USE OF A PHENOLIC COMPOUND FOR THE PREPARATION OF HYDROGELS BY UV PHOTORETICULATION

Abstract

The present invention relates to the use of a phenolic compound, particularly one that is biocompatible, water-soluble, and absorbs in a range of UV wavelengths, for the preparation of a hydrogel by UV photocuring, as well as the corresponding preparation process starting from a photocurable resin comprising the phenolic compound. The present invention also relates to said photocurable resin per se, as well as the hydrogel per se. (no figure)

Description

Title of the invention: USE OF A PHENOLIC COMPOUND FOR THE PREPARATION OF HYDROGELS BY UV PHOTOCROSSLINKING

[0001] The present invention relates to the use of a phenolic compound, in particular biocompatible, soluble in water and absorbing in a range of UV wavelengths for the preparation of a hydrogel by UV photocrosslinking, as well as the corresponding preparation process from a photocrosslinkable resin comprising the phenolic compound. The present invention also relates to said photocrosslinkable resin per se, as well as the hydrogel per se.

[0002] Hydrogels are three-dimensional polymeric materials that have the unique ability to retain large amounts of water while maintaining their structure. These materials have become extremely sought after, particularly in the medical field, for example in bioengineering, regenerative medicine or pharmacology, due to these exceptional properties.

[0003] Hydrogels provide an environment similar to that of biological tissues, making them ideal for tissue engineering. They can serve as matrices for cell culture and tissue regeneration, thus contributing to the creation of biomimetic grafts and prostheses.

[0004] Hydrogels can also be used as drug delivery carriers, providing controlled and prolonged release of active substances. This is particularly useful for the treatment of chronic diseases such as cancer, heart disease and diabetes.

[0005] Hydrogels are also used in diagnostic devices, such as glucose sensors and rapid diagnostic tests. Their ability to absorb and react with specific compounds makes them valuable for the detection of biomarkers and pathogens.

[0006] In this context, hydrogels having one or more cavities are particularly advantageous.

[0007] Hollow objects made from hydrogels are, for example, essential in the field of bioprinting. They can form complex three-dimensional structures, such as those found in blood vessels, nerve conduits, and even complete organs.

[0008] The creation of hollow hydrogel objects also allows for the design of targeted drug delivery systems. These hollow objects can be filled with drugs and inserted directly into a specific area of ​​the body, allowing for deli- precise beration and minimizing side effects.

[0009] The preparation of hydrogels by 3D printing is a constantly evolving field of research that aims to create hydrophilic three-dimensional structures from ad hoc resins. These 3D hydrogels can typically be prepared by UV photopolymerization.

[0010] This method uses monomeric or polymeric materials that are sensitive to ultraviolet (UV) rays. An aqueous resin containing these polymers is exposed to UV light through a pattern mask or by a projection process, which causes the material to selectively solidify to form the 3D hydrogel structure, layer by layer.

[0011] However, due to the high water content of the resin, this technique does not allow hollow hydrogels to be obtained, or those comprising cavities or holes, or only allows this in a partial and unsatisfactory manner, at the cost of using compounds unsuitable for biomedical applications, because in particular they are toxic or suspected of being so, and therefore not biocompatible.

[0012] An objective of the invention is thus to provide hollow hydrogels, or hydrogels comprising one or more cavities, with improved resolution.

[0013] Another objective of the invention is to provide such hydrogels using a 3D printing process using only biocompatible and mainly biosourced compounds.

[0014] Thus, the invention relates to the use of a water-soluble phenolic compound as a UV photo-absorber for the preparation of a 3D printed hydrogel by UV photo-crosslinking.

[0015] The invention also relates to the use of a water-soluble phenolic compound as a UV photo-absorber for the preparation of a hydrogel by UV photo-crosslinking.

[0016] The invention also relates to the use of a water-soluble and biocompatible phenolic compound as a UV photo-absorber for the preparation of a hydrogel by UV photo-crosslinking.

[0017] By "soluble in water" is meant in particular that a compound can be dissolved in water, in particular at a temperature of 0 to 100°C, at a level of 1x105 g / L or more.

[0018] By "as a UV photo-absorber" is meant in particular that the phenolic compound absorbs at a wavelength of 100 to 450 nm.

[0019] According to a particular embodiment, the phenolic compound is biocompatible.

[0020] By "biocompatible" is meant in particular non-toxic to the body, pharmaceutically acceptable, non-carcinogenic and not inducing significant inflammation in the body's tissues.

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[0034] According to a particular embodiment, the phenolic compound is biosourced. By "bio-sourced" we mean in particular derived from renewable organic matter, of microbial, plant, fungal or animal origin, in particular plant. According to a particular embodiment, the phenolic compound is derived from lignin. In the context of the present invention, the phenolic compound may optionally be in dimer form, either partially or totally. According to a particular embodiment, the phenolic compound has the following formula (I): [Chem.l] OH R / ' R 3 (I) in which: R1, R2, R3, R4, and R5 are independently selected from -H, -OH, -OR, with R being C1-C3 alkyl, in particular methyl, -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, -CH=CH-C(=O)OH, and -CH=CH-CH3, at least one of the groups Rb R2, R3, R4, and R5, in particular R3, being chosen from -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, -CH=CH-C(=O)OH and -CH=CH-CH3. According to a particular embodiment, R3 is chosen from -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, and -CH=CH-CH3. According to a particular embodiment, R2 and R4 are -H. According to a particular embodiment, R3 is chosen from -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, -CH=CH-C(=O)OH and -CH=CH-CH3, and: - Ri and R5 do not both represent -OR, especially when R3 is -C(=O)H; - Rb R2, R4, and R5 do not all represent four -H, in particular when R3 is -C(=O)OH or -CH=CH-C(=O)OH; and / or - Ri or R5 does not represent -OH, especially when R3 is -CH=CH-C(=O)OH. According to a particular embodiment, the phenolic compound is chosen from vanillin, vanillic acid, 4-hydroxybenzaldehyde, salicylic acid, 3-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, gentisic acid, protocatechuic acid, pyrogallolcarboxylic acid, phloroglucinic acid, gallic acid, syringic acid, orsellinic acid, ferulic acid, sinapic, and their mixtures.

[0035] According to a particular embodiment, the hydrogel consists of or comprises a compound chosen from water-soluble cellulose esters, hyaluronic acids, dextrans, chitosans, gum arabic, xanthan gum, alginates, pectins, polyethylene glycol and polyethylene glycol diacrylates, polyvinyl alcohol, polyacrylamide, poly(N-isopropylacrylamide), and mixtures thereof.

[0036] According to a particular embodiment, the hydrogel comprises at least one cavity.

[0037] By “the hydrogel comprises at least one cavity”, it is meant in particular that the hydrogel forms a 3D object comprising at least one cavity.

[0038] The at least one cavity has in particular a size of from 0.1 to 5000 μm.

[0039] According to a particular embodiment, the preparation of the hydrogel is carried out by additive manufacturing by UV photocrosslinking.

[0040] According to a particular embodiment, the preparation of the hydrogel is carried out by digital light processing (or DLP) or by stereolithography (SLA).

[0041] According to another aspect, the invention also relates to a method for preparing a hydrogel comprising a step (i) of UV exposure of a photo-crosslinkable resin comprising a water-soluble phenolic compound.

[0042] The invention relates in particular to a process for preparing a hydrogel comprising a step (i) of UV exposure of a photo-crosslinkable resin comprising a water-soluble and biocompatible phenolic compound.

[0043] All embodiments defined above relating to use also apply here, alone or in combination.

[0044] According to a particular embodiment, the hydrogel is a biocompatible hydrogel.

[0045] According to a particular embodiment, the resin comprises a monomer or a polymer carrying a photosensitive function.

[0046] By “polymer carrying a photosensitive function” is meant in particular a photocrosslinkable polymer.

[0047] By “monomer carrying a photosensitive function” is meant in particular a photopolymerizable and photocrosslinkable monomer.

[0048] This monomer may be an antioxidant or photoabsorber compound, as defined in particular above or below, which comprises one or more photosensitive functions as defined below.

[0049] This monomer may also be a monomer capable of forming a polymer as defined above or below.

[0050] In particular, the monomer or polymer carrying a photosensitive function is water-soluble.

[0051] In particular, the polymer carrying a photosensitive function is biocompatible.

[0052] According to a particular embodiment, the polymer is chosen from water-soluble cellulose esters, hyaluronic acids, dextrans, chitosans, gum arabic, xanthan gum, alginates, pectins, polyethylene glycol, polyacrylamides, poly(N-isopropylacrylamides), and mixtures thereof, functionalized with photosensitive functional groups.

[0053] By “photosensitive function” or “photosensitive functional group” is meant in particular a function chosen from acrylates, methacrylates, norbornenes, fumarate, allyl ether, vinyl ether, vinyl derivatives, maleimide.

[0054] According to a more particular embodiment, the polymer is a carboxymethylcellulose or a carboxymethylcellulose methacrylate. In the latter case, the carboxymethylcellulose methacrylate has in particular a degree of methacrylation of from 1 to 299%, for example approximately 34%.

[0055] According to a particular embodiment, the resin comprises a photoinitiator. The latter is well known to those skilled in the art and is, for example, lithium phenyl-2,4,6-trimethylbenzoylphosphinate, lithium phenylbis(2,4,6-trimethylbenzoyl)phosphine acid, sodium phenylbis(2,4,6-trimethylbenzoyl)phosphine acid, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] or 2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0056] According to a particular embodiment, the resin is a liquid resin.

[0057] According to a particular embodiment, the resin is a resin comprising a solvent selected from water, aqueous solutions, for example phosphate buffered saline (PBS), ethanol and mixtures thereof.

[0058] According to a particular embodiment, the resin additionally comprises at least one additive chosen from reinforcing fillers, in particular cellulose nanocrystals (NCC), antioxidants, crosslinking agents, pigments, viscosity modifiers, reinforcements, and mixtures thereof.

[0059] The additive is in particular cellulose nanocrystals.

[0060] According to a particular embodiment, the resin comprises carboxymethylcellulose methacrylate, lithium phenyl-2,4,6-trimethylbenzoylphosphinate, water, the phenolic compound, in particular vanillin, and optionally reinforcing fillers, in particular cellulose nanocrystals.

[0061] According to a particular embodiment, the resin comprises cellulose nanocrystals and / or 2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0062] According to a particular embodiment, the UV exposure is carried out at a wavelength of approximately 300 to approximately 405 nm, for example approximately 365, approximately 385 or approximately 405 nm.

[0063] According to a particular embodiment, the resin further comprises a photoi-

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[0076] initiator. According to a particular embodiment, the phenolic compound is present in the resin at a level of 10 4 to 10 4 mol% relative to the photoinitiator. According to a particular embodiment, the resin further comprises a monomer or a polymer carrying a photosensitive function, a solvent, and optionally at least one additive notably chosen from reinforcing fillers and antioxidants. According to a particular embodiment, the resin further comprises a monomer or a polymer carrying a photosensitive function, a photoinitiator, a solvent, and optionally at least one additive notably chosen from reinforcing fillers, notably cellulose nanocrystals, antioxidants. By “reinforcing fillers” we mean in particular cellulose nanocrystals, or any other filler allowing the material to be mechanically reinforced. According to a particular embodiment, the resin comprises: - a monomer or a polymer carrying a photosensitive function, in particular at a level of 0.1 to 50% m; - a photoinitiator, in particular at a level of 0.01 to 10%m; - a phenolic compound, in particular at a level of 105 to 10%m; - optionally reinforcing fillers, in particular cellulose nanocrystals; - optionally, an antioxidant; - Water, qsp. According to another aspect, the invention also relates to a photo-crosslinkable resin comprising a water-soluble phenolic compound, as defined above. The invention relates in particular to a photo-crosslinkable resin comprising a water-soluble and biocompatible phenolic compound, as defined above. All embodiments defined above relating to the use and / or method also apply here, alone or in combination. According to another aspect, the invention also relates to the use of the resin as defined above for the preparation of a hydrogel. All embodiments defined above relating to the use and / or method also apply here, alone or in combination. According to another aspect, the invention also relates to a hydrogel comprising a water-soluble phenolic compound, as defined above. The invention relates in particular to a hydrogel comprising a water-soluble and biocompatible phenolic compound, as defined above. All embodiments defined above relating to the use and / or to the process also apply here, alone or in combination.

[0077] According to another aspect, the invention also relates to the use of a hydrogel as defined above in biomedical applications such as the repair of biological tissues, the formation of extracellular matrices, the shaping of microfluidic systems for their integration into biosensors.

[0078] All embodiments defined previously relating to the use and / or the method also apply here, alone or in combination. DEFINITIONS

[0079] As used herein, the value ranges in the form of "xy" or "from x to y" or "between x and y" include the bounds x and y, the integers between these bounds, as well as all other real numbers between these bounds. For example, "1-5", or "from 1 to 5" or "between 1 and 5" designates the integers 1, 2, 3, 4 and 5, as well as all other real numbers between 1 and 5. Preferred embodiments include each individual integer in the value range, as well as any subcombination of these integers and any set of real numbers between these integers. For example, preferred values ​​for "1-5" might include the integers 1, 2, 3, 4, 5, 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, etc.

[0080] As used herein, the term "about" refers to a range of values ​​within ± 10% of a specific value. For example, the term "about 20" includes values ​​of 20 ± 10%, or values ​​from 18 to 22. FIGURES

[0081] [Fig.l] shows the evolution of the crosslinked thickness as a function of time for a formulation of mCMC and vanillin, according to example 3.

[0082] [Fig.2] shows the evolution of the crosslinked thickness as a function of time for a formulation of mCMC with NCC and vanillin, according to example 4.

[0083] [Fig.3] shows (a) the CAD of the hollow cube to be printed and (b) the hollow cube printed with the formulation with vanillin and NCC according to example 5. EXAMPLES

[0084] Example 1: preparation of a hydrogel according to the invention

[0085] The photosensitive cellulose formulation (Table 1), with vanillin as photoabsorber, was used for the manufacture of a hydrogel by DLP (Digital Light Processing). Water is the solvent and the main constituent of the formulation. The other components are soluble or dispersible (NCC) in water and biocompatible. Vanillin is soluble in water (10 g / L at 25 °C), biocompatible, antibacterial, absorbing at 365 / 385 nm

[0086] The DLP apparatus used is the DLP Asiga MAX (385 nm). During UV exposure, the methacrylate groups of the mCMC crosslink to form a network 3D of mCMC in which water and constituents are trapped. Formulation element %m Characteristics Distilled water 97.2 Solvent Carboxymethylcellulose methacrylate (mCMC) 2 DM = 34%, 90 kDa Polymer forming the main network of the hydrogel Lithium phenyl- 2,4,6-trimethylbenzoylphosphinate (LAP) 0.15 UV photoinitiator (320 - 405 nm) Vanillin 0.15 UV photoabsorber Cellulose nanocrystals (NCC) 0.5 Optional. May reinforce the network formed if desired

[0087] Table 1: Composition of the formulation (by mass)

[0088] A hollow object could be printed using the above-mentioned composition.

[0089] As a reference outside the invention, an identical formulation, composed of mCMC, LAP and water, and optionally NCC, but devoid of vanillin, was also printed by DLP. However, this formulation did not allow hollow objects to be obtained.

[0090] Example 2: preparation of another hydrogel according to the invention

[0091] A formulation similar to that described in Example 1, but without NCC and with Irgacure 2959 as photoinitiator, was also used successfully. In this formulation, the proportion of vanillin was 2.5.10 4 %m, and the exposures were carried out at 365 nm.

[0092] Curves showing the evolution of the printed layer thickness as a function of the exposure time were produced for such formulations, with formulations without vanillin as controls. This made it possible to show that vanillin did indeed play the role of photoabsorber at 365 nm.

[0093] Example 3: Study of a phenolic compound in a use according to the invention

[0094] Vanillin (0.15%m) was studied in a formulation of mCMC (2%m, DM = 34%) in water (97.7%m) and LAP (0.15%m).

[0095] Exposures of a layer of this formulation as a function of time were carried out (385 nm, 18 mW / cm2) ([Fig. 1]). The crosslinked thicknesses were measured. The addition of vanillin to the formulation reduced the crosslinked thickness by an average factor of 2.5 at each exposure time. In addition, the minimum time required to obtain a crosslinked layer was multiplied by 2 with the addition of vanillin (3 s without vanillin and 6 s with). Without wishing to be restricted to any theory, these two characteristics are those of a photoabsorber.

[0096] Example 4: Another study of a phenolic compound in a use according to the invention

[0097] Vanillin, in the formulation of Example 1, was also studied.

[0098] As in the case of the formulation without NCC (example 3), the crosslinked thickness has was reduced on average by a factor of 2.5 at each exposure time ([Fig.2]). In addition, the minimum time required to obtain a crosslinked layer was multiplied by 2 with the addition of vanillin (3 s without vanillin and 6 s with). The same properties as those observed for the formulation without NCC are therefore found. Without wishing to be restricted to any theory, NCCs do not have a photoabsorber effect, and vanillin is the only compound in the formulation allowing this characteristic. The photoabsorber properties of vanillin are preserved over time ([Fig.2]).

[0099] The stability of this formulation makes it possible to consider its printing by DLP and its conservation over time. Example 5: obtaining a hollow hydrogel

[0100] A hollow object could be printed using the formulation according to Example 4, which was not possible without the phenolic compound according to the invention ([Fig.3]).

[0101] The cube was printed with the Asiga Max DLP, at 385 nm, 18 mW / cm2, with a layer thickness of 500 pm, 10 s of exposure for the first layer and 6 s for the others. The crosslinking of the printed object continued under UV at 6 mW / cm2 for 3 min (dual wavelength 365-405 nm).

Claims

Claims

1. Use of a water-soluble and biocompatible phenolic compound as a UV photoabsorber for the preparation of a hydrogel by UV photocrosslinking.

2. Use according to claim 1, in which the phenolic compound is in dimer form, partially or totally.

3. Use according to any one of the preceding claims, wherein the phenolic compound is of the following formula (I): [Chem. 2] OH R / ' vf^R4 R 3 (I) in which: R1, R2, R3, R4, and R5 are independently selected from -H, -OH, -OR, with R being C1-C3 alkyl, in particular methyl, -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, -CH=CH-C(=O)OH, and -CH=CH-CH3, at least one of the groups RB R2, R3, R4, and R5, in particular R3, being selected from -C(=O)OH, -C(=O)H, -C(=O)CH3, -CH2-OH, and -ch=ch-ch3, the phenolic compound being in particular selected from vanillin, vanillic acid, 4-hydroxybenzaldehyde, salicylic acid, 3-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-Dihydroxybenzoic acid, gentisic acid, protocatechuic acid, pyrogallolcarboxylic acid, phloroglucinic acid, gallic acid, syringic acid, orsellinic acid, ferulic acid, sinapic acid, and mixtures thereof.

4. Use according to any one of the preceding claims, wherein the hydrogel consists of or comprises a compound selected from water-soluble cellulose esters, hyaluronic acids, dextrans, chitosans, gum arabic, xanthan gum, alginates, pectins, polyethylene glycol and polyethylene glycol diacrylates, polyvinyl alcohol, polyacrylamide, poly(N-isopropylacrylamide), and mixtures thereof.

5. Use according to any one of the preceding claims, wherein the hydrogel comprises at least one cavity.

6. A method of preparing a hydrogel comprising a step (i) of UV exposure of a photo-crosslinkable resin comprising a water-soluble and biocompatible phenolic compound.

7. Method according to claim 6, the resin further comprises a monomer or a polymer carrying a photosensitive function, a photoinitiator, a solvent, and optionally at least one additive notably chosen from reinforcing fillers, notably cellulose nanocrystals, antioxidants.

8. A method according to claim 6 or 7, wherein the preparation of the hydrogel is carried out by digital light processing or by stereolithography.

9. A photo-crosslinkable resin comprising a water-soluble and biocompatible phenolic compound, as defined in claims 6 to 7.

10. A hydrogel comprising a water-soluble and biocompatible phenolic compound, as defined in claims 1 to 5.

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