Particulate structures made from gold nanoparticles, their production method, and their use for treating solid tumors - Patents.com

Abstract

The present invention relates to a particulate structure comprising: a / biodegradable polymer particles; b / gold nanoparticles whose surfaces are coated with a macrocyclic chelating agent that complexes at least one target ion and / or radionuclide for medical imaging; and c / a polycation that has a positive charge over a pH range of 5 to 11, wherein the gold nanoparticles b / are encapsulated in the polymer particles a / and / or adsorbed to the surface of the polymer particles a / . The present invention also relates to a method for producing the particulate structure. The present invention further relates to the use of the particulate structure for radiotherapy or chemotherapy in cancer treatment.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to the field of chemistry and formulations applied to health, and in particular to novel particulate structures comprising multifunctional gold nanoparticles and the use of the novel particulate structures for radiotherapy, imaging and chemotherapy in the context of cancer treatment.

[0002] The present invention also relates in particular to a method for producing these novel particulate structures, which consists of encapsulating multifunctional gold nanoparticles in biodegradable polymer particles. [Prior art] The use of gold nanoparticles represents a promising strategy in cancer diagnosis and treatment (1), (2).

[0003] The reduction in size of nanoparticles allows for the probing of living organisms down to the cellular level. These nanoparticles are large enough not to cross the biological barriers of healthy tissue, yet small enough to penetrate the porous lining of blood vessels in solid tumors.

[0004] Gold nanoparticles are also attractive due to their unique properties. Indeed, gold is a particularly excellent noble metal, being highly insensitive to external chemical attack conditions and biocompatible for medical applications. Gold nanoparticles possess optical properties that can be tuned depending on their size, shape, and dielectric environment. These properties have led to their widespread use in photothermal therapy and imaging (3). Furthermore, due to its large atomic number, gold is characterized by a very high density and a very large effective cross-section for the absorption of X- and γ-photons. This property endows gold nanoparticles, regardless of size, with contrast agent behavior for X-ray tomodensitometry and radiosensitizing effects that can be utilized for radiotherapy (4, 5). Finally, the two main synthetic methods described by Brust and Frens are relatively easy to implement. The first method involves the reduction of gold salts with a strong reducing agent in the presence of a thiolated ligand. On the other hand, Frens' method uses the reducing agent sodium citrate on gold salts to form nanoparticles stabilized by citrate ions (6, 7). The functionalization of these gold nanoparticles can be carried out during or after synthesis, allowing for a wide range of properties to be enriched. By appropriately selecting the components used to synthesize multifunctional gold nanoparticles, it is possible to integrate therapeutic activity and imaging functions within one and the same object, despite their reduced size.

[0005] G. Laurent's paper (8) describes the development of multifunctional gold nanoparticles, i.e., gold nanoparticles containing elements of interest for medical imaging (Gd for MRI). 3+ , for SPET 111 ln 3+ , for PET 64 Cu 2+ Gold nanoparticles coated on their surfaces with macrocyclic chelators capable of complexing α- and β-glucan have shown considerable promise for image-guided radiotherapy.

[0006] These gold nanoparticles functionalized in this way indeed have potential as multimodal contrast agents (MRI, nuclear imaging) and radiosensitizers. Once intravenously injected, these nanoparticles have shown remarkable therapeutic efficacy after activation with X-rays. Furthermore, the biodistribution of these nanoparticles could be monitored by MRI, SPECT, and X-ray tomodensitometry. Thus, multifunctional gold nanoparticles represent an extremely interesting approach for tumor diagnosis and therapy due to their optical and radiosensitizing properties.

[0007] However, despite these promising results, the plasma half-life of these multifunctional gold nanoparticles is still very short, thus preventing their accumulation in the tumor area (accumulation level of approximately 2%). The excessively rapid elimination (renal clearance) of the nanoparticles can be explained by their small size (hydrodynamic diameter of approximately 6-7 nm), which is crucial for their excretion by the renal route.

[0008] Therefore, it has been proposed to increase the hydrodynamic diameter of gold nanoparticles to limit the problem of excessively rapid renal clearance. However, such an approach significantly reduces the nanoparticles' radiosensitizing properties and their excretion from the body via the renal route (9, 10).

[0009] Therefore, we came up with the idea of ​​encapsulating multifunctional gold nanoparticles in larger biodegradable polymer particles, which would allow the nano-objects to circulate in the blood for a longer period while maintaining renal excretion, thereby increasing their chances of accumulating in tumors.

[0010] Approaches for encapsulating gold nanoparticles in biodegradable polymer particles have already been described in the literature. Thus, we can refer to the encapsulation by simple oil-in-water emulsion or water-in-oil-in-water double emulsion described by Wang Y et al. (11) or other in situ synthesis of gold nanoparticles, i.e., direct synthesis inside polymer particles, as described by Luque-Michel et al. (12).

[0011] However, these methods suffer from low encapsulation yields and / or result in particles that are too large, i.e., on the order of micrometers, and lack of size uniformity (polydisperse particles). Furthermore, the entirely encapsulated gold particles are "naked" (i.e., unfunctionalized), which leads to a lack of colloidal stability in physiological environments and excretion problems during degradation of the polymer particles in vivo. [overview] One of the aims of the present invention is to develop novel particulate structures containing multifunctional gold nanoparticles that have improved accumulation at the level of the tumor region and a sufficiently long plasma half-life (i.e., 15-120 min) to better exploit the radiosensitizing potential of the multifunctional gold nanoparticles.

[0012] Another object of the present invention is to develop novel particulate structures that are biodegradable transporters with sufficiently long plasma half-lives (circulation times in the blood) to fully exploit the promising potential of multifunctional gold nanoparticles for image-guided radiotherapy.

[0013] Another object of the present invention is to develop novel particulate structures that have a sufficiently long plasma half-life to improve tumor accumulation, but are subsequently rapidly degraded in the blood and excreted by the renal route.

[0014] Another object of the present invention is to develop an original method for producing these novel particulate structures, which allows for the efficient encapsulation of multifunctional gold nanoparticles in biodegradable polymer particles, i.e., with an encapsulation yield of more than 90%, close to, or even equal to 100%.

[0015] Another object of the present invention is to develop a method for producing particulate structures having diameters on the order of nanometers, ie, 50 to 200 nm, and a narrow size distribution (ie, a low polydispersity index).

[0016] Another object of the present invention is to develop a method for producing the particulate structures defined above with good reproducibility, both in terms of the loading (encapsulation ratio) obtained and the particle size obtained.

[0017] In our work on the synthesis of biodegradable polymer particles encapsulating gold nanoparticles, we were particularly interested in methods based on the method of nanoprecipitation by solvent displacement ( 13 ).

[0018] Thus, they surprisingly discovered that the method for producing these particulate structures could be significantly improved by using polycations that are positively charged over a wide range of pH, i.e., the pH range 5-11.

[0019] Indeed, polycations allow the electrostatic entrapment of multifunctional gold nanoparticles, which facilitates and in particular enables their encapsulation in biodegradable polymer particles.

[0020] The present invention more particularly relates to a / biodegradable polymer particles; b / gold nanoparticles coated on their surface with a macrocyclic chelating agent that complexes at least one target ion and / or radionuclide for medical imaging; c / a polycation having a positive charge over the pH range of 5 to 11; The present invention relates to a particulate structure characterized in that the gold nanoparticles b / are encapsulated in the polymer particles a / and / or adsorbed on the surface of the polymer particles a / .

[0021] The term "nanoparticle" refers to an object of any shape with at least one dimension between 1 and 100 nanometers.

[0022] The particulate structure of the present invention particularly refers to biodegradable polymer particles a / in which gold nanoparticles b / are encapsulated and / or on whose surface gold nanoparticles b / are adsorbed.

[0023] For gold nanoparticles, possible shapes can be spheres, nanoshells (core-shell), or nanorods, although the spherical shape is an approximation. In fact, gold crystallizes in a face-centered cubic lattice, forming polyhedral objects that may resemble spheres.

[0024] According to the present invention, the gold nanoparticles and biodegradable polymer particles are preferably spherical in shape. Similarly, the particulate structures of the present invention are preferably spherical in shape.

[0025] The gold nanoparticles of the particulate structure of the present invention are surface-coated with a macrocyclic chelating agent that complexes at least one target ion and / or radionuclide for medical imaging, and may also be referred to by any of the terms "functional" gold nanoparticles (as opposed to "bare" gold nanoparticles), "multifunctional," "functionalized," radiosensitized functionalized gold nanoparticles, etc. These may hereinafter be simply referred to as gold nanoparticles b / . These gold nanoparticles b / thus consist of a gold core surrounded or coated with an organic layer consisting of a macrocyclic chelating agent that complexes the target ion and / or radionuclide.

[0026] The essential role of the organic layer is to provide colloidal stability as well as to allow complexation of elements (target ions, radionuclides) for medical imaging, allowing the gold nanoparticles b / to be tracked by imaging.

[0027] The functionalized gold nanoparticles b / may also be designated by the symbol Au@L(M), where Au represents gold and L(M) represents a macrocyclic chelator (i.e., L) that complexes the target ion and / or radionuclide (i.e., M).

[0028] The macrocyclic chelating agent L may also be referred to as a macrocyclic ligand or ligand.

[0029] Schematic diagrams of functionalized gold nanoparticles are shown in Figures 1a, 1b, and 1c.

[0030] Biodegradable polymers, in the sense of the present invention, refer to polymers that can be naturally decomposed or absorbed by the body of a subject. Biodegradable polymers may also be referred to as bioabsorbable polymers. Biodegradable or bioabsorbable polymer particles may hereinafter be referred to as polymer particles a / .

[0031] The polycation having a positive charge over a wide pH range as defined above can be referred to as polycation c / hereinafter. The polycation c / electrostatically interacts with gold nanoparticles b / , so that it is always located near the gold nanoparticles b / . Therefore, polycation c / can be encapsulated in polymer particles a / and / or adsorbed onto the surface of polymer particles a / .

[0032] The particulate structure of the present invention is further characterized in that it comprises a surfactant adsorbed on the surface of the polymer particles a / , and thus, when present, the surfactant is always present on the surface of the polymer particles a / and is not encapsulated within the polymer particles a / .

[0033] The presence of surfactant is a function of the biodegradable polymeric nature of the nanoparticles.

[0034] The surfactant of the present invention is in particular polyvinyl alcohol (PVA) and / or a poloxamer, preferably PVA.

[0035] Examples of poloxamers include those commercially available under the names Pluronic F-127 (Poloxamer 407), P85, and L64.

[0036] Schematic diagrams of particulate structures of the present invention having surfactants are shown in Figures 2a, 2b and 2c.

[0037] According to another embodiment of the present invention, the particulate structure further comprises at least one active ingredient encapsulated in the polymer particles a / , said active ingredient being preferably a chemotherapeutic agent and / or a fluorophore.

[0038] Examples of chemotherapeutic agents include temozolomide, paclitaxel, docetaxel, and etoposide.

[0039] Examples of fluorophores include indocyanine green (used in clinical practice for imaging) or other fluorophores such as cyanine 5, cyanine 7, or Dil (IUPAC name: "(2Z)-2-[(E)-3-(3,3-dimethyl-1-octadecylindol-1-ium-2-yl)prop-2-enylidene]-3,3-dimethyl-1-octadecylindole; perchlorate").

[0040] Thus, according to the invention, the polymer particles a / advantageously allow the co-encapsulation of functionalized gold nanoparticles b / and at least one active ingredient.

[0041] Schematic diagrams of particulate structures of the present invention having active ingredients are shown in Figures 3a, 3b and 3c.

[0042] According to the present invention, each of the above-mentioned macrocyclic chelating agents coating the gold nanoparticles is an anchoring functional group comprising at least one sulfur atom for attaching the macrocyclic chelator to the gold nanoparticle, preferably comprising two sulfur atoms forming an intracyclic disulfide bond; - at least one complexation moiety for ions and / or radionuclides of interest for medical imaging, the complexation moiety comprising at least one carboxylic acid and / or amine functional group; a spacer arm located between the anchor functional group and the complexation moiety; - optionally functionalization moieties that allow grafting of chelators to drugs for targeting cancer cells.

[0043] The attachment between at least one sulfur atom of the anchor functional group and the gold nanoparticle more particularly represents an ionocovalent bond, which is an intermediate bond between a covalent bond and an ionic bond.

[0044] The macrocyclic chelating agent that coats the gold particles is more specifically said anchor functional group is

[0045] [ka]

[0046] ,*-N-(CH2-CH2-SH)2, *-C(=O)-(CH2) n -SH, wherein n is an integer from 2 to 5, and mixtures thereof; said spacer arm *-(CH2)2-CO-NH-(CH2)2-NH-*, *-NH-(CH2-CH2-O) m -CH2-CH2-NH-* (wherein m is an integer equal to 0, 4 or 11) and mixtures thereof; said functionalization moiety, when present, *-NH-CH((CH2)4-NH2)-CO-*, *-NH-CH(CH2-OH)-CO-*, *-NH-CH(CH-OH-CH3)-CO-*, *-NH-CH(CH2-C6H4-OH)-CO-*,*-NH-CH((CH2) nIt is characterized in that it is a group derived from an amino acid selected from the group consisting of —NH—*)—CO—* (wherein n is 2 to 5) and mixtures thereof.

[0047] Examples of amino acids from which functionalization sites may be derived include lysine, serine, threonine, and tyrosine.

[0048] According to one embodiment of the present invention, the macrocyclic chelator is selected from the group comprising TADOTAGA, TANODAGA, TADFO, TA[DOTAGA-lys-NH2], TA[NODAGA-lys-NH2], TA[DOTAGA-lys-NODAGA] and mixtures thereof.

[0049] The meanings of these abbreviations are as follows:

[0050] DOTAGA: "1,4,7,10-tetraazacyclododecane-1-glutaric acid-4,7,10-triacetic acid."

[0051] NODAGA: "1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid."

[0052] DFO: "Deferoxamine."

[0053] TADOTAGA refers to a derivative of DOTAGA to which a thioctic acid (TA) functional group has been added.

[0054] TANODAGA refers to a derivative of NODAGA to which a thioctic acid (TA) functional group has been added.

[0055] TADFO refers to a derivative of DFO with a thioctic acid (TA) functional group added.

[0056] TA[DOTAGA-lys-NH2] denotes a derivative of TADOTAGA with an amine functional group added via the lysine.

[0057] TA[NODAGA-lys-NH2] represents a derivative of TANODAGA with an amine functional group added via the lysine.

[0058] TA[DOTAGA-lys-NODAGA] refers to a compound comprising a DOTAGA unit and a NODAGA unit attached together by a lysine, with a thioctic acid (TA) functional group attached.

[0059] The organic layer surrounding the gold core, which is comprised of a macrocyclic chelator, may be a "mixed" layer, meaning that it is comprised of a mixture of macrocyclic chelators.

[0060] Examples of mixtures include a mixture of TADOTAGA and TANODAGA [(TADOTAGA)(TANODAGA)], and a mixture of TADOTAGA and TADFO [(TADOTAGA)(TADFO)].

[0061] According to another embodiment of the present invention: - for medical imaging, more particularly for Magnetic Resonance Imaging (MRI), said ions of interest are selected from the group comprising Gd3+, Ho3+, Dy3+ and mixtures thereof; -Radionuclides for medical imaging, more specifically nuclear imaging (SPET or PET), 64 Cu, 89 Zr, 88 Ga, 111 In, and mixtures thereof.

[0062] Magnetic resonance imaging (MRI) is an imaging technique that allows three-dimensional visualization of biological tissues based on the principles of nuclear magnetic resonance (NMR). MRI utilizes the magnetic properties of protons in water (the main component of biological tissue, approximately 80%), which is environment- and therefore tissue-dependent.

[0063] Nuclear imaging techniques require the injection of radionuclides to perform functional imaging of the body. Two techniques are available: Single-Photon Emission Tomography (SPET), which uses emitters of gamma photons, and beta photon emission tomography (BPET). + It can be distinguished from Positron Emission Tomography (PET), which is based on the use of a positron emitter.

[0064] SPET and PET offer the advantage of being very sensitive and capable of performing functional imaging.

[0065] Thus, functionalized gold nanoparticles b / , represented as Au@L(M), may be accompanied by MRI (when M is an ion of interest), SPET or PET (when M is a radionuclide), and X-ray imaging (with gold).

[0066] The symbol @ indicates an attachment or other ionocovalent bond between the anchor functional group of the macrocyclic chelator L and the gold nanoparticle.

[0067] The particulate structure of the present invention is further characterized in that the polycation is selected from the group consisting of polyethyleneimine (PEI), polylysine, polyarginine, polyamidoamine (PANAM), poly(β-amino ester), chitosan, and mixtures thereof, and is preferably polyethyleneimine. A more specific example is branched (rather than linear) polyethyleneimine.

[0068] The term polycation is used because each of the above compounds contains amine groups, which may or may not be charged by protonation, depending on the pH. As noted above, polycations used in the context of the present invention have a positive charge over a wide range of pH, i.e., the pH range of 5 to 11.

[0069] According to another embodiment, the biodegradable polymer of the particles is selected from the group comprising poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), poly(glycolic acid) (PGA), polycaprolactone (PCL), polyanhydrides, copolymers of each of the aforementioned polymers with polyethylene glycol (PEG) and mixtures thereof, preferably PLGA or (PLGA-PEG) copolymers.

[0070] PLGA is a heterocopolymer of lactic acid and glycolic acid obtained by copolymerization. The monomers are linked together by ester bonds to give a linear aliphatic polyester containing x lactic acid units and y glycolic acid units. Thus, PLGA 75 / 25 specifies a copolymer with a composition of 75% lactic acid and 25% glycolic acid and a molecular weight between 7,000 and 17,000 g / mol. PLGA 50 / 50 is more particularly preferred.

[0071] PLGA is used in drug release due to its excellent biocompatibility and biodegradability in lactic acid and glycolic acid, two monomers that are naturally produced in metabolic pathways.

[0072] As a guideline, when the biodegradable polymer is a (PLGA-PEG) copolymer, the particulate structures of the present invention do not contain surfactants.

[0073] As a guide, structural formulas of macrocyclic chelators, polycations and biodegradable polymers are shown in Figure 4.

[0074] According to yet another embodiment of the particulate structure of the present invention, the macrocyclic chelating agent present on the surface of the gold nanoparticles binds to integrin α, which is overexpressed in tumor neovasculature. V β III The targeting agent is preferably a cyclic RGD peptide.

[0075] The addition of a targeting agent makes it possible to achieve active targeting in addition to passive targeting. Thus, the affinity of the biomolecule for receptors overexpressed at the level of the tumor or tumor neovasculature (in the case of RGD) allows for longer retention of gold nanoparticles in the target area.

[0076] The particulate structure further comprises: the hydrodynamic diameter of the polymer particles a / is between 50 and 200 nm, preferably between 70 and 160 nm; The gold nanoparticles b / are characterized in that their hydrodynamic diameter is between 3 and 15 nm, preferably between 6 and 10 nm.

[0077] The hydrodynamic diameter of a particle takes into account the diameter of the particle and the so-called "hydrated" layer of the particle.

[0078] In this case, the hydrodynamic diameter of the polymer particle a / is the diameter of the polymer particle a / with gold nanoparticles b / and / or surfactant adsorbed on its surface.

[0079] In other words, the diameter of the polymer particle a / with the layer formed by the gold nanoparticles b / and / or surfactant constitutes the hydrodynamic diameter of the polymer particle a / .

[0080] The diameter of the particulate structure is therefore equal to the hydrodynamic diameter of the polymer particle a / .

[0081] The hydrodynamic diameter of a gold nanoparticle b / denotes the diameter of a gold nanoparticle whose surface is coated with a macrocyclic chelating agent that complexes at least one ion and / or radionuclide of interest.

[0082] According to one embodiment of the present invention, the particulate structure is more particularly characterized in that gold nanoparticles b / and any active ingredient are encapsulated in polymer particles a / , said gold nanoparticles b / optionally being further adsorbed to the surface of polymer particles a / .

[0083] The present invention also relates to a method for producing the particulate structure defined above (i.e., gold nanoparticles b / (and any active ingredient) encapsulated in polymer particles a / and optionally adsorbed to the surface of polymer particles a / ). This method can be carried out by one or the other of the two methods described below, and is sometimes referred to as the "encapsulation process".

[0084] Method 1 According to one embodiment, the method of the present invention comprises: - contacting an aqueous suspension of gold nanoparticles b / with an aqueous solution of polycations to obtain aggregates of gold nanoparticles b / and polycations; - contacting the aggregate of gold nanoparticles b / and polycations defined in the preceding step with a mixture of a biodegradable polymer and a water-miscible organic solvent, optionally premixed with at least one active ingredient, to obtain a mixture of gold nanoparticles b / , polycations, biodegradable polymer and any active ingredient; - contacting the mixture of gold nanoparticles b / , polycation, polymer and any active ingredient defined in the preceding step with water, optionally containing a surfactant, to precipitate the polymer in the form of particles around the gold nanoparticles b / and any active ingredient, The encapsulation yield of said gold nanoparticles b / and optionally said active ingredient in said polymer particles a / is characterized by being at least 75%, preferably at least 90%, even more preferably at least 95%.

[0085] Method 2 According to another embodiment, the method of the present invention comprises: - contacting an aqueous solution of a polycation with a mixture of a biodegradable polymer and a water-miscible organic solvent, said organic solvent optionally being premixed with at least one active ingredient; - contacting the aggregate of the mixture of polycations and biodegradable polymers with organic solvent defined in the preceding step with an aqueous suspension of gold nanoparticles b / to obtain a mixture of gold nanoparticles b / , polycations, biodegradable polymers and any active ingredient; - contacting the mixture of gold nanoparticles b / , polycation, polymer and any active ingredient defined in the preceding step with water, optionally containing a surfactant, to precipitate the biodegradable polymer in the form of particles around the gold nanoparticles b / and any active ingredient, The encapsulation yield of said gold nanoparticles b / and optionally said active ingredient in said polymer particles a / is characterized by being at least 75%, preferably at least 90%, even more preferably at least 95%.

[0086] As already mentioned, the active ingredient may be a fluorophore and / or a chemotherapeutic agent.

[0087] The encapsulation yield of gold nanoparticles indicates the final weight of gold relative to the weight of gold used (i.e., the weight of encapsulated gold and, optionally, the weight of adsorbed gold). In fact, during the encapsulation process, it is possible that a certain percentage of gold nanoparticles will not end up in the biodegradable polymer particles but will be adsorbed onto the surface of the biodegradable polymer particles. The final weight of gold is the same as the weight of gold used if the encapsulation yield is 100%. Nevertheless, this may mean that a certain percentage of gold nanoparticles will end up on the surface of the biodegradable polymer particles.

[0088] The encapsulation yield of the active ingredient indicates the weight of the active ingredient encapsulated relative to the weight of the active ingredient used. The active ingredient always ends up inside the biodegradable polymer particles, never on the surface of the biodegradable polymer particles.

[0089] For biodegradable polymers, if the manufacturing yield is 100%, the final weight of the polymer is the same as the weight of the polymer used.

[0090] The encapsulation rate (also called loading rate) of gold nanoparticles refers to the final weight of gold relative to the weight of the biodegradable polymer particle formed (i.e., the weight of encapsulated gold and, optionally, the weight of adsorbed gold).

[0091] The loading of gold nanoparticles obtained by the encapsulation process refers to the final weight of gold relative to the weight of the biodegradable polymer particles formed (i.e., the weight of encapsulated gold and, optionally, the weight of adsorbed gold).

[0092] The encapsulation rate of the active ingredient indicates the final weight of the active ingredient (ie, the weight of the encapsulated active ingredient) relative to the weight of the biodegradable polymer particles formed.

[0093] These are the actual weights measured after compounding.

[0094] As a guideline, the encapsulation rate of gold nanoparticles is 1-4%, preferably 1-3%, and even more preferably about 1.4%.

[0095] The encapsulation rate of the active ingredient is 0.5 to 5%, preferably 1 to 3%, and even more preferably about 2%.

[0096] The above-described manufacturing method (encapsulation process) according to the present invention advantageously gives an encapsulation yield of more than 75%, preferably at least 90%, even more preferably at least 95%, whereas without the use of polycations the encapsulation yield and encapsulation rate are zero.

[0097] The use of the above polycations in the method of the invention advantageously makes it possible to obtain high encapsulation yields, i.e., encapsulation yields close to or equal to 100%, which is a considerable benefit, especially in terms of cost and time.

[0098] According to another embodiment of the present invention, the particulate structure is more particularly characterized in that gold nanoparticles b / are adsorbed on the surface of polymer particles a / and the active ingredient, if present, is encapsulated in the polymer particles a / .

[0099] In this case, the polymer particles a / are "filled" polymer particles a / , in which the active ingredient is optionally also present.

[0100] The present invention also relates to a method for producing the particulate structure defined above (i.e., gold nanoparticles b / are adsorbed on the surface of polymer particles a / and the active ingredient, if present, is encapsulated in the polymer particles a / ), which method is also called the "adsorption process" and - contacting a mixture of a biodegradable polymer and a water-miscible organic solvent with water, optionally premixed with at least one active ingredient, to precipitate the biodegradable polymer in the form of particles with the surfactant, if present, adsorbed on the surface; - contacting the polymer particles a / defined in the preceding step with an aqueous solution of a polycation to obtain polymer particles a / having the polycation adsorbed on their surface, the biodegradable polymer particles further encapsulating the active ingredient, if present; - contacting the polymer particles a / , on whose surface the polycations defined in the preceding step are adsorbed, with an aqueous suspension of gold nanoparticles b / , so that the gold nanoparticles b / are adsorbed on the surface of the polymer particles a / , The adsorption yield of the gold nanoparticles b / on the surface of the polymer particles a / is characterized by being 30 to 70%, preferably 40 to 60%.

[0101] The adsorption yield of gold nanoparticles indicates the final weight of gold (i.e., the weight of gold adsorbed) relative to the weight of gold used.

[0102] The loading of gold nanoparticles obtained by the adsorption process refers to the final weight of gold (ie, the weight of gold adsorbed) relative to the weight of the biodegradable polymer particles formed.

[0103] If no polycation is used, the adsorption yield can be zero.

[0104] The method of the present invention also relates to an encapsulation process by one of the two methods described above or to an adsorption process described above, the common original feature of which is the use of polycations.

[0105] When the loading obtained by the encapsulation process (i.e., gold nanoparticles inside the polymer particles and optionally on the surface of the polymer particles) is compared to that obtained by the adsorption process (gold nanoparticles only on the surface of the polymer particles), the loading is different, indicating that encapsulation is indeed present.

[0106] Schematic diagrams of the manufacturing method according to the present invention are shown in Figure 5a (encapsulation process) and Figure 5b (adsorption process).

[0107] According to an advantageous embodiment of the manufacturing method according to the invention: the concentration of said aqueous solution of gold nanoparticles b / is between 8 and 12 grams of gold nanoparticles per liter of water, the concentration of said aqueous solution of polycation is between 30 and 70 grams of polycation per liter of water, the concentration of the mixture of biodegradable polymer and water-miscible organic solvent is 10 to 20 grams of polymer per liter of solvent, said organic solvent being selected from the group comprising dimethyl sulfoxide (DMSO), dimethylformamide (DMF) and N-methylpyrrolidone; the amount of active ingredient in the organic solvent, if present, is such that the concentration of the active ingredient is between 0.15 and 0.75 grams per liter of solvent; The amount of surfactant in the water, if present, is between 5 and 10 grams of surfactant per liter of water.

[0108] These various concentrations or amounts are effective for both the encapsulation and adsorption processes.

[0109] As mentioned above, the presence or absence of a surfactant depends on the nature of the biodegradable polymer used. Therefore, if the biodegradable polymer is PEG or (PLGA-PEG) copolymer, there is no need to use a surfactant. If the biodegradable polymer is PLGA, the presence of a surfactant is necessary. The surfactant can be, for example, polyvinyl alcohol (PVA).

[0110] According to another advantageous embodiment of the production method according to the invention, the polycation / gold ratio, i.e. the ratio "aqueous solution of polycation / aqueous suspension of gold nanoparticles b / ", varies from 4 to 8, preferably 5.

[0111] According to yet another advantageous embodiment of the manufacturing method according to the invention, and more particularly of the encapsulation process, the pH of the aqueous solution of polycation varies between 9 and 11, preferably 10.8.

[0112] The pH of the polycation solution influences the size of the polymer particles obtained: a pH of 10.8 makes it possible to obtain polymer particles a / with a hydrodynamic diameter of about 150 nm.

[0113] The inventive production method according to the invention, which consists in using polycations, leads to the production of particulate structures with a monodisperse size, which can be adjusted depending on the polycation / gold ratio and on the pH of the aqueous solution of the polycation.

[0114] As a guideline, the polydispersity index of the particulate structure should be less than 0.25. The particulate structure of the present invention has a polydispersity index of about 0.16.

[0115] The polydispersity index describes the size distribution of a population of particles. The lower the index, the more monodisperse (uniformly sized) the sample. Traditional methods that do not use polycations produce particles that are polydisperse and / or generally large in size (on the order of micrometers), and involve low encapsulation yields.

[0116] The manufacturing method according to the present invention is advantageous in that it produces particles of uniform size in the nanometer order, as well as being highly reproducible both in terms of the resulting loading (encapsulation rate) and the size of the resulting particles.

[0117] The method of the present invention is also advantageous in that it allows the encapsulation of gold nanoparticles b / , i.e. gold nanoparticles that are already functionalized and have the contrast agent properties required in particular for MRI, and optionally active ingredients, with an encapsulation yield that is close to or even 100%.

[0118] A major field of application for the particulate structures of the present invention is imaging in conjunction with the treatment of tumors by radiotherapy.

[0119] Biodegradable polymer particles (a / ), such as PLGA particles, can act as a transporter, and encapsulated and / or adsorbed gold nanoparticles (b / ) can act as a contrast agent and radiosensitizer. The primary benefit of encapsulating (or adsorbing) gold nanoparticles (b / ) in (or onto) polymer particles (a / ) is to increase the plasma half-life of the gold nanoparticles (b / ), improving tumor accumulation and better utilizing their radiosensitizing properties. As a guideline, the plasma half-life of PLGA particles is 15 days. Thus, encapsulated and / or adsorbed gold nanoparticles (b / ) have the potential to circulate in the blood for a longer period of time and accumulate in larger amounts in tumors. Improved tumor accumulation of gold nanoparticles can enhance synergistic effects with radiotherapy. Furthermore, once the polymer particles degrade, the functionalized gold nanoparticles (b / ) can return to the bloodstream and be rapidly excreted via the renal route.

[0120] Furthermore, the role of the bioabsorbable polymer particles a / is not limited to the transport of the functionalized radiosensitized gold nanoparticles b / : in fact, in addition to the encapsulation of the gold nanoparticles b / , the polymer particles a / also allow the encapsulation of at least one active ingredient, such as a chemotherapeutic agent and / or a fluorophore.

[0121] This co-encapsulation gives the particulate structures of the present invention very interesting therapeutic properties, since they allow for improved tumor treatment by combining image-guided radiotherapy with chemotherapy.

[0122] The particulate structure of the present invention advantageously allows for the administration of radiation therapy to improve the efficacy of the treatment while reducing side effects, particularly in the case of tumor treatment.

[0123] The present invention also relates to a pharmaceutical composition containing a therapeutically effective amount of at least one particulate structure as defined above.

[0124] The amount of particulate structure may vary depending on the intended use and the age and weight of the patient.

[0125] The particulate structure or pharmaceutical composition of the present invention may be in a form suitable for administration by intravenous route, for example, as an injectable suspension.

[0126] The present invention also relates to a particulate structure as defined above for use in the treatment of cancerous solid tumors.

[0127] The present invention also relates to a method for the therapeutic treatment of cancerous solid tumors, comprising the administration to a subject of a therapeutically effective amount of at least one particulate structure or composition as defined above.

[0128] The present invention also relates to a particulate structure as defined above for use in radiotherapy or chemotherapy, more particularly in image-guided radiotherapy.

[0129] The present invention also relates to a method of therapeutic treatment by radiotherapy or chemotherapy, more particularly image-guided radiotherapy, comprising the administration to a subject of a therapeutically effective amount of at least one particulate structure or composition as defined above. [Brief description of the drawing] Other features, details and advantages will become more apparent upon reading the following detailed description and examining the accompanying drawings.

[0130] Figure 1a [Figure 1a] is a schematic diagram of a functionalized gold nanoparticle b / in which a macrocyclic chelator is complexed to an ion of interest.

[0131] Figure 1b [Figure 1b] is a schematic diagram of a functionalized gold nanoparticle b / in which a macrocyclic chelator is complexed to a radionuclide.

[0132] Figure 1c [Figure 1c] is a schematic diagram of functionalized gold nanoparticles b / in which a macrocyclic chelator is complexed to a target ion and a radionuclide.

[0133] Figure 2a [Figure 2a] is a schematic diagram of a particulate structure of the present invention, which contains biodegradable polymer particles a / encapsulating 100% gold nanoparticles b / inside. The gold nanoparticles form electrostatic interactions with polycations.

[0134] Figure 2b [FIG. 2b] is a schematic diagram of a particulate structure of the present invention that includes gold nanoparticles b / encapsulated in biodegradable polymer particles a / and adsorbed to the surface of the polymer particles a / .

[0135] Figure 2c [FIG. 2c] is a schematic diagram of the particulate structure of the present invention in which 100% of the gold nanoparticles b / are adsorbed onto the surface of the polymer particles a / .

[0136] A surfactant adsorbed on the surface of the polymer particle a / is depicted in each of Figures 2a, 2b, and 2c, although the presence of the latter is optional and each of these figures can also be depicted without the surfactant.

[0137] Polycations are not shown with positive charges in each of the particulate structures of the present invention so as not to clutter each of Figures 2a, 2b and 2c.

[0138] Figure 3a [Figure 3a] is a schematic diagram of a particulate structure of the present invention, which corresponds to that of Figure 2a, but further comprises an active ingredient encapsulated in polymer particles a / .

[0139] Figure 3b [Figure 3b] is a schematic diagram of a particulate structure of the present invention, which corresponds to that of Figure 2b, but further comprises an active ingredient encapsulated in polymer particles a / .

[0140] Figure 3c [Figure 3c] is a schematic diagram of a particulate structure of the present invention, which corresponds to that of Figure 2c, but further comprises an active ingredient encapsulated in polymer particles a / .

[0141] The active ingredients are represented by stars in each of Figures 3a, 3b and 3c.

[0142] Figure 4a [Figure 4a] shows the structural formula of the macrocyclic chelating agent (L).

[0143] Figure 4b [Figure 4b] shows the structural formula of the polycation.

[0144] Figure 4c [Figure 4c] shows the structural formula of the biodegradable polymer.

[0145] Figure 5a [Figure 5a] shows a method for producing a particulate structure of the present invention, in which gold nanoparticles b / are encapsulated in polymer particles a / , and some of the gold nanoparticles b / are also adsorbed on the surface of polymer particles a / (encapsulation process by Method 2).

[0146] Figure 5b [FIG. 5b] shows a method for producing a particulate structure of the present invention, in which gold nanoparticles b / are adsorbed onto the surface of polymer particles a / (adsorption process).

[0147] When an active ingredient is added, the latter is mixed with the organic solvent and the biodegradable polymer in either an encapsulation or adsorption process.

[0148] In these figures, "AuNp" refers to gold nanoparticles.

[0149] Figure 6 [Figure 6] shows a transmission electron micrograph of a particulate structure of the present invention, in which polymer particles a / containing several encapsulated and / or adsorbed gold nanoparticles can be seen.

[0150] Figure 7 [Figure 7] shows a hemokinetic graph showing the change in injected gold dose (as a percentage) per gram of blood as a function of time, for gold nanoparticles alone (denoted by "AuNp"), gold nanoparticles encapsulated in PLGA particles (denoted by "NP3"), or gold nanoparticles encapsulated in PLGA-PEG particles (denoted by "NP3-PEG").

[0151] Description of the embodiment Example Preparation of the following particulate structures according to the present invention: - the biodegradable polymer a / is poly(lactic-co-glycolic acid) (PLGA) or a conjugate of poly(lactic-co-glycolic acid) and polyethylene glycol (PLGA-PEG), - the macrocyclic chelator is TADOTAGA and the target ion is gadolinium (Gd3+); - The polycation is polyethyleneimine (PEI).

[0152] The surfactant is polyvinyl alcohol (PVA) and the water-miscible organic solvent is dimethyl sulfoxide (DMSO).

[0153] Gold nanoparticles b / whose surfaces are coated with the chelating agent TADOTAGA that complexes gadolinium ions are hereinafter referred to as "Au@TADOTAGA(Gd)".

[0154] material More specifically, PLGA 50:50 (MW 7000-17000 Da) (commercially available under the name Resomer® RG 502H) is obtained from Evonik Industries (Evonik Rohm GmbH), and PLGA-PEG 50:50 (PLGA: MW 25000 Da, PEG: MW 5000 Da) is obtained from Sigma Aldrich (St. Louis, USA).

[0155] Chloroauric acid (HAuCl 3H O), sodium borohydride (NaBH), PVA (MW 30,000–70,000 Da), branched polyethyleneimine (PEI) (MW 25,000 Da), gadolinium chloride (GdCl 6H O), and dimethyl sulfoxide (DMSO) are obtained from Sigma-Aldrich (Saint Louis, USA). The ligand TADOTAGA is obtained from Chematech (Dijon, France).

[0156] Synthesis of Au@TADOTAGA(Gd) nanoparticles The synthesis of gold nanoparticles is adapted from the single-phase protocol developed by Brust et al. (6). Gold nanoparticles are obtained by reducing gold salt (HAuCl4·3H2O) with NaBH4 in the presence of the ligand TADOTAGA. The adsorption of TADOTAGA onto the surface of the gold nanoparticles allows for control of size and colloidal stability, and allows for the immobilization of gadolinium. More specifically, HAuCl4·3H2O (50 mg, 1.22 × 10 OH) dissolved in methanol (20 mL) is used. -4 mol) in a 250 mL round-bottom flask. -4 mol) is added to the gold salt solution with stirring. The mixture turns from yellow to orange. After a few minutes, NaBH4 (48 mg, 12.7 × 10 mol) dissolved in water (3 mL) is added. -4 Add 1000 mg of ethanol (1000 mol) at room temperature with vigorous stirring. Maintain stirring for 1 hour. Then, dialyze the mixture using a 6000-8000 kDa MWCO membrane.

[0157] Prior to the encapsulation process in polymer particles, the gold suspension is concentrated and gadolinium is trapped in the TADOTAGA chelator to obtain the final Au@TADOTAGA(Gd) suspension ([Au] = 51 mM, [Gd] = 5 mM). This is done by stirring the suspension overnight with GdCl3·6H2O (370 µL of 135 mM for 10 mL of Au@TADOTAGA(Gd) suspension). The 5 mM gadolinium concentration ensures suspension stability and optimal MRI signal.

[0158] Synthesis of PLGA or PLGA-PEG polymer particles encapsulating Au@TADOTAGA(Gd) The method for preparing polymer particles encapsulating gold nanoparticles b / (Au@TADOTAGA(Gd)) is based on the method of nanoprecipitation by solvent displacement (13) but has the novel feature of using PEI. We found that the size of the polymer particles can be tuned as a function of the PEI / gold ratio and the pH of the aqueous solution of PEI.

[0159] In particular, the inventors found during their research that a PEI / gold ratio of 5 and a pH of about 10.8 were suitable for obtaining polymer particles with a hydrodynamic diameter of about 160 nm. In fact, a size of 160 nm ± 15 nm is advantageous in that it allows for the encapsulation of a satisfactory amount of gold nanoparticles b / while at the same time allowing for a satisfactory production yield.

[0160] An aqueous solution of PEI (25 μL, 5% w / w) is mixed with 1 mL of a solution of PLGA or PLGA-PEG in DMSO (15 mg / mL and 18 mg / mL, respectively).

[0161] To obtain a hydrodynamic diameter of the PLGA particles close to 160 nm±15 nm, 1 N HCl is added beforehand to the aqueous solution of PEI.

[0162] For the preparation of different particles, only the PEI concentration is adjusted to adjust the PEI / gold ratio. Regardless of the PEI concentration, the same volume of HCl is added to the solution as for the preparation of PLGA particles with a diameter of approximately 160 nm.

[0163] A suspension of Au@TADOTAGA(Gd) (25 μL, 10 mg / mL (i.e., 51 mM)) is added to the aforementioned solution containing PEI and PLGA.

[0164] Next, 4 mL of PVA dissolved in water at 0.75% was slowly added to the mixture and pre-vortexed.

[0165] To prepare PLGA particles by adsorption of gold nanoparticles, PLGA particles are preformed following the same protocol as conventional PLGA particles.

[0166] Then, 25 μL of a 5% solution of PEI was transferred to the PLGA particle suspension while stirring. After 5 min of incubation, 25 μL of a 10 mg / mL (i.e., 51 mM) Au@TADOTAGA(Gd) suspension was finally added to the PEI-coated PLGA particles.

[0167] The various preparations are washed three times by ultracentrifugation at 30,000 g for 1 hour at 4 °C to remove free gold nanoparticles. Finally, the preparations are lyophilized using sucrose as a cryoprotectant, except for the batch used to determine the production yield, encapsulation yield, and encapsulation rate.

[0168] These parameters are determined as follows:

[0169]

number

[0170] The different characteristics of the particles obtained according to this protocol by varying the PEI / gold ratio are listed in Table 1 below:

[0171] [Table 1]

[0172] Thus, we obtain particles with hydrodynamic diameters of 130 nm to 200 nm (the size can be further reduced by adjusting the PEI / gold ratio) and an encapsulation rate of approximately 1.4. The reduction in size inevitably leads to a decrease in production yield due to the need for centrifugation for cleaning.

[0173] NP3 particles (PEI / gold ratio 5) are selected for in vivo testing. These particles represent a good compromise between size and production yield. The encapsulation rate is half that of the encapsulation protocol (NP3 adsorption), demonstrating the encapsulation of gold nanoparticles. The presence of gold is confirmed by transmission electron microscopy imaging (see Figure 6).

[0174] Image-guided therapy The particulate structures of the present invention are promising candidates for image-guided therapy if they exhibit appropriate behavior after intravenous injection, including increased plasma half-life compared to gold nanoparticles, such as accumulation in the area to be treated, absence of nanoparticles in surrounding healthy tissue, and preferential renal excretion (compared to hepatobiliary route).

[0175] Therefore, blood kinetic studies were performed in rats by injecting 500 μL of NP3 suspension (or NP3-PEG) (100 mg / mL in PLGA) or an equivalent amount of gold nanoparticles "alone" (AuNp). This was performed by intravenous injection (penile vein) after isoflurane anesthesia. Blood samples were taken from the tail at various time points, and the amount of gold present in the samples was then measured by atomic absorption spectroscopy.

[0176] The results obtained are shown in FIG.

[0177] Conclusion: Encapsulation, whether performed with PLGA or PLGA-PEG, increases the plasma half-life of gold nanoparticles.

[0178] The encapsulation process of the present invention advantageously allows the encapsulation of gold nanoparticles in particles of reduced size (between 100 and 200 nm) with a yield approaching 100% while maintaining a low polydispersity index. The particulate structures thus obtained allow the plasma half-life of gold nanoparticles to be increased and therefore have considerable potential for improving the therapeutic efficacy of said gold nanoparticles.

[0179] The above-described embodiments are merely illustrative, and the present invention is not limited to the above-described embodiments, but includes all modifications that can be conceived by a person skilled in the art within the scope of protection sought.

[0180] References list Non-patent literature For all intents and purposes, the following non-patented material is referenced: (1) J.F. Hainfeld et al., Phys. Med. Biol., 49 (2004) N309-315 ; (2) Gautier Laurent et al, Nanoscale, 8( 2016) 12054-65 ; (3) A.M. Gobin et al, Nano Lett., 7 (2007) 1929-1934 ; (4) J.F. Hainfeld et al, Br. J. Radiol., 79 (2006) 248-253 ; (5) K.T. Butterworth et al, Nanoscale, 4 (2012) 4830-4838 ; (6) M. Brust et al, J. Chem. Soc. Chem, Commun., (1995) 0, 1655-1656 ; (7) P.C.S. John Turkevich, Discuss Faraday Soc, 11 (n.d.) 55-75 ; (8) Thesis of G. Laurent, Synthesis of multifunctional nanoparticles for image-guided radiotherapy. Organic chemistry. Franche-Comte University, 2014 ; (9) T. Butterworth et al., Nanoscale, 2012 ; 4, 4830-4838 ; (10) M. Yu et al., ACS nano, 2015, 9, 6655-6674 ; (11) Wang Y et al., Biomed Opt Express, 2016, 7, 4125-4138 ; (12) Luque-Michel et al., Nanoscale, 2016, 8, 6495-6506 ; (13) H. Fessi et al., International Journal of Pharmaceutics, 1989, 55, R1-R4. [Brief explanation of the drawings]

[0181] [Figure 1a] FIG. 1 is a schematic representation of functionalized gold nanoparticles b / in which a macrocyclic chelator is complexed to an ion of interest. [Figure 1b] FIG. 1 is a schematic representation of functionalized gold nanoparticles b / in which a macrocyclic chelator is complexed to a radionuclide. [Figure 1c] FIG. 1 is a schematic representation of functionalized gold nanoparticles b / in which a macrocyclic chelator is complexed to an ion of interest and a radionuclide. [Figure 2a] 1 is a schematic diagram of a particulate structure of the present invention comprising biodegradable polymer particles a / encapsulating 100% gold nanoparticles b / inside thereof, where the gold nanoparticles form electrostatic interactions with polycations. [Figure 2b] FIG. 1 is a schematic diagram of a particulate structure of the present invention comprising gold nanoparticles b / encapsulated in biodegradable polymer particles a / and adsorbed to the surface of the polymer particles a / . [Figure 2c] 2A, 2B, and 2C are schematic diagrams of particulate structures of the present invention in which 100% of gold nanoparticles b / are adsorbed on the surface of polymer particles a / . A surfactant adsorbed on the surface of polymer particles a / is depicted in each of Figures 2A, 2B, and 2C. However, the presence of the latter is optional, and each of these figures can also be depicted without the surfactant. Polycations are not depicted with positive charges in each of Figures 2A, 2B, and 2C so as not to complicate each of the particulate structures of the present invention. [Figure 3a] 2a is a schematic representation of a particulate structure of the present invention, corresponding to that of FIG. 2a, but further comprising an active ingredient encapsulated in polymer particles a / . [Figure 3b] 2b is a schematic representation of a particulate structure of the present invention, corresponding to that of FIG. 2b, but further comprising an active ingredient encapsulated in polymer particles a / . [Figure 3c]3a, 3b and 3c are schematic illustrations of particulate structures of the present invention, corresponding to those of FIG. 2c, but further comprising an active ingredient encapsulated in polymer particles a / . The active ingredient is represented by a star in each of FIGS. 3a, 3b and 3c. [Figure 4a] The structural formula of the macrocyclic chelating agent (L) is shown below. [Figure 4b] The structural formula of polycation is shown below. [Figure 4c] The structural formula of the biodegradable polymer is shown below. [Figure 5a] This shows a method for producing the particulate structure of the present invention, in which gold nanoparticles b / are encapsulated in polymer particles a / , and some of the gold nanoparticles b / are also adsorbed on the surface of polymer particles a / (encapsulation process by method 2). [Figure 5b] The figures show a method for producing the particulate structure of the present invention, in which gold nanoparticles b / are adsorbed onto the surface of polymer particles a / (adsorption process). When an active ingredient is added, the latter is mixed with an organic solvent and a biodegradable polymer, either in the encapsulation process or the adsorption process. In these figures, "Au Np" refers to gold nanoparticles. [Figure 6] A transmission electron micrograph of a particulate structure of the invention is shown, in which polymer particles a / containing several encapsulated and / or adsorbed gold nanoparticles can be seen. [Figure 7] 1 shows a hemokinetic graph showing the change in injected gold dose (as a percentage) per gram of blood as a function of time, for gold nanoparticles alone (denoted by "AuNp"), gold nanoparticles encapsulated in PLGA particles (denoted by "NP3"), or gold nanoparticles encapsulated in PLGA-PEG particles (denoted by "NP3-PEG").

Claims

1. a / biodegradable polymer particles; b / gold nanoparticles coated on their surfaces with a macrocyclic chelating agent that complexes at least one target ion and / or radionuclide for medical imaging; c / a polycation having a positive charge over the pH range of 5 to 11; a particulate structure characterized in that the gold nanoparticles b / are encapsulated in the polymer particles a / and optionally adsorbed on the surfaces of the polymer particles a / ; The polycation c / is located near the gold nanoparticle b / due to electrostatic interactions with the gold nanoparticle b / , and the polycation c / is therefore encapsulated in the polymer particle a / and optionally adsorbed to the surface of the polymer particle a / . the biodegradable polymer is selected from the group comprising poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), poly(glycolic acid) (PGA), polycaprolactone (PCL), polyanhydrides, copolymers of each of the foregoing polymers with polyethylene glycol (PEG), and mixtures thereof; the polycation is selected from the group comprising polyethyleneimine (PEI), polylysine, polyarginine, polyamidoamine (PAMAM), poly(β-amino ester), chitosan, and mixtures thereof; Particulate structure.

2. 2. The particulate structure according to claim 1, characterized in that it comprises a surfactant adsorbed on the surface of the polymer particles a / , the surfactant being preferably polyvinyl alcohol (PVA) and / or poloxamer.

3. 3. The particulate structure according to claim 1 or 2, characterized in that it comprises at least one active ingredient encapsulated in the polymer particles a / , said active ingredient being preferably a chemotherapeutic agent and / or a fluorophore.

4. The macrocyclic chelating agents coating the gold nanoparticles each comprise: - an anchoring functional group containing at least one sulfur atom for attaching the macrocyclic chelator to the gold nanoparticle, preferably containing two sulfur atoms forming an intracyclic disulfide bond; at least one complexation moiety for ions and / or radionuclides of interest for medical imaging, the complexation moiety comprising at least one carboxylic acid and / or amine functional group; a spacer arm located between the anchor functional group and the complexation moiety; 4. Particulate structure according to any one of claims 1 to 3, characterized in that it comprises, optionally, functionalization sites that allow the grafting of chelating agents with agents for targeting cancer cells.

5. the anchoring functional group of the macrocyclic chelating agent is 【Chemistry 1】 , *-N-(CH ２ -CH ２ -SH)2, *-C(=O)-(CH ２ ) n-SH, where n is an integer from 2 to 5, and mixtures thereof; the spacer arm of the macrocyclic chelator is *-(CH ２ )2-CO-NH-(CH ２ )2-NH-*, *-NH-(CH ２ -CH ２ —O)m-CH ２ -CH ２ a radical selected from the group consisting of -NH-*, where m is an integer equal to 0, 4 or 11, and mixtures thereof; - the functionalized moiety of the macrocyclic chelating agent, if present, *-NH-CH((CH ２ ) ４ -NH ２ )-CO-*, *-NH-CH(CH ２ -OH)-CO-*, *-NH-CH(CH-OH-CH ３ )-CO-*, *-NH-CH(CH ２ -C ６ H ４ -OH)-CO-*,*-NH-CH((CH ２ ) ｎ The particulate structure according to claim 4, characterized in that the group is derived from an amino acid and is selected from the group consisting of —NH—*)—CO—* (wherein n is 2 to 5) and mixtures thereof.

6. The macrocyclic chelating agent is TADOTAGA, TANODAGA, TADFO, TA [DOTAGA-lys-NH ２ ], TA[NODAGA-lys-NH ２ 6. The particulate structure according to claim 1, wherein the particulate structure is selected from the group consisting of TA[DOTAGA-lys-NODAGA], TA[DOTAGA-lys-NODAGA] and mixtures thereof.

7. - said ions of interest for medical imaging, more particularly for magnetic resonance imaging (MRI), are selected from the group comprising Gd3+, Ho3+, Dy3+ and mixtures thereof; said radionuclides for medical imaging, more particularly for nuclear imaging (SPET or PET), ６４ Cu, ８９ Zr, ８８ Ga, １１１ 7. The particulate structure according to claim 1, wherein the metal is selected from the group consisting of In, In, and mixtures thereof.

8. The particulate structure according to any one of claims 1 to 7, wherein the polycation is polyethyleneimine.

9. The particulate structure according to any one of claims 1 to 8, wherein the biodegradable polymer is poly(lactic acid-co-glycolic acid) or a [poly(lactic acid-co-glycolic acid)-polyethylene glycol] copolymer.

10. The gold nanoparticles b / are integrin α overexpressed in tumor neovasculature. Ｖ β ＩＩＩ 10. The particulate structure according to claim 1, characterized in that its surface is coated with a macrocyclic chelating agent bound to an active agent that targets the targeting agent, the targeting agent being preferably a cyclic RGD peptide.

11. the hydrodynamic diameter of said polymer particles a / is between 50 and 200 nm, preferably between 70 and 160 nm; - Particulate structure according to any one of claims 1 to 10, characterized in that the hydrodynamic diameter of the gold nanoparticles b / is between 3 and 15 nm, preferably between 6 and 10 nm.

12. 12. The particulate structure according to claim 1, wherein the gold nanoparticles b / and any active ingredient are encapsulated in the polymer particles a / , and the gold nanoparticles b / are further adsorbed onto the surface of the polymer particles a / .

13. - contacting an aqueous suspension of gold nanoparticles b / with an aqueous solution of polycations c / to obtain aggregates of gold nanoparticles b / and polycations c / ; - contacting the aggregate of gold nanoparticles b / and polycations c / defined in the preceding step with a mixture of a biodegradable polymer a / and a water-miscible organic solvent, optionally premixed with at least one active ingredient, to obtain a mixture of gold nanoparticles b / , polycations c / , biodegradable polymer a / and any active ingredient; - contacting the mixture of the gold nanoparticles b / , polycation c / , biodegradable polymer a / and any active ingredient defined in the preceding step with water, optionally containing a surfactant, in order to precipitate the biodegradable polymer a / in the form of particles around the gold nanoparticles b / and any active ingredient, 13. The method for producing a particulate structure according to any one of claims 1 to 12, characterized in that the encapsulation yield of the gold nanoparticles b / and any active ingredient in the biodegradable polymer particles a / is at least 75%, preferably at least 90%, and even more preferably at least 95%.

14. - contacting an aqueous solution of polycation c / with a mixture of biodegradable polymer a / and a water-miscible organic solvent, said organic solvent optionally being premixed with at least one active ingredient; - contacting the aggregate of the mixture of polycations c / and biodegradable polymer a / with organic solvent defined in the preceding step with an aqueous suspension of gold nanoparticles b / to obtain a mixture of gold nanoparticles b / , polycations c / , biodegradable polymer a / and any active ingredient; - contacting the mixture of the gold nanoparticles b / , polycation c / , biodegradable polymer a / and any active ingredient defined in the preceding step with water, optionally containing a surfactant, in order to precipitate the biodegradable polymer a / in the form of particles around the gold nanoparticles b / and any active ingredient, 13. The method for producing a particulate structure according to any one of claims 1 to 12, characterized in that the encapsulation yield of the gold nanoparticles b / and any active ingredient in the biodegradable polymer particles a / is at least 75%, preferably at least 90%, and even more preferably at least 95%.

15. the concentration of said aqueous solution of gold nanoparticles b / is between 8 and 12 grams of gold nanoparticles per liter of water; the concentration of said aqueous solution of polycation c / is between 30 and 70 grams of polycation per liter of water; the concentration of the mixture of biodegradable polymer a / and water-miscible organic solvent is between 10 and 20 grams of polymer per liter of solvent, said organic solvent being selected from the group comprising dimethyl sulfoxide (DMSO), dimethylformamide (DMF) and N-methylpyrrolidone; the amount of active ingredient in said organic solvent, if present, is in a concentration of 0.1 to 0.75 grams of active ingredient per liter of solvent; - A process according to claim 13 or 14, characterized in that the amount of surfactant in the water, if present, is between 5 and 10 grams of surfactant per liter of water.

16. The particulate structure according to any one of claims 1 to 12 for use in the treatment of cancerous solid tumors.

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