Modified natural polysaccharide, antibacterial and anti-inflammatory self-healing gel material as well as preparation method and application of modified natural polysaccharide and antibacterial and anti-inflammatory self-healing gel material

Abstract

The invention provides a modified natural polysaccharide, an antibacterial anti-inflammatory self-healing gel material as well as a preparation method and application of the modified natural polysaccharide and the antibacterial anti-inflammatory self-healing gel material. The modified natural polysaccharide is prepared by introducing a 1, 4-dihydropyridine structural unit and a boric acid structural unit with anti-oxidation characteristics into a natural polysaccharide structure through a multi-component reaction. According to the anti-inflammatory self-healing gel material, an interactive dynamic bone scaffold is formed in gel through boric acid ester bonds between modified natural polysaccharide and a compound containing a cis-diol structure, so that the gel has a self-healing characteristic, and the anti-inflammatory self-healing gel material can be prepared by adjusting the content of a grafted boric acid structure unit or the proportion of the modified polysaccharide in a gel system. The mechanical property, the degradability and the swelling property of the gel network are regulated and controlled. The obtained anti-inflammatory self-healing gel material can be applied to repair of different soft tissues such as skin and oral cavity, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biomedical polymer materials, specifically relating to a modified natural polysaccharide, an antibacterial and anti-inflammatory self-healing gel material, its preparation method, and its application. Background Technology

[0002] Periodontal disease is a chronic inflammatory disease that develops from dental plaque due to the interaction between the host response and oral microbiota. It can manifest as destruction of periodontal tissues and even tooth loss, which is a leading cause of tooth loss in adults. Mechanical therapy (surgical or non-surgical) for plaque control has long been the primary clinical treatment. However, periodontal tissues are difficult to regenerate, and long-term treatment outcomes are often unsatisfactory. Therefore, in addition to mechanical therapy, developing other treatments for periodontal disease has been a focus of attention. Research indicates that both bacteria and oxidative stress are associated with periodontal disease, meaning that blocking either one alone may not yield better results. Based on this, gel materials containing antibacterial and antioxidant agents are considered an effective treatment for periodontal disease.

[0003] Gels are three-dimensional polymer network systems formed through physical or chemical cross-linking reactions of monomers. They can carry drugs, are simple and easy to prepare, have tunable properties, and possess excellent biocompatibility, hydrophilicity, biodegradability, and cytosol-like matrix characteristics, making them a hot research topic in the biomedical field. Due to their excellent physicochemical properties and biological functions, gels have become ideal biomaterials for treating periodontal disease in recent years. When used in dental treatment, the softness of gels allows them to conform to irregularly shaped defects, fully cover wounds, and alleviate the patient's foreign body sensation.

[0004] Natural polysaccharides are highly biocompatible and readily available materials, most of which possess antibacterial and healing-promoting effects, and exhibit pH and temperature sensitivity. Gel materials with chitosan, cellulose, and other polysaccharides as the main components show broad application prospects in the treatment of oral diseases. However, gels prepared by combining natural polysaccharides with other polymers often suffer from defects such as brittleness, poor mechanical strength, and lack of anti-inflammatory effects, limiting their application. Adding cross-linking agents can enhance the stability and mechanical strength of natural polysaccharide gels, but the amount of cross-linking agent is often difficult to control. Furthermore, most cross-linking agents used to cross-link polysaccharides, such as formaldehyde, glutaraldehyde, silane coupling agents, and epichlorohydrin, have certain biotoxicity, potentially posing biosafety risks. Therefore, modifying natural polysaccharides to develop polysaccharide materials with both antibacterial and anti-inflammatory effects, and forming gel materials with controllable strength and morphology through dynamic chemical bond cross-linking, can significantly improve tissue repair effects, possessing significant clinical significance and application value. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a gel material composed of antioxidant-modified natural polysaccharides and compounds with cis-diol structures linked by borate ester dynamic bonds, as well as its preparation method and applications.

[0006] One objective of this invention is to provide a modified natural polysaccharide whose molecular structure includes polysaccharide structural units and modified structural units containing 1,4-dihydropyridine and boric acid structures. The modified natural polysaccharide is obtained by introducing structural units containing 1,4-dihydropyridine and boric acid into the polysaccharide structure through a multi-component reaction, thereby yielding an antioxidant-modified natural polysaccharide.

[0007] According to the present invention, the modified natural polysaccharide comprises the structure shown in formula (Ⅰ):

[0008]

[0009] In formula (Ⅰ), X is a residue linked to a single hydroxyl group in the polysaccharide structure, R1 is one of the boric acid-substituted phenyl groups or their derivatives, and R2 and R3 are independently one of H, hydroxyl, unsubstituted or substituted aromatic group, unsubstituted or substituted heterocyclic group, and C1-C8 alkyl group; preferably, R1 is one of p-aldehyde borate phenyl, o-aldehyde borate phenyl, 4-fluoro-3-aldehyde borate phenyl, and 3-fluoro-4-aldehyde borate phenyl, and R2 and R3 are independently one of H, thiophene, methylthiophene, phenyl, chlorophenyl, methoxyphenyl, and C1-C6 alkyl group.

[0010] A second objective of this invention is to provide a method for preparing the modified natural polysaccharide described in one objective of this invention, comprising:

[0011] (1) The natural polysaccharide was added to the first solvent and dissolved completely, and then reagent (a) was added to react to obtain a polysaccharide derivative containing β-diketone;

[0012] (2) Continue to add aldehydes containing boric acid, ammonia sources and compounds containing 1,3-diketones, and carry out multi-component reactions under the action of reagent (b);

[0013] (3) Add a precipitation solvent to the system after the reaction in step (2) to precipitate the product, filter, wash and vacuum dry the precipitated product to obtain the modified natural polysaccharide.

[0014] According to the present invention, in the method for preparing the modified natural polysaccharide:

[0015] The natural polysaccharide is selected from at least one of chitosan, dextran, pullulan, amylose, inulin, fructan, cellulose, lignin, fucoidan, red algae polysaccharide, trifoliate polysaccharide, wolfberry polysaccharide, astragalus polysaccharide, poria cocos polysaccharide, and lentinan, preferably from at least one of chitosan, dextran, and cellulose;

[0016] The first solvent is selected from at least one of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and ionic liquids, preferably at least one of ionic liquids and N,N-dimethylformamides. The ionic liquid may be 1-butyl-3-methylimidazolium hexafluorophosphate, 1-allyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-(2-hydroxyethyl)-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hydroxide, 1-allyl-3-methylimidazolium hydroxide, 1-butyryl-3-methylimidazolium trifluoromethanesulfonic acid, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, etc. The first solvent is an anhydrous solvent with a water content of less than or equal to 50 ppm.

[0017] The reagent (a) is selected from at least one of dienone, tert-butyl acetoacetate, isopropyl acetoacetate, and 2,2,6-trimethyl-4-hydro-1,3-dioxane-4-one;

[0018] The aldehyde compound containing the boric acid structure is selected from at least one of boric acid benzaldehyde compounds and fluoroboric acid benzaldehyde compounds, preferably from at least one of p-aldehyde phenylboronic acid, o-aldehyde phenylboronic acid, 4-fluoro-3-aldehyde phenylboronic acid, and 3-fluoro-4-aldehyde phenylboronic acid;

[0019] The ammonia source compound is selected from at least one of ammonium acetate, ammonium carbonate, ammonium nitrate, ammonium sulfate, urea, ammonium carbamate, and ammonia water, preferably from at least one of ammonium acetate, urea, and ammonia water;

[0020] The compound containing the 1,3-diketone structure is selected from at least one of 1,3-cyclohexanedione or its derivatives, preferably from at least one of 1,3-cyclohexanedione, 5-methyl-1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 5-hydroxy-1,3-cyclohexanedione, 5-(2,3,4-trimethoxyphenyl)-1,3-cyclohexanedione, 5-(4-methoxyphenyl)-1,3-cyclohexanedione, 5-(3-chlorophenyl)-1,3-cyclohexanedione, and 5-(5-methyl-2-thiophene)-1,3-cyclohexanedione.

[0021] The reagent (b) is selected from at least one of amino acid compounds and aromatic weak acid compounds, preferably from at least one of glycine, proline, aspartic acid, sodium bisulfate, tryptophan, histidine, lysine, arginine, benzenesulfonic acid, and phenylboronic acid, and more preferably from at least one of glycine, proline, and lysine.

[0022] The precipitation solvent is selected from at least one of ultrapure water, methanol, ethanol, acetone, acetonitrile, diethyl ether, dichloromethane, chloroform, and methyl tert-butyl ether.

[0023] According to the present invention, in step (1) of the method for preparing the modified natural polysaccharide:

[0024] The amount of the first solvent is not particularly limited and can be selected within a wide range, as long as it can fully dissolve the natural polysaccharide. For example, if the volume of the first solvent is 1 mL, the mass of the natural polysaccharide is 0.01 to 0.6 g, preferably 0.02 to 0.15 g.

[0025] Optionally, a second solvent is added to aid dissolution during the dissolution process of the natural polysaccharide. The second solvent is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide, and water, and is chosen to be a solvent different from the first solvent. The second solvent has a solubilizing effect, and its addition can increase the solubility and dispersibility of the natural polysaccharide in the first solvent. The addition of the second solvent is optional and depends on the concentration of the natural polysaccharide. Preferably, the second solvent is 0-100 vol% of the first solvent by volume percentage, and more preferably 0-40 vol%.

[0026] The dissolution conditions for the natural polysaccharide are as follows: dissolution temperature is 30–90℃, preferably 40–80℃; dissolution time is 0.1–12 hours, preferably 1–4 hours.

[0027] The molar ratio of the natural polysaccharide to reagent (a) is 1:(0.01~1), preferably 1:(0.05~0.9):1, wherein the natural polysaccharide is measured by the number of moles of its repeating units;

[0028] The reaction conditions for the natural polysaccharide and reagent (a) are as follows: the reaction temperature is 10-140℃, preferably 15-125℃; the reaction time is 0.5-12 hours, preferably 1-8 hours.

[0029] According to the present invention, in step (2) of the method for preparing the modified natural polysaccharide:

[0030] The molar ratio of the aldehyde compound containing boric acid structure, the ammonia source compound, and the compound containing 1,3-diketone structure is 1:(1-3):(1-2), preferably 1:(1.2-1.6):(1-1.4);

[0031] The molar ratio of the aldehyde compound containing boric acid structure to reagent (a) is (1-3):1, preferably (1-1.5):1;

[0032] The molar ratio of the reagent (b) to the aldehyde compound containing the boric acid structure is (0.01–0.5):1, preferably (0.05–0.2):1;

[0033] The reaction temperature of the multi-component reaction is 40–90°C, preferably 60–80°C;

[0034] The reaction time for the multi-component reaction is 1 to 12 hours, preferably 2 to 6 hours;

[0035] After the multi-component reaction is completed, the reaction product is collected by solvent precipitation. Specifically, after the multi-component reaction is completed, the reaction solution is poured into a precipitation solvent, the precipitate is collected and repeatedly washed until the solvent is almost colorless, the product is centrifuged, filtered, washed, and finally dried to obtain the antioxidant modified natural polysaccharide containing 1,4-dihydropyridine and boric acid structural units. The washing can be done with the same solvent as the precipitation solvent, and the drying after washing can be done using common drying processes, such as vacuum drying at 20-30°C.

[0036] A third objective of this invention is to provide an antibacterial, anti-inflammatory, and self-healing gel material comprising a reaction product of a modified natural polysaccharide and a compound containing a cis-diol structure, and / or a mixture thereof. The modified natural polysaccharide is either the modified natural polysaccharide described in one objective of this invention or a modified natural polysaccharide obtained by the preparation method described in another objective of this invention. The gel material is formed by combining an antioxidant-modified natural polysaccharide with a compound containing a cis-diol structure via borate ester bonds. The compound containing a cis-diol structure is selected from at least one of polyols, compounds containing catechol groups, compounds containing pyrogallol groups, and polysaccharide compounds, preferably at least one of polyethylene glycol, polyvinyl alcohol, tannic acid, and guar gum.

[0037] The fourth objective of this invention is to provide a method for preparing the antibacterial and anti-inflammatory self-healing gel material described in the third objective of this invention, comprising the step of mixing and solidifying a solution A containing modified natural polysaccharides with a solution B containing a cis-diol structure compound into a gel.

[0038] According to the present invention, in the preparation method of the antibacterial and anti-inflammatory self-healing gel material:

[0039] The solvents in solutions A and B are selected from modified natural polysaccharides and good solvents containing cis-diol structures. Specifically, the solvents in solutions A and B may be the same or different, and are independently selected from at least one of water, weak acid aqueous solution, phosphate buffer solution, and physiological saline. Among them, the weak acid aqueous solution is selected from at least one of acetic acid, phosphoric acid, hypochlorous acid, and boric acid aqueous solution, and the phosphate buffer solution can be selected from a phosphate buffer solution with a pH of 6.8 to 7.4.

[0040] In solution A, the mass percentage of modified natural polysaccharide is 1-50 wt%, preferably 1-25 wt%.

[0041] The preparation temperature of solution A is 0–60°C, preferably 10–30°C;

[0042] The mass percentage of the cis-diol structure compound in solution B is 1-10 wt%, preferably 2-6 wt%.

[0043] The preparation temperature of solution B is 20–90°C, preferably 60–80°C;

[0044] The volume ratio of solution A to solution B is 1:(0.1-5), preferably 1:(0.5-3);

[0045] The mixing temperature of solution A and solution B is 0–60°C, preferably 15–35°C.

[0046] During the above mixing process, the boric acid groups on the antioxidant-modified natural polysaccharide structure and the hydroxyl groups on the cis-diol-containing compound structure undergo chemical cross-linking to form borate ester bonds, thus constituting a gel network structure. By adjusting the volume ratio of solution A and solution B, the gelation time and gel strength of the desired gel material can be controlled.

[0047] The fifth objective of this invention is to provide an antibacterial, anti-inflammatory, and self-healing gel material as described in the third objective of this invention, or an antibacterial, anti-inflammatory, and self-healing gel material prepared by the method described in the fourth objective of this invention, for use in wound repair materials and inflammation treatment materials. For example, it can be used for the repair of various soft tissue injuries and the treatment of inflammation, such as those to the skin and oral cavity.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) This invention enables the large-scale, simple, and efficient preparation of modified polysaccharides with antioxidant properties and groups with aggregation-induced luminescence properties. This invention uses widely available and inexpensive natural polysaccharides as the main raw materials, and obtains modified polysaccharides with antioxidant properties in high yield through a simple preparation reaction process under mild reaction conditions.

[0050] (2) This invention enables the efficient preparation of functionalized natural polysaccharides through surface modification. Using natural polysaccharides as the main raw material, 1,4-dihydropyridine and boric acid structural units are introduced into the polysaccharide molecular structure through multi-component reactions. This endows the natural polysaccharides with antioxidant properties while retaining the biocompatibility, non-immunogenicity, and degradability of the natural materials. Simultaneously, the boric acid structure can also form dynamic chemical bonds with the cis-diol structural units, thereby achieving the construction of a self-healing gel structure.

[0051] (3) The gel material obtained in this invention forms an interactive dynamic bone scaffold within the gel through borate ester bonds, giving the gel self-repairing and shear thinning properties. When applied to defective sites, its self-healing properties allow it to precisely adhere to surrounding tissues, effectively avoiding invasive surgery during treatment and fully filling periodontal sites of different shapes, thereby achieving periodontal tissue repair and alleviating periodontal inflammation.

[0052] (4) The gel material obtained by the present invention has high hydrophilicity and internal three-dimensional porous structure, which is conducive to cell migration and material transport, can effectively improve the microenvironment of damaged / inflammatory tissues, promote tissue regeneration, and has good application prospects in the field of tissue repair, especially in the treatment of periodontitis.

[0053] (5) The gel material obtained by the present invention can regulate the antioxidant, antibacterial, mechanical properties, degradation and swelling properties of the gel network by adjusting the content of grafted boric acid structural units or the proportion of modified polysaccharides in the gel system, so that the gel material can be applied to the repair of different soft tissues such as skin and oral cavity, and has broad application prospects in the fields of biomedicine and wound repair.

[0054] (6) The gel material obtained by the present invention does not use potentially toxic crosslinking agents during preparation, which ensures the biosafety of the gel material during use; moreover, the preparation process is simple, easy to operate, and easy to realize industrial production.

[0055] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein. Attached Figure Description

[0056] Figure 1 This is a photograph of the modified polysaccharide from Example 1 of the present invention.

[0057] Figure 2 This is an electron microscope image of the gel material obtained in Example 1 of the present invention.

[0058] Figure 3 These are photographs of the self-healing properties of the gel material obtained in Example 1 of the present invention, wherein a is an image of the gel material cut in half, and b is an image of the gel material self-healing after being spliced ​​along the cut.

[0059] Figure 4 The results are the free radical quenching ability test results of the gel materials obtained in Examples 1-6 and Comparative Example 1 of this invention.

[0060] Figure 5 The image shows the infrared spectrum of the modified chitosan obtained in Example 1 of this invention, where a is the characteristic absorption peak of -CH3, b is the absorption peak of chitosan amide I and amide II bands, c is the C=C absorption peak on the benzene ring, d is the characteristic absorption peak of BO, and e is the characteristic absorption peak of the benzene ring. Detailed Implementation

[0061] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0062] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0063] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0064] The present invention will be described in detail below through embodiments.

[0065] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0066] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0067] Gel penetration strength test method:

[0068] Nanoindentation tests were performed using an Optics11 Piuma Nanoindenter nanomechanical testing machine to accurately measure the gel strength of the material.

[0069] Antioxidant performance testing method:

[0070] Free radical quenching ability test method: Mix aqueous solution of 2,2'-adiazonium salt of bis-3-ethylbenzothiazoline-6-sulfonic acid with aqueous solution of potassium persulfate, and place in the dark for 14 hours to obtain ABTS. +· Original solution. Add ABTS +· The stock solution was diluted with PBS buffer to an absorbance of approximately 0.7 to obtain ABTS. +· Working solution. Prepare a 2 mg / mL G1-G6 gel solution using PBS buffer. Mix the gel solution with ABTS. +· The working solutions were mixed in equal proportions, and the change in absorbance of the solution at 734 nm was detected using an ELISA reader.

[0071] Self-healing performance testing method:

[0072] The molded gel material was cut in half and spliced ​​back together along the cut after 30 minutes. After 1 hour, the boundary changes at the contact point of the cut were observed, and the integrity of the material was also observed.

[0073] Compressive strength test method:

[0074] The compressive properties of materials were tested using a physical property testing instrument according to the method specified in GB / T 1041—2008, and stress-strain curves were plotted to obtain the compressive strength of the materials. Five tests were performed on each material, and the average value was taken. The specifications of the compressive property test samples were cylindrical, Ф(36±1)mm×H(18±0.5)mm, and the testing rate was 1mm / s.

[0075] Example 1

[0076] (1) Preparation of modified natural polysaccharides

[0077] At 70°C, 4 g (24 mmol per repeating unit) of chitosan was added to 100 mL of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The chitosan was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 h. Then, p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture. The reaction mixture was then heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in ethanol, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 20°C to obtain antioxidant modified chitosan containing boric acid groups, which has the following structural formula:

[0078]

[0079] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0080] At 20°C, antioxidant-modified chitosan was dissolved in a 2% glacial acetic acid solution to prepare a 3% (w / w) chitosan-glacial acetic acid solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 and allowed to stand at a constant temperature to obtain an antibacterial, anti-inflammatory, self-healing gel material G1.

[0081] Example 2

[0082] (1) Preparation of modified natural polysaccharides

[0083] At 70°C, 4 g (24 mmol per repeating unit) of chitosan was added to 100 mL of ionic liquid (1-allyl-3-methylimidazolium chloride), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The chitosan was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 h. Then, 4-fluoro-3-aldehyde phenylboronic acid (483.6 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture. The reaction mixture was then heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in ethanol, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 30°C to obtain antioxidant modified chitosan containing boric acid groups, which has the following structural formula:

[0084]

[0085] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0086] At 20°C, antioxidant-modified chitosan was dissolved in a 2% glacial acetic acid solution to prepare a 3% (w / w) chitosan-glacial acetic acid solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 and allowed to stand at a constant temperature to obtain antibacterial, anti-inflammatory, and self-healing gel material G2.

[0087] Example 3

[0088] (1) Preparation of modified natural polysaccharides

[0089] At 80°C, 4 g (24 mmol per repeating unit) of cellulose was added to 100 mL of ionic liquid (1-allyl-3-methylimidazolium chloride), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The cellulose was allowed to dissolve completely for 2 hours to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 hours. Then, p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture. The reaction mixture was then heated to 80°C and reacted for 4 hours. After the reaction was completed, the reaction solution was precipitated in diethyl ether, the product was centrifuged and filtered, washed with ethanol 3-5 times until the washing solution was colorless, and finally the product was vacuum dried at 20°C to obtain antioxidant modified cellulose containing boric acid groups, which has the following structural formula:

[0090]

[0091] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0092] At 20°C, antioxidant-modified cellulose was dissolved in distilled water to prepare an 8% (w / w) cellulose solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 25°C, the 8% cellulose solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 and allowed to stand at a constant temperature to obtain antibacterial, anti-inflammatory, and self-healing gel material G3.

[0093] Example 4

[0094] (1) Preparation of modified natural polysaccharides

[0095] At 70°C, 4 g (24 mmol per repeat unit) of dextran was added to 100 mL of N,N-dimethylformamide, and 25 mL of anhydrous dimethyl sulfoxide was added to aid dissolution. The dextran was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 h. Then, p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture, and the mixture was heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in acetonitrile, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 20°C to obtain antioxidant modified dextran containing boric acid groups, which has the following structural formula:

[0096]

[0097] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0098] At 20°C, antioxidant-modified dextran was dissolved in distilled water to prepare a 20% (w / w) dextran solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 20% dextran solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 and allowed to stand at a constant temperature to obtain antibacterial, anti-inflammatory, and self-healing gel material G4.

[0099] Example 5

[0100] (1) Preparation of modified natural polysaccharides

[0101] At 70°C, 4 g (24 mmol per repeating unit) of chitosan was added to 100 mL of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The chitosan was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 h. Then, p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture. The reaction mixture was then heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in ethanol, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 20°C to obtain antioxidant modified chitosan containing boric acid groups, which has the following structural formula:

[0102]

[0103] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0104] At 20°C, antioxidant-modified chitosan was dissolved in a 2% glacial acetic acid solution to prepare a 3% (w / w) chitosan-glacial acetic acid solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 2:1 and allowed to stand at a constant temperature to obtain the antibacterial, anti-inflammatory, and self-healing gel material G5.

[0105] Example 6

[0106] (1) Preparation of modified natural polysaccharides

[0107] At 70°C, 4 g (24 mmol per repeating unit) of chitosan was added to 100 mL of ionic liquid (1-allyl-3-methylimidazolium chloride), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The chitosan was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was cooled to 20°C, and diene (201.6 mg, 2.4 mmol) was added, followed by stirring for 1.5 h. Then, p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction mixture. The reaction mixture was then heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in ethanol, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 20°C to obtain antioxidant modified chitosan containing boric acid groups, which has the following structural formula:

[0108]

[0109] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0110] At 20°C, antioxidant-modified chitosan was dissolved in a 2% glacial acetic acid solution to prepare a 3% (w / w) chitosan-glacial acetic acid solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:2 and allowed to stand at a constant temperature to obtain antibacterial, anti-inflammatory, and self-healing gel material G6.

[0111] Example 7

[0112] (1) Preparation of modified natural polysaccharides

[0113] At 70°C, 4 g (24 mmol per repeating unit) of chitosan was added to 100 mL of ionic liquid (1-allyl-3-methylimidazolium chloride), and 25 mL of anhydrous N,N-dimethylformamide was added to aid dissolution. The chitosan was allowed to dissolve completely for 1.5 h to form a stable solution. The solution was then heated to 120°C, and tert-butyl acetoacetate (395 mg, 2.5 mmol) was added, followed by stirring for 6 h. The solution was then cooled to 25°C, and p-aldehyde phenylboronic acid (431.8 mg, 2.88 mmol), 5,5-dimethyl-1,3-cyclohexanedione (403.67 mg, 2.88 mmol), ammonium acetate (279.8 mg, 3.63 mmol), and glycine (18.2 mg, 0.24 mmol) were added to the reaction system. The reaction system was then heated to 75°C and reacted for 4 h. After the reaction was completed, the reaction solution was precipitated in ethanol, the product was centrifuged and filtered, and washed with ethanol 3-5 times until the washing solution was colorless. Finally, the product was vacuum dried at 20°C to obtain antioxidant modified chitosan containing boric acid groups, which has the following structural formula:

[0114]

[0115] (2) Preparation of antibacterial, anti-inflammatory and self-healing gel materials

[0116] At 20°C, antioxidant-modified chitosan was dissolved in a 2% glacial acetic acid solution to prepare a 3% (w / w) chitosan-glacial acetic acid solution. At 80°C, polyvinyl alcohol was dissolved in distilled water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 and allowed to stand at a constant temperature to obtain antibacterial, anti-inflammatory, and self-healing gel material G7.

[0117] Comparative Example 1

[0118] The aldehyde used in Example 1 was replaced with benzaldehyde to prepare the antioxidant chitosan. Everything else was the same as in Example 1. 3% antioxidant chitosan glacial acetic acid solution and 3% polyvinyl alcohol aqueous solution were mixed evenly at a volume ratio of 1:1 to obtain C1.

[0119] Comparative Example 2

[0120] Chitosan was dissolved in a 2% glacial acetic acid solution at 20°C to prepare a 3% (w / w) chitosan-glacial acetic acid solution. Polyvinyl alcohol was dissolved in distilled water at 80°C to prepare a 3% (w / w) polyvinyl alcohol aqueous solution. At 30°C, the 3% chitosan-glacial acetic acid solution and the 3% polyvinyl alcohol aqueous solution were mixed thoroughly at a volume ratio of 1:1 to obtain C2.

[0121] Test Example 1

[0122] The gelation properties of the materials described in Examples 1-7 and Comparative Examples 1-2 were observed, and the results are as follows:

[0123] Table 1

[0124]

[0125] Test Example 2

[0126] Antioxidant test results as follows Figure 4 As shown, G1–G6 and C1 all exhibited significant antioxidant capacity, rapidly quenching free radicals in the system. The antioxidant capacity of G1–G6 varied with the content of modified polysaccharides in the gel system, with G4 having the highest content of modified polysaccharides and exhibiting the fastest free radical quenching rate. In contrast, the unmodified polysaccharides (Comparative Example 2) could not quench free radicals.

[0127] Test Example 3

[0128] The materials described in Examples 1-7 and Comparative Examples 1-2 were subjected to mechanical strength tests, and the results are as follows:

[0129] Table 2

[0130] Material Compressive strength (kPa) Example 1 42 Example 2 39 Example 3 21 Example 4 11 Example 5 57 Example 6 33 Example 7 37 Comparative Example 1 — Comparative Example 2 —

[0131] The results show that the gel materials prepared by the method of the present invention all have good mechanical strength, which is related to the type of modified natural polysaccharide and the proportion of modified natural polysaccharide in the gel.

[0132] Test Example 4

[0133] The self-healing properties of the materials described in Examples 1-7 and Comparative Examples 1-2 were tested. The molded gel material was cut in half, and after 30 minutes, the halves were joined together along the cut. The boundary changes at the contact point of the gel material cut and the overall integrity of the material were observed (examples are shown below). Figure 3 As shown in the image, the specific results are as follows:

[0134] Table 3

[0135] Material Does it have self-healing properties? Self-healing time Example 1 It has high self-healing properties <30min Example 2 It has high self-healing properties <30min Example 3 It has a certain degree of self-healing properties <1h Example 4 It has a certain degree of self-healing properties <1h Example 5 High self-healing properties <15min Example 6 It has a certain degree of self-healing properties <45min Example 7 It has high self-healing properties <30min Comparative Example 1 No self-healing properties — Comparative Example 2 No self-healing properties —

[0136] Test results show that the gel materials prepared by the method of the present invention all have self-healing properties, while the comparative samples did not show any self-healing properties.

[0137] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0138] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0139] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0140] In the context of this specification, except where expressly stated, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A modified natural polysaccharide, comprising a polysaccharide structural unit and a modified structural unit comprising a 1,4-dihydropyridine structure and a boronic acid structure in a molecular structure of the modified natural polysaccharide.

2. The modified natural polysaccharide according to claim 1, characterized in that, The modified natural polysaccharide comprises a structure represented by formula (I) : In formula (I), X is a residue of a single hydroxyl group in the polysaccharide structure, R 1 is one of a boronic acid-substituted phenyl group or a derivative group thereof, and R 2 and R 3 are independently one of H, a hydroxyl group, an unsubstituted or substituted aromatic hydrocarbon group, an unsubstituted or substituted heterocyclic group, and a C 1-C 8 alkyl group; preferably, R 1 is one of a p-formyl boronic acid phenyl group, an o-formyl boronic acid phenyl group, a 4-fluoro-3-formyl boronic acid phenyl group, and a 3-fluoro-4-formyl boronic acid phenyl group, and R 2 and R 3 are independently one of H, a thiophenyl group, a methylthiophenyl group, a phenyl group, a chlorophenyl group, a methoxyphenyl group, and a C 1-C 6 alkyl group. 3.A method for preparing the modified natural polysaccharide according to any one of claims 1-2, comprising: (1) adding a natural polysaccharide to a first solvent to dissolve the natural polysaccharide, and then adding a reagent (a) to obtain a polysaccharide derivative comprising a β-diketone; (2) continuously adding an aldehyde compound comprising a boronic acid structure, an ammonia source compound, and a compound comprising a 1,3-diketone structure to perform a multi-component reaction under the action of a reagent (b); (3) adding a precipitation solvent to the system after the reaction in step (2) to precipitate, and then filtering, washing, and vacuum drying the precipitated product to obtain the modified natural polysaccharide. 4.The method according to claim 3, wherein the natural polysaccharide is at least one of chitosan, dextran, pullulan, amylose, inulin, levan, cellulose, lignin, fucoidan, porphyran, radix ophiopogonis polysaccharide, lycium barbarum polysaccharide, astragalus polysaccharide, grifola polysaccharide, and lentinan; and / or the first solvent is at least one of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and an ionic liquid; and / or the reagent (a) is at least one of a diketene, tert-butyl acetoacetate, isopropyl acetoacetate, and 2,2,6-trimethyl-4-hydro-1,3-dioxane-4-ketone; and / or the aldehyde compound comprising a boronic acid structure is at least one of a benzaldehyde boronic acid compound and a fluorine-containing benzaldehyde boronic acid compound; and / or the ammonia source compound is at least one of ammonium acetate, ammonium carbonate, ammonium nitrate, ammonium sulfate, urea, ammonium carbamate, and ammonia water. ​ ​ ​ ​ ​ The compound containing 1,3-diketone structure is selected from at least one of 1,3-cyclohexanedione or its derivatives, preferably at least one of 1,3-cyclohexanedione, 5-methyl-1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 5-hydroxy-1,3-cyclohexanedione, 5-(2,3,4-trimethoxyphenyl)-1,3-cyclohexanedione, 5-(4-methoxyphenyl)-1,3-cyclohexanedione, 5-(3-chlorophenyl)-1,3-cyclohexanedione, 5-(5-methyl-2-thiophene)-1,3-cyclohexanedione; and / or, The reagent (b) is selected from at least one of amino acid compounds, aromatic weak acid compounds, preferably at least one of glycine, proline, aspartic acid, sodium bisulfate, tryptophan, histidine, lysine, arginine, benzenesulfonic acid, phenylboronic acid, more preferably at least one of glycine, proline, lysine; and / or, The precipitating solvent is selected from at least one of ultrapure water, methanol, ethanol, acetone, acetonitrile, diethyl ether, dichloromethane, chloroform, methyl tert-butyl ether.

5. The preparation method according to claim 3, characterized in that, In step (1): The mass amount of the natural polysaccharide is 0.01-0.6 g, preferably 0.02-0.15 g, based on 1 mL of the first solvent; and / or, The dissolving condition of the natural polysaccharide is that the dissolving temperature is 30-90°C, preferably 40-80°C; the dissolving time is 0.1-12 hours, preferably 1-4 hours; and / or, The molar ratio of the natural polysaccharide to the reagent (a) is 1:(0.01-1), preferably 1:(0.05-0.9), wherein the natural polysaccharide is calculated by the number of moles of its repeating units; and / or, The reaction condition of the natural polysaccharide and the reagent (a) is that the reaction temperature is 10-140°C, preferably 15-125°C; the reaction time is 0.5-12 hours, preferably 1-8 hours.

6. The preparation method according to claim 3, characterized in that, In step (2): The molar ratio of the aldehyde compound containing boronic acid structure, the ammonia source compound and the compound containing 1,3-diketone structure is 1:(1-3): (1-2), preferably 1:(1.2-1.6):(1-1.4); and / or, The molar ratio of the aldehyde compound containing boronic acid structure to the reagent (a) is (1-3):1, preferably (1-1.5):1; and / or, The molar ratio of the reagent (b) to the aldehyde compound containing boronic acid structure is (0.01-0.5):1, preferably (0.05-0.2):1; and / or, The reaction temperature of the multi-component reaction is 40-90°C, preferably 60-80°C; and / or, The reaction time of the multi-component reaction is 1-12 hours, preferably 2-6 hours.

7. An antibacterial and anti-inflammatory self-healing gel material, comprising a reaction product of a modified natural polysaccharide and a compound containing cis-diol structure and / or a mixture thereof, wherein the modified natural polysaccharide is the modified natural polysaccharide according to any one of claims 1-2 or obtained by the preparation method according to any one of claims 3-6. 8.The antibacterial and anti-inflammatory self-healing gel material of claim 7, wherein the compound containing cis-diol structure is at least one selected from the group consisting of polyols, compounds containing pyrocatechol groups, compounds containing pyrogallol groups, and polysaccharide compounds, and is preferably at least one selected from the group consisting of polyethylene glycol, polyvinyl alcohol, tannic acid, and guar gum. 9.A method for preparing the antibacterial and anti-inflammatory self-healing gel material of any one of claims 7 to 8, comprising the step of mixing and coagulating a solution A containing modified natural polysaccharide and a solution B containing a compound containing cis-diol structure into a gel. 10.The method of claim 9, wherein the solvent in the solution A and the solution B is the same or different and is independently at least one selected from the group consisting of water, weak acid aqueous solution, phosphate buffer solution, and physiological saline; and / or the mass percentage of the modified natural polysaccharide in the solution A is 1-50 wt%, and is preferably 1-25 wt%; and / or the preparation temperature of the solution A is 0-60℃, and is preferably 10-30℃; and / or the mass percentage of the compound containing cis-diol structure in the solution B is 1-10 wt%, and is preferably 2-6 wt%; and / or the preparation temperature of the solution B is 20-90℃, and is preferably 60-80℃; and / or the volume ratio of the solution A to the solution B is 1:(0.1-5), and is preferably 1:(0.5-3); and / or the mixing temperature of the solution A and the solution B is 0-60℃, and is preferably 15-35℃. 11.The antibacterial and anti-inflammatory self-healing gel material of any one of claims 7 to 8 or the antibacterial and anti-inflammatory self-healing gel material prepared by the method of any one of claims 9 to 10, for use in wound repair materials and inflammation treatment materials. ​ ​ ​ ​ ​ ​ ​ ​

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