Magnetic nano-enzyme antibacterial fiber as well as preparation method and application thereof

Abstract

The invention relates to the field of functional fibers, in particular to a magnetic nano-enzyme antibacterial fiber and a preparation method and application thereof, the magnetic nano-enzyme antibacterial fiber comprises a biopolymer fiber carrier and a nano-enzyme which is grafted on the surface of the fiber carrier and has a core-shell structure; the nano-enzyme comprises an inner core formed by magnetic Fe3O4 nano-particles and a shell formed by transition metal sulfide, the surface of the nano enzyme is modified with a polymer layer containing a catechol group; the magnetic nano-enzyme antibacterial fiber can continuously generate hydroxyl radicals under the activation of low-intensity magnetic field pulse less than or equal to 10mT. Through three innovations of structural design, interface engineering and function regulation and control, technical breakthrough is achieved in the aspects of antibacterial efficiency, interface stability, long-acting activity and the like.

Description

Technical Field

[0001] The present invention relates to the field of functional fibers, and in particular to a magnetic nanoenzyme antibacterial fiber and a preparation method and application thereof. Background Art

[0002] In the field of biomedical materials, fiber-based antibacterial materials have become an important choice for wound dressings, surgical sutures and protective textiles due to their high specific surface area and flexible processability.

[0003] Traditional antibacterial fibers are mainly loaded with metal ions (such as silver, copper), quaternary ammonium compounds or photocatalytic materials (such as TiO2, ZnO) by physical adsorption or covalent binding, but these technical routes have significant defects: silver-based antibacterial agents continuously release Ag in the body fluid environment. + The effects of these agents on the skin can lead to cytotoxicity, and long-term use may cause localized silver deposition in tissues. Organic antimicrobial agents, on the other hand, suffer from poor heat resistance and are prone to migration and loss, with their antimicrobial efficacy decreasing by over 60% after repeated washing. Furthermore, existing antimicrobial mechanisms generally rely on environmental conditions (such as ultraviolet light, high temperatures, or high concentrations of hydrogen peroxide), and their effectiveness plummets in low-light and low-oxygen environments, such as deep wounds.

[0004] In recent years, magnetic nanozyme technology has garnered attention due to its tunable enzyme-like activity and magnetic responsiveness. Fe₃O₄ nanoparticles have been shown to possess intrinsic peroxidase activity, generating reactive oxygen species (ROS) in the presence of H₂O₂. However, single magnetic nanozymes face two major bottlenecks: First, enzyme activity relies heavily on strong magnetic fields (typically >50 mT) for activation. Such high field strengths not only consume significant energy but also may interfere with medical electronic devices. Second, bare Fe₃O₄ is susceptible to iron dissolution in physiological environments, leading to free radical quenching and activity decay. To address these issues, some studies have attempted to enhance stability by constructing core-shell structures, such as by encapsulating Fe₃O₄ with SiO₂. However, the insulating SiO₂ layer blocks electron transfer, significantly reducing enzyme activity. Another approach is to enhance catalytic efficiency by utilizing two-dimensional materials, such as combining MoS₂ with Fe₃O₄. However, existing studies have shown that mechanically mixed Fe₃O₄ and MoS₂ composites exhibit low loading rates on fiber supports and, due to weak interfacial bonding, exhibit significant nanoparticle shedding in simulated body fluid flushing environments.

[0005] At the application level, existing antimicrobial fibers struggle to reconcile the conflict between long-lasting bactericidal efficacy and biosafety. Especially for chronic wound treatment, the formation of drug-resistant biofilms requires materials with penetrating bactericidal capabilities. However, traditional materials, such as quaternary ammonium-modified fibers, only inhibit floating bacteria and are ineffective against mature biofilms. Furthermore, most magnetic antimicrobial systems require a continuous external energy supply to maintain activity, which not only complicates treatment but also poses a risk of damaging new tissue due to thermal effects.

[0006] Therefore, the development of an antibacterial fiber that is driven by a low magnetic field, does not release heavy metals, and can efficiently break down biofilms has become a key breakthrough in solving the problem of clinical wound infection. It is also a technical highland that urgently needs to be conquered in the current intersection of materials science and biomedical engineering. Summary of the Invention

[0007] The present invention aims to solve the contradiction between the difficulty in coordinating long-term sterilization and biosafety in the fiber-based antibacterial materials in the prior art, and therefore provides a magnetic nanoenzyme antibacterial fiber and its preparation method and application to overcome the above-mentioned shortcomings.

[0008] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: In the first aspect, the present invention first provides a magnetic nanozyme antibacterial fiber, comprising a biopolymer fiber carrier; and, Nanozymes with a core-shell structure grafted onto the surface of a fiber carrier; The nanozyme comprises a core composed of magnetic Fe3O4 nanoparticles and a shell composed of transition metal sulfide; The surface of the nanozyme is modified with a polymer layer containing catechol groups; The magnetic nanozyme antibacterial fiber can continuously generate hydroxyl radicals under the activation of a weak magnetic field pulse of ≤10 mT.

[0009] As described in the background, the application of magnetic nanozyme technology in the field of antimicrobial materials has long been limited by two major contradictions: First, maintaining sufficient catalytic activity often requires the application of high-intensity magnetic fields (generally exceeding 50 mT), which not only wastes energy but also hinders clinical translation due to interference from strong magnetic fields with medical devices. Second, conventional coating strategies designed to enhance nanozyme stability can shield the magnetic core from electron exchange with the outside world, leading to a sharp drop in catalytic efficiency. This fundamental contradiction is particularly acute on fiber carriers. When nanozymes are loaded onto flexible fibers, physical friction and fluid erosion accelerate particle shedding, while the interfacial stability of traditional ionic bonds or van der Waals forces is far from sufficient to maintain long-term efficacy. Furthermore, chronic wound infections are often accompanied by biofilm formation. The reactive oxygen species released by existing antimicrobial fibers have a short half-life and weak penetration, making it difficult to penetrate the physical barrier of the biofilm, allowing drug-resistant bacteria such as Pseudomonas aeruginosa to continue to grow. It was precisely because of the insight into the three technical gaps of strong magnetic field dependence, interface instability, and insufficient biomembrane penetration that the inventors of this case abandoned the conventional idea of ​​simply superimposing magnetic materials and catalysts, and instead sought breakthroughs from the perspective of nanoscale magnetoelectric coupling and biointerface chemistry.

[0010] Specifically, the establishment of the creative solution of this application stems from the collaborative design of the multi-level structure of the material: First, by constructing a heterojunction with a magnetic Fe3O4 core and a transition metal sulfide shell, the electron orbital hybridization effect at the core-shell interface is cleverly utilized to trigger the spin polarization process that originally required a strong magnetic field to drive it under a weak field. This design overturns the classic understanding that "magnetic field intensity determines magnetic moment orientation". Experiments have confirmed that when the thickness of the sulfide shell is controlled at the nanometer level, its surface defect states can significantly reduce the magnetic anisotropy, so that a weak magnetic field pulse of ≤10mT can induce the directional arrangement of the core magnetic moment, thereby changing the sulfide band structure through spin-orbit coupling and activating peroxidase-like activity. Secondly, to address the fiber-nanozyme interface binding problem, a polymer layer containing catechol groups was creatively introduced. The unique bidentate chelating ability of the catechol groups in this polymer can form multiple coordination bonds with the functional groups of the biopolymer fiber carrier. Compared with the traditional single-point binding mode, its binding energy is increased several times, and the loading rate can still exceed 90% under simulated body fluid flushing. Crucially, this polymer layer is not an inert coating. Its quinone-like structure can serve as an electron shuttle channel, accelerating the migration of holes generated by shell catalysis to the fiber surface, avoiding catalyst passivation caused by hole accumulation, and thus breaking the "activity-stability trade-off" dilemma commonly encountered in core-shell structures.

[0011] Therefore, the technical effects of this application are reflected in the following three aspects of synergistic gains: First, in terms of energy input, the energy consumption of a weak magnetic field pulse of ≤10mT is only one percent of that of the traditional solution, and due to the electron storage effect of the sulfide shell during the pulse interval, the continuous generation time of hydroxyl radicals is extended to more than 2 hours after the magnetic field is turned off, completely breaking free from the constraints of resisting continuous strong magnetic fields. Secondly, in terms of biological interface interaction, the nanozyme forms a stable chelating network through the polymer layer and the fiber, allowing the material to maintain catalytic integrity under repeated bending and friction, while the free catechol group can actively capture iron ions in the wound exudate, generating new catalytic sites in situ, forming a "self-enhanced" antibacterial mechanism. Finally, in terms of pathogen clearance, the half-life of the generated hydroxyl radicals is significantly extended, and their diffusion depth can penetrate bacterial biofilms of more than 50 microns, achieving precise killing of dormant bacteria wrapped in extracellular polymers. In contrast, traditional silver ion antibacterial agents can only act on the surface of the biofilm. This trinity of characteristics, namely "low-energy activation, adaptive stability, and deep clearance", enables the fiber to demonstrate disruptive advantages in deep infection models such as diabetic foot ulcers. It achieves effective antibacterial protection for multiple days with a single magnetic pulse treatment without interfering with implanted devices such as pacemakers. At the same time, the free radical scavenging ability of catechol polymers can precisely regulate the concentration of hydroxyl radicals, avoiding damage to granulation tissue caused by high-concentration free radicals. For the first time, it coordinates the conflicting needs of high-efficiency antibacterial and promotion of healing at the molecular level.

[0012] Finally, while some existing technologies mention the possibility of combining transition metal sulfides with Fe3O4, these methods involve physical mixing or simple deposition, failing to address interfacial electron transport barriers. Previously, the application of polydopamine on fibers was limited to enhancing hydrophilicity or cell adhesion, and its role as a bridge in magneto-electric energy conversion had never been explored. This proposal, through the triple innovation of "core-shell heterojunction design, interface chelation engineering, and weak magnetic field pulse regulation," achieves efficient and sustained activation of nanozymes for the first time under conditions close to the Earth's magnetic field strength. This design paradigm, which integrates magnetic properties, catalytic chemistry, and biomaterial interface science, opens up a new path for low-energy intelligent antibacterial materials.

[0013] Preferably, the transition metal sulfide is MoS2, and the catechol group-containing polymer is polydopamine; The particle size of the nanozyme is 5-10 nm.

[0014] Preferably, the biopolymer fiber carrier is a polysaccharide fiber containing divalent metal ions; The nanozyme is anchored on the fiber surface through the chelation between divalent metal ions and the polymer containing catechol groups.

[0015] The technical features of this application are achieved by divalent metal ions (such as Ca 2+ The bidentate chelation between the nanozyme and the polysaccharide fiber carrier builds a dynamic and stable "ion bridge" network between the nanozyme and the polysaccharide fiber carrier, which achieves a triple breakthrough effect compared with traditional covalent coupling or physical adsorption: first, the coordination bond formed by the chelation has both the strength of the covalent bond and the reversibility of the ionic bond, which enables the nanozyme to resist shedding through dynamic reorganization of the bonding site when the fiber is repeatedly deformed, solving the problem of loss of active components caused by stress deformation of the flexible carrier; second, the specific binding of the catechol group to the divalent metal ions can block the monovalent ions (Na + / K + ) competitive replacement, maintaining interface stability in a physiological salt environment and avoiding the failure risk of traditional ion exchange carriers; thirdly, the metal ions in the chelate network act as electron transfer media, accelerating the directional migration of free radicals generated by nanozyme catalysis to the fiber surface, increasing the efficiency of hydroxyl radical generation by more than 3 times. At the same time, the chelate structure captures free metal ions to inhibit the Fenton reaction, accurately regulating the free radical concentration to a safe threshold (0.05-0.1 μM), eliminating the risk of tissue oxidative damage while effectively killing bacteria.

[0016] Preferably, the polysaccharide fiber is calcium alginate fiber or calcium alginate-chitosan composite fiber.

[0017] Preferably, the transition metal sulfide layer has sulfur vacancy defects, and the sulfur vacancy concentration is 0.5-1.5 at%.

[0018] The sulfur vacancy defects in this application can act as spin polarization centers, significantly enhancing the interfacial electronic coupling between the Fe3O4 core and the sulfide shell, increasing the electron transfer efficiency in weak magnetic fields (≤10mT) by more than three times and significantly increasing the yield of hydroxyl radicals compared to traditional defect-free sulfides. Furthermore, a sulfur vacancy concentration of 0.5-1.5 at% forms a metastable lattice structure that dynamically captures free sulfur ions in body fluids during the catalytic process, enabling in-situ vacancy repair. This allows the material to retain 95% of its initial activity after 50 cycles of repeated magnetic activation, completely resolving the rapid deactivation of traditional catalysts due to active site annihilation.

[0019] Preferably, the fiber further comprises hydrogen peroxide sustained-release microcapsules embedded in the fiber, wherein the microcapsules are composed of CaO2@SiO2.

[0020] This application can achieve the following three breakthrough gains by embedding CaO2@SiO2 sustained-release microcapsules: (1) Spatiotemporal synergy of self-supply of substrates. The SiO2 mesoporous shell can precisely regulate the hydrolysis rate of CaO2, significantly extending the release half-life of H2O2, thereby matching the magnetic activation cycle of nanozymes and continuously supplying enzyme reaction substrates deep in the wound surface; (2) CaO2 released by microcapsules 2+ It can form a dynamic ion bridge with calcium alginate fibers, thereby triggering the intelligent swelling of the fiber network, simultaneously promoting the exposure of nanozyme active sites and the formation of new blood vessels, and synergistically improving the antibacterial-healing efficiency; (3) The SiO2 shell can control the local H2O2 concentration within a safe window, avoiding the explosive release of free radicals caused by high concentrations of H2O2, thereby stabilizing the ·OH generation rate within the therapeutic window.

[0021] In a second aspect, the present application also provides a method for preparing a magnetic nanozyme antibacterial fiber, comprising the following steps: (S.1) Preparation of nanozymes with Fe3O4@transition metal sulfide@catechol-containing polymer layer; (S.2) mixing the nanozyme with a biopolymer spinning solution and forming the nanozyme by wet spinning; (S.3) Ionic crosslinking and curing are performed in a magnetic field environment of ≤10 mT.

[0022] This application creatively reconstructs the preparation path: first, it subverts the conventional process of "fiberization first, then modification" by in situ constructing a polymer layer containing catechol groups during the nanozyme synthesis stage (step S.1), so that its surface is pre-enriched with chelating sites, laying a molecular foundation for subsequent fiber interface bonding; then, wet spinning (step S.2) and weak magnetic field induced cross-linking (step S.3) are integrated into a single-step integrated process, using the weak energy of a magnetic field of ≤10mT to trigger the directional arrangement of the nanozyme magnetic moment, and simultaneously drive the ionic cross-linking and curing of the biopolymer chain.

[0023] Among them, in the early stage of ionic crosslinking (such as sodium alginate encountering Ca 2+ During the sol-gel transition phase, applying a pulsed magnetic field of ≤10 mT can generate an oscillating magnetic moment in the Fe3O4 core. This micro-vibration not only promotes the exposure of the edge active sites of the transition metal sulfide shell, but also induces conformational stretching of the polymer containing catechol groups, so that the ortho-phenolic hydroxyl groups react with divalent metal ions (Ca2+) under the action of the magnetic field. 2+ / Zn 2+ ) forms a bidentate chelate network perpendicular to the magnetic field lines. Compared to the random mesh structure formed by traditional cross-linking in the absence of a magnetic field, this oriented chelate network allows the nanozymes to form an ordered array on the fiber surface. Furthermore, when the magnetic field strength is ≤10 mT, the nanozyme magnetic moment undergoes only periodic deflections rather than complete fixation. This dynamic oscillation effectively inhibits nanoparticle aggregation during gel curing, solving the phase separation problem at high loading rates and enabling continuous and stable industrial production.

[0024] Preferably, the magnetic field environment is a gradient magnetic field with a magnetic field strength of 1-5 mT; The ionic crosslinking curing adopts Ca 2+ Solution, cross-linking time is 10-30 min.

[0025] Preferably, CaO2@SiO2 microcapsules are added during the wet spinning process, with the addition amount being 1-5 wt% of the mass of the spinning solution.

[0026] In a third aspect, the present invention further provides the use of the magnetic nanozyme antibacterial fiber as described in any of the above items in the preparation of antibacterial materials or wound dressings.

[0027] Therefore, this application has the following beneficial effects: (1) Ultra-low field strength activation breakthrough: Only a weak magnetic field pulse of ≤10 mT is needed to efficiently stimulate peroxidase-like activity, completely breaking away from the dependence of traditional magnetic materials on strong magnetic fields (>50 mT), and achieving low-energy antibacterial properties in a near-physiological environment; (2) Innovation in interface stability: The catechol-containing polymer layer forms a dynamic chelating network with the biopolymer fiber carrier through multiple coordination bonds, which keeps the nanozyme almost zero-shedding under body fluid flushing and mechanical deformation; (3) Long-lasting free radical generation: The core-shell heterojunction design enables the electron storage effect to be maintained even after the magnetic field is turned off, achieving a single magnetic pulse triggering and continuous release of hydroxyl radicals for more than two hours; (4) Cross-scenario universality: The flexible base of the biopolymer carrier is adaptable to various forms such as wound dressings, filter membranes, and textiles, and the weak magnetic field conditions are compatible with the environment of medical electronic equipment, breaking through the barriers to clinical transformation. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below generally represent only a portion of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0029] Example 1 A method for preparing magnetic nanoenzyme antibacterial fiber comprises the following steps: Step S.1: Add 1.5 g of sodium citrate to 40 mL of a 0.1 mol / L FeCl3·6H2O ethanol solution and hydrothermally react at 200°C for 12 h to obtain Fe3O4 nanoparticles with a diameter of 5 nm. Fe3O4 was dispersed in 30 mL of deionized water, and 0.05 mol / L Na2MoO4 and 0.15 mol / L thiourea were added. The mixture was solvothermally reacted at 180 °C for 8 h to form a MoS2 shell (2 nm thick) to obtain Fe3O4@MoS2. 10 mg / mL dopamine hydrochloride (Tris-HCl buffer, pH=8.5) was added and stirred for polymerization under nitrogen protection for 3 h to obtain Fe3O4@MoS2@PDA nanozyme (particle size 8±0.5 nm).

[0030] Step S.2: 5 wt% sodium alginate aqueous solution was mixed with the above nanozymes (nanozymes accounted for 15 wt%), ball-milled for 2 h, and finally extruded through a spinneret with a pore size of 100 μm to Ca 2+ Coagulation bath (ethanol / water = 1:4 solution containing 5 wt% CaCl2).

[0031] Step S.3: The wet-spun nascent fibers were placed in a 1 mT gradient magnetic field (permanent magnet array spacing 10 cm) and2+ Cross-link and cure in the solution for 10 min, then take out and dry to obtain the finished product.

[0032] Example 2 Step S.1: Prepare Fe3O4@MoS2@PDA nanozyme using the same method as in Example 1.

[0033] Step S.2: 8 wt% sodium alginate-chitosan (mass ratio 3:1) mixture was mixed with nanozymes (10 wt%), ball-milled and dispersed for 2 h, and finally extruded through a spinneret with a pore size of 100 μm into a coagulation bath containing 3 wt% CaCl2 + 2 wt% acetic acid to obtain wet-spun nascent fibers.

[0034] Step S.3: The as-spun fibers were placed in a 5 mT pulsed magnetic field (electromagnetic coil, 1 Hz frequency) and crosslinked in a Ca²⁺ solution for 30 min, and then dried to obtain the finished product.

[0035] Example 3 Step S.1: Prepare nanozyme in the same manner as in Example 1.

[0036] Step S.2: Mix 6 wt% sodium alginate solution with nanozymes (12 wt%) and CaO2@SiO2 microcapsules (accounting for 1 wt% of the spinning solution mass), and finally extrude it through a spinneret with a pore size of 100 μm into a coagulation bath containing 3 wt% CaCl2 + 2 wt% acetic acid to obtain wet-spun nascent fibers.

[0037] The preparation method of CaO2@SiO2 microcapsules is as follows: (1) Dehydrate the CaO2 powder in a vacuum drying oven at 60°C for 12 hours to remove surface adsorbed water. Then, disperse the dried CaO2 in anhydrous ethanol (concentration: 50 mg / mL) and ultrasonicate for 30 minutes to form a uniform suspension. (2) Preparation of SiO2 sol: Mix 40 mL of ethanol, 10 mL of deionized water, and 3 mL of ammonia (catalyst), add 0.5 g of CTAB, and stir for 10 minutes. Then, dissolve 3 mL of TEOS in 10 mL of ethanol and add it dropwise to solution A (drop rate: 1 mL / min) to obtain SiO2 sol; (3) The pretreated CaO2 suspension (step 1) was slowly added to the SiO2 sol (step 2), with the mass ratio of CaO2 to TEOS being 1:0.8. Under nitrogen protection, the mixture was stirred at a constant temperature of 35°C for 6 hours to form a SiO2 gel layer on the CaO2 surface through a hydrolysis-condensation reaction.

[0038] Step S.3: Place the as-spun fiber in a 3 mT static magnetic field (NdFeB permanent magnet) and 2+Cross-link in the solution for 20 minutes and dry to obtain the finished product.

[0039] Example 4 Step S.1: Fe3O4@MoS2 was prepared as in Example 1. Fe3O4@MoS2 was placed in a 5% H2 / 95% N2 atmosphere and annealed at 350°C for 1.5 h (sulfur vacancy concentration 1.0 at%), and then the PDA layer was modified as in Example 1.

[0040] Step S.2: Mix 6 wt% sodium alginate solution with nanozymes (10 wt%) and CaO2@SiO2 microcapsules (accounting for 5 wt% of the spinning solution mass), and finally extrude it through a spinneret with a pore size of 100 μm into a coagulation bath containing 3 wt% CaCl2 + 2 wt% acetic acid to obtain wet-spun nascent fibers.

[0041] Step S.3: Place the as-spun fiber in a 4 mT static magnetic field (NdFeB permanent magnet) and 2+ Cross-link in the solution for 25 minutes and dry to obtain the finished product.

[0042] Example 5 Step S.1: Preparation of Fe3O4@MoS2 was the same as in Example 1. Fe3O4@MoS2 was placed in a 2% H2 / 98% N2 atmosphere and annealed at 300 °C for 1 h to obtain a sulfur vacancy concentration of 0.5 at%. It was then modified with tannic acid (containing catechol groups): the nanozyme was immersed in a 1 mg / mL tannic acid solution (pH = 7.0) and adsorbed with oscillation for 2 h.

[0043] Step S.2: Pure calcium alginate spinning solution (7 wt%) was mixed with nanozymes (18 wt%), and finally extruded through a spinneret with a pore size of 100 μm into a coagulation bath containing 3 wt% CaCl2 + 2 wt% acetic acid to obtain wet-spun nascent fibers.

[0044] Step S.3: Place the as-spun fiber in a 2 mT static magnetic field (NdFeB permanent magnet) and 2+ Cross-link in the solution for 15 minutes and dry to obtain the finished product.

[0045] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step S.1, only Fe3O4 nanoparticles (5nm) and MoS2 nanosheets (50-100nm) are physically mixed (mass ratio 1:1), and PDA solution is added for coating, and the other conditions are the same.

[0046] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the prepared Fe3O4@MoS2 core-shell nanozyme is not PDA-modified, and the silane coupling agent KH-550 is used instead of PDA for surface amination, and the fiber is grafted through an amino-carboxyl condensation reaction.

[0047] Comparative Example 3 Comparative Example 3 used commercially available silver-loaded calcium alginate fiber (NLFZX-1001, Zhangjiagang Nair Nanotechnology Co., Ltd.).

[0048] The fibers in Examples 1-5 and Comparative Examples 1-3 were tested. The test methods are as follows: 1. Antibacterial rate: Bacterial species: Escherichia coli (ATCC 25922); Bacterial solution concentration: 10 6 CFU / mL; Magnetic field conditions: 5 mT pulsed magnetic field (on 10 min / off 10 min); Test duration: 6 hours.

[0049] 2. Nanozyme shedding rate: Simulated body fluid: PBS buffer containing 0.1% Tween-80 (pH = 7.4); Test method: Oscillate at 37°C for 24 h (120 rpm), and detect the amount of Fe / Mo dissolved by ICP-MS.

[0050] 3.Activity maintenance rate After the magnetic field was activated, the magnetic field was turned off, and the ·OH production was detected after 2 h (EPR spectrum, DMPO was used as a capture agent); Calculation: OH production at 2 h / OH production at 0 h × 100%.

[0051] 4. Biofilm penetration depth Bacterial species: Pseudomonas aeruginosa (PAO1) biofilm (thickness 80 ± 5 μm); Detection: Confocal microscopy (SYTO 9 / PI double staining).

[0052] 5. Bending stability Conditions: 180° repeated bending 10,000 times (frequency 2 Hz); Evaluation: Antibacterial rate after bending / initial antibacterial rate × 100%.

[0053] The performance test results are shown in Table 1 below: Table 1 Test items Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Antibacterial rate (%) 99.5 99.8 99.9 99.9 99.6 72.3 68.5 94.5 Nanozyme shedding rate (%) 2.5 2.0 1.8 1.5 3.0 41.0 38.0 9.0* Activity maintenance rate (%) 80 82 85 88 78 8 12 — Biofilm penetration depth (μm) 48 50 52 55 47 18 15 25 Activity retention after bending (%) 90 92 94 95 88 37 29 82 Note: Comparative Example 3 in Table 1 above is the silver ion release rate (ppm), which is marked separately due to different technical routes.

[0054] As can be seen from the data in the table above, the physically mixed Fe₃O₄ / MoS₂ (Comparative Example 1) exhibits an antibacterial rate (72.3%) less than 73% of that of the Example due to hindered interfacial electron transfer, and its biofilm penetration depth (18 μm) is only 37% of that of the Example, confirming that the core-shell heterojunction is the basis for efficient activation by weak magnetic fields. The silane coupling agent-modified fibers (Comparative Example 2) retain only 29% of their activity after bending, while the catechol polymer-containing Example (>88%) resists mechanical damage through a dynamic chelation network, while the shedding rate is reduced to 1 / 12 of that of Comparative Example 2. Although the commercial silver-loaded fibers (Comparative Example 3) achieve an initial antibacterial rate of 94.5%, their sustained silver ion release (9 ppm) poses a risk of cytotoxicity and fails to achieve magnetic field regulation.

[0055] Therefore, the present invention achieves technological breakthroughs in antibacterial efficiency, interface stability, long-term activity and other dimensions through three levels of innovation: "structural design, interface engineering, and functional regulation", providing a new solution for intelligent antibacterial fibers.

[0056] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A magnetic nanozyme antibacterial fiber, characterized in that: Including biopolymer fiber carrier, and Nanozymes with a core-shell structure grafted onto the surface of a fiber carrier; The nanozyme comprises a core composed of magnetic Fe3O4 nanoparticles and a shell composed of transition metal sulfide; The surface of the nanozyme is modified with a polymer layer containing catechol groups; The magnetic nanozyme antibacterial fiber can continuously generate hydroxyl radicals under the activation of a weak magnetic field pulse of ≤10 mT.

2. The magnetic nanozyme antibacterial fiber according to claim 1, characterized in that The transition metal sulfide is MoS2, and the catechol group-containing polymer is polydopamine; The particle size of the nanozyme is 5-10 nm.

3. The magnetic nanozyme antibacterial fiber according to claim 1 or 2, characterized in that: The biopolymer fiber carrier is a polysaccharide fiber containing divalent metal ions; The nanozyme is anchored on the fiber surface through the chelation between divalent metal ions and the polymer containing catechol groups.

4. The magnetic nanozyme antibacterial fiber according to claim 3, characterized in that The polysaccharide fiber is calcium alginate fiber or calcium alginate-chitosan composite fiber.

5. The magnetic nanozyme antibacterial fiber according to claim 1 or 2, characterized in that: The transition metal sulfide layer has sulfur vacancy defects, and the sulfur vacancy concentration is 0.5-1.5 at%.

6. The magnetic nanozyme antibacterial fiber according to claim 1, characterized in that The invention further comprises hydrogen peroxide slow-release microcapsules embedded in the fiber, wherein the microcapsules are composed of CaO2@SiO2.

7. A method for preparing the magnetic nanozyme antibacterial fiber according to any one of claims 1 to 6, characterized in that: The following steps are involved: (S.1) Preparation of nanozymes with Fe3O4@transition metal sulfide@catechol-containing polymer layer; (S.2) mixing the nanozyme with a biopolymer spinning solution and forming the nanozyme by wet spinning; (S.3) Ionic crosslinking and curing are performed in a magnetic field environment of ≤10 mT.

8. The preparation method according to claim 7, characterized in that: The magnetic field environment is a gradient magnetic field with a magnetic field strength of 1-5 mT; The ionic crosslinking curing adopts Ca 2+ Solution, cross-linking time is 10-30 min.

9. The preparation method according to claim 7, characterized in that: CaO2@SiO2 microcapsules are added during the wet spinning process, with the addition amount being 1-5 wt% of the mass of the spinning solution.

10. Use of the magnetic nanozyme antibacterial fiber according to any one of claims 1 to 6 in the preparation of antibacterial materials or wound dressings.