receptors, peptides, vitamins, minerals and / or steroids.

Mention may be made, as representative of the drugs which may be incorporated into these particles, of anti-inflammatory compounds, anesthetics, chemotherapeutic agents, immunotoxins, immunosuppressive agents, steroids, antibiotics, antivirals, antifungals, antiparasitics, immunizing substances, immunomodulators and analgesics. Thus, as medicaments which can be incorporated into these particles, mention may in particular be made of molsidomine, ketoconazole, gliclazide, diclofenac, levonorgestrel, paclitaxel, hydrocortisone, pancratistatin, ketoprofen, diazepam, ibuprofen, nifedipine, testosterone, tamoxifen, furosemide, tolbutamide, chloramphenicol, benzodiazepine, naproxene, dexamethasone, diflunisal, anadamide, pilocarpine, daunorubicin and doxoriazicine.

Likewise, it is possible to incorporate into the particles, compounds for diagnostic purposes. It can thus be substances detectable by X-rays, fluorescence, ultrasound, nuclear magnetic resonance or radioactivity. The particles can thus include magnetic particles, radio-opaque materials (such as air or barium) or fluorescent compounds. For example, fluorescent compounds such as rhodamine or Nile red can be included in particles with a hydrophobic core. Alternatively, gamma emitters (for example Indium or Technetium) can be incorporated. Hydrophilic fluorescent compounds can also be encapsulated in the particles, but with a lower yield compared to hydrophobic compounds, due to the lower affinity with the matrix. Commercial magnetic particles with controlled surface properties can also be incorporated into the particle matrix or covalently attached to one of their constituents. The active material can be incorporated into these particles during their formation process or, on the contrary, be loaded at the level of the particles once they are obtained.

The particles in accordance with the invention can comprise up to 95% by weight of an active material. The active ingredient can thus be present in an amount varying from 0.001 to 990 mg / g of particle and preferably from 0.1 to 500 mg / g. It should be noted that in the case of the encapsulation of certain macromolecular compounds (DNA, oligonucleotides, proteins, peptides, etc.) even lower charges may be sufficient. The particles according to the invention can be administered in different ways, for example by the oral, parenteral, ocular, pulmonary, nasal, vaginal, cutaneous, buccal routes, etc. The non-invasive oral route is a preferred route.

In general, particles administered orally can undergo different processes: translocation (capture and then passage of the digestive epithelium by intact particles), bioadhesion (immobilization of particles on the surface of the mucosa by an adhesion mechanism) and transit. For these first two phenomena, the surface properties play a major role. Advantageously, the particles further comprise at least one molecule covalently or non-covalently linked to their surface.

The fact that certain particles according to the invention have numerous free hydroxyl functions on the surface, proves to be particularly advantageous for binding a biologically active molecule thereof, intended for targeting or detectable. It is thus possible to envisage functionalizing the surface of these particles so as to modify their surface properties and / or target them more specifically to certain tissues or organs. Optionally, the particles thus functionalized can be maintained at the target level by the use of a magnetic field, during medical imaging or while an active compound is released. Likewise, targeting molecule type ligands such as receptors, lectins, antibodies or fragments thereof can be attached to the surface of the particles. This type of functionalization falls within the competence of a person skilled in the art.

Generally, the coupling of these ligands or molecules to the surface of the particles is carried out either covalently by attaching the ligand to the oligosaccharide covering the particles or non-covalently, that is to say by affinity. Thus, certain lectins may be attached by specific affinity to the oligosaccharides located on the surface of particles according to the present invention, thereby enhancing the cell recognition properties of these particles. For this type of application, it would be advantageous to functionalize the materials according to the present invention by grafting sugar residues at the level of the cyclic oligosaccharides. It may also be advantageous to graft the ligand via a spacer arm, to allow it to reach its target in an optimal conformation. Alternatively, the ligand can be carried by another polymer used in the composition of the particles. This aspect was mentioned previously.

The invention also relates to the use of the particles obtained according to the invention for encapsulating one or more active materials as defined above.

Another aspect of the invention also relates to pharmaceutical or diagnostic compositions comprising particles of the invention preferably associated with at least one pharmaceutically acceptable and compatible vehicle. For example, the particles can be administered in gastro capsules resistant, or incorporated into gels, implants or tablets. They can also be prepared directly in an oil (such as Migliol®) and this suspension administered in a capsule or injected at a specific site (for example tumor). These particles are in particular useful as stealth vectors, that is to say capable of escaping the immune defense system of the organism and / or as bioadhesive vectors.

The examples and figure appearing below are presented by way of illustration and without limitation of the present invention.

Figures:

Figure 1: Schematic representations of different conformational structures of the materials according to the invention. Figure 2: Chromatogram of the product of the reaction of β cyclodextrin with the polyester PCL-diacid (H0 ₂ C-PCL-C0 ₂ H).

EXAMPLES

EXAMPLE 1

Synthesis of R-PCL-COOH (R = C ₉ H ₁₉ )

Monofunctionalized PCL polymers with a molar mass varying from 2000 to 5000 g / mole of the R-PCL-C0 ₂ H type (R = C ₉ H ₁₉ ) were obtained from 3.2 g of freshly distilled monomer (ε-caprolactone) ) and 0.3 g of high purity capric acid (C ₉ H ₁₉ C0 ₂ H). The acid and ε-caprolactone were introduced into a flask surmounted by an ascending condenser. After a severe purging of the reagents, the flask was introduced into an oil bath thermostatically controlled at 235 ° C. The reaction continued for 6 h 30 min under an inert atmosphere (argon). It was stopped by immersion of the balloon in ice. The solid obtained was hot dissolved in 15 ml THF, then was precipitated at room temperature with cold methanol.

After three successive precipitations, the yield by weight of the reaction is 60-70%. The number-average molar masses (Mn) and by weight (Mw) were determined by steric exclusion chromatography (CES) (eluent THF 1 ml / min, universal calibration carried out with polystyrene standards). Mn is equal to 3420 g / mole and Mw to 4890 g / mole; the polydispersity index is therefore equal to 1, 4.

A number average molar mass equal to 3200 g / mole was determined by titration with a 10 ^"2 M KOH / EtOH solution of the polymer samples of approximately 100 mg dissolved in an acetone-water mixture.

EXAMPLE 2. Synthesis of HOOC-PCL-COOH

The bifunctionalized polymer HOOC-PCL-COOH was synthesized according to the procedure of Example 1.

The succinic acid (99.9%, Aldrich) used as initiator was dried under vacuum at 110 ° C for 24 hours. The monomer (ε-caprolactone) was freshly purified by distillation on calcium hydride, under reduced pressure.

The polymerization from 0.2 g of succinic acid and 4 g of ε-caprolactone made it possible to obtain after 3 hours of reaction 3.2 g of polymer (yield by weight 76% after four successive precipitations). Determination of terminal COOH groups by KOH / EtOH

10 ^"2 M made it possible to determine an acidity corresponding to a molar mass of 3500 g / mole.

By CES, Mn is equal to 4060 g / mole and Mw to 4810 g / mole, the polydispersity index is 1.2. EXAMPLE 3

SYNTHESIS OF βCD-PCL-BCD

3 g of H0 ₂ C-PCL-C0 ₂ H obtained according to Example 2 are anhydrized by azeotropic distillation, then dried under vacuum in a

5 flask of 50 ml. The flask is then fitted with an ascending refrigerant and connected to an empty / argon ramp. 5 ml of anhydrous THF are added to the flask and after dissolution of the polymer, 0.304 g of carbonyl diimidazole (CDI) are added and the mixture is brought to reflux of THF.

A release of C0 ₂ is observed. It subsides after two hours. The reaction is stopped after 3 hours, the THF is evaporated and 2.92 g of β

Anhydrous CD dissolved in 25 ml of anhydrous DMSO are added.

The whole is heated to 140 ° C. under argon for 3 hours. The DMSO is evaporated and then the crude reaction product dissolved in 500 ml of chloroform. This solution is introduced into a 5 2 liter separatory funnel and stirred with 1 liter of water. After decantation, the aqueous phase is in the form of a stable emulsion. This emulsion is broken by evaporation with Rotovap®. The polymer is obtained in the form of a precipitate. Subsequently, this precipitate is again washed with water, then recovered by filtration, washed with ether and dried. The yield is 75% by weight.

The copolymer is characterized by gel permeation chromatography (refractometer and viscometer detectors) using a Visco Gel column (GMHHR-N, Viscotek, GB, heated to 60 ° C), calibrated with polystyrene standards (calibration universal). The copolymer is dissolved in N, N-dimethyl acetamide (DMAC) at a concentration of 5 mg / ml. The volume injected is 100 μl. The eluent is DMAC containing 0.5% lithium bromide, at a flow rate of 0.5 ml / min.

The chromatogram (Figure 2) shows that it is a unique product, with some traces of unreacted βCD. The number-average molar mass o is 8,330 g / mole and the weight-average molar mass is 10,790 g / mole. This copolymer contains approximately 35% by weight of βCD.

EXAMPLE 4

INCORPORATION OF TAMOXIFENE

All glassware and equipment in contact with tamoxifen is previously silicone-coated.

A 20 μg / ml tamoxifen solution is prepared from tamoxifen base (Sigma, France) and tritiated tamoxifen (specific activity 80 Ci / mole, ethanolic solution 5.2 mCi / ml, Perkin Elmer, EU) so as to obtain a ³ H isotopic dilution of tamoxifen / tamoxifen base equal to 1 / 170,000 (mole / mole).

For this, the base tamoxifen (powder) and tritiated (ethanolic solution) are dissolved in a minimum volume of ethanol. The ethanol is then evaporated under a stream of nitrogen. The residue thus obtained is dissolved in ultrapure water (Milli Q) by stirring at room temperature for 18 h.

10 ml of this solution are introduced into a pill box containing 10 mg of copolymer of Example 3 in the form of a fine powder. The suspension is kept stirring at room temperature for 48 hours. The polymer is separated from the supernatant by centrifugation at 30,000 rpm for 30 min (Beckman L7-55 Ultracentrifuge, EU).

The radioactivity in the supernatant is determined by counting in liquid scintillation the tritiated tamoxifen (Beckman counter LS-6000-TA, EU). For this, 200 μl of supernatant is mixed with 4 ml of Ultimagold ™ scintillation liquid (Packard, Netherlands). For each of the two samples prepared, two independent measurements are made and the average of the four measurements is calculated. The radioactivity in the supernatants corresponds to a concentration of 6.25 ± 0.13 μg / ml in tamoxifen.

Two controls (pill boxes containing tamoxifen solutions, in the absence of polymer) are subjected to the same treatment. The residual radioactivity in the supernatants corresponds to a concentration of 13.26 ± 0.54 μg / ml in tamoxifen.

By difference, in total 70 μg of tamoxifen are incorporated into the copolymer. This corresponds to 7 μg of tamoxifen / mg of copolymer.

It is found that the material according to the invention allows the incorporation of a high amount of tamoxifen, a compound which is particularly difficult to incorporate. Furthermore, it is noted that the radioactivity values measured in the supernatants of the two samples produced are very close, which shows that the incorporation into the material according to the invention is carried out in a reproducible manner.

Claims

1. Material composed of at least one biodegradable polymer and of a cyclic oligosaccharide, characterized in that at least one molecule of said oligosaccharide is grafted via a covalent bond to at least one molecule of said biodegradable polymer.

2. Material according to claim 1, characterized in that is grafted in addition by a covalent bond at the level of said biodegradable polymer, a second molecule of cyclic oligosaccharide, a second molecule of said biodegradable polymer and / or a molecule distinct from said biodegradable polymer and said cyclic oligosaccharide.

3. Material according to one of claims 1 or 2, characterized in that the covalent bond established between the biodegradable polymer molecule and the other molecule (s) is an ester type bond.

4. Material according to claim 3, characterized in that the covalent bond derives from the reaction between a carboxylic function, activated or not, present on the molecule of the biodegradable polymer and a hydroxyl function present on the grafted molecule.

5. Material according to one of the preceding claims, characterized in that the biodegradable polymer corresponds to formula (I):

(R- _i ) - rP ° 'y ^mèrθ biodegradable -I - (R ₂ ) m (I)

in which: - n and m represent independently of each other, either 0 or 1,

- RT represents a Cι-C ₂₀ alkyl group, a polymer different from the biodegradable polymer, or a copolymer containing PEG blocks or ethylene oxide units, a protected reactive function present on the polymer, a carboxylic function or a hydroxyl function, and

- R ₂ represents a hydroxyl function or a carboxylic function.

6. Material according to one of the preceding claims, characterized in that the biodegradable polymer is chosen from poly (lactic acid) (PLA), poly (glycolic acid) (PGA), poly (ε- caprolactone) (PCL), synthetic polymers such as polyanhyd wrinkles, poly (alkylcyanoacrylates), polyorthoesters, polyphosphazenes, polyamides, polyamino acids, polyamidoamines, poly (alkylene d-tartrate), polycarbonates, polysiloxane, polyesters, or poly (malic acid), as well as their copolymers and derivatives.

7. Material according to one of the preceding claims, characterized in that the biodegradable polymer is a polyester of molecular weight less than 50,000 g / mole.

8. Material according to one of the preceding claims, characterized in that the biodegradable polymer is a polycaprolactone.

9. Material according to one of the preceding claims, characterized in that the cyclic polysaccharide is a cyclodextrin.

10. Material according to claim 9, characterized in that the biodegradable polymer is grafted to at least two molecules of cyclodextrin.

11. Material according to one of the preceding claims, characterized in that it is a copolymer having a biodegradable polymer backbone and at least two cyclodextrin grafts, optionally grafted with one or more molecules of biodegradable polymer of natures chemical substances which may or may not be separate from those of the polymer constituting the skeleton of said material.

12. Material according to one of the preceding claims, characterized in that said biodegradable polymer is grafted to at least one molecule of cyclodextrin and one molecule of a separate polymer.

13. Material according to claim 12, characterized in that the separate polymer is a polyethylene glycol.

14. Material according to one of claims 9 to 13, characterized in that said material contains a mass content of cyclic oligosaccharide at least equal to 10%.

15. Material according to one of claims 9 to 14, characterized in that it contains a mass content of cyclic oligosaccharide of between 20 and 40% by weight.

16. Material according to one of the preceding claims, characterized in that the cyclic oligosaccharide is a cyclodextrin.

17. Material according to one of the preceding claims, characterized in that it has a linear, branched or crosslinked structure.

18. Material according to one of the preceding claims, characterized in that it is derived from a biodegradable polymer chosen from polycaprolactone, a polyester and polylactic acid.

19. Method for preparing a material according to one of the preceding claims, characterized in that at least one molecule of a biodegradable polymer or one of its derivatives carrying at least one reactive function is brought into contact, with at least at least one molecule of a cyclic oligosaccharide, under conditions favorable to the establishment of a covalent bond between the two types of molecules and in that said material is recovered.

20. Method according to claim 19, characterized in that the biodegradable polymer is as defined in claims 5 to 8.

21. The method of claim 19 or 20, characterized in that the reactive function of the biodegradable polymer is an activated carboxylic acid function.

22. Method according to one of claims 19 to 21, characterized in that the cyclic polysaccharide is a cyclodextrin.

23. The method of claim 22, characterized in that the cyclodextrin and the biodegradable polymer are brought into contact in a mass ratio varying from 2:98 to 40:60.

24. Particle obtained from a material according to one of claims 1 to 18.

25. Particle according to claim 24, characterized in that it consists of a material derived from at least one molecule of polycaprolactone or of poly (lactic acid) linked by an ester-type bond to one and preferably at least two molecules of cyclodextrin.

26. Particle according to claim 25, characterized in that they are nanoparticles.

27. Particle according to claim 25, characterized in that it is microparticles.

28. Particle according to one of claims 24 to 27, characterized in that it further comprises an active substance.

29. Particle according to claim 28, characterized in that the active substance is chosen from peptides, proteins, carbohydrates, nucleic acids, lipids, polysaccharides, or organic or inorganic molecules capable of inducing a biological effect and / or of manifesting therapeutic activity.

30. Particles according to claim 28, characterized in that the active substance is chosen from molsidomine, ketoconazole, gliclazide, diclofenac, levonorgestrel, paclitaxel, hydrocortisone, pancratistatin, ketoprofen, diazepam, ibuprofen, nifedipine, testosterone, tamoxifen, furosemide, tolbutamide, chloramphenicol, benzodiazepine, naproxene, dexamethasone, diflunisal, anadamide, pilocarp daunorubicin, doxorubicin and 5 diazepam.

31. Particle according to one of claims 28 to 30, characterized in that it comprises up to 95% by weight of active material.

32. Particle according to one of claims 24 to 31, o characterized in that it further comprises at least one molecule covalently linked to its surface.

33. Particle according to one of claims 24 to 31, characterized in that it further comprises at least one molecule non-covalently linked to its surface. 5

34. Particle according to claim 32 or 33, characterized in that this molecule is a biologically active molecule, a molecule intended for targeting or which can be detected.

35. Particle according to claim 34, characterized in that it is a targeting molecule chosen from receptors, o antibodies and fragments of antibodies and lectins.

36. Use of the particles according to one of claims 24 to 35 for encapsulating at least one active material.

37. Use according to claim 36, characterized in that the active materials are chosen from peptides, proteins, carbohydrates, nucleic acids, lipids, or organic or inorganic molecules capable of inducing a biological effect and / or having therapeutic activity .

38. Pharmaceutical composition, characterized in that it comprises particles according to one of claims 24 to 35.

39. A diagnostic composition characterized in that it comprises particles according to one of claims 24 to 35.

40. Use of the particles according to one of claims 24 to 35, as "stealthy" vectors.

41. Use of the particles according to one of claims 24 to 34 as bioadhesive vectors.