A silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions, its preparation method and application

Abstract

This invention discloses a silver nanorod@mesoporous iron(III) oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions, its preparation method, and its application. Specifically: 1) AgNRs are prepared, and a MesoFe3O4 shell is constructed on their surface using a template method to obtain AgNRs@MesoFe3O4; 2) Antibacterial agents are loaded into AgNRs@MesoFe3O4 using cyclic ultrasonic impregnation-low-temperature vacuum drying; 3) A sodium alginate solution containing drug-loaded AgNRs@MesoFe3O4 is poured into the bottom layer of a mold to obtain a nanomaterial layer, and a mixed solution containing AlgMA and sodium alginate is poured into the top layer; 4) UV curing and Ca2+ curing are performed. 2+ The solution impregnation method achieves dual in-situ gelation of the above solution. The solution is impregnated in a solution containing osteogenic drugs, rinsed, dried, and sterilized by irradiation to obtain a heterogeneous hydrogel. This material disrupts biofilms and kills bacteria, exhibiting both antibacterial and osteogenic functions.

Description

Technical Field

[0001] This invention relates to the preparation technology of functional hydrogel materials, specifically to a silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions, its preparation method and application. Background Technology

[0002] Infected bone defects are one of the most challenging problems in orthopedic clinical practice, often caused by infection following severe open trauma, debridement of osteomyelitis, or internal fixation surgery. Clinically, to maintain the mechanical stability and alignment of the bone, implantable devices such as plates, intramedullary nails, or external fixators are typically used to fix the bone defect area. However, the surfaces of these implants provide an ideal interface for bacterial adhesion and colonization. Once bacteria attach to the implant surface or necrotic bone tissue, they secrete extracellular polysaccharide matrix, gradually forming a dense biofilm. Biofilm formation is a critical turning point in the progression from acute to chronic infection—its dense barrier effectively resists antibiotic penetration while escaping phagocytosis and clearance by the body's immune cells, leading to recurrent and persistent infections, ultimately developing into chronic osteomyelitis, nonunion, or even amputation, causing immense physical and psychological suffering and financial burden on patients.

[0003] In clinical settings involving bone infections with established biofilms, current standard treatments primarily include thorough debridement, systemic antibiotic administration, and local implantation of antibiotic-treated bone cement. However, these methods all have significant limitations: while thorough debridement removes most necrotic tissue and biofilms, it often leaves large bone defects, making subsequent repair extremely difficult; systemic antibiotic treatment struggles to achieve effective bactericidal concentrations at the local infection site, and long-term use can lead to hepatotoxicity, nephrotoxicity, and drug-resistant strains; while antibiotic-treated bone cement can achieve high-concentration local drug release, as a non-degradable polymethyl methacrylate material, it requires a second surgery for removal, and the residual bone cement itself can become a carrier for bacterial recolonization after drug release. More importantly, all of the above methods focus on the single goal of sterilization, failing to simultaneously address the issue of bone regeneration after debridement. The stepwise approach of infection control and bone-inducing repair not only prolongs the treatment cycle but also increases the patient's suffering from multiple surgeries and medical costs.

[0004] To address the aforementioned clinical challenges, the development of an implantable filling material that combines highly effective antibacterial properties with osteogenic properties, allowing for in-situ filling of bone defects after thorough debridement, could potentially achieve synergistic treatment of infection control and bone regeneration. An ideal material should possess the following characteristics: First, it should be able to penetrate and disrupt existing bacterial biofilms, effectively killing residual bacteria within the biofilm; second, it should have long-lasting antibacterial activity to prevent infection recurrence; third, it should have good biocompatibility and osteoinductive activity, guiding the regeneration of new bone tissue; and fourth, it should possess controllable drug release properties and suitable mechanical support.

[0005] Of particular note is the unique pathophysiological characteristics of the infection microenvironment, especially the local inflammatory response caused by bacterial infection, which is often accompanied by increased tissue fluid exudation, decreased pH, and increased activity of various enzymes. This invention cleverly utilizes this microenvironmental characteristic: the underlying sodium alginate network forms a physical hydrogel through calcium ion cross-linking. While structurally stable under normal physiological conditions, it rapidly dissociates upon exposure to infectious bodily fluids due to the chelating effect of inflammatory mediators on calcium ions and the disruption of cross-linking points by the local slightly acidic environment. This intelligent responsiveness allows for the rapid release of AgNRs@MesoFe3O4 nanoparticles loaded on the underlying layer. The released magnetic nanoparticles, guided by an in vitro applied magnetic field, can directionally accumulate on the implant surface or at the edge of bone defects in the biomembrane region. Through magnetic force, they physically shear and disrupt the biomembrane structure, significantly enhancing the penetration ability of antibacterial agents into the biomembrane. Simultaneously, the photothermal effect of silver nanorods can further synergistically disrupt the integrity of the biomembrane under near-infrared irradiation, while the sustained-release properties of mesoporous iron oxide ensure the sustained release of the antibacterial agent. This multi-level synergistic strategy of "reacting to the infection microenvironment, targeting and enriching with magnetic fields, physically destroying the biofilm, and synergistically killing bacteria with chemicals / photothermal agents" provides a novel treatment approach for refractory bone infections that have already formed biofilms. Summary of the Invention

[0006] The purpose of this invention is to address the problems of non-responsiveness and low biofilm killing ability of traditional antibacterial materials, and to provide a silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection function, as well as its preparation method and application.

[0007] This invention is achieved using the following technical solution: A method for preparing a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions includes the following steps: 1) Silver nanorods (AgNRs) ethanol dispersion were prepared by solvothermal method, and a mesoporous iron oxide (MesoFe3O4) shell was constructed on its surface by template method to obtain AgNRs@MesoFe3O4 core-shell composite nanomaterials. 2) The antibacterial agent was loaded into AgNRs@MesoFe3O4 using a cyclic ultrasonic impregnation-low temperature vacuum drying process to obtain drug-loaded AgNRs@MesoFe3O4 composite nanomaterials; 3) Take a mold, pour a sodium alginate solution containing AgNRs@MesoFe3O4 into the bottom layer of the mold to obtain a layer containing nanomaterials, and pour a mixed solution containing AlgMA and sodium alginate into the top layer. 4) UV curing and Ca 2+ The solution impregnation method achieves double in-situ gelation of the solution in step 3), and the double-layer hydrogel is obtained after demolding. After rinsing the hydrogel, it is impregnated in a solution containing osteogenic drugs, and then rinsed, dried, and sterilized by irradiation to obtain a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with osteogenic and intelligent anti-infection functions. 5) Applying a composite magnetic field drives the movement of nanomaterials inside the composite heterogeneous hydrogel material, destroying the bacterial biofilm structure, and simultaneously combining photothermal activation to promote the release of antibacterial agents inside the composite heterogeneous hydrogel material to kill bacteria.

[0008] Furthermore, in step 1), the preparation process of AgNRs is as follows: A polyol solvothermal method was used. 1%–3% polyvinylpyrrolidone (PVP), molecular weight K30, 0.5%–1.5% silver nitrate (AgNO3), 0.2%–0.4% hexadecyltrimethylammonium bromide (CTAB), and 0.02%–0.04% copper chloride (CuCl2·2H2O) were dissolved in 95.06%–98.28% ethylene glycol to obtain a mixture. The mixture was transferred to a high-pressure reactor and reacted at 140–180°C for 6–12 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged, washed successively with acetone and deionized water, and finally dispersed in anhydrous ethanol to obtain an AgNRs ethanol dispersion for later use.

[0009] Furthermore, in step 1), the preparation process of the AgNRs@MesoFe3O4 material is as follows: By mass percentage, 2%–5% ferric chloride hexahydrate FeCl3·6H2O as the iron source, 1%–3% citric acid monohydrate C6H8O7·H2O as the complexing agent to regulate the iron ion release rate, 15%–25% sodium acetate as the alkali source and electrostatic stabilizer, 3%–8% hexadecyltrimethylammonium bromide CTAB as the mesoporous template agent, 1%–4% polyethylene glycol PEG-400 as the dispersant and pore size expander, 0.5%–2% urea CO(NH2)2 as the precipitation aid to promote uniform nucleation, 0.1%–0.5% ethylenediaminetetraacetic acid EDTA as the metal ion chelating agent to prevent excessively rapid hydrolysis of iron ions, and 0.1%–0.5% sodium dodecyl sulfate SDS as the co-templating agent to adjust the mesoporous structure are dissolved in 52%–77.3% ethylene glycol and stirred for 30–60 minutes to mix evenly to obtain the precursor solution. Take the AgNRs ethanol dispersion and add it to the precursor solution at a ratio of 0.05%~0.5% of the total mass of AgNRs. Simultaneously, add 0.5%~2% of polyvinylpyrrolidone (PVP) (molecular weight K90) as a surface coupling agent to enhance the interfacial bonding between the silver core and the iron shell. After ultrasonic dispersion for 20~40 minutes, transfer to a high-pressure reactor, seal, and react at 180~220℃ to allow Fe3O4 nanocrystals to grow and self-assemble in situ on the AgNRs surface, forming an AgNRs@MesoFe3O4 composite structure. After the reaction, allow it to cool naturally to room temperature. Magnetic separation of the reaction product is performed using an external magnetic field. The supernatant is discarded, and the magnetic product is collected and washed several times with ethanol and deionized water. The washed product is dispersed in a solution containing 0.1~0.5 mol / L... The CTAB and SDS templates were completely removed by refluxing in an ethanol solution of NH4NO3 at 60-80°C for 6-12 hours. Finally, the product was collected by magnetic separation, washed with deionized water until neutral, and dried in a vacuum drying oven at 40-60°C for 12-24 hours to obtain AgNRs@MesoFe3O4 core-shell composite material.

[0010] Furthermore, in step 2), the antibacterial agent is loaded into AgNRs@MesoFe3O4 using a cyclic ultrasonic impregnation-low temperature vacuum drying process. The specific process is as follows: The AgNRs@MesoFe3O4 core-shell composite material obtained in step 1) was dispersed in deionized water to prepare a suspension with a concentration of 5-20 mg / mL for later use; an antibacterial drug solution with a concentration of 10-100 mg / mL was prepared; the suspension and the antibacterial drug solution were mixed at a volume ratio of 1:1 to 1:3 to obtain a mixture, and the mixture was subjected to ultrasonic treatment at a power of 200-500. In an ultrasonic bath, the mixture was ultrasonically impregnated for 10-30 minutes under ice-water bath conditions. Then, the ultrasonically mixed solution was transferred to a petri dish, and the surface was covered with a breathable covering film to prevent product dispersion. It was then placed in a vacuum drying oven and vacuum dried at 30-50°C for 30-60 minutes. After the solvent partially evaporated, the antibacterial drug solution was added back to the original volume, and ultrasonic impregnation and low-temperature vacuum drying were repeated several times. Finally, the product was centrifuged, washed with deionized water to remove the surface-adsorbed antibacterial drug, and dried in a vacuum drying oven at 30-40°C for 12-24 hours to obtain drug-loaded AgNRs@MesoFe3O4 composite nanomaterials.

[0011] Furthermore, the antibacterial agent is one or more of antibiotic antibacterial agents, metal ion antibacterial agents, or other organic antibacterial agents; The antibiotic antibacterial agents include tetracycline hydrochloride, vancomycin hydrochloride, gentamicin, or ciprofloxacin; the metal ion antibacterial agents include silver nitrate, copper sulfate, or zinc nitrate; and other organic antibacterial agents include chlorhexidine acetate or polyhexamethylene guanidine. Further, in step 3), a mold is taken, and a sodium alginate solution containing AgNRs@MesoFe3O4 loaded with the drug is poured into the bottom layer of the mold to form a layer containing nanomaterials. A mixed solution containing AlgMA and sodium alginate is poured into the upper layer. The specific process is as follows: Weigh out sodium alginate powder and add it to deionized water. Stir magnetically in a water bath at 40-60°C for 2-4 hours until completely dissolved to prepare a sodium alginate solution with a mass fraction of 1%-3%. Let it stand to remove bubbles and set aside for later use. Add the drug-loaded AgNRs@MesoFe3O4 composite nanomaterial to the sodium alginate solution at 0.1%~1.0% of the mass of the sodium alginate solution, and disperse it ultrasonically for 3~5 minutes to obtain the drug-loaded AgNRs@MesoFe3O4 sodium alginate solution. The upper mixed solution consists of 5%~15% AlgMA, 0.25%~0.75% sodium alginate solution and 0.1%~0.5% photoinitiator, dissolved in PBS buffer and stirred in a water bath at 60~70℃ in the dark for 30~60 minutes until completely dissolved. Take a mold, which is a semi-permeable membrane with a plastic frame inserted inside. Place the mold horizontally and slowly pour the drug-loaded sodium alginate solution into the bottom of the mold. Shake to make the liquid surface level. The pouring height is 0.25~0.75 mm. Place it in a refrigerator at 4℃ and let it stand to allow it to initially gel and obtain the bottom layer containing nanomaterials. Then, slowly pour the pre-prepared upper mixed solution along the inner wall of the mold onto the bottom layer to avoid dispersing the bottom layer. The pouring height is 2~6 mm. The whole process should be carried out in the dark.

[0012] Furthermore, in step 4), UV curing and Ca are used. 2+ The solution impregnation method achieves double in-situ gelation of the solution in step 3), resulting in a double-layer hydrogel after demolding. The hydrogel is then rinsed and impregnated in a solution containing osteogenic drugs. After rinsing, drying, and irradiation sterilization, a silver nanorod@mesoporticotinic ferric oxide composite heterogeneous hydrogel material is obtained. The specific process is as follows: After casting, the mold was placed under a UV lamp at a wavelength of 365 nm and a power of 5~20 mW / cm². 2 Irradiation for 30-180 seconds under certain conditions causes the upper mixed solution to crosslink and solidify, resulting in an upper gel layer, which, together with the bottom layer containing nanomaterials, forms a bilayer hydrogel. Separately, anhydrous calcium chloride is dissolved in deionized water to prepare a 2%-5% calcium chloride solution as a crosslinking agent. The UV-cured mold, along with the bilayer hydrogel, is immersed in the calcium chloride crosslinking solution and crosslinked and solidified at 4-10℃ for 6-48 hours, allowing calcium ions to diffuse through the semi-permeable membrane into the bottom layer, achieving full crosslinking of sodium alginate. The cross-linked bilayer hydrogel was removed from the mold, rinsed several times with deionized water, and then immersed in a solution containing 0.001~5 mg / mL of osteogenic drug to achieve drug adsorption equilibrium. The solution was then soaked at 4~25℃ for 12~24 hours to achieve drug adsorption equilibrium. After immersion, the bilayer hydrogel was removed and rinsed several times with PBS buffer. The surface moisture was wiped dry with sterile gauze and sterilized by irradiation to obtain silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material.

[0013] Furthermore, the bone-promoting drug includes one or more of chemical drugs, active ingredients of traditional Chinese medicine, or bioactive factors; The chemical drugs include dexamethasone, sodium β-glycerophosphate, or ascorbic acid; the active ingredients of traditional Chinese medicine include icariin, naringin, tanshinone IIA, or baicalin; and the bioactive factors include bone morphogenetic protein BMP-2, transforming growth factor TGF-β, or insulin-like growth factor IGF-1.

[0014] Furthermore, in step 5), a composite magnetic field is applied to drive the movement of nanomaterials inside the composite heterogeneous hydrogel material, disrupting the bacterial biofilm structure. Simultaneously, photothermal activation promotes the release of antibacterial agents within the composite heterogeneous hydrogel material, killing the bacteria. Specifically: A composite magnetic field, consisting of a directional static magnetic field and an alternating / rotating magnetic field, is applied for treatment. The directional static magnetic field is perpendicular to the hydrogel substrate and points from the gel interior towards the bacterial biofilm. The magnetic field strength is 0.1-0.5 T, and the application is sustained for 10-30 minutes. This magnetic gradient force continuously drives the released magnetic drug-loaded AgNRs@MesoFe3O4 composite nanomaterials to directionally accumulate and permeate from the gel substrate into the bacterial biofilm, allowing the nanomaterials to effectively penetrate and distribute within the biofilm. Simultaneously, an alternating magnetic field is applied. This alternating magnetic field has a strength of 0.3-1.0 T, a frequency of 10-100 Hz, and an application time of 10-20 minutes. This exerts physical shearing and disruption on the formed bacterial biofilm structure, enhancing biofilm permeability. After the magnetic field application, the biofilm is irradiated with an 808 nm near-infrared laser with a power density of 0.5-2.0 W / cm². 2 The irradiation time is 5-15 minutes, and the local temperature is raised to 40-45℃ by utilizing the photothermal conversion effect of AgNRs; the membrane rupture and near-infrared laser irradiation operations are repeated for 3-7 days.

[0015] A silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions is prepared by any of the methods described.

[0016] Application of a heterogeneous hydrogel material in the preparation of medical devices for treating infected bone defects.

[0017] Compared with the prior art, the present invention has the following advantages: 1) This invention constructs a core-shell structure of AgNRs@MesoFe3O4 at the nanomaterial level. This design takes into account multiple clinical characteristics of biofilm-associated bone infections. Silver nanorods serve as the core, and their high aspect ratio structure endows them with excellent local surface plasmon resonance effects, enabling efficient photothermal conversion under near-infrared light irradiation. Simultaneously, the silver nanorods themselves continuously release silver ions, providing intrinsic long-lasting antibacterial activity. The design of the MesoFe3O4 shell is particularly ingenious: firstly, the shell forms a physical shield for the silver core, slowing down the oxidation rate of silver and making the release of silver ions more gradual and sustained, solving the application bottleneck of easy aggregation and inactivation of nanosilver; secondly, the shell itself has magnetic response characteristics, giving the nanoparticles in vitro manipulability; thirdly, the regular mesoporous channels inside the shell serve as a drug reservoir, enabling programmed release of antibacterial agents; fourthly, the abundant iron ions on the shell surface can be utilized by local tissues after material degradation, promoting the expression of osteogenic genes and becoming an auxiliary factor for subsequent osteogenic repair. This multifunctional core-shell structure design integrates five major functions into a single nanomaterial: photothermal, magnetic response, drug sustained release, intrinsic antibacterial, and osteopromoting. Each function is independent yet synergistic with the others.

[0018] 2) The bilayer hydrogel structure constructed in this invention is a biomimetic design aimed at the clinical treatment needs of controlling infection first and then promoting repair in infectious bone defects. The lower layer is a sodium alginate layer loaded with drug-eluting AgNRs@MesoFe3O4, with a thickness of only 0.25~0.75 mm. As a thin layer structure, it ensures that nanoparticles can quickly penetrate into infected tissue after release. The calcium ion cross-linking network of sodium alginate acts as a "smart switch," which can slowly and responsively dissociate in the infected microenvironment to achieve local targeted release of nanoparticles. The upper layer is a composite layer of sodium alginate and AlgMA, with a thickness of 2~6 mm. As a thick layer structure, it provides sufficient three-dimensional space for cell migration and tissue regeneration. The AlgMA photocross-linking network provides stable mechanical support and maintains the spatial morphology of the bone defect area. The osteogenic drug loaded in the composite layer can be continuously released and directionally induce osteogenic differentiation. A small amount of sodium alginate is incorporated into the upper AlgMA layer, and after UV curing, it is released through Ca2+. 2+ Cross-linking forms an interpenetrating network, enhancing the bonding strength between the two layers. This bilayer structure enables the partitioning of anti-infection and bone function-promoting functions, as well as the sequential connection of treatment processes.

[0019] 3) Addressing the unique microenvironmental characteristics of biofilm infection sites, this invention designs a "smart switch" mechanism for the underlying sodium alginate layer. Clinical studies have shown that bacterial biofilm infection foci exhibit an acidic pH environment (5.5-6.5) due to bacterial metabolic acid production and inflammatory responses. Simultaneously, inflammatory mediators such as lactic acid and phosphate ions can chelate calcium ions. This invention utilizes this pathological characteristic, employing a calcium-ion-crosslinked sodium alginate physical hydrogel as the underlying matrix. Under normal physiological conditions, the gel network structure remains intact, and nanoparticles are effectively anchored. When the hydrogel is implanted into the infection site, the local acidic environment disrupts the carboxyl-Ca groups. 2+ Coordination bonds and the competitive chelation of calcium ions by inflammatory mediators lead to the rapid dissociation of the physical cross-linked network, releasing the loaded AgNRs@MesoFe3O4 nanoparticles. This "on-demand release" mechanism has three clinical implications: first, it ensures that nanoparticles are released only at the site of infection, avoiding systemic distribution; second, the timing of release is positively correlated with the severity of infection—the more severe the infection and the more significant the changes in the microenvironment, the faster and more abundant the release of nanoparticles; and third, it provides a material basis for subsequent magnetic field-driven and photothermal sterilization.

[0020] 4) The difficulty in treating biofilms lies in the fact that the physical barrier formed by their extracellular polysaccharide matrix resists antibiotic penetration and immune cell clearance. This invention addresses this clinical challenge by innovatively employing a "two-step magnetic field-driven" strategy to achieve physical membrane disruption. The released AgNRs@MesoFe3O4 nanoparticles are first driven by a directional static magnetic field (0.1~0.5 T) applied perpendicular to the gel substrate, causing them to migrate directionally towards the infected area and accumulate on the surface and inside the biofilm, solving the key problem of how nanoparticles penetrate tissue to reach the biofilm. Based on this, an alternating or rotating magnetic field (0.3~1.0 T, 10~100 Hz) is superimposed, driving the nanoparticles already accumulated inside the biofilm to produce random motion, rotation, or oscillation, resulting in physical shearing and tearing of the extracellular polysaccharide matrix and bacterial cell walls. This physical membrane disruption mechanism has unique advantages: it is independent of the bacterial metabolic state and drug resistance, and is equally effective against dormant bacteria inside the biofilm; it can be repeatedly applied, and its efficiency in destroying mature biofilms is significantly better than simple chemical sterilization.

[0021] 5) After the biofilm is physically disrupted, the previously protected bacteria are exposed, at which point a synergistic bactericidal phase begins. Near-infrared light irradiation (808 nm, 0.5~2.0 W / cm²) 2(After 5-15 minutes) the photothermal effect of AgNRs is activated, raising the local temperature to 40-45℃. This temperature range has a triple effect: the thermal effect itself can directly kill heat-sensitive bacteria; the temperature increase increases the fluidity of bacterial cell membranes, thereby increasing the uptake of antibacterial drugs; and the temperature increase promotes the accelerated release of antibacterial drugs loaded in the MesoFe3O4 shell, forming a "thermo-induced burst release" effect. The released antibacterial drugs synergistically work with the silver ions continuously released by the silver nanorods to attack bacteria from multiple targets such as the cell wall, cell membrane, and DNA, significantly improving the bactericidal efficiency and effectively preventing the emergence of drug-resistant bacteria.

[0022] 6) A major challenge after treatment of infected bone defects is infection recurrence. This invention achieves long-lasting antibacterial and recurrence prevention through a triple mechanism: AgNRs continuously release silver ions, producing a sustained antibacterial effect and forming a baseline sustained-release barrier; the MesoFe3O4 shell physically shields the silver nucleus, slowing down the oxidation rate of silver and prolonging the half-life of silver ion release, achieving a smooth and sustained release kinetic; when clinical monitoring indicates an increased risk of infection recurrence, near-infrared light irradiation can be repeatedly applied to activate the photothermal effect for direct sterilization, while simultaneously promoting the supplementary release of drugs stored within the mesopores. This dual-mode antibacterial strategy of "baseline sustained release + on-demand activation" enables the material to have an active defense capability against infection recurrence.

[0023] 7) After infection control, bone defect repair becomes the primary challenge. This invention employs a sodium alginate / AlgMA dual-network structure in the upper layer to load osteogenic drugs. The AlgMA photocrosslinking network provides structural stability, and its porous structure provides a three-dimensional scaffold for cell adhesion, proliferation, and migration. Sodium alginate segments interpenetrate within the AlgMA network, forming a semi-interpenetrating structure, and its abundant hydrophilic groups provide more binding sites for osteogenic drugs. This dual-network structure has a dual regulatory effect on drug release: on the one hand, the diffusion of drug molecules within the network is physically hindered, achieving slow release; on the other hand, as the upper gel gradually degrades in vivo, the loaded drug is continuously released, with the release cycle matching the bone regeneration time window. The types of loaded drugs cover chemical drugs, active ingredients from traditional Chinese medicine, and bioactive factors, which can be flexibly combined according to clinical needs to achieve multi-target osteogenic therapy. It is worth emphasizing that the iron ions generated by the degradation of the lower nanomaterials can promote the expression of osteogenic-related genes, forming a "synergistic" osteogenic microenvironment.

[0024] 8) This invention achieves multi-dimensional synergistic innovation in raw material selection and process design. At the nanomaterial preparation level, the polyol solvothermal synthesis of AgNRs is combined with the template-based coating of MesoFe3O4, using PVP as a surface coupling agent to enhance the core-shell interface bonding. In the surfactant system design, CTAB is used to regulate the morphology of AgNRs, and CTAB and SDS are used together as composite template agents to regulate the mesoporous structure. In the solvothermal reaction system, citric acid is introduced as an iron ion complexing agent, urea as a precipitation aid, and EDTA as a metal ion chelating agent; the synergistic effect of these multi-component aids ensures uniform nucleation and growth of Fe3O4 nanocrystals on the AgNRs surface. At the drug loading process level, a pioneering cyclic ultrasonic impregnation-low-temperature vacuum drying technology is used to achieve efficient loading of antibacterial drugs within the mesopores. At the gel construction level, physically cross-linked sodium alginate and photocross-linked AlgMA are co-constructed into a bilayer, employing UV curing first, followed by Ca... 2+ A stepwise cross-linking strategy following diffusion. This series of innovative combinations of raw materials and processes enables the organic integration of inorganic nanomaterials, organic antibacterial drugs, and polymeric hydrogel substrates.

[0025] 9) This invention employs a mold structure in which a plastic frame is inserted into a semi-permeable membrane. Its ingenious design lies in the fact that the semi-permeable membrane allows Ca... 2+ Selective permeability enables cross-linking of the lower layer while blocking the diffusion of macromolecules; the framework structure facilitates demolding and transfer, avoiding gel breakage; the hydrophilic surface of the semi-permeable membrane helps the lower sodium alginate solution spread evenly, ensuring the uniformity of the thickness of the ultra-thin bottom layer; the mold can be reused, reducing preparation costs.

[0026] 10) The pioneering cyclic ultrasonic impregnation-low-temperature vacuum drying technology for drug loading is innovative in several ways: it utilizes ultrasonic cavitation to promote the entry of antibacterial drugs into mesoporous channels, solving the problem of low drug loading efficiency due to passive diffusion in mesoporous materials; it employs low-temperature vacuum drying to avoid thermal inactivation of the drug; through multiple cycles, it achieves cumulative drug loading within the mesopores, resulting in a drug loading capacity more than twice that of conventional impregnation methods; and finally, rapid washing ensures that the drug is mainly loaded inside the mesopores rather than on the surface, achieving a sustained-release effect. This process is applicable to both hydrophilic and hydrophobic antibacterial drugs, demonstrating good versatility.

[0027] 11) Examining the above functions within the clinical context of biofilm-related bone infection reveals that this invention achieves a perfect spatiotemporal cascade. In the initial implantation phase (0-2 days), the material is positioned in the debridement-treated bone defect area. The underlying sodium alginate acts as a sentinel, sensing the infection microenvironment and enabling on-demand release of nanoparticles. During the release phase (2-3 days), nanoparticles accumulate in the infected area under the drive of a directional magnetic field. A rotating magnetic field further physically disrupts the biofilm, opening channels for subsequent sterilization. During the sterilization phase (3-7 days), near-infrared light irradiation activates the photothermal effect, synergistically killing bacteria with released antibacterial drugs and silver ions. Daily repetition ensures thorough removal. During the repair phase (after 7 days), once the infection is controlled, the upper dual-network structure continuously releases osteogenic drugs, inducing osteogenic differentiation of mesenchymal stem cells. Simultaneously, iron ions generated from the degradation of the lower layer promote the expression of osteogenic genes, forming a synergistic osteogenic microenvironment. Throughout this process, the lower nanoparticles gradually degrade after fulfilling their mission, while the upper scaffold persists until new bone formation. This intelligent multi-level strategy of "infection response release - magnetic enrichment - physical membrane disruption - photothermal sterilization - promoting bone repair" is sequential in time, accurately positioned in space, and mutually dependent in function. It is precisely the precise design of this invention for complex bone infections, providing a brand-new materials science strategy for overcoming clinically refractory infectious bone defects. Attached Figure Description

[0028] Figure 1 A schematic diagram of the construction process of a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-intelligent anti-infection function; Figure 2 A schematic diagram of the magnetic drive and photothermal conversion sterilization process in a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-intelligent anti-infection function; Figure 3 SEM results of silver nanorods@mesoporous iron oxide in a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-intelligent anti-infection function; Figure 4 Photographs of the coating results of silver nanorods@mesoporous iron oxide composite heterogeneous hydrogel material with bone-inspiring and intelligent anti-infection functions after being used in a rabbit infection model (a corresponds to Example 1, b corresponds to Example 4). Detailed Implementation

[0029] The invention will be further illustrated below with specific examples.

[0030] Example 1: 1) Silver nanorods were first prepared using a polyol solvothermal method. 3 g of polyvinylpyrrolidone (PVP, molecular weight K30), 1 g of silver nitrate, 0.3 g of CTAB, and 0.03 g of CuCl2·2H2O were dissolved in 95.67 g of ethylene glycol and magnetically stirred until completely dissolved. The mixture was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and reacted at 160 °C for 8 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 8000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed three times each with acetone and deionized water. Finally, it was dispersed in anhydrous ethanol to prepare a 10 mg / mL AgNRs ethanol dispersion for later use. Subsequently, a mesoporous iron oxide shell was coated onto the surface of the silver nanorods using a solvothermal-template method. 3 g FeCl3·6H2O, 2 g citric acid monohydrate, 20 g sodium acetate, 5 g CTAB, 2 g polyethylene glycol (PEG-400), 1 g urea, 0.3 g EDTA, and 0.3 g SDS were dissolved in 66.4 g ethylene glycol. The solution was magnetically stirred for 40 minutes to ensure complete dissolution of all components, resulting in a homogeneous precursor solution. The above AgNRs ethanol dispersion was slowly added dropwise to the precursor solution at a ratio of 0.2% of the total mass of AgNRs. Simultaneously, 1 g PVP (molecular weight K90) was added as a surface coupling agent. The mixture was ultrasonically dispersed for 30 minutes to ensure uniform dispersion of silver nanorods. The mixture was transferred to a high-pressure reactor, sealed, and reacted at 200℃ for 18 hours to allow Fe3O4 nanocrystals to grow and self-assemble in situ on the AgNRs surface. After the reaction, the mixture was allowed to cool naturally to room temperature. Magnetic separation was performed using an external magnetic field. The supernatant was discarded, and the magnetic product was collected and washed three times each with ethanol and deionized water. The washed product was dispersed in 200 mL of ethanol solution containing 0.3 mol / L NH4NO3 and refluxed at 70 °C for 8 hours to completely remove CTAB and SDS template. Finally, the product was collected by magnetic separation, washed repeatedly with deionized water until neutral, and dried in a vacuum drying oven at 50 °C for 18 hours to obtain AgNRs@MesoFe3O4 core-shell composite material.

[0031] 2) Take 100 mg of the prepared AgNRs@MesoFe3O4 nanoparticles and disperse them in 10 mL of deionized water to prepare a 10 mg / mL suspension. Separately, weigh 500 mg of tetracycline hydrochloride and dissolve it in 10 mL of deionized water to prepare a 50 mg / mL antibacterial drug solution. Mix the AgNRs@MesoFe3O4 suspension and the tetracycline hydrochloride solution at a volume ratio of 1:2 (i.e., mix 5 mL of the suspension with 10 mL of the drug solution), and use a cyclic ultrasonic impregnation-low temperature vacuum drying process to load the antibacterial drug in the mesopores. The specific operation is as follows: The mixture was placed in an ultrasonic bath with an ultrasonic power of 300 W and ultrasonically treated for 20 minutes under ice-water bath conditions. Then, the ultrasonically treated mixture was transferred to a petri dish, and the surface was covered with a sealing film with small holes to prevent sample scattering. It was then placed in a vacuum drying oven and vacuum dried at 40℃ for 45 minutes. After the solvent partially evaporated, tetracycline hydrochloride solution was added back to the original volume (15 mL), and ultrasonic impregnation was performed again for 20 minutes, followed by low-temperature vacuum drying. This cycle was repeated 4 times, i.e., adding tetracycline hydrochloride solution - ultrasonic impregnation - low-temperature vacuum drying. Finally, the product was centrifuged at 10000 rpm for 10 minutes, quickly washed once with deionized water to remove the drug adsorbed on the surface, and then dried in a vacuum drying oven at 35℃ for 18 hours to obtain the drug-loaded AgNRs@MesoFe3O4 composite nanoparticle material.

[0032] 3) First, prepare the sodium alginate base solution: Weigh 2 g of sodium alginate powder and add it to 98 g of deionized water. Stir magnetically in a 50°C water bath for 3 hours until completely dissolved to prepare a 2% sodium alginate solution. Let it stand to remove bubbles and set aside. Take 20 mg of the above-mentioned drug-loaded AgNRs@MesoFe3O4 nanoparticles and add them to 10 mL of sodium alginate solution (the nanoparticles account for 0.2% of the mass of the sodium alginate solution). Disperse ultrasonically for 3 minutes to obtain the drug-loaded sodium alginate solution. Separately, prepare the upper gel solution: Weigh 1 g of AlgMA (substitution degree approximately 80%), 0.05 g of sodium alginate, and 0.03 g of photoinitiator Irgacure 2959. Dissolve them in 8.92 mL of deionized water and stir in a 65°C water bath in the dark for 40 minutes until completely dissolved to prepare an upper gel solution containing 10% AlgMA, 0.5% sodium alginate, and 0.3% photoinitiator. Take a self-made mold (a cuboid plastic frame inserted into a 0.22 μm pore size semi-permeable membrane to form an open cuboid) and place it horizontally. Use a pipette to draw up the drug-loaded sodium alginate solution and slowly pour it into the bottom of the mold to a pouring height of 0.5 mm (calculated based on the bottom area of ​​the mold). Gently shake the mold to level the surface and place it in a 4°C refrigerator for 15 minutes to allow for initial gelation, forming a bottom layer containing nanomaterials. Then, slowly pour the pre-prepared upper gel solution along the inner wall of the mold onto the bottom layer to a pouring height of 4 mm, taking care to avoid dispersing the bottom layer. The entire operation should be carried out in complete darkness.

[0033] 4) Place the mold after casting under a UV lamp at a wavelength of 365 nm and a power of 10 mW / cm². 2 Irradiation for 90 seconds under certain conditions allows the upper AlgMA solution to fully crosslink and solidify, forming an upper gel layer that, together with the bottom layer containing nanomaterials, constitutes a bilayer hydrogel. Separately, 5 g of anhydrous calcium chloride is dissolved in 95 g of deionized water to prepare a 5% (w / w) calcium chloride solution as a crosslinking agent. The UV-cured mold, along with the bilayer hydrogel, is immersed in the calcium chloride crosslinking solution and crosslinked and cured at 4°C for 24 hours, allowing calcium ions to diffuse through the semi-permeable membrane into the bottom layer, achieving full crosslinking of sodium alginate.

[0034] The cross-linked bilayer hydrogel was removed from the mold and rinsed three times with deionized water. A bone-promoting drug solution was prepared: 10 mg of dexamethasone and 100 mg of sodium β-glycerophosphate were weighed and dissolved in 100 mL of deionized water to prepare a mixed solution containing 0.1 mg / mL dexamethasone and 1 mg / mL sodium β-glycerophosphate. The hydrogel was immersed in the above bone-promoting drug solution and soaked at 4°C for 18 hours to achieve drug adsorption equilibrium. After removal, the gel surface was rinsed twice with PBS buffer and gently dried with sterile gauze. 60Sterilization by Co irradiation was performed with an irradiation dose of 15 kGy and an irradiation time of 3 hours, resulting in a bilayer composite hydrogel with a drug-loaded AgNRs@MesoFe3O4 sodium alginate layer at the bottom and a sodium alginate and AlgMA composite layer at the top, namely a silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material.

[0035] 5) An extract of the above gel was prepared and co-cultured with bone marrow mesenchymal stem cells (BMSCs) for 7 days. CCK-8 results showed a cell viability of approximately 92.6%. An inhibition zone experiment was conducted using 1 cm x 1 cm gel samples; without photothermal activation, the inhibition zone was 1.46 cm. 2 The inhibition zone experiment result after 10 minutes of photothermal activation was 3.12 cm. 2 After 21 days of Transwell chamber experiments and BMSC culture, Alizarin Red S (ARS) staining showed a significant increase in calcium nodule formation in the experimental group. Alkaline phosphatase (ALP) staining and activity quantification also indicated that the ALP expression level in the experimental group was significantly higher than that in the control group (blank sodium alginate / AlgMA hydrogel). The prepared bilayer hydrogel was cut into rectangular pieces, with its bottom layer (drug-loaded layer) as the inner side, and tightly adhered to the surface of an instrument in a rabbit infectious bone defect model where a bacterial biofilm had already formed (samples have been taken for verification). After the hydrogel came into contact with the infected site, it was incubated at 37°C for 48 hours. The infection microenvironment induced the dissociation of the bottom sodium alginate network, promoting the release of drug-loaded AgNRs@MesoFe3O4 nanoparticles. After incubation, a composite magnetic field was applied for treatment: First, a directional static magnetic field with a strength of 0.3 T was applied perpendicular to the plane of the hydrogel substrate and directed from the inside of the gel towards the infected site for 10 minutes, driving the released magnetic nanoparticles to directionally accumulate in the infected area. Simultaneously, an alternating magnetic field with a strength of 0.6 T and a frequency of 50 Hz was applied for 15 minutes, driving the nanoparticles already accumulated within the biomembrane to move, causing physical shear disruption of the biomembrane structure. Immediately after the magnetic field treatment, the infected area was irradiated with a near-infrared laser with a wavelength of 808 nm and a laser power density of 1.0 W / cm². 2 The irradiation time was 10 minutes. Utilizing the photothermal conversion effect of AgNRs, the local temperature was raised to approximately 42°C, promoting the release of antibacterial drugs and synergistic bactericidal action. The above magnetic drive and photothermal activation procedures were repeated once daily for 3 consecutive days. Fourteen days post-treatment, samples of surrounding tissue fluid and the sample surface were collected for bacterial smearing. Results showed virtually no colony formation. Figure 4 As shown in Figure a, samples were taken 28 days post-surgery for Micro-CT examination, and the results showed that new bone formation occurred at the contact surface between the instrument and the bone.

[0036] Example 2: 1) Silver nanorods were first prepared using a polyol solvothermal method. 3 g of polyvinylpyrrolidone (PVP, molecular weight K30), 1 g of silver nitrate, 0.3 g of CTAB, and 0.03 g of CuCl2·2H2O were dissolved in 95.67 g of ethylene glycol and magnetically stirred until completely dissolved. The mixture was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and reacted at 160 °C for 8 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 8000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed three times each with acetone and deionized water. Finally, it was dispersed in anhydrous ethanol to prepare a 10 mg / mL AgNRs ethanol dispersion for later use. Subsequently, a mesoporous iron oxide shell was coated onto the surface of the silver nanorods using a solvothermal-template method. 3 g FeCl3·6H2O, 2 g citric acid monohydrate, 20 g sodium acetate, 5 g CTAB, 2 g polyethylene glycol (PEG-400), 1 g urea, 0.3 g EDTA, and 0.3 g SDS were dissolved in 66.4 g ethylene glycol. The solution was magnetically stirred for 40 minutes to ensure complete dissolution of all components, resulting in a homogeneous precursor solution. The above AgNRs ethanol dispersion was slowly added dropwise to the precursor solution at a ratio of 0.2% of the total mass of AgNRs. Simultaneously, 1 g PVP (molecular weight K90) was added as a surface coupling agent. The mixture was ultrasonically dispersed for 30 minutes to ensure uniform dispersion of silver nanorods. The mixture was transferred to a high-pressure reactor, sealed, and reacted at 200℃ for 18 hours to allow Fe3O4 nanocrystals to grow and self-assemble in situ on the AgNRs surface. After the reaction, the mixture was allowed to cool naturally to room temperature. Magnetic separation was performed using an external magnetic field. The supernatant was discarded, and the magnetic product was collected and washed three times each with ethanol and deionized water. The washed product was dispersed in 200 mL of ethanol solution containing 0.3 mol / L NH4NO3 and refluxed at 70 °C for 8 hours to completely remove CTAB and SDS template. Finally, the product was collected by magnetic separation, washed repeatedly with deionized water until neutral, and dried in a vacuum drying oven at 50 °C for 18 hours to obtain AgNRs@MesoFe3O4 core-shell composite material.

[0037] 2) Take 100 mg of the prepared AgNRs@MesoFe3O4 nanoparticles and disperse them in 10 mL of deionized water to prepare a 10 mg / mL suspension. Separately, weigh 500 mg of tetracycline hydrochloride and dissolve it in 10 mL of deionized water to prepare a 50 mg / mL antibacterial drug solution. Mix the AgNRs@MesoFe3O4 suspension and the tetracycline hydrochloride solution at a volume ratio of 1:2 (i.e., mix 5 mL of the suspension with 10 mL of the drug solution), and use a cyclic ultrasonic impregnation-low temperature vacuum drying process to load the antibacterial drug in the mesopores. The specific operation is as follows: The mixture was placed in an ultrasonic bath with an ultrasonic power of 300 W and ultrasonically treated for 20 minutes under ice-water bath conditions. Then, the ultrasonically treated mixture was transferred to a petri dish, and the surface was covered with a sealing film with small holes to prevent sample scattering. It was then placed in a vacuum drying oven and vacuum dried at 40℃ for 45 minutes. After the solvent partially evaporated, tetracycline hydrochloride solution was added back to the original volume (15 mL), and ultrasonic impregnation was performed again for 20 minutes and low-temperature vacuum drying. This cycle was repeated 4 times. Finally, the product was centrifuged at 10000 rpm for 10 minutes, quickly washed once with deionized water to remove the drug adsorbed on the surface, and then dried in a vacuum drying oven at 35℃ for 18 hours to obtain the drug-loaded AgNRs@MesoFe3O4 composite nanoparticle material.

[0038] 3) Weigh 1 g AlgMA (approximately 80% substitution), 0.05 g sodium alginate, and 0.03 g photoinitiator Irgacure2959, dissolve them in 8.92 mL of PBS buffer, and stir in a 65°C water bath in the dark for 40 minutes until completely dissolved, preparing a sodium alginate / AlgMA composite gel solution containing 10% AlgMA, 0.5% sodium alginate, and 0.3% photoinitiator. Take 20 mg of the above drug-loaded AgNRs@MesoFe3O4 nanoparticles and add them to 10 mL of the prepared sodium alginate and AlgMA composite gel solution (nanoparticles account for 0.2% of the total mass of the solution). Sonicate and disperse for 3 minutes to ensure uniform dispersion of the nanoparticles in the gel precursor solution, obtaining the drug-loaded composite gel solution. Take a self-made mold (a cuboid plastic frame is inserted into a 0.22 μm pore size semi-permeable membrane to form an open cuboid), and place the mold horizontally. Use a pipette to draw up the drug-loaded composite gel solution and slowly pour it into the bottom of the mold at a pouring height of 4 mm (the volume is calculated based on the bottom area of ​​the mold). Gently shake the mold to make the liquid surface level. The entire operation should be carried out in the dark.

[0039] 4) Place the mold after casting under a UV lamp at a wavelength of 365 nm and a power of 10 mW / cm². 2Irradiate the gel under UV-cured conditions for 90 seconds to allow AlgMA to fully crosslink and cure. Separately, dissolve 5 g of anhydrous calcium chloride in 95 g of deionized water to prepare a 5% (w / w) calcium chloride solution as a crosslinking agent. Immerse the UV-cured mold along with the gel in the calcium chloride crosslinking solution and crosslink and cure at 4°C for 24 hours. This allows calcium ions to diffuse through the semi-permeable membrane into the gel, achieving full crosslinking of sodium alginate.

[0040] The cross-linked hydrogel was removed from the mold and rinsed three times with deionized water. The osteopromoting drug solution was prepared: 10 mg of dexamethasone and 100 mg of sodium β-glycerophosphate were weighed and dissolved in 100 mL of PBS buffer to prepare a mixed solution containing 0.1 mg / mL dexamethasone and 1 mg / mL sodium β-glycerophosphate. The hydrogel was immersed in the above osteopromoting drug solution and soaked at 4°C for 18 hours to achieve drug adsorption equilibrium. After removal, the gel surface was rinsed twice with PBS buffer and gently dried with sterile gauze. 60 Co irradiation sterilization, with an irradiation dose of 15 kGy and an irradiation time of 3 hours, yields the composite hydrogel.

[0041] 5) Compared to Example 1, this example reduces the layered design of the gel, directly mixing the drug-loaded AgNRs@MesoFe3O4 into the gel matrix composed of sodium alginate and AlgMA. The extract of the above gel was prepared and co-cultured with BMSCs for 7 days. Related CCK-8 results showed a cell viability of approximately 90.1%. An inhibition zone experiment was conducted using 1 cm * 1 cm gel samples; without photothermal activation, the inhibition zone was 0.91 cm. 2 The inhibition zone experiment result after 10 minutes of photothermal activation was 2.74 cm. 2After 21 days of Transwell chamber experiments and BMSC culture, ARS staining showed a significant increase in calcium nodule formation in the experimental group. ALP staining and activity quantification analysis also indicated that the ALP expression level in the experimental group was significantly higher than that in the control group (blank sodium alginate / AlgMA hydrogel). The prepared composite hydrogel was cut into rectangular pieces and tightly adhered to the surface of an instrument in a rabbit model of infected bone defect with a pre-existing bacterial biofilm (verified by sampling). After contacting the hydrogel with the infected site, it was incubated at 37°C for 48 hours to induce the dissociation of the sodium alginate network using the infected microenvironment, thereby promoting the release of drug-loaded AgNRs@MesoFe3O4 nanoparticles. After incubation, a composite magnetic field was applied for treatment: First, a directional static magnetic field with a strength of 0.3 T was applied perpendicular to the plane of the hydrogel adhesion surface and directed from the inside of the gel towards the infected site for 10 minutes, driving the released magnetic nanoparticles to directionally accumulate in the infected area. Simultaneously, an alternating magnetic field with a strength of 0.6 T and a frequency of 50 Hz was applied for 15 minutes. Immediately after the magnetic field treatment, the infected area was irradiated with a near-infrared laser with a wavelength of 808 nm and a laser power density of 1.0 W / cm². 2 The irradiation time was 10 minutes, utilizing the photothermal conversion effect of AgNRs to raise the local temperature to approximately 42°C. The above magnetic drive and photothermal activation procedures were repeated once daily for 3 consecutive days. Fourteen days post-surgery, samples of surrounding tissue fluid and the sample surface were collected for bacterial smearing, showing a small amount of colony formation. Simultaneously, on 28 days post-surgery, samples were taken for Micro-CT examination, indicating a small amount of new bone formation at the instrument-bone contact surface. The antibacterial and osteointegration-promoting effects were slightly inferior to those in Example 1.

[0042] Example 3: 1) Silver nanorods were first prepared using a polyol solvothermal method. 3 g of polyvinylpyrrolidone (PVP, molecular weight K30), 1 g of silver nitrate, 0.3 g of CTAB, and 0.03 g of CuCl2·2H2O were dissolved in 95.67 g of ethylene glycol and magnetically stirred until completely dissolved. The mixture was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and reacted at 160 °C for 8 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 8000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed three times each with acetone and deionized water. Finally, it was dispersed in anhydrous ethanol to prepare a 10 mg / mL AgNRs ethanol dispersion for later use. Subsequently, a mesoporous iron oxide shell was coated onto the surface of the silver nanorods using a solvothermal-template method. 3 g FeCl3·6H2O, 2 g citric acid monohydrate, 20 g sodium acetate, 5 g CTAB, 2 g polyethylene glycol (PEG-400), 1 g urea, 0.3 g EDTA, and 0.3 g SDS were dissolved in 66.4 g ethylene glycol. The solution was magnetically stirred for 40 minutes to ensure complete dissolution of all components, resulting in a homogeneous precursor solution. The above AgNRs ethanol dispersion was slowly added dropwise to the precursor solution at a ratio of 0.2% of the total mass of AgNRs. Simultaneously, 1 g PVP (molecular weight K90) was added as a surface coupling agent. The mixture was ultrasonically dispersed for 30 minutes to ensure uniform dispersion of silver nanorods. The mixture was transferred to a high-pressure reactor, sealed, and reacted at 200℃ for 18 hours to allow Fe3O4 nanocrystals to grow and self-assemble in situ on the AgNRs surface. After the reaction, the mixture was allowed to cool naturally to room temperature. Magnetic separation was performed using an external magnetic field. The supernatant was discarded, and the magnetic product was collected and washed three times each with ethanol and deionized water. The washed product was dispersed in 200 mL of ethanol solution containing 0.3 mol / L NH4NO3 and refluxed at 70 °C for 8 hours to completely remove CTAB and SDS template. Finally, the product was collected by magnetic separation, washed repeatedly with deionized water until neutral, and dried in a vacuum drying oven at 50 °C for 18 hours to obtain AgNRs@MesoFe3O4 core-shell composite material.

[0043] 2) Take 100 mg of the prepared AgNRs@MesoFe3O4 nanoparticles and disperse them in 10 mL of deionized water to prepare a 10 mg / mL suspension. Separately, weigh 500 mg of tetracycline hydrochloride and dissolve it in 10 mL of deionized water to prepare a 50 mg / mL antibacterial drug solution. Mix the AgNRs@MesoFe3O4 suspension and the tetracycline hydrochloride solution at a volume ratio of 1:2 (i.e., mix 5 mL of the suspension with 10 mL of the drug solution), and use a cyclic ultrasonic impregnation-low temperature vacuum drying process to load the antibacterial drug in the mesopores. The specific operation is as follows: The mixture was placed in an ultrasonic bath with an ultrasonic power of 300 W and ultrasonically treated for 20 minutes under ice-water bath conditions. Then, the ultrasonically treated mixture was transferred to a petri dish, and the surface was covered with a sealing film with small holes to prevent sample scattering. It was then placed in a vacuum drying oven and vacuum dried at 40℃ for 45 minutes. After the solvent partially evaporated, tetracycline hydrochloride solution was added back to the original volume (15 mL), and ultrasonic impregnation was performed again for 20 minutes and low-temperature vacuum drying. This cycle was repeated 4 times. Finally, the product was centrifuged at 10000 rpm for 10 minutes, quickly washed once with deionized water to remove the drug adsorbed on the surface, and then dried in a vacuum drying oven at 35℃ for 18 hours to obtain the drug-loaded AgNRs@MesoFe3O4 composite nanoparticle material.

[0044] 3) First, prepare the sodium alginate base solution: Weigh 2 g of sodium alginate powder and add it to 98 g of deionized water. Stir magnetically in a 50°C water bath for 3 hours until completely dissolved to prepare a 2% sodium alginate solution. Let it stand to remove bubbles and set aside. Take 20 mg of the above-mentioned drug-loaded AgNRs@MesoFe3O4 nanoparticles and add them to 10 mL of sodium alginate solution (the nanoparticles account for 0.2% of the mass of the sodium alginate solution). Disperse ultrasonically for 3 minutes to obtain the drug-loaded sodium alginate solution. Separately, prepare the upper gel solution: Weigh 1 g of AlgMA (substitution degree approximately 80%), 0.05 g of sodium alginate, and 0.03 g of photoinitiator Irgacure 2959. Dissolve them in 8.92 mL of deionized water and stir in a 65°C water bath in the dark for 40 minutes until completely dissolved to prepare an upper gel solution containing 10% AlgMA, 0.5% sodium alginate, and 0.3% photoinitiator. Take a self-made mold (a cuboid plastic frame inserted into a 0.22 μm pore size semi-permeable membrane to form an open cuboid) and place it horizontally. Use a pipette to draw up the drug-loaded sodium alginate solution and slowly pour it into the bottom of the mold to a pouring height of 0.5 mm (calculated based on the bottom area of ​​the mold). Gently shake the mold to level the surface and place it in a 4°C refrigerator for 15 minutes to allow for initial gelation, forming a bottom layer containing nanomaterials. Then, slowly pour the pre-prepared upper gel solution along the inner wall of the mold onto the bottom layer to a pouring height of 4 mm, taking care to avoid dispersing the bottom layer. The entire operation should be carried out in complete darkness.

[0045] 4) Place the mold after casting under a UV lamp at a wavelength of 365 nm and a power of 10 mW / cm². 2 Irradiate for 90 seconds under the specified conditions to allow the upper AlgMA solution to fully crosslink and solidify. Separately, dissolve 5 g of anhydrous calcium chloride in 95 g of deionized water to prepare a 5% (w / w) calcium chloride solution as a crosslinking agent. Immerse the UV-cured mold along with the double-layer hydrogel in the calcium chloride crosslinking solution and crosslink and solidify at 4°C for 24 hours. This allows calcium ions to diffuse through the semi-permeable membrane into the bottom layer, achieving full crosslinking of sodium alginate.

[0046] The cross-linked bilayer hydrogel was removed from the mold, rinsed three times with deionized water, and dialyzed against free calcium ions using deionized water. Afterward, the gel surface was rinsed twice with PBS buffer and gently dried with sterile gauze. 60 Sterilization by Co irradiation was performed at a dose of 15 kGy for 3 hours, resulting in a bilayer composite hydrogel with a drug-loaded AgNRs@MesoFe3O4 sodium alginate layer at the bottom and a sodium alginate and AlgMA composite layer at the top.

[0047] 5) Compared to Example 1, this example reduces the addition of osteopromoting drugs. The extract of the above gel was prepared and co-cultured with BMSCs for 7 days. Related CCK-8 results showed a cell viability of approximately 87.4%. An inhibition zone experiment was conducted using 1 cm x 1 cm gel samples; without photothermal activation, the inhibition zone was 1.34 cm. 2 The inhibition zone experiment result after 10 minutes of photothermal activation was 3.26 cm. 2After 21 days of Transwell chamber experiments and BMSC culture, ARS and ALP staining and activity quantification analysis also showed that the samples had virtually no osteogenic ability. The prepared bilayer hydrogel was cut into rectangular pieces, with its bottom layer (drug-loaded layer) as the inner side, and tightly adhered to the surface of an instrument in a rabbit model of infected bone defects where a bacterial biofilm had already formed (verified by sampling). After contacting the hydrogel with the infected site, it was incubated at 37°C for 48 hours. The infection microenvironment induced the dissociation of the bottom sodium alginate network, promoting the release of drug-loaded AgNRs@MesoFe3O4 nanoparticles. After incubation, a composite magnetic field was applied for treatment: First, a directional static magnetic field with a strength of 0.3 T was applied perpendicular to the plane of the hydrogel substrate and directed from the inside of the gel towards the infected site for 10 minutes, driving the released magnetic nanoparticles to directionally accumulate in the infected area. Simultaneously, an alternating magnetic field with a strength of 0.6 T and a frequency of 50 Hz was applied for 15 minutes, driving the nanoparticles already accumulated within the biomembrane to move, causing physical shear disruption of the biomembrane structure. Immediately after the magnetic field treatment, the infected area was irradiated with a near-infrared laser with a wavelength of 808 nm and a laser power density of 1.0 W / cm². 2 The irradiation time was 10 minutes. Utilizing the photothermal conversion effect of AgNRs, the local temperature was raised to approximately 42°C, promoting the release of antibacterial drugs and synergistically killing bacteria. The above magnetic drive and photothermal activation procedures were repeated once daily for 3 consecutive days. Fourteen days post-surgery, samples of surrounding tissue fluid and the sample surface were collected for bacterial smearing. Results showed virtually no colony formation. Simultaneously, on 28 days post-surgery, samples were taken for Micro-CT examination, revealing minimal new bone formation at the instrument-bone contact surface, indicating that treatment of infection synergistically promotes bone formation.

[0048] Example 4: 1) Silver nanorods were first prepared using a polyol solvothermal method. 3 g of polyvinylpyrrolidone (PVP, molecular weight K30), 1 g of silver nitrate, 0.3 g of CTAB, and 0.03 g of CuCl2·2H2O were dissolved in 95.67 g of ethylene glycol and magnetically stirred until completely dissolved. The mixture was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and reacted at 160 °C for 8 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 8000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed three times each with acetone and deionized water. Finally, it was dispersed in anhydrous ethanol to prepare a 10 mg / mL AgNRs ethanol dispersion for later use. Subsequently, a mesoporous iron oxide shell was coated onto the surface of the silver nanorods using a solvothermal-template method. 3 g FeCl3·6H2O, 2 g citric acid monohydrate, 20 g sodium acetate, 5 g CTAB, 2 g polyethylene glycol (PEG-400), 1 g urea, 0.3 g EDTA, and 0.3 g SDS were dissolved in 66.4 g ethylene glycol. The solution was magnetically stirred for 40 minutes to ensure complete dissolution of all components, resulting in a homogeneous precursor solution. The above AgNRs ethanol dispersion was slowly added dropwise to the precursor solution at a ratio of 0.2% of the total mass of AgNRs. Simultaneously, 1 g PVP (molecular weight K90) was added as a surface coupling agent. The mixture was ultrasonically dispersed for 30 minutes to ensure uniform dispersion of silver nanorods. The mixture was transferred to a high-pressure reactor, sealed, and reacted at 200℃ for 18 hours to allow Fe3O4 nanocrystals to grow and self-assemble in situ on the AgNRs surface. After the reaction, the mixture was allowed to cool naturally to room temperature. Magnetic separation was performed using an external magnetic field. The supernatant was discarded, and the magnetic product was collected and washed three times each with ethanol and deionized water. The washed product was dispersed in 200 mL of ethanol solution containing 0.3 mol / L NH4NO3 and refluxed at 70 °C for 8 hours to completely remove CTAB and SDS template. Finally, the product was collected by magnetic separation, washed repeatedly with deionized water until neutral, and dried in a vacuum drying oven at 50 °C for 18 hours to obtain AgNRs@MesoFe3O4 core-shell composite material.

[0049] 2) First, prepare the sodium alginate base solution: Weigh 2 g of sodium alginate powder and add it to 98 g of deionized water. Stir magnetically in a 50°C water bath for 3 hours until completely dissolved to prepare a 2% sodium alginate solution. Let it stand to remove bubbles and set aside. Take 20 mg of the above AgNRs@MesoFe3O4 nanoparticles and add them to 10 mL of sodium alginate solution (the nanoparticles account for 0.2% of the mass of the sodium alginate solution). Disperse ultrasonically for 3 minutes to obtain a sodium alginate solution containing AgNRs@MesoFe3O4. Prepare a separate upper gel solution: Weigh 1 g AlgMA (approximately 80% substitution), 0.05 g sodium alginate, and 0.03 g photoinitiator Irgacure2959, dissolve them in 8.92 mL of deionized water, and stir in a 65°C water bath in the dark for 40 minutes until completely dissolved, preparing an upper gel solution containing 10% AlgMA, 0.5% sodium alginate, and 0.3% photoinitiator. Take a self-made mold (a cuboid plastic frame is inserted into a 0.22 μm pore size semi-permeable membrane to form an open cuboid), and place the mold horizontally. Use a pipette to draw up the sodium alginate solution containing AgNRs@MesoFe3O4, and slowly pour it into the bottom of the mold to a pouring height of 0.5 mm (calculated based on the bottom area of ​​the mold). Gently shake to level the liquid surface, and place in a 4°C refrigerator for 15 minutes to allow preliminary gelation, forming a bottom layer containing nanomaterials. Then, the pre-prepared upper layer gel solution is slowly poured onto the bottom layer along the inner wall of the mold to a height of 4 mm. Care should be taken to avoid dispersing the bottom layer. The entire operation should be carried out in the dark.

[0050] 3) Place the mold after casting under a UV lamp at a wavelength of 365 nm and a power of 10 mW / cm². 2 Irradiate for 90 seconds under the specified conditions to allow the upper AlgMA solution to fully crosslink and solidify. Separately, dissolve 5 g of anhydrous calcium chloride in 95 g of deionized water to prepare a 5% (w / w) calcium chloride solution as a crosslinking agent. Immerse the UV-cured mold along with the double-layer gel into the calcium chloride crosslinking solution and crosslink and solidify at 4°C for 24 hours. This allows calcium ions to diffuse through the semi-permeable membrane into the bottom layer, achieving full crosslinking of sodium alginate.

[0051] The cross-linked bilayer hydrogel was removed from the mold and rinsed three times with deionized water. A bone-promoting drug solution was prepared: 10 mg of dexamethasone and 100 mg of sodium β-glycerophosphate were weighed and dissolved in 100 mL of deionized water to prepare a mixed solution containing 0.1 mg / mL dexamethasone and 1 mg / mL sodium β-glycerophosphate. The hydrogel was immersed in the above bone-promoting drug solution and soaked at 4°C for 18 hours to achieve drug adsorption equilibrium. After removal, the gel surface was rinsed twice with PBS buffer and gently dried with sterile gauze. 60Sterilization by Co irradiation was performed with an irradiation dose of 15 kGy and an irradiation time of 3 hours, resulting in a bilayer composite hydrogel with an AgNRs@MesoFe3O4 sodium alginate layer as the bottom layer and a sodium alginate and AlgMA composite layer as the top layer.

[0052] 4) Compared to Example 1, this example reduces the antibacterial agent loading in AgNRs@MesoFe3O4. The extract of the above gel was prepared and co-cultured with BMSCs for 7 days. Related CCK-8 results showed a cell viability of approximately 94.4%. An inhibition zone experiment was conducted using 1cm x 1cm gel samples; without photothermal activation, the inhibition zone was 0.46 cm. 2 The inhibition zone experiment result after 10 minutes of photothermal activation was 1.22 cm. 2 After culturing BMSCs in a Transwell chamber for 21 days, ARS and ALP staining and quantitative activity analysis showed that its osteogenic effect was close to that of Example 1. The prepared bilayer hydrogel was cut into rectangular pieces, with its bottom layer (containing the AgNRs@MesoFe3O4 layer) as the inner side, and tightly adhered to the surface of an instrument in a rabbit model of infected bone defects where a bacterial biofilm had already formed (samples verified). After contacting the hydrogel with the infected site, it was incubated at 37°C for 48 hours. The infection microenvironment induced the dissociation of the bottom sodium alginate network, promoting the release of AgNRs@MesoFe3O4 nanoparticles. After incubation, a composite magnetic field was applied for treatment: First, a directional static magnetic field with a strength of 0.3 T was applied perpendicular to the hydrogel adhesion surface and pointing from the inside of the gel towards the infection site for 10 minutes, driving the released magnetic nanoparticles to directionally accumulate in the infection area. Simultaneously, an alternating magnetic field with a strength of 0.6 T and a frequency of 50 Hz was applied for 15 minutes, driving the nanoparticles already accumulated within the biomembrane to move and physically shear and disrupt the biomembrane structure. Immediately after the magnetic field treatment, the infection area was irradiated with a near-infrared laser with a wavelength of 808 nm and a laser power density of 1.0 W / cm². 2 The irradiation time was 10 minutes, utilizing the photothermal conversion effect of AgNRs to raise the local temperature to approximately 42°C. The above magnetic drive and photothermal activation procedures were repeated once daily for 3 consecutive days. Fourteen days post-treatment, samples of surrounding tissue fluid and the sample surface were collected for bacterial plating. Results showed significant colony formation, such as... Figure 4 As shown in Figure b, the infection was not effectively treated. Furthermore, a Micro-CT scan was performed 28 days post-surgery, and the results showed that there was virtually no new bone formation at the contact surface between the instrument and the bone.

Claims

1. A method for preparing a silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions, characterized in that, Includes the following steps: 1) Silver nanorods (AgNRs) ethanol dispersion were prepared by solvothermal method, and a mesoporous iron oxide (MesoFe3O4) shell was constructed on its surface by template method to obtain AgNRs@MesoFe3O4 core-shell composite nanomaterials. 2) The antibacterial agent was loaded into AgNRs@MesoFe3O4 using a cyclic ultrasonic impregnation-low temperature vacuum drying process to obtain drug-loaded AgNRs@MesoFe3O4 composite nanomaterials; 3) Take a mold, pour a sodium alginate solution containing AgNRs@MesoFe3O4 into the bottom layer of the mold to obtain a layer containing nanomaterials, and pour a mixed solution containing AlgMA and sodium alginate into the top layer. 4) UV curing and Ca 2+ The solution impregnation method achieves double in-situ gelation of the solution in step 3), and the double-layer hydrogel is obtained after demolding. After rinsing the hydrogel, it is impregnated in a solution containing osteogenic drugs, and then rinsed, dried, and sterilized by irradiation to obtain a silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with osteogenic and intelligent anti-infection functions. 5) Applying a composite magnetic field drives the movement of nanomaterials inside the composite heterogeneous hydrogel material, destroying the bacterial biofilm structure, and simultaneously combining photothermal activation to promote the release of antibacterial agents inside the composite heterogeneous hydrogel material to kill bacteria.

2. The preparation method of the silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 1, characterized in that, In step 1), the preparation process of AgNRs is as follows: A polyol solvothermal method was used. 1%–3% polyvinylpyrrolidone (PVP), molecular weight K30, 0.5%–1.5% silver nitrate (AgNO3), 0.2%–0.4% hexadecyltrimethylammonium bromide (CTAB), and 0.02%–0.04% copper chloride (CuCl2·2H2O) were dissolved in 95.06%–98.28% ethylene glycol to obtain a mixture. The mixture was transferred to a high-pressure reactor and reacted at 140–180°C for 6–12 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged, washed successively with acetone and deionized water, and finally dispersed in anhydrous ethanol to obtain an AgNRs ethanol dispersion for later use.

3. The preparation method of the silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 1, characterized in that, In step 1), the preparation process of the AgNRs@MesoFe3O4 material is as follows: By mass percentage, 2%~5% of ferric chloride hexahydrate FeCl3·6H2O, 1%~3% of citric acid monohydrate C6H8O7·H2O, 15%~25% of sodium acetate, 3%~8% of hexadecyltrimethylammonium bromide CTAB, 1%~4% of polyethylene glycol PEG-400, 0.5%~2% of urea CO(NH2)2, 0.1%~0.5% of ethylenediaminetetraacetic acid EDTA, and 0.1%~0.5% of sodium dodecyl sulfate SDS are dissolved in 52%~77.3% ethylene glycol and stirred for 30~60 minutes to mix evenly to obtain a precursor solution. Take AgNRs ethanol dispersion and add it to the precursor solution at a ratio of 0.05%~0.5% of the total mass of AgNRs in the precursor solution. At the same time, add 0.5%~2% of polyvinylpyrrolidone (PVP) with a molecular weight of K90, which accounts for 0.5%~2% of the total mass of the precursor solution. After ultrasonic dispersion for 20~40 minutes, transfer it to a high-pressure reactor, seal it, and react it at 180~220℃. After the reaction is completed, allow it to cool naturally to room temperature. Magnetically separate the reaction product using an external magnetic field, discard the supernatant, collect the magnetic product, and wash it several times with ethanol and deionized water. Disperse the washed product in an ethanol solution containing 0.1~0.5 mol / L NH4NO3 and reflux it at 60~80℃ for 6~12 hours. Finally, collect the product by magnetic separation, wash it with deionized water until neutral, and dry it in a vacuum drying oven at 40~60℃ for 12~24 hours to obtain the AgNRs@MesoFe3O4 core-shell composite material.

4. The preparation method of the silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 1, characterized in that, In step 2), the antibacterial agent is loaded into AgNRs@MesoFe3O4 using a cyclic ultrasonic impregnation-low temperature vacuum drying process. The specific process is as follows: The AgNRs@MesoFe3O4 core-shell composite material obtained in step 1) was dispersed in deionized water to prepare a suspension with a concentration of 5-20 mg / mL for later use; an antibacterial drug solution with a concentration of 10-100 mg / mL was prepared; the suspension and the antibacterial drug solution were mixed at a volume ratio of 1:1 to 1:3 to obtain a mixture, and the mixture was subjected to ultrasonic treatment at a power of 200-500. In an ultrasonic bath, the mixture was ultrasonically impregnated for 10-30 minutes under ice-water bath conditions. Then, the ultrasonically mixed solution was transferred to a petri dish, covered with a breathable covering film, and placed in a vacuum drying oven at 30-50°C for 30-60 minutes. After the solvent partially evaporated, the antibacterial drug solution was added back to the original volume, and ultrasonic impregnation and low-temperature vacuum drying were repeated several times. Finally, the product was centrifuged, washed with deionized water, and placed in a vacuum drying oven at 30-40°C for 12-24 hours to obtain drug-loaded AgNRs@MesoFe3O4 composite nanomaterials.

5. The preparation method of the silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 4, characterized in that, The antibacterial agent is one or more of the following: antibiotic antibacterial agents, metal ion antibacterial agents, or other organic antibacterial agents; The antibiotic antibacterial agents include tetracycline hydrochloride, vancomycin hydrochloride, gentamicin or ciprofloxacin; the metal ion antibacterial agents include silver nitrate, copper sulfate or zinc nitrate; and other organic antibacterial agents include chlorhexidine acetate or polyhexamethylene guanidine.

6. The method for preparing the silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 1, characterized in that, In step 3), a mold is taken, and a sodium alginate solution containing AgNRs@MesoFe3O4 loaded with the drug is poured into the bottom layer of the mold to obtain a layer containing nanomaterials. A mixed solution containing AlgMA and sodium alginate is then poured into the top layer. The specific process is as follows: Weigh out sodium alginate powder and add it to deionized water. Stir magnetically in a water bath at 40-60°C for 2-4 hours until completely dissolved to prepare a sodium alginate solution with a mass fraction of 1%-3%. Let it stand to remove bubbles and set aside for later use. Add 0.1% to 1.0% of the mass of the sodium alginate solution to the drug-loaded AgNRs@MesoFe3O4 composite nanomaterial, and ultrasonically disperse for 3 to 5 minutes to obtain the sodium alginate solution loaded with AgNRs@MesoFe3O4. The mixed solution consists of 5%~15% AlgMA by mass, 0.25%~0.75% sodium alginate solution by mass, and 0.1%~0.5% photoinitiator by mass, dissolved in PBS buffer, and stirred in a water bath at 60~70℃ in the dark for 30~60 minutes until completely dissolved. Take a mold, which is a semi-permeable membrane with a plastic frame inserted inside. Place the mold horizontally, slowly pour the drug-loaded sodium alginate solution into the bottom of the mold, shake to make the liquid surface level, and pour to a height of 0.25~0.75 mm. Place it in a refrigerator at 4℃ and let it stand to allow it to initially gel and obtain the bottom layer containing nanomaterials. Then, slowly pour the mixed solution along the inner wall of the mold onto the bottom layer, with a pouring height of 2~6 mm, and keep the whole process away from light.

7. The preparation method of the silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection function according to claim 1, characterized in that, In step 4), UV curing and Ca are used. 2+ The solution impregnation method achieves double in-situ gelation of the solution in step 3), resulting in a double-layer hydrogel after demolding. The hydrogel is then rinsed and impregnated in a solution containing osteogenic drugs. After rinsing, drying, and irradiation sterilization, a silver nanorod@mesoporticotinic ferric oxide composite heterogeneous hydrogel material is obtained. The specific process is as follows: After casting, the mold was placed under a UV lamp at a wavelength of 365 nm and a power of 5~20 mW / cm². 2 Irradiation for 30-180 seconds under certain conditions causes the upper mixed solution to crosslink and solidify, resulting in an upper gel layer, which, together with the bottom layer containing nanomaterials, forms a bilayer hydrogel. Separately, anhydrous calcium chloride is dissolved in deionized water to prepare a 2%-5% calcium chloride solution as a crosslinking agent. The UV-cured mold, along with the bilayer hydrogel, is immersed in the calcium chloride crosslinking solution and crosslinked and cured at 4-10℃ for 6-48 hours, allowing calcium ions to diffuse through the semi-permeable membrane into the bottom layer. The cross-linked bilayer hydrogel was removed from the mold, rinsed several times with deionized water, and then immersed in a solution containing 0.001~5 mg / mL osteogenic drug for 12~24 hours at 4~25℃. After immersion, the bilayer hydrogel was removed and rinsed several times with PBS buffer, dried with sterile gauze, and sterilized by irradiation to obtain silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material. The bone-promoting drugs include one or more of chemical drugs, active ingredients of traditional Chinese medicine, or bioactive factors; wherein the chemical drugs include dexamethasone, sodium β-glycerophosphate, or ascorbic acid, the active ingredients of traditional Chinese medicine include icariin, naringin, tanshinone IIA, or baicalin, and the bioactive factors include bone morphogenetic protein BMP-2, transforming growth factor TGF-β, or insulin-like growth factor IGF-1.

8. The preparation method of the silver nanorod@mesoporous iron oxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions according to claim 1, characterized in that, In step 5), a composite magnetic field is applied to drive the movement of nanomaterials inside the composite heterogeneous hydrogel material, disrupting the bacterial biofilm structure. Simultaneously, photothermal activation promotes the release of antibacterial agents within the composite heterogeneous hydrogel material, killing the bacteria. Specifically: A composite magnetic field, consisting of a directional static magnetic field and an alternating / rotating magnetic field, is applied for treatment. The directional static magnetic field is perpendicular to the hydrogel substrate and points from the gel interior towards the bacterial biofilm. The magnetic field strength is 0.1-0.5 T, and the application is sustained for 10-30 minutes. This magnetic gradient force continuously drives the released magnetic drug-loaded AgNRs@MesoFe3O4 composite nanomaterials to directionally accumulate and penetrate from the gel substrate into the bacterial biofilm, allowing the nanomaterials to effectively penetrate and distribute within the biofilm. Simultaneously, an alternating magnetic field is applied. The alternating magnetic field strength is 0.3-1.0 T, the magnetic field frequency is 10-100 Hz, and the application time is 10-20 minutes, causing physical shearing and disruption of the formed bacterial biofilm structure. After the magnetic field application, a near-infrared laser with a wavelength of 808 nm is used to irradiate the biofilm, with a laser power density of 0.5-2.0 W / cm². 2 The irradiation time is 5-15 minutes, and the local temperature is raised to 40-45℃ by utilizing the photothermal conversion effect of AgNRs; the membrane rupture and near-infrared laser irradiation operations are repeated for 3-7 days.

9. A silver nanorod@mesoporous iron tetroxide composite heterogeneous hydrogel material with bone-promoting and intelligent anti-infection functions, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. The application of the heterogeneous hydrogel material as described in claim 9 in the preparation of medical devices.

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