A polydopamine-manganese dioxide loaded magnesium oxide-based nanosenzyme hydrogel, a preparation method and application thereof

Abstract

The application belongs to the technical field of biomedical materials, and particularly relates to a hydrogel based on a magnesium oxide-based nanoscale enzyme loaded with polydopamine-manganese dioxide as well as a preparation method and application thereof. The magnesium oxide-based nanoscale enzyme of polydopamine-manganese dioxide is integrated in a double-crosslinked three-dimensional network hydrogel which can be cured in situ and has a self-healing property, fundamentally overcoming the problems of coalescence inactivation and initial burst release of the nanoscale enzyme under a complex physiological microenvironment, and realizing long-acting, stable and on-demand supply of active components (Mg 2+ , Mn 2+ ) in a lesion area. Moreover, due to the self-healing and in-situ light curing properties of the hydrogel, the system can perfectly fit and anchor in an irregular periodontal pocket after injection, thereby constructing a local, persistent and intelligently responsive drug delivery and microenvironment regulation platform, and providing sustained biochemical and mechanical support for periodontal tissue regeneration.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to a hydrogel based on magnesium oxide-based nanoenzymes loaded with polydopamine-manganese dioxide, its preparation method, and its application. Background Technology

[0002] Periodontitis is a chronic inflammatory disease caused by plaque biofilm and is a leading cause of tooth loss in adults worldwide. Its pathological process involves not only infection by periodontal pathogens (such as *Porphyromonas gingivalis*) but also an excessive immune inflammatory response in the host, leading to progressive alveolar bone resorption and destruction. The complex anatomy of periodontal pockets and the moist oral microenvironment make it difficult for traditional treatments such as subgingival scaling and systemic antibiotics to effectively eliminate pathogens and regulate the disordered immune microenvironment.

[0003] In recent years, tissue-engineered hydrogels, especially injectable hydrogels, have attracted widespread attention due to their ability to perfectly fill irregular periodontal defects and serve as delivery carriers for cells and active factors. Meanwhile, photothermal therapy using nanomaterials provides a novel and effective strategy for eliminating periodontal pathogens. However, single-function hydrogels struggle to address the sequential and synergistic demands of "antibacterial-anti-inflammatory-osteogenic" responses in periodontitis treatment. For example, excessive or uncontrolled inflammatory responses can hinder subsequent bone regeneration; and simple antibacterial action cannot correct the disrupted immune balance.

[0004] Therefore, developing a smart hydrogel system that integrates injectable molding, highly efficient antibacterial properties, immunomodulation, and osteogenic induction has become a current research focus. Furthermore, by introducing composite nanozymes with antibacterial, antioxidant, and osteogenic functions, a responsive hydrogel treatment platform combining dynamic plasticity and long-term mechanical stability can be constructed. This platform enables synergistic intervention throughout the entire process, from clearing bacterial films and alleviating inflammation to promoting bone regeneration, and has significant clinical implications for advancing the comprehensive treatment of periodontitis and functional tissue regeneration. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a hydrogel loaded with polydopamine-manganese dioxide magnesium oxide-based nanoenzymes to promote the repair of alveolar bone defects.

[0006] Therefore, the first technical solution of this application discloses a hydrogel of magnesium oxide-based nanozyme loaded with polydopamine-manganese dioxide, comprising: magnesium oxide-based nanozyme coated with polydopamine-manganese dioxide, methacrylated macromolecular protein, oxidized polysaccharide and photoinitiator;

[0007] The methacrylated macromolecular protein and oxidized polysaccharide form a double-crosslinked three-dimensional network structure through a Schiff base reaction and a photopolymerization reaction initiated by a photoinitiator, and the magnesium oxide-based nanoenzyme coated with polydopamine-manganese dioxide is dispersed in the double-crosslinked three-dimensional network structure.

[0008] Furthermore, the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme has a core-shell structure, with a core of magnesium oxide, an intermediate layer of polydopamine, and a shell of manganese dioxide.

[0009] Furthermore, the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme is obtained by dispersing mesoporous magnesium oxide in an alkaline buffer solution containing dopamine, which self-polymerizes to form a polydopamine coating layer, and then reacts with potassium permanganate to deposit manganese dioxide, thereby obtaining the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme.

[0010] Furthermore, the double-crosslinked three-dimensional network structure includes:

[0011] First cross-linking: Dynamic covalent cross-linking formed by the Schiff base reaction between the aldehyde group of methacrylated macromolecular protein and the amino group of oxidized polysaccharide;

[0012] The second crosslinking: a permanent covalent crosslinking formed by photopolymerization of the carbon-carbon double bonds of methacrylated macromolecular proteins under the action of a photoinitiator.

[0013] Furthermore, the mass ratio of the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme, methacrylated macromolecular protein, oxidized polysaccharide, and photoinitiator is (1-4):30:(5-15):(0.2-0.5).

[0014] Furthermore, the methacrylated macromolecular protein is selected from one or more of methacrylated gelatin, methacrylated silk fibroin, and methacrylated collagen; the oxidized polysaccharide is selected from one or more of oxidized chondroitin sulfate, oxidized hyaluronic acid, oxidized sodium alginate, and oxidized chitosan; and the photoinitiator is selected from one or more of lithium phenyl-2,4,6-trimethylbenzoylphosphonate and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone.

[0015] The second technical solution of this application discloses a method for preparing the above-mentioned magnesium oxide-based nanozyme hydrogel loaded with polydopamine-manganese dioxide, comprising the following steps:

[0016] (1) Preparation of magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide: Mesoporous magnesium oxide is dispersed in an alkaline buffer containing dopamine, and self-polymerizes to form a polydopamine coating layer. Then, it reacts with potassium permanganate to deposit manganese dioxide, thus obtaining magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide.

[0017] (2) Preparation of hydrogel: Mix methacrylated macromolecular protein solution, oxidized polysaccharide solution, nanozyme obtained in step (1) with photoinitiator, and solidify by light irradiation to form a magnesium oxide-based nanozyme loaded with a double cross-linked three-dimensional network structure.

[0018] Furthermore, the mesoporous magnesium oxide in step (1) is prepared by a hydrothermal-calcination method: magnesium acetate tetrahydrate is hydrothermally reacted with urea at 120°C for 6-10 h, and then calcined at 650-750°C for 3-5 h; the self-polymerization reaction time is 3-6 h; the reaction with potassium permanganate is a light-protected reaction and the time is 6-9 h.

[0019] Furthermore, in step (2), the mass fraction of the methacrylated macromolecular protein solution is 20-40%, the mass fraction of the oxidized polysaccharide solution is 5%-15%, the two are mixed at a volume ratio of 1:1, the amount of nanozyme added is 0.5-5 mg / mL, the amount of photoinitiator added is 0.2-0.5 parts by mass, and the light irradiation conditions are a wavelength of 330-390 nm and a time of 30-60 s.

[0020] The third technical solution of this application discloses the application of the above-mentioned magnesium oxide-based nanoenzyme hydrogel loaded with polydopamine-manganese dioxide in the preparation of drugs or medical devices for treating periodontitis or promoting bone regeneration.

[0021] Furthermore, the applications include: using near-infrared light to irradiate the hydrogel to generate a photothermal effect for antibacterial purposes, and using the hydrogel to release Mg in an acidic microenvironment. 2+ and Mn 2+ It regulates immunity and promotes bone differentiation.

[0022] as well as,

[0023] A pharmaceutical composition comprising the above-described hydrogel of magnesium oxide-based nanozyme loaded with polydopamine-manganese dioxide, and a pharmaceutically acceptable carrier and / or excipients.

[0024] A medical device, which is an implant or dressing, includes the above-described hydrogel containing magnesium oxide-based nanozymes loaded with polydopamine-manganese dioxide.

[0025] Beneficial effects:

[0026] (1) This invention designs a three-layer core-shell composite nanozyme structure of magnesium oxide-manganese dioxide-polydopamine nanozyme, wherein the core is magnesium oxide, the middle layer is polydopamine, and the outer shell is manganese dioxide, so that the nanozyme has the core function of integrating "ion therapy (osteogenesis), photothermal therapy (antibacterial) and enzyme catalytic therapy (anti-inflammatory)", realizing the leap from "single-function material" to "multifunctional synergistic treatment system", effectively enhancing the antibacterial ability and antioxidant stress resistance of hydrogel.

[0027] (2) This invention constructs an intelligent double cross-linked three-dimensional network platform that combines dynamic plasticity (dynamic covalent cross-linking formed by the Schiff base reaction of aldehyde groups of methacrylated macromolecular proteins and amino groups of oxidized polysaccharides) and long-term mechanical stability (permanent covalent cross-linking formed by photopolymerization of carbon-carbon double bonds of methacrylated macromolecular proteins under the action of photoinitiators). While maintaining the good ability of hydrogels to be injected at specific points, cured in situ and self-healed, it significantly improves the mechanical strength and structural stability of macromolecular proteins, and specifically solves the dual requirements of material operability and mechanical properties in the repair of bone defects in periodontitis.

[0028] (3) This invention integrates magnesium oxide-based nanozymes of polydopamine-manganese dioxide into a double-crosslinked three-dimensional network hydrogel that can be solidified in situ and has self-healing properties, fundamentally overcoming the problems of aggregation and inactivation and initial burst release of nanozymes in complex physiological microenvironments, and further realizing the active component (Mg 2+ Mn 2+ It provides long-term, stable, and on-demand drug delivery to the lesion area; and thanks to the self-healing and in-situ light-curing properties of hydrogel, the system can perfectly adhere to and anchor itself in irregular periodontal pockets after injection, thereby constructing a local, long-lasting, and intelligently responsive drug delivery and microenvironment regulation platform, providing continuous biochemical and mechanical support for periodontal tissue regeneration. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 TEM image of the magnesium oxide-based nanozyme of polydopamine-manganese dioxide as an example;

[0031] Figure 2 EDS elemental distribution diagram of the magnesium oxide-based nanozyme of polydopamine-manganese dioxide as an example;

[0032] Figure 3This is a schematic diagram illustrating the application of the hydrogel in the embodiment;

[0033] Figure 4 SEM images of the hydrogel used in the example;

[0034] Figure 5 The hydrogel used in the examples was subjected to Mg treatment in acidic (pH 5) and neutral (pH 7.4) conditions. 2+ Mn 2+ The cumulative release amount;

[0035] Figure 6 The strain scan rheological curve of the hydrogel used in the example;

[0036] Figure 7 The frequency-scan rheological curve of the hydrogel used in the example;

[0037] Figure 8 Rheological curves of the hydrogel used in the example with alternating strain scanning;

[0038] Figure 9 The pressure-strain curve of the hydrogel in the example;

[0039] Figure 10 The Young's modulus statistics of the hydrogel in the example are shown in the figure.

[0040] Figure 11 Photothermal images of the hydrogel used in this embodiment;

[0041] Figure 12 The photothermal heating curve of the hydrogel in the example;

[0042] Figure 13 The figure shows the in vitro antibacterial performance test results of the hydrogel in the example.

[0043] Figure 14 The figure shows the blood compatibility test results of the hydrogel used in the example.

[0044] Figure 15 The nanozyme and hydrogel used in this embodiment promote osteogenic differentiation of BMSCs by ALP staining and quantitative analysis.

[0045] Figure 16 ARS staining and quantitative analysis of polynanozymes and hydrogels promoting osteogenic differentiation of BMSCs, as shown in the example.

[0046] Figure 17 The figure shows the proportion of M1 cell phenotypes regulated by nanozymes and hydrogels in RAW 264.7 polarization, as illustrated in the examples.

[0047] Figure 18 The figure shows the proportion of M2 cell phenotypes regulated by nanozymes and hydrogels in RAW 264.7 polarization, as illustrated in the examples. Detailed Implementation

[0048] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0049] The first embodiment of this application discloses a hydrogel of magnesium oxide-based nanozyme loaded with polydopamine-manganese dioxide, comprising: magnesium oxide-based nanozyme coated with polydopamine-manganese dioxide, methacrylated macromolecular protein, oxidized polysaccharide and photoinitiator;

[0050] The methacrylated macromolecular protein and oxidized polysaccharide form a double-crosslinked three-dimensional network structure through a Schiff base reaction and a photopolymerization reaction initiated by a photoinitiator, and the magnesium oxide-based nanoenzyme coated with polydopamine-manganese dioxide is dispersed in the double-crosslinked three-dimensional network structure.

[0051] The mass ratio of the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme, methacrylated macromolecular protein, oxidized polysaccharide, and photoinitiator is (1-4):30:(5-15):(0.2-0.5); the methacrylated macromolecular protein is selected from one or more of methacrylated gelatin, methacrylated silk fibroin, and methacrylated collagen; the oxidized polysaccharide is selected from one or more of oxidized chondroitin sulfate, oxidized hyaluronic acid, oxidized sodium alginate, and oxidized chitosan; and the photoinitiator is selected from one or more of lithium phenyl-2,4,6-trimethylbenzoylphosphonate and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone.

[0052] In this embodiment, the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme has a core-shell structure, with magnesium oxide as the core, polydopamine as the middle layer, and manganese dioxide as the outer shell. This gives the nanozyme a core function integrating "ion therapy (osteogenesis), photothermal therapy (antibacterial), and enzyme catalytic therapy (anti-inflammatory)," achieving a leap from a "single-function material" to a "multi-functional synergistic treatment system," effectively enhancing the antibacterial and antioxidant capabilities of the hydrogel.

[0053] In a further embodiment, the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme is obtained by dispersing mesoporous magnesium oxide in an alkaline buffer containing dopamine, self-polymerizing to form a polydopamine coating layer, and then reacting it with potassium permanganate to deposit manganese dioxide, thereby obtaining the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme.

[0054] The mesoporous magnesium oxide, obtained through coating technology or porous structure design, possesses controllable pore size and has the function of slow-release and controlled-release magnesium oxide. The mesoporous magnesium oxide described in this application is preferably prepared by the following method.

[0055] 30-40 parts by mass of magnesium acetate tetrahydrate were dissolved in deionized water to obtain a magnesium acetate solution with a mass fraction of 6-8%, and 9-12 parts by mass of urea were dissolved in deionized water to obtain a urea solution with a mass fraction of 4.5-6%. The urea solution was slowly added dropwise to the magnesium acetate solution to carry out a hydrothermal reaction. After purification and drying, the solution was calcined in a muffle furnace to obtain mesoporous magnesium oxide.

[0056] The preferred process parameters for the hydrothermal reaction are: reaction temperature 120 ℃, reaction time 6~10 h, calcination temperature 650~750 ℃, calcination time 3~5 h, purification by filtration or centrifugation, and drying at 80~120 ℃.

[0057] The buffer solution used in the "dopamine-containing alkaline buffer" is preferably Tris-HCl buffer (0.1 M, pH 8.5). The preferred process parameters for the self-polymerization are: reaction time 3-6 h, purification by filtration or centrifugation, and drying at 80-120 °C; the preferred process parameters for the deposition reaction are: reaction in the dark, time 6-9 h, purification by filtration or centrifugation, and vacuum drying at 40-80 °C.

[0058] It is understood that the above-mentioned method for preparing magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide also includes purification and drying of the obtained reaction products or intermediate reaction products, which are conventional methods in this field. Furthermore, the double-crosslinked three-dimensional network structure includes:

[0059] First cross-linking: Dynamic covalent cross-linking formed by the Schiff base reaction between the aldehyde group of methacrylated macromolecular protein and the amino group of oxidized polysaccharide;

[0060] The second crosslinking: a permanent covalent crosslinking formed by photopolymerization of the carbon-carbon double bonds of methacrylated macromolecular proteins under the action of a photoinitiator.

[0061] By constructing an intelligent dual-crosslinked three-dimensional network platform that combines dynamic plasticity (dynamic covalent crosslinking formed by the Schiff base reaction of aldehyde groups of methacrylated macromolecular proteins and amino groups of oxidized polysaccharides) and long-term mechanical stability (permanent covalent crosslinking formed by photopolymerization of carbon-carbon double bonds of methacrylated macromolecular proteins under the action of photoinitiators), the mechanical strength and structural stability of macromolecular proteins are significantly improved while maintaining the good site injection, in-situ curing and self-healing capabilities of hydrogels. This platform specifically addresses the dual requirements of material operability and mechanical properties in the repair of bone defects in periodontitis.

[0062] The second embodiment of this application discloses a method for preparing the above-mentioned magnesium oxide-based nanozyme hydrogel loaded with polydopamine-manganese dioxide, comprising the following steps:

[0063] (1) Preparation of magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide: Mesoporous magnesium oxide is dispersed in an alkaline buffer containing dopamine, and self-polymerizes to form a polydopamine coating layer. Then, it reacts with potassium permanganate to deposit manganese dioxide, thus obtaining magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide.

[0064] (2) Preparation of hydrogel: The methacrylated macromolecular protein solution, the oxidized polysaccharide solution, the nanozyme obtained in step (1) and the photoinitiator are mixed and cured by light irradiation to form a magnesium oxide-based nanozyme hydrogel with a double cross-linked three-dimensional network structure loaded with polydopamine-manganese dioxide. The mesoporous magnesium oxide in step (1) is prepared by hydrothermal-calcination method: magnesium acetate tetrahydrate and urea are hydrothermally reacted at 120℃ for 6-10 h, and then calcined at 650-750℃ for 3-5 h; the self-polymerization reaction time is 3-6 h; the reaction with potassium permanganate is a light-protected reaction and the time is 6-9 h. In step (2), the mass fraction of the methacrylated macromolecular protein solution is 20-40%, the mass fraction of the oxidized polysaccharide solution is 5%-15%, and the two are mixed at a volume ratio of 1:1. The amount of nanozyme added is 0.5-5 mg / mL, the amount of photoinitiator added is 0.2-0.5 parts by mass, and the light irradiation conditions are a wavelength of 330-390 nm and a time of 30-60 s.

[0065] In this embodiment, the methacrylated macromolecular protein is dissolved in PBS buffer solution (0.1 M, pH 7.4); the oxidized polysaccharide is dissolved in PBS buffer solution (0.1 M, pH 7.4); in order to better disperse the solution evenly, this embodiment preferably uses ultrasonic treatment to promote solution dispersion.

[0066] The above preparation method integrates polydopamine-manganese dioxide magnesium oxide-based nanozymes into a double-crosslinked three-dimensional network hydrogel that can be solidified in situ and has self-healing properties. This fundamentally overcomes the problems of nanozyme aggregation and inactivation and initial burst release in complex physiological microenvironments, and further realizes the active component (Mg) 2+ Mn 2+ It provides long-term, stable, and on-demand drug delivery to the lesion area; and thanks to the self-healing and in-situ light-curing properties of hydrogel, the system can perfectly adhere to and anchor itself in irregular periodontal pockets after injection, thereby constructing a local, long-lasting, and intelligently responsive drug delivery and microenvironment regulation platform, providing continuous biochemical and mechanical support for periodontal tissue regeneration.

[0067] The technical means and effects of this application will be described in more detail below through specific embodiments.

[0068] Example 1

[0069] (1) Preparation of magnesium oxide-based nanozymes of polydopamine-manganese dioxide: First, 34 parts by mass of magnesium acetate tetrahydrate were dissolved in deionized water, and 9 parts by mass of urea were dissolved in deionized water to obtain a 4.5% urea solution. The urea solution was slowly added dropwise to the magnesium acetate solution, and the reaction was carried out at 120 °C for 8 h. After centrifugation and purification, the solution was dried at 100 °C and calcined at 650 °C for 3 h to obtain mesoporous magnesium oxide. Then, 2 parts by mass of mesoporous magnesium oxide were dispersed in Tris-HCl buffer (0.1 M, pH 8.5) to obtain a 0.2% magnesium oxide suspension. 0.8 parts by mass of dopamine hydrochloride were added, and the reaction was carried out at room temperature for 3 h. After centrifugation and purification, the solution was calcined at 650 °C for 3 h to obtain a 0.2% magnesium oxide suspension. Magnesium oxide coated with polydopamine was obtained by drying at ℃; finally, 2 parts by mass of the polydopamine-coated magnesium oxide were dispersed in deionized water to obtain a 0.5% polydopamine-coated magnesium oxide suspension. After sonication, 0.8 parts by mass of potassium permanganate were added, and the reaction was carried out for 6 h. After centrifugation and purification, the magnesium oxide-based nanozyme of polydopamine-manganese dioxide was obtained.

[0070] (2) Preparation of hydrogel enhanced with magnesium oxide nanozyme loaded with polydopamine-manganese dioxide: 30 parts by mass of methacrylated gelatin (a type of methacrylated macromolecular protein) were dissolved in phosphate buffer to obtain a 30% methacrylated gelatin solution, and 10 parts by mass of chondroitin sulfate were dissolved in phosphate buffer to obtain a 10% chondroitin sulfate solution. The two solutions were then mixed at a volume ratio of 1:1 and stirred at 37 °C for 20 min. Then, 0.5 parts by mass of lithium phenyl-2,4,6-trimethylbenzoylphosphonate were added, and 0, 0.1, 0.2, and 0.4 parts by mass of magnesium oxide nanozyme loaded with polydopamine-manganese dioxide (i.e., 0, 1, 2, and 4 mg / mL, respectively) were added to the above mixed solution. The mixture was then sonicated for 30 min to ensure uniform dispersion, and irradiated under ultraviolet light at a wavelength of 365 nm for 60 minutes. s, forming magnesium oxide-based nanozyme-enhanced hydrogels based on polydopamine-manganese dioxide loaded, named GGC (0 mg / mL), GGCM-1 (0.1 mg / mL), GGCM-2 (0.2 mg / mL), and GGCM-3 (0.4 mg / mL), respectively.

[0071] Example 2

[0072] (1) Preparation of magnesium oxide-based nanozymes of polydopamine-manganese dioxide: First, 40 parts by mass of magnesium acetate tetrahydrate were dissolved in deionized water, and 12 parts by mass of urea were dissolved in deionized water to obtain a 6% urea solution. The urea solution was slowly added dropwise to the magnesium acetate solution, and the reaction was carried out at 120 °C for 10 h. After purification by filtration and drying at 120 °C, the solution was calcined at 750 °C for 4 h to obtain mesoporous magnesium oxide. Then, 1 part by mass of mesoporous magnesium oxide was dispersed in Tris-HCl buffer (0.1 M, pH 8.5) to obtain a 0.1% magnesium oxide suspension. 1.2 parts by mass of dopamine hydrochloride were added, and the reaction was carried out at room temperature for 3 h. After purification by filtration and drying at 80 °C, the solution was calcined at 80 °C for 4 h to obtain mesoporous magnesium oxide. Magnesium oxide coated with polydopamine was obtained by drying at ℃; finally, 1 part by mass of the polydopamine-coated magnesium oxide was dispersed in deionized water to obtain a 0.25% polydopamine-coated magnesium oxide suspension. After sonication, 1.2 parts by mass of potassium permanganate were added, and the reaction was carried out for 9 h. After centrifugation and purification, the magnesium oxide-based nanozyme of polydopamine-manganese dioxide was obtained.

[0073] (2) Preparation of smart hydrogel based on magnesium oxide nanozyme reinforced by polydopamine-manganese dioxide: 30 parts by mass of methacrylated gelatin were dissolved in phosphate buffer to obtain a 30% methacrylated gelatin solution, and 5 parts by mass of oxidized hyaluronic acid were dissolved in phosphate buffer to obtain a 5% oxidized polysaccharide solution. The two solutions were then mixed at a volume ratio of 1:1 and stirred at 37 °C for 60 min. Then, 0.25 parts by mass of lithium phenyl-2,4,6-trimethylbenzoylphosphonate were added, and 2.5 parts by mass of magnesium oxide nanozyme based on polydopamine-manganese dioxide was added to the above mixed solution. The mixture was then sonicated for 15 min to disperse it evenly. The mixture was then irradiated with ultraviolet light at a wavelength of 380 nm for 40 s to crosslink and form a hydrogel based on magnesium oxide nanozyme reinforced by polydopamine-manganese dioxide.

[0074] The present invention provides the following experimental data, all of which are experimental results obtained from Example 1:

[0075] Experimental Example 1: Characterization and Testing of Magnesium Oxide-Based Nanozymes of Polydopamine-Manganese Dioxide

[0076] The magnesium oxide-based polydopamine-manganese dioxide nanozyme prepared in step (1) of Example 1 was subjected to TEM and EDS experiments, and the results are as follows: Figure 1 , 2 As shown.

[0077] Figure 1 The image shows a TEM image of GGCM-2, a magnesium oxide-based nanozyme of polydopamine-manganese dioxide, which has a uniform particle size distribution (approximately 100 nm) and is mostly distributed in an aggregated state.

[0078] Figure 2 The EDS elemental distribution diagram of the magnesium oxide-based nanozyme GGCM-2, composed of polydopamine and manganese dioxide, confirms that Mg, N, and Mn elements are uniformly distributed, and the composite structure has been successfully constructed.

[0079] Experiment Example 2: Application Experiment

[0080] The GGC hydrogel prepared in Example 1 was applied, such as... Figure 3 As shown: The GGC hydrogel precursor was injected into the target window in the oral cavity and cured by ultraviolet light. The hydrogel was found to be stably anchored in the wound area and closely adhered to the irregular periodontal tissue. This demonstrates that the hydrogel prepared in this application has good in-situ curing ability and wound adaptability. It can effectively cover and protect the periodontal defect site, and provide an ideal physical support and drug delivery platform for its subsequent antibacterial, anti-inflammatory and bone repair promotion. Figure 3 This is a schematic diagram illustrating the application of magnesium oxide-based nanozyme hydrogels loaded with polydopamine-manganese dioxide, demonstrating the hydrogel's ability to be injected at specific points and cured in situ.

[0081] Example 3: Characterization and Testing of Magnesium Oxide-Based Nanozymes Enhanced Hydrogels Supported by Polydopamine-Manganese Dioxide

[0082] The four hydrogels prepared in Example 1 were characterized by SEM. It was found that the loading of nanoparticles into the magnesium oxide-based nanozymes GGCM-1, GGCM-2, and GGCM-3, compared to the unloaded nanozyme hydrogel GGC, did not disrupt the structural integrity of the hydrogel network. This indicates that GGCM-1, GGCM-2, and GGCM-3 possess the same site-specific injection and in-situ curing capabilities as GGC. Example 4: pH Response Performance Test

[0083] Figure 5 The hydrogels with different polydopamine-manganese dioxide magnesium oxide-based nanozyme contents from Example 1 were tested under acidic (pH 5) and neutral (pH 7.4) conditions. 2+ Mn 2+ The cumulative release of the hydrogels was measured, and the results showed that hydrogels with different contents of polydopamine-manganese dioxide magnesium oxide-based nanozymes all exhibited significant pH responsiveness, making them suitable for selective drug delivery in periodontitis.

[0084] Experimental Example 5: Rheological and Mechanical Property Testing

[0085] The rheological properties of GGCM hydrogel were tested using a rotational rheometer. Figure 6 The strain scan curves are shown (strain 0.1%~100%, angular frequency 1 rad / s). Figure 7The results show frequency scan curves (strain 1%, angular frequency 0.1~100 rad / s). The results indicate that the storage modulus (G') of all GGCM hydrogels is higher than the loss modulus (G"), suggesting the formation of a stable three-dimensional network structure. Based on the superior structural stability of GGCM-2 among the components, it was used as a representative for alternating strain scan tests. Figure 8 The alternating strain scan curves (1% and 200% alternating strain, angular frequency 1.0 rad / s) of GGCM-2 show that after high strain failure, G' and G” can recover to their initial levels under low strain, indicating that GGCM-2 hydrogel has good self-healing properties. The compressive mechanical properties of GGCM hydrogel were tested using an electronic universal testing machine (sample size Φ14×7 mm, compression rate 10 mm / min; compressive stress-strain curves were recorded and Young's modulus was calculated). Figure 9 As shown, all hydrogels exhibited good compressive strength during compression and did not crack within 50% strain range, indicating their excellent structural integrity and flexibility. Figure 10 The corresponding Young's modulus statistics are shown in the graph. The Young's modulus of GGC is approximately 16 kPa, that of GGCM-1 is approximately 45 kPa, that of GGCM-2 is approximately 53 kPa, and that of GGCM-3 is approximately 18 kPa. The results indicate that the Young's modulus first increases and then decreases with increasing nanozyme content, with GGCM-2 exhibiting the highest Young's modulus, demonstrating good compressive strength.

[0086] Experimental Example 6: Photothermal Performance Test

[0087] The photothermal properties of the four hydrogels prepared in Example 1 were tested, and the results were as follows: Figures 11-12 Experimental results (photothermal images of GGCM hydrogels with different polydopamine-manganese dioxide magnesium oxide-based nanozyme contents) Figure 11 ) and the photothermal performance curves of the hydrogel ( Figure 12 This indicates that under 808 nm near-infrared light irradiation (power density 1.5 W / cm²), 2 After 5 min of irradiation, the temperature of GGC hydrogel showed no significant change; GGCM-1 heated to 44.7 ℃; GGCM-2 heated to 58.7 ℃; and GGCM-3 heated to 75.5 ℃. Literature reports that the effective temperature for photothermal antibacterial action is approximately 50 ℃, and excessively high temperatures (>70 ℃) may damage surrounding healthy tissue. In summary, GGCM-2, under NIR irradiation, reached 58.7 ℃, achieving the effective antibacterial temperature threshold without exceeding the safe range. Combined with its excellent performance in the aforementioned rheological and mechanical tests, GGCM-2 was selected as the GGCM hydrogel group for subsequent biological research.

[0088] Test Example 7 Antibacterial Performance Test

[0089] The GGCM hydrogel prepared in Example 1 was subjected to in vitro antibacterial tests. *Escherichia coli*, *Staphylococcus aureus*, and *Porphyromonas gingivalis* were selected as model strains. Three groups were established: the GGC group, the unilluminated GGCM group (GGCM NIR-), and the 808 nm illuminated group (GGCM NIR+, power density 1.5 W / cm²). 2 Irradiation time: 5 min. Figure 13 As shown, the GGC and GGCM NIR- groups exhibited inhibition rates of 30%-50% against the three bacteria, mainly due to the adsorption effect of the material itself. However, the GGCM NIR+ group showed inhibition rates exceeding 95% against all three bacteria under near-infrared light irradiation, with an inhibition rate of 99.50% against *Porphyromonas gingivalis*, significantly higher than the un-illuminated group (p<0.001). These results indicate that GGCM hydrogel possesses excellent photothermal antibacterial effects under near-infrared light irradiation.

[0090] Experimental Example 8: Blood Compatibility Test

[0091] The in vitro blood compatibility of the materials was evaluated using anticoagulated whole blood from rats. Physiological saline was used as the negative control group (0% hemolysis) and distilled water was used as the positive control group (100% hemolysis). The hemolysis rate of each group of materials was detected. Figure 14 The results show the blood compatibility test results of the materials, where MPM is a magnesium oxide-based nanozyme coated with polydopamine-manganese dioxide, GGC is a blank double-network hydrogel, and GGCM is a composite hydrogel loaded with MPM nanozyme. The results show that the hemolysis rates of the MPM, GGC, and GGCM groups are approximately 2.1%, 3.2%, and 2.2%, respectively, all below the 5% international hemolysis threshold for biomaterials, indicating that the prepared materials all have good blood compatibility.

[0092] Experimental Example 9: Osteogenic Performance Test

[0093] BMSCs were used to assess the osteogenic differentiation capacity of each group of materials. ALP staining and quantitative analysis were performed on day 7 after osteogenic induction, and ARS staining and quantitative analysis were performed on day 21. Figure 15 For ALP staining and quantification results, the GGCM group showed the deepest ALP staining and the highest quantification value; Figure 16 For ARS staining and quantification results, the GGCM group had the most mineralized nodules, the deepest staining, and the highest quantitative value. The osteogenic effect of the GGCM hydrogel group was better than that of the MPM group, indicating that the GGCM hydrogel can regulate the release of appropriate amounts of Mg. 2+ and Mn 2+ It promotes osteogenic differentiation of BMSCs and has stronger osteogenic activity.

[0094] Test Example 10: Anti-inflammatory Performance Test

[0095] An in vitro inflammation model was constructed by stimulating mouse monocytes / macrophages (RAW 264.7 cells) with lipopolysaccharide (LPS). Four groups were established: an LPS model group (LPS stimulation only), a GGC group (LPS stimulation + GGC treatment), an MPM group (LPS stimulation + MPM treatment), and a GGCM group (LPS stimulation + GGCM treatment). Macrophage phenotypes were detected by flow cytometry. CD86⁺CD206⁻ were identified as M1 pro-inflammatory macrophages, and CD86⁻CD206⁺ were identified as M2 anti-inflammatory macrophages. Figure 17-18 The flow cytometry analysis of macrophage polarization showed that the proportion of M1 cells was low in the control group; the proportion of M1 cells was highest and the proportion of M2 cells was lowest in the LPS model group, indicating that the inflammation model was successfully constructed. Compared with the LPS model group, the proportion of M1 cells decreased and the proportion of M2 cells increased in the GGC and MPM groups; the proportion of M1 cells was lowest and the proportion of M2 cells was highest in the GGCM group. These results indicate that GGCM hydrogel can significantly promote the transformation of RAW 264.7 cells from M1 to M2, demonstrating good immunomodulatory properties.

[0096] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A hydrogel containing magnesium oxide-based nanozymes loaded with polydopamine-manganese dioxide, characterized in that, include: Magnesium oxide-based nanozymes, methacrylated macromolecular proteins, oxidized polysaccharides, and photoinitiators coated with polydopamine-manganese dioxide; The methacrylated macromolecular protein and oxidized polysaccharide form a double-crosslinked three-dimensional network structure through a Schiff base reaction and a photopolymerization reaction initiated by a photoinitiator, and the magnesium oxide-based nanoenzyme coated with polydopamine-manganese dioxide is dispersed in the double-crosslinked three-dimensional network structure.

2. The hydrogel according to claim 1, characterized in that, The polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme has a core-shell structure, with magnesium oxide as the core, polydopamine as the middle layer, and manganese dioxide as the outer shell.

3. The hydrogel according to claim 1, characterized in that, The polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme is obtained by dispersing mesoporous magnesium oxide in an alkaline buffer containing dopamine, which self-polymerizes to form a polydopamine coating layer, and then reacts with potassium permanganate to deposit manganese dioxide, thereby obtaining the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme.

4. The hydrogel according to claim 1, characterized in that, The mass ratio of the polydopamine-manganese dioxide-coated magnesium oxide-based nanozyme, methacrylated macromolecular protein, oxidized polysaccharide and photoinitiator is (1-4):30:(5-15):(0.2-0.5).

5. The hydrogel according to claim 1, characterized in that, The methacrylated macromolecular protein is selected from one or more of methacrylated gelatin, methacrylated silk fibroin, and methacrylated collagen; the oxidized polysaccharide is selected from one or more of oxidized chondroitin sulfate, oxidized hyaluronic acid, oxidized sodium alginate, and oxidized chitosan; the photoinitiator is selected from one or more of lithium phenyl-2,4,6-trimethylbenzoylphosphonate and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone.

6. A method for preparing a magnesium oxide-based nanoenzyme hydrogel loaded with polydopamine-manganese dioxide as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide: Mesoporous magnesium oxide is dispersed in an alkaline buffer containing dopamine, and self-polymerizes to form a polydopamine coating layer. Then, it reacts with potassium permanganate to deposit manganese dioxide, thus obtaining magnesium oxide-based nanozymes coated with polydopamine-manganese dioxide. (2) Preparation of hydrogel: Mix methacrylated macromolecular protein solution, oxidized polysaccharide solution, nanozyme obtained in step (1) with photoinitiator, and solidify by light irradiation to form a magnesium oxide-based nanozyme loaded with a double cross-linked three-dimensional network structure.

7. The use of the magnesium oxide-based nanoenzyme hydrogel loaded with polydopamine-manganese dioxide according to any one of claims 1-5 in the preparation of drugs or medical devices for treating periodontitis or promoting bone regeneration.

8. The application according to claim 7, characterized in that, include: The hydrogel is used to generate a photothermal effect by irradiating it with near-infrared light for antibacterial purposes, and the hydrogel releases Mg in an acidic microenvironment. 2+ and Mn 2+ It regulates immunity and promotes bone differentiation.

9. A pharmaceutical composition comprising a hydrogel of a magnesium oxide-based nanozyme loaded with polydopamine-manganese dioxide as described in any one of claims 1-5, and a pharmaceutically acceptable carrier and / or excipients.

10. A medical device, which is an implant or dressing, characterized in that, Hydrogels containing magnesium oxide-based nanozymes loaded with polydopamine-manganese dioxide as described in any one of claims 1-5.

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