Periodontal bone defect repair hydrogel and preparation method thereof

Abstract

The present application belongs to the technical field of hydrogel, and particularly relates to a periodontal bone defect repair hydrogel and a preparation method thereof; wherein the periodontal bone defect repair hydrogel comprises the following raw materials in parts by weight: 5-20 parts of gelatin, 1-10 parts of sodium alginate, 2.5-15 parts of bioactive filler, and 1-10 parts of hydroxyapatite; the gelatin and the sodium alginate are compounded and synergized to provide a stable carrier basis for uniform dispersion and long-acting effect of functional components. The bioactive filler prepared by the present application is surface core-shell coated and modified by PCL on zinc silicate, a PCL hydrophobic thin layer effectively blocks the burst release of zinc ions in the early stage, with slow degradation of PCL, gradient slow release of zinc and silicon ions, so that the antibacterial and anti-inflammatory functions and the bone formation function time of the material are accurately matched with the alveolar bone regeneration cycle. Meanwhile, sodium magnesium lithium silicate is further introduced and uniformly inserted into the hydrogel network, which significantly improves the compactness of the hydrogel network.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel technology, specifically relating to a periodontal bone defect repair hydrogel and its preparation method. Background Technology

[0002] Periodontal disease is a common chronic infectious oral disease. Persistent bacterial invasion and local chronic inflammation can induce alveolar bone resorption and periodontal ligament damage, ultimately leading to irregular periodontal bone defects, severely affecting masticatory function and oral occlusal stability. Current routine clinical treatments can only remove local inflammatory lesions but cannot effectively repair damaged alveolar bone tissue, easily resulting in postoperative inflammation recurrence, continued bone resorption, and poor defect healing.

[0003] Hydrogels are widely used in the repair of periodontal bone defects due to their good biocompatibility, injectability, and adaptability to defect morphology. Existing periodontal restorative hydrogels mostly use single or simple compound polymer matrices such as gelatin, sodium alginate, and hyaluronic acid. While these matrix materials can meet basic tissue filling and cell support requirements, they generally suffer from insufficient mechanical strength, weak resistance to saliva erosion, and poor wet structural stability. In the complex environment of dynamic chewing and continuous saliva infiltration in the oral cavity, they are prone to swelling, collapse, and loss, making it difficult to maintain support space for bone defects in the long term. Furthermore, traditional polymeric hydrogels have limited biological functions, acting only as physical scaffolds and lacking active antibacterial, anti-inflammatory, and bone-repair-promoting activities. They cannot specifically improve the pathological microenvironment of high inflammation and high oxidative stress in the periodontal region, and are unable to fundamentally inhibit pathological periodontal bone resorption, resulting in limited restorative effects. In view of the many shortcomings of the existing technologies, the development of a periodontal bone defect repair hydrogel with stable structure, controllable ion release, and long-lasting antibacterial and anti-inflammatory effects as well as time-promoting ossification has become the focus and challenge of technological research and development in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a periodontal bone defect repair hydrogel and its preparation method. This invention incorporates bioactive fillers, with polycaprolactone thin-layer coating effectively resolving the early burst toxicity issue of zinc silicate ions, enabling time-controlled release of zinc and silicon active ions. Sodium magnesium lithium silicate nanosheets further optimize the dispersibility of functional components, inhibit particle aggregation, and enhance the overall mechanical structure and erosion resistance of the gel. This invention solves the technical problems of existing periodontal repair hydrogels, such as weak resistance to saliva erosion, easy swelling and loss in the moist dynamic environment of the oral cavity, limited functionality, lack of active anti-inflammatory and antibacterial capabilities, and mismatch between ion release cycle and bone regeneration sequence. Through the complementary structure and synergistic function of its components, this invention can precisely regulate the periodontal inflammatory microenvironment in the early stages, inhibit the proliferation of pathogenic bacteria and pathological bone resorption, and continuously induce angiogenesis and bone tissue mineralization remodeling in the mid-to-late stages, achieving integrated repair of inflammation control, bone resorption inhibition, and time-sequential bone regeneration.

[0005] To address the shortcomings of existing technologies, the present invention adopts the following technical solution: This invention provides a periodontal bone defect repair hydrogel, which comprises the following raw materials in parts by weight: 5-20 parts gelatin, 1-10 parts sodium alginate, 2.5-15 parts bioactive filler, 1-10 parts hydroxyapatite, and 1.2-5 parts dopamine hydrochloride. The bioactive filler comprises raw materials in the following mass ratio: zinc silicate: polycaprolactone (PCL): sodium magnesium lithium silicate (Laponite / lithium magnesium silicate) = 10:1:5-20; The preparation method of the bioactive filler includes the following steps: A1. Zinc silicate was weighed and dispersed in dichloromethane at a ratio of 1-5 g to 100 mL. The mixture was ultrasonically dispersed for 15 min to form a uniform suspension. PCL was added to the suspension and stirred at room temperature for 30 min until completely dissolved to form an organic phase. The resulting organic phase was slowly added dropwise to a deionized water system containing polyvinyl alcohol and stirred at high speed to form an emulsion. The mixture was stirred at room temperature and pressure for 4-8 h to form a core-shell structure. The product was collected by centrifugation, washed, and dried under low temperature and vacuum for 24 h to obtain a core-shell nanocomposite. A2. Sodium magnesium lithium silicate is slowly sprinkled into deionized water. The ratio of sodium magnesium lithium silicate to deionized water is 1-5g:100mL. The solution is allowed to stand at room temperature for 2 hours to swell. The sodium magnesium lithium silicate sheets are completely peeled off by high-speed stirring combined with ice-water bath ultrasonic treatment to form a transparent and stable colloidal dispersion. The solution is allowed to stand for 2 hours to degas and obtain a sodium magnesium lithium silicate dispersion without agglomeration or sedimentation. A3. The core-shell nanocomposite was added to a sodium magnesium lithium silicate dispersion and treated with ultrasonic dispersion combined with low-speed magnetic stirring to ensure uniform compounding of the two functional components. After standing for 1 hour to remove bubbles, a stable bioactive filler was obtained.

[0006] Further, the preparation method of zinc silicate is as follows: zinc nitrate hexahydrate and tetraethyl orthosilicate are taken, and the mass ratio of zinc nitrate hexahydrate to tetraethyl orthosilicate is 1-1.5:1. They are dissolved in a mixed solvent of ethanol-deionized water and magnetically stirred until completely dissolved to form a transparent precursor solution. After stirring at room temperature for 30 min, dilute ammonia is slowly added dropwise to adjust the pH of the system to 8.0-9.0 to promote uniform nucleation of the precursor. Then, the reaction is carried out at a constant temperature of 55 ℃ with low-speed stirring for 4 h to form a uniform zinc silicate precursor sol. After the reaction is completed, the mixture is centrifuged, washed, and dried at low temperature to obtain zinc silicate nanoparticles.

[0007] This invention also provides a method for preparing a hydrogel for repairing periodontal bone defects, specifically including the following steps: Step 1: Weigh gelatin into a round-bottom flask, add MES buffer solution at pH 5.5, the ratio of gelatin to MES buffer solution is 1-2 g: 100 mL, stir at 250 rpm in a 50 ℃ water bath for 30 min to dissolve the gelatin completely into a pale yellow clear liquid, stop heating, cool to room temperature, then add EDC and NHS, stir at room temperature to activate the carboxyl groups for 30 min, weigh dopamine hydrochloride and add it to MES buffer solution (pH 5.5) to dissolve, the mass ratio of gelatin, EDC and NHS is 2-4:0.5:0.3, after purging with nitrogen to remove oxygen, immediately inject into the above reaction solution, protect the reaction system from light, stir at room temperature for 24 h, after the reaction is completed, dialyze with a dialysis bag with a molecular weight cutoff of 8000-14000 in acidic deionized water at pH 5-6 for 2 days, then dialyze in deionized water for 1 day to neutral, and freeze dry to obtain a silvery white solid; Step 2: Dissolve sodium alginate in deionized water to prepare a sodium alginate solution. The ratio of sodium alginate to deionized water is 1-2.5g:50mL. Stir the reaction at room temperature in the dark for 4-8 hours. Add ethylene glycol to terminate the reaction. The ratio of sodium alginate, sodium periodate, and ethylene glycol is 1g:0.8g:0.5-1mL. Dialyze the solution with deionized water for 3 days. Freeze-dry the solution to obtain oxidized sodium alginate. Disperse nano-hydroxyapatite powder in PBS buffer. The ratio of nano-hydroxyapatite powder to PBS buffer is 1-4:20mL. Sonicate the solution for 20 minutes to form a uniform hydroxyapatite suspension. Step 3: Dissolve the silvery-white solid prepared in Step 1 in PBS buffer to prepare solution i. The volume ratio of silvery-white solid to PBS buffer is 1-2 g: 10 mL. Dissolve sodium oxidized alginate in PBS buffer to prepare solution ii. The volume ratio of sodium oxidized alginate to PBS buffer is 1-2.5 g: 50 mL. Mix solution i and solution ii at a volume ratio of 1:1 and stir well. Add the hydroxyapatite suspension and stir well to obtain the matrix mixture. Step 4: Mix the bioactive filler and matrix mixture at a volume ratio of 1:1 to 1:3, stir at room temperature for 10-15 min, let stand for 30 min to remove bubbles, let stand at room temperature for 10-30 min, and then slowly add sterile CaCl2 solution to carry out ionic cross-linking to obtain periodontal bone defect repair hydrogel.

[0008] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention employs a combination of gelatin and sodium alginate to construct a dual-network hydrogel matrix. Gelatin, through temperature-induced physical cross-linking, imparts excellent flexibility, cell adhesion, and self-healing properties to the hydrogel. Sodium alginate, through calcium ion cross-linking, rapidly shapes the gel, effectively enhancing its structural stability and resistance to deformation. The synergistic combination of these two components provides a stable carrier basis for the uniform dispersion and long-lasting effects of the functional components. This invention also utilizes PCL to modify the core-shell coating of zinc silicate. The hydrophobic PCL layer effectively blocks the burst release of zinc ions in the early stages, avoiding the cytotoxic risks associated with high concentrations of zinc ions. As PCL slowly degrades, zinc and silicon ions are released in a gradient, allowing the antibacterial, anti-inflammatory, and bone-functionalizing effects of the material to precisely match the alveolar bone regeneration cycle, achieving an orderly repair transition from early inflammation regulation to mid-to-late-stage bone tissue remodeling. Simultaneously, the PCL coating significantly improves the interfacial compatibility between inorganic nanoparticles and the hydrophilic gel matrix, inhibiting particle aggregation and sedimentation, and ensuring the long-term stable dispersion of the functional components. This invention further introduces two-dimensional sodium magnesium lithium silicate nanosheets, which, with their excellent colloidal dispersibility and physical cross-linking enhancement, are uniformly interwoven within the hydrogel network, anchoring zinc silicate / PCL core-shell particles, inhibiting the migration and precipitation of functional particles, and significantly improving the density, mechanical stability, and resistance to saliva erosion of the hydrogel network. Simultaneously, the confinement effect of the sodium magnesium lithium silicate sheets helps regulate the ion release rate, forming a dual drug release regulation mechanism with the PCL sustained-release barrier, further optimizing the material's biosafety and long-term repair performance. The components of this invention complement each other, ultimately achieving an integrated repair effect that provides structural stability adapted to the complex oral environment, safe and long-lasting sequential energy release, simultaneous regulation of the inflammatory microenvironment, and inhibition of pathological bone resorption and bone tissue regeneration. Attached Figure Description

[0009] Figure 1 Figure showing the antibacterial properties of the periodontal bone defect repair hydrogel prepared in this invention; Figure 2 The osteogenic properties of the periodontal bone defect repair hydrogel prepared in this invention; Figure 3 An image of alveolar bone in the hydrogel for periodontal bone defect repair prepared according to the present invention. Detailed Implementation

[0010] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0012] Example 1: This example provides a periodontal bone defect repair hydrogel, which comprises the following raw materials in parts by weight: 5 parts gelatin, 1 part sodium alginate, 2.5 parts bioactive filler, 1 part hydroxyapatite, and 1.2 parts dopamine hydrochloride. The bioactive filler comprises raw materials in the following mass ratio: zinc silicate:PCL:sodium magnesium lithium silicate = 10:1:5; The preparation method of the bioactive filler includes the following steps: A1. Zinc silicate nanoparticles were weighed and dispersed in dichloromethane at a ratio of 1 g to 100 mL. The mixture was ultrasonically dispersed for 15 min to form a uniform suspension. PCL was added to the suspension and stirred at room temperature for 30 min until completely dissolved to form an organic phase. The resulting organic phase was slowly added dropwise to a deionized water system containing 0.5% polyvinyl alcohol by mass. The mixture was stirred at high speed to form an oil-in-water emulsion. The mixture was stirred at room temperature and pressure for 4 h to allow the dichloromethane to slowly evaporate and PCL molecules to gradually deposit on the surface of the zinc silicate particles to form a core-shell structure. The product was collected by centrifugation, washed three times with deionized water, and dried under vacuum at 40 °C for 24 h to obtain a core-shell nanocomposite. A2. Sodium magnesium lithium silicate was slowly sprinkled into deionized water at a ratio of 1g:100mL. The solution was allowed to stand at room temperature for 2 hours to swell. Then, high-speed stirring at 800 rpm combined with ultrasonic treatment in an ice-water bath at a power of 200 W for 30 minutes was used to completely peel off the sodium magnesium lithium silicate sheets, forming a transparent and stable colloidal dispersion. The solution was allowed to stand for 2 hours to degas, resulting in a sodium magnesium lithium silicate dispersion without agglomeration or sedimentation. A3. The core-shell nanocomposite was added to a sodium magnesium lithium silicate dispersion and treated with a combination of ultrasonic dispersion and low-speed magnetic stirring (200 rpm, 30 min). The ultrasonic power was 200 W and the time was 10 min to ensure uniform compounding of the two functional components. After standing for 1 h to remove bubbles, a stable bioactive filler was obtained.

[0013] The method for preparing zinc silicate is as follows: Zinc nitrate hexahydrate and tetraethyl orthosilicate, with a mass ratio of 1:1, are dissolved in a mixed solvent of anhydrous ethanol and deionized water, with a volume ratio of 1:1. The solution is magnetically stirred until completely dissolved, forming a transparent precursor solution. After stirring at room temperature for 30 min, dilute ammonia is slowly added dropwise to adjust the pH of the system to 8.0, promoting uniform nucleation of the precursor. Subsequently, the reaction is carried out at a constant temperature of 55 ℃ with low-speed stirring for 4 h to form a uniform zinc silicate precursor sol. After the reaction is completed, the product is centrifuged and washed three times repeatedly with anhydrous ethanol to remove residual salt ions and organic solvents. The obtained product is dried at 60 ℃ to obtain zinc silicate.

[0014] This embodiment also provides a method for preparing a periodontal bone defect repair hydrogel, which specifically includes the following steps: Step 1: Weigh gelatin into a round-bottom flask, add MES buffer solution at pH 5.5 (gelatin to MES buffer ratio 1g:100mL), and dissolve in a 50℃ water bath at 250 rpm for 30 min until the gelatin is completely dissolved into a pale yellow, clear liquid. Stop heating and cool to room temperature. Then add EDC and NHS, and activate the carboxyl groups at room temperature at 250 rpm for 30 min. Weigh dopamine hydrochloride into a 10 mL amber vial, add MES buffer solution (pH 5.5) and dissolve (dopamine hydrochloride to MES buffer ratio 0.5g:2mL). The mass ratio of gelatin, EDC, and NHS is 2:0.5:0.3. After purging with nitrogen to remove oxygen, immediately inject the solution into the above reaction mixture. Protect the reaction system from light and stir at room temperature for 24 h. After the reaction is complete, use a dialysis bag with a molecular weight cutoff of 8000 to perform a pH 5.5 dialysis. Dialyze in acidic deionized water at 5% for 2 days, then dialyze in deionized water for 1 day until neutral, and freeze-dry to obtain a silvery-white solid. Step 2: Dissolve sodium alginate in deionized water to prepare a sodium alginate solution. The ratio of sodium alginate to deionized water is 1g:50mL. Stir the reaction at room temperature in the dark for 4 hours. Add ethylene glycol to terminate the reaction. The ratio of sodium alginate, sodium periodate and ethylene glycol is 1g:0.8g:0.5mL. Dialyze the solution with deionized water for 3 days. Freeze dry to obtain oxidized sodium alginate. Disperse nano-hydroxyapatite powder in PBS buffer. The ratio of nano-hydroxyapatite powder to PBS buffer is 1:20mL. Sonicate the solution for 20 minutes to form a uniform hydroxyapatite suspension. Step 3: Dissolve the silvery-white solid prepared in Step 1 in PBS buffer to prepare solution i, with a volume ratio of silvery-white solid to PBS buffer of 1g:10mL. Dissolve sodium oxidized alginate in PBS buffer, with a volume ratio of sodium oxidized alginate to PBS buffer of 1g:50mL to prepare solution ii. Mix solution i and solution ii at a volume ratio of 1:1 and stir until homogeneous. Add the hydroxyapatite suspension to the mixture and stir until homogeneous to obtain the matrix mixture. Step 4: Mix the bioactive filler and matrix mixture at a volume ratio of 1:1, stir at room temperature for 10 min, let stand for 30 min to remove bubbles, let stand at room temperature for 10 min, and then slowly add a 1% (w / w) sterile CaCl2 solution to carry out ionic cross-linking to obtain a periodontal bone defect repair hydrogel.

[0015] Example 2: This example provides a periodontal bone defect repair hydrogel, which comprises the following raw materials in parts by weight: 10 parts gelatin, 6 parts sodium alginate, 10 parts bioactive filler, 5 parts hydroxyapatite, and 2.5 parts dopamine hydrochloride. The bioactive filler comprises raw materials in the following mass ratio: zinc silicate:PCL:sodium magnesium lithium silicate = 10:1:12; The preparation method of the bioactive filler includes the following steps: A1. Zinc silicate nanoparticles were weighed and dispersed in dichloromethane at a ratio of 3 g: 100 mL. The mixture was ultrasonically dispersed for 15 min to form a uniform suspension. PCL was added to the suspension and stirred at room temperature for 30 min until completely dissolved. The resulting organic phase was slowly added dropwise to a deionized water system containing 1% polyvinyl alcohol by mass. The mixture was stirred at high speed to form an oil-in-water emulsion. The mixture was stirred at room temperature and pressure for 5.5 h to allow the dichloromethane to slowly evaporate and PCL molecules to gradually deposit on the surface of the zinc silicate particles, forming a core-shell structure. The product was collected by centrifugation, washed three times with deionized water, and dried under vacuum at 40 °C for 24 h to obtain a core-shell nanocomposite. A2. Sodium magnesium lithium silicate was slowly sprinkled into deionized water at a ratio of 3g:100mL. The solution was allowed to stand at room temperature for 2 hours to swell. Then, high-speed stirring at 1000 rpm combined with ultrasonic treatment in an ice-water bath at a power of 300W for 30 minutes was used to completely peel off the sodium magnesium lithium silicate sheets, forming a transparent and stable colloidal dispersion. The solution was allowed to stand for 2 hours to degas, resulting in a sodium magnesium lithium silicate dispersion without agglomeration or sedimentation. A3. The core-shell nanocomposite was added to a sodium magnesium lithium silicate dispersion and treated with a combination of ultrasonic dispersion and low-speed magnetic stirring (300 rpm, 30 min). The ultrasonic power was 200 W and the time was 10 min to ensure uniform compounding of the two functional components. After standing for 1 h to remove bubbles, a stable bioactive filler was obtained.

[0016] The method for preparing zinc silicate is as follows: Zinc nitrate hexahydrate and tetraethyl orthosilicate, with a mass ratio of zinc nitrate hexahydrate to tetraethyl orthosilicate of 1.2:1, are dissolved in anhydrous ethanol-deionized water mixed solvent, with a volume ratio of anhydrous ethanol to deionized water of 2:1. The solution is magnetically stirred until completely dissolved, forming a transparent precursor solution. After stirring at room temperature for 30 min, dilute ammonia is slowly added dropwise to adjust the pH of the system to 8.5, promoting uniform nucleation of the precursor. Subsequently, the reaction is carried out at a constant temperature of 55 ℃ with low-speed stirring for 4 h to form a uniform zinc silicate precursor sol. After the reaction is completed, the product is centrifuged and washed three times repeatedly with anhydrous ethanol to remove residual salt ions and organic solvents. The obtained product is dried at 60 ℃ to obtain zinc silicate.

[0017] This embodiment also provides a method for preparing a periodontal bone defect repair hydrogel, which specifically includes the following steps: Step 1: Weigh gelatin into a round-bottom flask, add MES buffer solution (pH 5.5), with a gelatin to MES buffer ratio of 1.5 g: 100 mL. Dissolve the gelatin in a 50 °C water bath at 250 rpm for 30 min until completely dissolved into a pale yellow, clear liquid. Stop heating and cool to room temperature. Then add EDC and NHS, and activate the carboxyl groups by stirring at 250 rpm at room temperature for 30 min. Weigh dopamine hydrochloride into a 10 mL amber vial, add MES buffer solution (pH 5.5) to dissolve it, with a dopamine to MES buffer ratio of 0.5 g: 2 mL. The mass ratio of gelatin, EDC, and NHS is 3:0.5:0.3. After purging with nitrogen to remove oxygen, immediately inject the solution into the above reaction mixture. Protect the reaction system from light and stir at room temperature for 24 h. After the reaction is complete, use a dialysis bag with a molecular weight cutoff of 12000 to analyze the solution at pH 10. Dialyze in 5.5% acidic deionized water for 2 days, then dialyze in deionized water for 1 day until neutral, and freeze-dry to obtain a silvery-white solid. Step 2: Dissolve sodium alginate in deionized water to prepare a sodium alginate solution. The ratio of sodium alginate to deionized water is 1.5g:50mL. Stir the reaction at room temperature in the dark for 6 hours. Add ethylene glycol to terminate the reaction. The ratio of sodium alginate, sodium periodate and ethylene glycol is 1g:0.8g:0.8mL. Dialyze the solution with deionized water for 3 days. Freeze dry to obtain oxidized sodium alginate. Disperse nano-hydroxyapatite powder in PBS buffer. The ratio of nano-hydroxyapatite powder to PBS buffer is 3:20mL. Sonicate for 20 minutes to form a uniform hydroxyapatite suspension. Step 3: Dissolve the silvery-white solid prepared in Step 1 in PBS buffer to prepare solution i, with a volume ratio of silvery-white solid to PBS buffer of 1.5g:10mL. Dissolve sodium oxidized alginate in PBS buffer, with a volume ratio of sodium oxidized alginate to PBS buffer of 2g:50mL to prepare solution ii. Mix solution i and solution ii at a volume ratio of 1:1 and stir until homogeneous. Add the hydroxyapatite suspension to the mixture and stir until homogeneous to obtain the matrix mixture. Step 4: Mix the bioactive filler and matrix mixture at a volume ratio of 1:2, stir at room temperature for 15 min, let stand for 30 min to remove bubbles, let stand at room temperature for 20 min, and then slowly add a 3% (w / w) sterile CaCl2 solution to carry out ionic cross-linking to obtain a periodontal bone defect repair hydrogel.

[0018] Example 3: This example provides a periodontal bone defect repair hydrogel, which comprises the following raw materials in parts by weight: 20 parts gelatin, 10 parts sodium alginate, 15 parts bioactive filler, 10 parts hydroxyapatite, and 5 parts dopamine hydrochloride. The bioactive filler comprises raw materials in the following mass ratio: zinc silicate:PCL:sodium magnesium lithium silicate = 10:1:20; The preparation method of the bioactive filler includes the following steps: A1. Zinc silicate nanoparticles were weighed and dispersed in dichloromethane at a ratio of 5 g: 100 mL. The mixture was ultrasonically dispersed for 15 min to form a uniform suspension. PCL was added to the suspension and stirred at room temperature for 30 min until completely dissolved. The resulting organic phase was slowly added dropwise to a deionized water system containing 2% polyvinyl alcohol by mass. The mixture was stirred at high speed to form an oil-in-water emulsion. The mixture was stirred at room temperature and pressure for 8 h to allow the dichloromethane to slowly evaporate and PCL molecules to gradually deposit on the surface of the zinc silicate particles, forming a core-shell structure. The product was collected by centrifugation, washed three times with deionized water, and dried under vacuum at 40 °C for 24 h to obtain a core-shell nanocomposite. A2. Sodium magnesium lithium silicate was slowly sprinkled into deionized water at a ratio of 5g:100mL. The solution was allowed to stand at room temperature for 2 hours to swell. Then, high-speed stirring at 1200 rpm combined with ultrasonic treatment in an ice-water bath at a power of 400 W for 30 minutes was used to completely peel off the sodium magnesium lithium silicate sheets, forming a transparent and stable colloidal dispersion. The solution was allowed to stand for 2 hours to degas, resulting in a sodium magnesium lithium silicate dispersion without agglomeration or sedimentation. A3. The core-shell nanocomposite was added to a sodium magnesium lithium silicate dispersion and treated with a combination of ultrasonic dispersion and low-speed magnetic stirring (400 rpm, 30 min). The ultrasonic power was 200 W and the time was 10 min to ensure uniform compounding of the two functional components. After standing for 1 h to remove bubbles, a stable bioactive filler was obtained.

[0019] The method for preparing zinc silicate is as follows: Zinc nitrate hexahydrate and tetraethyl orthosilicate, with a mass ratio of zinc nitrate hexahydrate to tetraethyl orthosilicate of 1.5:1, are dissolved in a mixed solvent of anhydrous ethanol and deionized water, with a volume ratio of anhydrous ethanol to deionized water of 3:1. The solution is magnetically stirred until completely dissolved, forming a transparent precursor solution. After stirring at room temperature for 30 min, dilute ammonia is slowly added dropwise to adjust the pH of the system to 9.0, promoting uniform nucleation of the precursor. Subsequently, the reaction is carried out at a constant temperature of 55 ℃ with low-speed stirring for 4 h to form a uniform zinc silicate precursor sol. After the reaction is completed, the solution is centrifuged and washed three times repeatedly with anhydrous ethanol to remove residual salt ions and organic solvents. The obtained product is dried at a low temperature of 60 ℃ to obtain zinc silicate.

[0020] This embodiment also provides a method for preparing a periodontal bone defect repair hydrogel, which specifically includes the following steps: Step 1: Weigh gelatin into a round-bottom flask, add MES buffer solution at pH 5.5 (gelatin to MES buffer ratio 2g:100mL), and dissolve in a 50℃ water bath at 250 rpm for 30 min until the gelatin is completely dissolved into a pale yellow, clear liquid. Stop heating and cool to room temperature. Then add EDC and NHS, and activate the carboxyl groups at 250 rpm for 30 min at room temperature. Weigh dopamine hydrochloride into a 10 mL brown vial, add MES buffer solution (pH 5.5) and dissolve (dopamine hydrochloride to MES buffer ratio 0.5g:2mL). The mass ratio of gelatin, EDC, and NHS is 4:0.5:0.3. After purging with nitrogen to remove oxygen, immediately inject the solution into the above reaction mixture. Protect the reaction system from light and stir at room temperature for 24 h. After the reaction is complete, use a dialysis bag with a molecular weight cutoff of 14000 to analyze the solution at pH 5.5. Dialyze in acidic deionized water at 6% for 2 days, then dialyze in deionized water for 1 day until neutral, and freeze-dry to obtain a silvery-white solid. Step 2: Dissolve sodium alginate in deionized water to prepare a sodium alginate solution. The ratio of sodium alginate to deionized water is 2.5g:50mL. Stir the reaction at room temperature in the dark for 8 hours. Add ethylene glycol to terminate the reaction. The ratio of sodium alginate, sodium periodate and ethylene glycol is 1g:0.8g:1mL. Dialyze the solution with deionized water for 3 days. Freeze-dry the solution to obtain oxidized sodium alginate. Disperse nano-hydroxyapatite powder in PBS buffer. The ratio of nano-hydroxyapatite powder to PBS buffer is 4:20mL. Sonicate the solution for 20 minutes to form a uniform hydroxyapatite suspension. Step 3: Dissolve the silvery-white solid prepared in Step 1 in PBS buffer to prepare solution i, with a volume ratio of silvery-white solid to PBS buffer of 2g:10mL. Dissolve sodium oxidized alginate in PBS buffer, with a volume ratio of sodium oxidized alginate to PBS buffer of 2.5g:50mL to prepare solution ii. Mix solution i and solution ii at a volume ratio of 1:1 and stir until homogeneous. Add the hydroxyapatite suspension to the mixture and stir until homogeneous to obtain the matrix mixture. Step 4: Mix the bioactive filler and matrix mixture at a volume ratio of 1:3, stir at room temperature for 15 min, let stand for 30 min to remove bubbles, let stand at room temperature for 30 min, and then slowly add a 5% (w / w) sterile CaCl2 solution to carry out ionic cross-linking to obtain a periodontal bone defect repair hydrogel.

[0021] The difference between Comparative Example 1 and Example 2 is that the addition of bioactive filler was omitted, while the rest is exactly the same as Example 2.

[0022] The difference between Comparative Example 2 and Example 2 is that zinc silicate is added directly without coating, while the rest is exactly the same as Example 2.

[0023] The difference between Comparative Example 3 and Example 2 is that the addition of sodium magnesium lithium silicate is omitted, while the rest is exactly the same as Example 2.

[0024] Experimental Examples: Using the periodontal bone defect repair hydrogels prepared in Examples 1-3 and Comparative Examples 1-3 of this invention as test samples, the following experimental examples were conducted: 1. Cell compatibility / cytotoxicity: The biocompatibility of the test samples was quantitatively assessed by evaluating their effect on the proliferation and viability of L929 and MC3t3-E1 cells (iCell, China) using a CCK-8 assay kit. L929 and MC3t3-E1 cells were cultured at 5 × 10⁻⁶ cells / cells. 3Cells were seeded at various densities in 96-well plates and cultured with test sample extract medium at 37 °C in a 5% CO2 incubator for 1, 3, and 5 days, respectively. The light-treated group was irradiated with a 660 nm laser for 3 min. At different time intervals, the extract was aspirated, and 100 μL of CCK-8 working solution (prepared by mixing CCK-8 solution and complete medium at a 1:9 ratio) was added to each well. The plates were then incubated at 37 °C in the dark for 2 h. Finally, the absorbance at 450 nm was measured using a microplate reader. Cell viability was calculated using the following formula: Cell viability = OD 试样 / OD 对照 The test results are recorded in Table 1.

[0025] 2. Antibacterial activity: The in vitro antibacterial properties were studied using the plate count method. 0.1 mL of Staphylococcus aureus / Escherichia coli bacterial suspension (1.0 × 10⁻⁶) was used. 8 CFU / mL and 0.1 mL of the test sample diluted at different ratios with 24-hour extract were placed in 96-well plates and incubated for 30 min. 50 μL of the solution was then added to an agar plate in a clean bench and spread evenly using a bacterial spreader until no obvious water stains remained. The agar plates were sealed with sealing film and incubated at 37°C for 24 h before colony counting. Antibacterial rate (%) = (N... 对照组 -N 实验组 ) / N 对照组 ×100%, where N 对照组 N represents the number of colonies after culturing without adding sample extract. 实验组 The colony count is shown in Table 1 after incubation with the sample extract. The antibacterial rate results are recorded in Table 1, and the antibacterial plate photographs are shown below. Figure 1 As shown.

[0026] 3. In vivo osteogenicity: Preparation of osteogenic induction medium: MEM medium containing 10% FBS, 1% penicillin-dextrose antibody, 10 nmol / L dexamethasone, 10 mmol / L β-glycerophosphate sodium, and 50 mg / L ascorbic acid. Osteogenic induction and alkaline phosphatase staining experiments: 1.0 × 10⁻⁶ MC3T3-E1 cells in logarithmic growth phase were used. 5 MC3t3-E1 cells were seeded at a density of 1 cell / well in 24-well plates. When cells reached 80% confluence, the medium was replaced with osteogenic induction medium containing or without MB / BG@LG and LG extract. The medium was changed every 3 days for a total of 7 or 14 days. The light-treated group was illuminated at 660 nm for 3 min. After co-culture, the culture medium was removed, and the cells were gently washed three times with PBS to terminate induction. MC3t3-E1 cells were fixed with 4% paraformaldehyde, washed three times with PBS, and then incubated with the working solution of the ALP kit. After incubation at room temperature in the dark for 20 min, cell staining was observed under a light microscope. Results are as follows: Figure 2 As shown.

[0027] 4. Establishment of a periodontitis model: A rat model of chronic periodontitis was established to observe the therapeutic effect of the test sample on chronic periodontitis and evaluate its anti-inflammatory and osteogenic effects in vivo. Eight-week-old female SD rats were selected and randomly divided into 6 groups (N=3 / group). Rats were completely anesthetized by intraperitoneal injection. The rats were fixed, and then, without damaging the surrounding gingival tissue, non-absorbable sutures were placed subgingivally on both sides of the maxillary second molar, and a high-sugar (10% sucrose) diet was administered. *Porphyromonas gingivalis* was inoculated and applied around the maxillary second molar every three days. After 3 weeks, the establishment of the rat periodontitis model was checked with a periodontal probe. For rats with successfully established periodontitis, the original ligatures were removed, and a normal diet was resumed. For two consecutive weeks, different treatments were applied to the maxillary second molar every 3 days, and the test sample was injected into the periodontal pocket. The groups were defined as healthy (healthy rats without periodontitis), periodontitis (ligation + high-sugar feeding group), and the test sample group. At the end of the 4-week treatment, all rats were euthanized by intraperitoneal injection of an overdose of anesthetic, and the maxillary alveolar bone and surrounding gingival tissue were separated. The alveolar bone growth in the periodontitis group and the Example 2 group is as follows: Figure 3 As shown.

[0028] Table 1: Performance test results of the periodontal bone defect repair hydrogel prepared in this invention

[0029] As shown in Table 1, the cell viability of Examples 1-3 of the present invention in L929 cells and MC3T3-E1 cells were over 98% and 96%, respectively, which were not significantly different from Comparative Example 1 without zinc ions (P>0.05). This indicates that the present invention effectively shields Zn through polycaprolactone core-shell coating. 2+ The early release of zinc ions eliminated the cytotoxic risk of zinc-based materials. However, in Comparative Example 2, the direct addition of zinc silicate without polycaprolactone coating significantly reduced cell viability, confirming the damage to cell activity caused by the early release of zinc ions and thus demonstrating the necessity of the core-shell structure design of this invention. Regarding antibacterial properties, Examples 1-3 achieved antibacterial rates of over 94% and 96% against Staphylococcus aureus and Escherichia coli, respectively, significantly better than Comparative Example 1, confirming the broad-spectrum antibacterial activity imparted to the hydrogel by zinc ion release. Although Comparative Example 2, due to the early release of Zn... 2+ The burst release showed a high antibacterial rate, but its cell survival rate was much lower than that of the examples, indicating that the antibacterial effect at the expense of cell compatibility has no clinical application value. In Comparative Example 3, the antibacterial rate decreased slightly after the sodium magnesium lithium silicate was removed. This was attributed to the uneven dispersion of core-shell structure particles due to the absence of sodium magnesium lithium silicate, which affected the uniform and sustained release of zinc ions.

[0030] Figure 1The images show plate images of the control group and the plate colony counting method of Example 2 of the present invention. It can be seen that the number of Staphylococcus aureus and Escherichia coli colonies in Example 2 group is significantly reduced compared with that in Example 2 group, indicating that the periodontal bone defect repair hydrogel prepared by the present invention has excellent antibacterial properties. Figure 2 This describes the ALP staining status of Group 2 and the control group in Example 2 of this invention, serving as an early indicator of ALP osteogenic differentiation. Figure 2 As can be seen, the staining degree of the second group was deeper and the positive expression range was wider, indicating that the composite microenvironment constructed by the hydrogel of the present invention can effectively induce stem cell adhesion and osteogenic activation, significantly promote early osteogenic differentiation of cells, and has good bone induction ability, laying a good foundation for subsequent bone tissue mineralization and regeneration. Figure 3 Three-dimensional micro-CT images of alveolar bone from rats with periodontitis and rats treated in Example 2 of this invention. The bone defect area in Example 2 of this invention was effectively repaired, and the bone tissue structure was more complete and dense. This confirms that the composite hydrogel of this invention can effectively inhibit pathological periodontal bone resorption, significantly promote alveolar bone regeneration and remodeling, and has excellent in vivo repair effect on inflammatory periodontal bone defects.

[0031] In summary, this invention employs a mild preparation process involving stepwise preparation, layered modification, and dual-network crosslinking. First, it modifies zinc silicate using a polycaprolactone core-shell coating structure, effectively avoiding the cytotoxicity caused by the early burst release of zinc ions. This allows for the time-controlled release of zinc and silicon active ions, endowing the hydrogel with multiple repair functions, including long-lasting antibacterial, anti-inflammatory, inhibition of pathological bone resorption, and promotion of angiogenesis and bone mineralization. Then, it utilizes the unique layered structure of lithium magnesium silicate to improve the dispersion uniformity of functional components, effectively inhibiting particle aggregation and precipitation, while simultaneously strengthening the overall network structure of the hydrogel, significantly enhancing the material's mechanical stability and resistance to saliva erosion. The complementary advantages and synergistic effects of the components in this invention construct an integrated repair system with excellent biocompatibility, structural stability, microenvironment regulation capabilities, and time-sequential bone regeneration and repair performance. This system can meet the repair needs of irregular inflammatory bone defects in the periodontium, demonstrating excellent clinical practical value and industrialization prospects.

[0032] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A hydrogel for repairing periodontal bone defects, characterized in that, The raw materials include the following parts by weight: 5-20 parts gelatin, 1-10 parts sodium alginate, 2.5-15 parts bioactive filler, 1-10 parts hydroxyapatite, and 1.2-5 parts dopamine hydrochloride. The bioactive filler comprises raw materials in the following mass ratio: zinc silicate:PCL:sodium magnesium lithium silicate = 10:1:5-20; The preparation method of the bioactive filler includes the following steps: A1. Weigh zinc silicate and disperse it in dichloromethane. Disperse it by ultrasonication to form a suspension. Add PCL to the suspension and stir until dissolved to form an organic phase. Drop the obtained organic phase into a deionized water system containing polyvinyl alcohol and stir at high speed to form an emulsion. Centrifuge, wash, and dry to obtain a core-shell nanocomposite. A2. Sodium magnesium lithium silicate is sprinkled into deionized water, allowed to stand and swell, stirred at high speed and combined with ice water bath sonication, allowed to stand and degas to obtain sodium magnesium lithium silicate dispersion. A3. The core-shell nanocomposite was added to a sodium magnesium lithium silicate dispersion, ultrasonically dispersed and then stirred at low speed with magnetic force. After standing to remove bubbles, a bioactive filler was obtained.

2. The periodontal bone defect repair hydrogel according to claim 1, characterized in that, In step A1, the ratio of zinc silicate to dichloromethane is 1-5g:100mL; In step A2, the ratio of sodium magnesium lithium silicate to deionized water is 1-5g:100mL.

3. The periodontal bone defect repair hydrogel according to claim 1, characterized in that, The method for preparing zinc silicate is as follows: zinc nitrate hexahydrate and tetraethyl orthosilicate are dissolved in a mixed solvent and stirred until dissolved. Dilute ammonia is added dropwise to adjust the pH. The mixture is then stirred at low temperature and low speed, centrifuged, washed, and dried at low temperature to obtain zinc silicate.

4. The periodontal bone defect repair hydrogel according to claim 3, characterized in that, The mass ratio of zinc nitrate hexahydrate to tetraethyl orthosilicate is 1-1.5:

1.

5. A method for preparing a periodontal bone defect repair hydrogel according to any one of claims 1-4, characterized in that, Specifically, the following steps are included: Step 1: Weigh out gelatin and dissolve it in MES buffer solution to form a gelatin solution. Add EDC and NHS, stir, weigh out dopamine hydrochloride, add it to the solution, react, dialyze, and freeze dry to obtain a silvery-white solid. Step 2: Dissolve sodium alginate in deionized water to prepare sodium alginate solution, add sodium periodate, stir to react, then add ethylene glycol to terminate the reaction, dialyze, freeze dry to obtain oxidized sodium alginate, disperse hydroxyapatite in PBS buffer, sonicate to form hydroxyapatite suspension. Step 3: Dissolve the silvery-white solid in PBS buffer to form solution i, dissolve sodium oxidized alginate in PBS buffer to form solution ii, mix solution i and solution ii, stir well, add hydroxyapatite suspension to it, stir, and obtain matrix mixture; Step 4: Mix the bioactive filler with the matrix mixture, stir, let stand to remove bubbles, and then add sterile CaCl2 solution dropwise to obtain a periodontal bone defect repair hydrogel.

6. The preparation method according to claim 5, characterized in that, In step 1, the reaction is carried out under nitrogen protection and in the dark; The ratio of gelatin to MES buffer is 1-2 g: 100 mL.

7. The preparation method according to claim 5, characterized in that, In step 1, the mass ratio of gelatin, EDC, and NHS is 2-4:0.5:0.3; In step 2, the ratio of sodium alginate, sodium periodate and ethylene glycol is 1g:0.8g:0.5-1mL.

8. The preparation method according to claim 5, characterized in that, In step 3, the ratio of the silvery-white solid to PBS buffer is 1-2 g: 10 mL; The ratio of sodium oxidized alginate to PBS buffer is 1-2.5g:50mL.

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