A high-entropy Fe3O4 nanoparticle, its preparation method and application

Abstract

This invention provides high-entropy Fe3O4 nanoparticles, their preparation method, and applications, belonging to the field of nanomaterials technology. The nanoparticles have a spinel crystal structure and the general chemical formula (Fe3O4) 1‑x M x The high-entropy Fe3O4 nanoparticles contain five or more metal elements, wherein M is a doping metal element selected from one or more of Mn, Fe, Co, Ni, Cu, Zn, Mg, Mo, Cr, V, and Al, with a particle size distribution of 0.05 ≤ x ≤ 0.80. The invention also provides a method for preparing the high-entropy Fe3O4 nanoparticles, comprising mixing an iron source with a doping metal element precursor in a molar ratio, and then performing a flame spray pyrolysis reaction or a melting reaction to produce high-entropy Fe3O4 nanoparticles. The high-entropy Fe3O4 nanoparticles possess highly lattice-distorted structures and abundant mixed-valence active sites, exhibiting SOD-like, CAT-like, and GPx-like multiple enzyme catalytic activities and DPPH free radical scavenging capabilities.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, and specifically relates to a high-entropy Fe3O4 nanoparticle, its preparation method, and its application. Background Technology

[0002] Stroke, especially ischemic stroke, is a serious central nervous system disease characterized by localized brain ischemia, hypoxia, and subsequent reperfusion injury. Numerous studies have shown that the explosive and abnormal accumulation of reactive oxygen species (ROS) in the lesion microenvironment during ischemia / reperfusion (I / R) is a crucial factor driving neuronal apoptosis, neuroinflammation, and severe oxidative stress. Therefore, efficiently clearing ROS from the lesion area is considered an important therapeutic strategy for reducing brain tissue damage and improving stroke prognosis. However, while natural antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) possess strong activity, they suffer from poor stability, are easily inactivated, have limited sources, and have short half-lives in vivo, making it difficult to effectively cross the blood-brain barrier (BBB), thus failing to meet the clinical needs for sustained antioxidant and neuroprotective effects on the brain.

[0003] Nanozymes are a class of functional nanomaterials with enzyme-mimicking catalytic activity that have attracted widespread attention in recent years. Iron(III) oxide (Fe3O4) nanoparticles are among the most extensively studied nanozyme materials, naturally possessing peroxidase-like activity. They can catalyze the oxidation of substrates in the presence of hydrogen peroxide and are widely used in biosensing, anti-tumor, and anti-inflammatory fields. However, the enzyme activity of traditional single-component Fe3O4 nanoparticles is relatively limited, making it difficult to achieve multi-modal ROS synergistic scavenging in complex redox microenvironments, thus restricting their application potential in multifactorial diseases such as ischemic stroke.

[0004] High-entropy materials are solid solution materials composed of five or more elements in near equimolar ratios. Their structures exhibit high lattice distortion and abundant disordered interfaces, effectively increasing catalytic active sites and enhancing structural stability and surface energy. Existing techniques show that the lattice distortion introduced by the synergistic multi-component structure in high-entropy structures can influence the distribution of active sites and electronic structure of catalysts, thus exhibiting significantly enhanced catalytic performance in redox reactions. Introducing a high-entropy strategy into the Fe3O4 spinel system, and achieving synergistic enhancement of multi-mode enzyme catalytic activity through multi-element synergistic solid solution regulation of the nanoparticle's electronic structure, is a research direction with significant application value. Currently, there is a lack of systematic research and patent protection for high-entropy spinel Fe3O4 nanoparticles and their multiple enzyme catalytic activities. Summary of the Invention

[0005] To address the aforementioned issues, this invention introduces multiple transition metal elements into the spinel-structured Fe3O4 lattice for synergistic solid solution, preparing Fe3O4 nanoparticles with a high-entropy solid solution structure (hereinafter referred to as high-entropy Fe3O4). This results in Fe3O4 nanoparticles exhibiting excellent SOD-like, CAT-like, and GPx-like multi-catalytic activities, enabling highly efficient synergistic scavenging of multiple ROS in the microenvironment of ischemic stroke. By precisely controlling the type and content of doping elements, the lattice distortion degree and the number of surface active sites of Fe3O4 nanoparticles can be significantly improved, further enhancing the multi-enzyme catalytic activity and stability of high-entropy Fe3O4 nanoparticles.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A high-entropy iron(III) oxide nanoparticle, wherein the nanoparticle has a spinel (general formula AB₂O₄) crystal structure and a general chemical formula of (Fe₂O₄)₃. 1-x M x )3O4, wherein M is a doping metal element selected from one or more of Mn, Fe, Co, Ni, Cu, Zn, Mg, Mo, Cr, V, and Al, with 0.05≤x≤0.80; the nanoparticles contain five or more metal elements.

[0007] In this invention, all doped metal elements are dissolved together in a spinel lattice, forming a high-entropy solid solution structure with five or more elements. In this high-entropy solid solution, metal ions of different valence states (such as Fe) are dissolved together. 2+ / Fe 3+ Co 2+ / Co 3+ Mn 2+ / Mn 3+ / Mn 4+ Cu 1+ / Cu 2+ Zn 2+ (etc.) synergistically occupy the tetrahedral and octahedral sites of spinel, forming abundant mixed valence active centers and oxygen vacancy defects.

[0008] Preferably, M includes four elements: Mn, Co, Cu, and Zn, which together with Fe constitute a five-element high-entropy spinel solid solution with the general chemical formula (Fe... 1-a-b-c-d Mn a Co b Cu c Zn d )3O4, where 0.05≤a, b, c, d≤0.30, and a+b+c+d≤0.80.

[0009] Preferably, when M includes four elements: Mn, Co, Cu, and Zn, the molar ratio of Fe, Mn, Co, Cu, and Zn is 1:1:1:1:1. That is, the metal elements in the nanoparticles satisfy the principle of near-equimolar ratio, with the molar fraction of each metal element not less than 10% of the total metal molar amount, to ensure the formation of a stable high-entropy solid solution phase. The general chemical formula of the high-entropy iron(III) oxide nanoparticles is (Fe... 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 )3O4.

[0010] The present invention also provides a method for preparing the high-entropy iron oxide nanoparticles, comprising the following steps: mixing an iron source with a precursor of a doped metal element by molar ratio and reacting the mixture to prepare high-entropy iron oxide nanoparticles.

[0011] Preferably, the iron source is selected from one or more of ferric nitrate, ferric chloride, ferric acetate, ferric sulfate, and ferric oxide; the precursor of the doped metal element is selected from one or more of nitrates, acetates, chlorides, sulfates, carbonates, and oxides of the doped metal element, preferably nitrates and / or acetates.

[0012] Preferably, the reaction is a flame spray pyrolysis reaction or a melting reaction.

[0013] The principle of flame spray pyrolysis reaction is as follows: utilizing the extremely high temperature gradient (10) generated by the high-temperature flame. 4 With a cooling rate on the order of K / s, the phase transformation from liquid precursor to solid nanocrystals is completed within a millisecond timescale. By precisely controlling the reducing microenvironment at the center and edge of the flame, in-situ solid solution and valence state control of multi-component metal ions in a high-entropy lattice are achieved.

[0014] The principle behind the formation of high-entropy oxides through melting reaction is as follows: Multiple metal precursors (acetate or nitrate) are calcined in a solid state at high temperatures (700~1000℃). Each precursor component first decomposes into its corresponding metal oxide, followed by solid-state diffusion and ion interdiffusion driven by the high temperature. According to the principle of high-entropy thermodynamics, when five or more elements in equimolar ratios are co-solidified, the configurational entropy of the system (ΔS_mix = -R·Σxi·ln xi) increases significantly, reducing the mixing Gibbs free energy (ΔG_mix = ΔH_mix - T·ΔS_mix). This thermodynamically drives the formation of a stable single-phase solid solution within the spinel lattice, rather than multiphase separation. Under a protective atmosphere (N2 / H2), some Fe... 3+ Reduced in situ to Fe 2+ This satisfies the charge balance of spinel (AB2O4), ultimately forming a high-entropy spinel solid solution structure.

[0015] Preferably, the flame spray pyrolysis reaction includes the following steps: S1. Disperse the iron source and the precursor of the doped metal element in an organic solvent to obtain a liquid phase. S2. The liquid phase obtained in S1 is fed into a flame reactor, and an oxidant is introduced to carry out a flame spray pyrolysis reaction.

[0016] Preferably, in S1, the organic solvent is anhydrous ethanol, and the total metal ion concentration in the liquid phase is 0.01~1 mol / L, more preferably 0.1~0.5 mol / L.

[0017] Preferably, in S2, the oxidant is oxygen or air, the flame fuel is methane, and the flame temperature is 1000~1500℃.

[0018] Preferably, the melting reaction includes the following steps: J1. Add the iron source and the precursor of the doped metal element to an organic solvent and ball mill to obtain a slurry; J2. The slurry obtained from J1 is fed into a heating device and calcined and melted under a protective atmosphere.

[0019] Preferably, in J1, the organic solvent is anhydrous ethanol.

[0020] Preferably, in J2, the heating device is a tube furnace, the protective atmosphere is an inert or reducing atmosphere, the calcination temperature is 700~1000℃, and the calcination time is 4~6 h.

[0021] This invention also provides the application of the high-entropy iron tetroxide nanoparticles as nanoenzymes.

[0022] Preferably, the application is selected from any one or more of the following I-VII: I. Preparation of reactive oxygen species (ROS) scavengers and biological microenvironment regulators The reactive oxygen species (ROS) scavenger is used to remove superoxide anions (ROS). ), hydroxyl radicals ( The biological microenvironment regulator is used to regulate the redox balance of the tissue microenvironment and inhibit oxidative stress-mediated cell damage.

[0023] II. Preparation of drugs or implantable biomaterials for treating nervous system diseases and repairing nerve damage.

[0024] The neurological diseases include neurodegenerative diseases and cerebrovascular diseases. The neurodegenerative diseases include Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and Huntington's disease; the cerebrovascular diseases include protection against ischemic stroke and its reperfusion injury.

[0025] The nerve injury repair includes spinal cord injury, peripheral nerve injury, postoperative repair of neuroma, and functional modification of the nerve conduit.

[0026] III. Preparation of reagents or drugs for treating cardiovascular and metabolic diseases

[0027] It is used to treat ischemia-reperfusion injury after myocardial infarction, atherosclerosis, and vascular endothelial damage caused by hypertension. It is used to treat complications of diabetes, such as diabetic foot and diabetic retinopathy.

[0028] IV. Preparation of dressings or reagents to promote skin and tissue regeneration and repair.

[0029] Used for anti-inflammatory and repair purposes on chronic, difficult-to-heal wounds (such as pressure sores and diabetic foot ulcers); Used in medical aesthetics for anti-photoaging, reducing post-laser inflammatory response, and scar suppression.

[0030] V. Preparation of reagents or drugs for treating orthopedic-related inflammatory diseases.

[0031] It is used to treat osteoarthritis, rheumatoid arthritis, and osteoporosis caused by excessive ROS leading to chondrocyte apoptosis or osteoclast overactivation.

[0032] VI. Fabrication of magnetic target drug delivery systems or micro / nano robot control platforms

[0033] The superparamagnetism of the nanozyme can be used as a drug carrier for magnetic field-driven localization, magnetothermal therapy, or MRI contrast-enhanced imaging.

[0034] VII. Preparation of tumor synergistic therapy or antibacterial products

[0035] Utilizing its peroxidase-like (POD) activity in an acidic environment (TME), it generates reactive oxygen species for tumor dynamic therapy or the clearance of high-density microbial communities (biofilms).

[0036] This invention constructs Fe3O4 nanoparticles with a high-entropy solid solution structure by optimizing the types and contents of doping elements. The high-entropy solid solution structure can effectively improve the degree of lattice distortion and increase the number of surface reactive sites, thereby obtaining higher and more stable multi-enzyme catalytic activity than traditional single-component Fe3O4. In addition, the multi-component solid solution structure improves the stability of the material in aqueous systems, giving the nanoparticles better dispersibility and tolerance in biologically relevant environments.

[0037] This invention utilizes a multi-element synergistic solid solution high-entropy strategy to prepare high-entropy Fe3O4 nanoparticles with the following excellent properties: (i) SOD-like activity: It can convert toxic superoxide anions (… (ii) Catalytic disproportionation into less toxic H2O2; (iii) CAT-like activity: efficiently decomposes H2O2 into harmless H2O and O2; (iv) GPx-like activity: synergistically utilizes glutathione (GSH) to reduce H2O2, thereby lowering peroxide levels. These three components form a highly efficient cascaded ROS scavenging reaction network, effectively reducing oxidative stress levels in the stroke microenvironment.

[0038] Compared with the prior art, the present invention has the following technical effects: (1) The high-entropy Fe3O4 nanoparticles prepared by this invention have multiple enzyme catalytic activities such as SOD, CAT and GPx and DPPH free radical scavenging ability. The three enzyme activities form an efficient cascade reaction, which synergistically scavenges multiple ROS and significantly reduces the level of oxidative stress in the microenvironment of ischemic stroke lesions. (2) The high-entropy structure endows Fe3O4 nanoparticles with high lattice distortion and abundant mixed valence active sites (Fe 2+ / Fe 3+ (In synergy with other dopants in multiple valence states), it effectively increases the density of catalytic active sites, improves the structural stability and catalytic activity of the material, and has better stability compared with natural enzymes; (3) The preferred embodiment of the present invention is the Mn-Fe-Co-Cu-Zn pentagonal high-entropy system. Each of the five elements has unique redox properties, and the synergistic effect is significantly better than any quaternary or lower low-entropy formulation, demonstrating outstanding technical effect. (4) The preparation method provided by the present invention is simple, the reaction is controllable, the precursor is widely available, and it is easy to scale up production. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 The TEM morphology and EDS elemental distribution of the high-entropy Fe3O4 nanoparticles in Example 1 are shown.

[0041] Figure 2 The image shows the XRD diffraction pattern of the high-entropy Fe3O4 nanoparticles in Example 1.

[0042] Figure 3 The XRD diffraction patterns of the high-entropy Fe3O4 nanoparticles in Examples 2-6 are shown.

[0043] Figure 4 The bar graphs show the SOD-like enzyme activity of high-entropy Fe3O4 nanoparticles in Examples 1 and Comparative Examples 1-4.

[0044] Figure 5 The bar chart shows the superoxide anion radical inhibition rate of high-entropy Fe3O4 nanoparticles in Examples 1 and Comparative Examples 1-4.

[0045] Figure 6 The bar graphs show the CAT-like enzyme activity of high-entropy Fe3O4 nanoparticles in Examples 1 and Comparative Examples 1-4.

[0046] Figure 7 The bar graphs show the GPx enzyme activity of high-entropy Fe3O4 nanoparticles in Examples 1 and Comparative Examples 1-4.

[0047] Figure 8 The graph shows the DPPH radical activity of high-entropy Fe3O4 nanoparticles in Examples 1 and 1-4.

[0048] Figure 9 The bar graph shows the DPPH radical scavenging rate of high-entropy Fe3O4 nanoparticles in Example 1 and Comparative Examples 1-4.

[0049] Figure 10 Representative images of coronal brain slices stained with TTC after using high-entropy Fe3O4 nanoparticles from Example 1 for rat ischemic stroke injury.

[0050] Figure 11 Representative images of H&E staining of rat ischemic stroke injury using high-entropy Fe3O4 nanoparticles from Example 1. Detailed Implementation

[0051] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0052] Example 1

[0053] High-entropy Fe3O4 nanoparticles were prepared by flame spray pyrolysis at a flame temperature of 1000 ℃, including the following steps: S1. Preparation of a high-entropy precursor molecular-level homogeneous solution: Following a molar ratio of Fe:Mn:Co:Cu:Zn = 1:1:1:1:1, high-purity (>99.9%) ferric nitrate nonahydrate (Fe(NO3)3·9H2O), manganese nitrate tetrahydrate (Mn(NO3)2·4H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), copper nitrate trihydrate (Cu(NO3)2·3H2O), and zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were weighed sequentially. These metal salts were dissolved in anhydrous ethanol, which served not only as a solvent but also as a high-enthalpy fuel for the subsequent combustion reaction. High-shear magnetic stirring (500-800 rpm) and ultrasonic cavitation treatment (20 min) ensured a highly uniform diffusion distribution of the various metal cations at the molecular level, guaranteeing the accuracy of the final product's stoichiometry. The total metal ion concentration was adjusted to 0.4 mol / L to control the solute loading of the aerosol droplets.

[0054] S2. Atomization and Kinetic Mass Transfer Process: Subsequently, flame spray pyrolysis is performed: using a precision injection pump, the precursor solution is fed into the flame reactor system at a feed rate of 600 mL / h; an oxidant (air, flow rate 30 L / min) at a pressure of 1.5-2.5 bar is introduced, and through the shearing effect of the high-speed airflow at the nozzle, the precursor solution is broken down into median particle sizes (D...). 50 ( ) are fine droplet aerosols of 5-15 µm.

[0055] S3. High-Temperature Pyrolysis and Lattice Construction at the Flame Center: A stable swirling flame was ignited using methane (flow rate 3 L / min), and the core flame temperature was precisely controlled to be stable at 1000 °C. After entering the high-temperature zone, aerosol droplets instantly underwent solvent evaporation, solute precipitation, and pyrolysis oxidation. By adjusting the fuel / air-oxygen ratio, a locally fuel-rich reducing region was formed at the flame center. In this microenvironment, some Fe... 3+ Reduced in situ to Fe 2+ To meet the charge balance requirements of the spinel structure (AB₂O₄), under high temperature, five elements—Fe, Mn, Co, Cu, and Zn—overcome their respective lattice energy differences and, through the reduction in Gibbs free energy brought about by high configurational entropy, forcibly dissolve into the single-phase spinel structure, effectively suppressing multiphase separation and grain coarsening, thus producing (Fe 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles.

[0056] S4. Particle Quenching and Efficient Collection: After leaving the flame zone, the nanoparticles are rapidly carried by the airflow into the quenching zone. The extremely high cooling rate freezes the disordered solid solution state at high temperature, preserving abundant surface oxygen vacancies and catalytically active sites. The generated high-entropy nanoparticle powder is collected through a glass fiber filter located at the end of the system. The resulting product exhibits extremely high specific surface area and excellent superparamagnetic properties.

[0057] Example 2

[0058] Using the same molar ratios and precursor preparation method as in Example 1, the total metal ion concentration in the precursor solution was 0.4 mol / L. The flame spray pyrolysis conditions were the same as in Example 1, but the flame core temperature was controlled at 1250℃, ultimately yielding (Fe... 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles were collected by a glass fiber filter.

[0059] Example 3

[0060] Using the same molar ratios and precursor preparation method as in Example 1, the total metal ion concentration in the precursor solution was 0.4 mol / L. The flame spray pyrolysis conditions were the same as in Example 1, but the flame core temperature was controlled at 1500℃, ultimately yielding (Fe... 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles were collected by a glass fiber filter.

[0061] Example 4

[0062] The preparation of high-entropy Fe3O4 nanoparticles by solid-phase ball milling includes the following steps: J1. Weigh out ferrous acetate (Fe(CH3COO)2), manganese acetate (Mn(CH3COO)2·4H2O), cobalt acetate (Co(CH3COO)2·4H2O), copper acetate (Cu(CH3COO)2·H2O), and zinc acetate (Zn(CH3COO)2·2H2O) according to the molar ratio of Fe:Mn:Co:Cu:Zn = 1:1:1:1:1.

[0063] The above raw materials were added to a mixed solvent of deionized water and anhydrous ethanol (volume ratio 1:1), placed in an agate jar, and zirconia grinding balls (ball-to-material ratio approximately 10:1, ball diameter 5-10 mm) were added. The mixture was then ball-milled using a planetary ball mill at 300-500 rpm for 12-24 h to obtain a homogeneous wet slurry. The slurry was dried at 80℃, ground into powder, and then placed in a tube furnace. It was calcined at 700℃ for 4 h under a N2 / H2 (volume ratio 95:5) mixed protective atmosphere to promote high-temperature solid-phase diffusion of the components, forming a high-entropy spinel solid solution structure. After cooling, the calcined product was ball-milled again with deionized water for 24 h to refine it. The slurry was then freeze-dried to obtain (Fe 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles.

[0064] Example 5

[0065] Compared with Example 4, the only difference is that the calcination temperature is 850℃ and the calcination time is 4 h; the other steps are exactly the same, and the final product is (Fe). 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles.

[0066] Example 6

[0067] Compared with Example 4, the only difference is that the calcination temperature is 1000℃ and the calcination time is 5 h. The other steps are exactly the same, and the final product is (Fe). 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 3O4 nanoparticles.

[0068] Figure 1 Figure A shows the TEM morphology and EDS elemental distribution of the high-entropy Fe3O4 nanoparticles obtained in Example 1. It is a pentagonal Mn-Fe-Co-Cu-Zn system. As can be seen from Figure A, the (Fe3O4) nanoparticles prepared in Example 1... 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 The 3O4 nanoparticles exhibit a spherical morphology and uniform particle size under transmission electron microscopy (TEM). Figure B shows that the particle size ranges from 20 to 50 nm. Figure E and subsequent EDS elemental distribution diagrams demonstrate that the five elements Fe, Mn, Co, Cu, and Zn are uniformly distributed within the nanoparticles, confirming the successful synthesis of a high-entropy spinel solid solution structure.

[0069] Figure 2 The image shows the XRD diffraction pattern of the high-entropy Fe3O4 nanoparticles in Example 1, indicating that their crystal form is consistent with Fe3O4.

[0070] Figure 3 The images show the XRD diffraction patterns of Examples 2-6. Examples 2 and 3 used the same molar ratios and flame spray pyrolysis method as Example 1, while Examples 4-6 used solid-state ball milling, i.e., melt reaction to prepare high-entropy Fe3O4 nanoparticles. The XRD patterns of the above examples all show a single Fe3O4 crystal form.

[0071] Comparative Example 1

[0072] The difference between Comparative Example 1 and Example 1 is that only pure Fe3O4 was prepared without adding any doped metal elements, including the following steps: A precursor solution with a total metal ion concentration of 0.4 mol / L was prepared by dissolving ferric nitrate nonahydrate (Fe(NO3)3·9H2O) in ethanol. This solution was fed into a flame reactor at a feed rate of 600 mL / min, where methane (3 L / min) and air (30 L / min) were swirled and combusted, with the flame core temperature controlled at 1000 °C, ultimately producing conventional Fe3O4 nanoparticles without high entropy.

[0073] Comparative Example 2

[0074] The difference between Comparative Example 2 and Example 1 is that the nanoparticles are a ternary Fe-Co-Mn system, including the following steps: According to the molar ratio of Fe:Co:Mn = 1:1:1, ferric nitrate, cobalt nitrate, and manganese nitrate were weighed and dissolved in ethanol to prepare a precursor solution with a total metal ion concentration of 0.4 mol / L. The flame spray synthesis conditions were the same as in Example 1 (temperature 1000℃), ultimately producing (Fe... 1 / 3 Co 1 / 3 Mn 1 / 3 3O4 nanoparticles.

[0075] Comparative Example 3

[0076] The difference between Comparative Example 3 and Example 1 is that the nanoparticles are a quaternary Fe-Co-Mn-Cu system (without added Zn), and the following steps are included: According to the molar ratio of Fe:Mn:Co:Cu = 1:1:1:1, ferric nitrate, manganese nitrate, cobalt nitrate, and copper nitrate were weighed and dissolved in ethanol to prepare a precursor solution with a total metal ion concentration of 0.4 mol / L. The flame spray synthesis conditions were the same as in Example 1 (temperature 1000℃), ultimately producing (Fe... 0.25 Mn 0.25 Co 0.25 Cu 0.253O4 nanoparticles.

[0077] Comparative Example 4

[0078] The difference between Comparative Example 4 and Example 1 is that the nanoparticles are a quaternary Fe-Co-Mn-Zn system (without Cu added), and include the following steps: According to the molar ratio of Fe:Mn:Co:Zn = 1:1:1:1, ferric nitrate, manganese nitrate, cobalt nitrate, and zinc nitrate were weighed and dissolved in ethanol to prepare a precursor solution with a total metal ion concentration of 0.4 mol / L. The flame spray synthesis conditions were the same as in Example 1 (temperature 1000℃), ultimately producing (Fe... 0.25 Mn 0.25 Co 0.25 Zn 0.25 3O4 nanoparticles.

[0079] Test case

[0080] The nanoparticles prepared in Example 1 and Comparative Examples 1-4 were tested for SOD-like enzyme activity, CAT-like enzyme activity, GPx-like enzyme activity, and DPPH free radical scavenging ability, respectively. 1) SOD-like enzyme activity test: Accurately weigh high-entropy Fe3O4 nanoparticles, disperse them in PBS buffer solution (pH 7.4), and prepare gradient concentration solutions of 0.05~1 mg / mL. Using a SOD-like enzyme activity kit, monitor the absorbance change of NBT (nitroblue tetrazolium) at 560 nm using an ELISA reader, calculate the inhibition rate of superoxide anion free radicals by the nanoparticles, and convert it into SOD enzyme activity (U / mg). 2) CAT-like enzyme activity test: Weigh high-entropy Fe3O4 nanoparticles, disperse them in PBS buffer solution (pH 7.4), and prepare gradient concentration solutions of 0.05~1 mg / mL. Using a CAT-like enzyme activity kit, calculate the H2O2 decomposition rate (μmol / min·mg) by monitoring the change of H2O2 concentration over time. 3) GPx-like enzyme activity test: Weigh high-entropy Fe3O4 nanoparticles, disperse them in PBS buffer solution (pH 7.4), and prepare gradient concentration solutions of 0.05~1 mg / mL. Use a GPx activity detection kit to indirectly measure the GPx-like enzyme activity (μmol / min·mg) by monitoring the NADPH consumption rate at 340 nm. 4) DPPH free radical scavenging test: Prepare nanoparticle solutions with gradient concentrations of 0.05~1 mg / mL, mix with an equal volume of 0.1 mmol / L DPPH ethanol solution, react in the dark for 30 min, monitor the change in absorbance at 517 nm, and calculate the DPPH free radical scavenging rate (%).

[0081] The test results of the above embodiments and comparative examples are shown in Table 1.

[0082] Table 1 Enzyme activity test results

[0083] As shown in Table 1, the (Fe,Mn,Co,Cu,Zn)3O4 nanoparticles prepared by five-element high-entropy doping in Example 1 simultaneously possess SOD-like, CAT-like, and GPx-like multiple enzyme activities as well as DPPH free radical scavenging ability. Moreover, the activities of the three enzymes are significantly higher than those of Comparative Examples 1-4, which fully demonstrates the effectiveness of the high-entropy solid solution strategy.

[0084] Comparative Example 1, pure Fe3O4, exhibited the lowest multiplex enzyme activity, indicating that it is dependent solely on Fe. 2+ / Fe 3+ A single mixed valence state cannot achieve efficient multi-mode ROS removal.

[0085] Comparative Example 2 is a ternary Fe-Co-Mn system, while Comparative Examples 3 and 4 are quaternary systems. The results of the above comparative examples show that the enzyme activity increases sequentially with the increase of the number of doping elements, which verifies the positive effect of multi-component synergistic solid solution on improving catalytic activity.

[0086] Furthermore, Comparative Examples 3 and 4, lacking either Zn or Cu, showed significantly lower performance than the pentagonal system of Example 1. This indicates that Mn, Fe, Co, Cu, and Zn are all indispensable elements in constructing highly efficient multiplex enzymes, particularly Mn's multivalent states (Mn... 2+ / Mn 3+ / Mn 4+ Enhanced SOD-like and GPx-like activity; Co redox activity enhanced CAT-like and GPx-like catalysis; Cu (Cu 1+ / Cu 2+ The rapid electron transfer synergistically enhances the activities of GPx-like and CAT-like compounds; the introduction of Zn stabilizes the spinel lattice structure and regulates the distribution of d-orbital electrons, thereby improving the overall density of catalytic active sites. These results demonstrate the significant technical advantages of the pentagonal high-entropy formulation of this invention compared to any quaternary or lower-order combination.

[0087] The SOD-like enzyme activity results of high-entropy Fe3O4 nanoparticles in Examples 1 and 1-4 are shown in the figure. Figure 4 The results of superoxide anion radical inhibition rate are shown in [the table below]. Figure 5 The results of the CAT-like enzyme activity bar chart are shown below. Figure 6 The results of the bar chart of GPx enzyme activity are shown below. Figure 7 The results of the DPPH free radical activity bar chart are shown below. Figure 8 The DPPH free radical scavenging rate results are shown in [the table below]. Figure 9The groups in the figures are all Examples 1 and Comparative Examples 1-4. The data results in the above figures are consistent with those in Table 1.

[0088] Figure 10 This image shows a representative coronal brain section after TTC staining of rat ischemic stroke injury using high-entropy Fe3O4 nanoparticles from Example 1. TTC staining is a biochemical staining method commonly used for rapid detection of tissue cell viability (especially in cerebral or myocardial ischemia-infarction). The groups in the image represent the sham-operated group, the stroke injury treatment group, and the group treated with Example 1 after stroke injury, respectively. The white areas represent areas of brain tissue necrosis; the more white areas, the more severe the injury. It can be observed that the brain injury treated with Example 1 was effectively inhibited after the injury, preventing further deterioration of brain tissue necrosis.

[0089] Figure 11 Representative images of H&E staining of high-entropy Fe3O4 nanoparticles from Example 1 in rats with ischemic stroke injury are shown. H&E staining is the most basic and widely used routine staining method in histology and pathology. The groups in the image are the sham surgery group, the stroke injury treatment group, and the group treated with Example 1 after stroke injury, respectively. Tissue state is analyzed by the dye binding to the cell nucleus and cytoplasm. Due to the influence of stroke injury, necrotic cells cannot bind to the dye, thus white blank areas are found in brain sections representing brain tissue damage. The brain injury treated with Example 1 after the injury was effectively inhibited, preventing the continuous deterioration of brain tissue necrosis.

[0090] In summary, regarding the preparation method, the flame spray pyrolysis method (Examples 1-3) exhibited the highest enzyme catalytic activity with the same composition, which is attributed to its extremely high cooling rate (>10). 5 K / s effectively inhibits grain growth, "quenching" the high-entropy solid solution structure within the 20-30 nm range, and forming abundant oxygen vacancy defects on the particle surface. These defects are the core active centers for enzyme-like catalysis. The activity at a flame temperature of 1000℃ (Example 1) is superior to that at 1250℃ (Example 2) and 1500℃ (Example 3), indicating that appropriately lowering the synthesis temperature helps maintain a high specific surface area. The solid-phase ball milling method (Examples 4-6) exhibits good overall performance and excellent thermal stability. While the activity decreases slightly with increasing calcination temperature, it still remains at a high level.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-entropy iron(III) oxide nanoparticle, characterized in that, The nanoparticles have a spinel crystal structure and the general chemical formula (Fe) 1-x M x )3O4, wherein M is a doping metal element selected from one or more of Mn, Fe, Co, Ni, Cu, Zn, Mg, Mo, Cr, V, and Al, with 0.05≤x≤0.80; the nanoparticles contain five or more metal elements.

2. The high-entropy iron oxide nanoparticles according to claim 1, characterized in that, M includes four elements: Mn, Co, Cu, and Zn. Together with Fe, they form a five-element high-entropy spinel solid solution with the general chemical formula (Fe). 1-a-b-c-d Mn a Co b Cu c Zn d )3O4, where 0.05≤a, b, c, d≤0.30, and a+b+c+d≤0.80; And / or, when M includes four elements: Mn, Co, Cu, and Zn, the molar ratio of Fe, Mn, Co, Cu, and Zn is 1:1:1:1:1, and the general chemical formula of the high-entropy iron(III) oxide nanoparticles is (Fe... 0.2 Mn 0.2 Co 0.2 Cu 0.2 Zn 0.2 )3O4.

3. The method for preparing high-entropy iron oxide nanoparticles according to claim 1 or 2, characterized in that, Includes the following steps: By mixing an iron source with a precursor doped with a metallic element according to a molar ratio, high-entropy iron oxide nanoparticles are produced.

4. The method for preparing high-entropy iron oxide nanoparticles according to claim 3, characterized in that, The iron source is selected from one or more of ferric nitrate, ferric chloride, ferric acetate, ferric sulfate, and ferric oxide; the precursor of the doped metal element is selected from one or more of nitrates, acetates, chlorides, sulfates, carbonates, and oxides of the doped metal element, preferably nitrates and / or acetates.

5. The method for preparing high-entropy iron oxide nanoparticles according to claim 3 or 4, characterized in that, The reaction is a flame spray pyrolysis reaction or a melting reaction.

6. The method for preparing high-entropy iron oxide nanoparticles according to claim 5, characterized in that, The flame spray pyrolysis reaction includes the following steps: S1. Disperse the iron source and the precursor of the doped metal element in an organic solvent to obtain a liquid phase. S2. The liquid phase obtained in S1 is fed into a flame reactor, and an oxidant is introduced to carry out a flame spray pyrolysis reaction.

7. The method for preparing high-entropy iron oxide nanoparticles according to claim 6, characterized in that, In S1, the organic solvent is anhydrous ethanol, and the total metal ion concentration in the liquid phase is 0.01~1 mol / L, preferably 0.1~0.5 mol / L; And / or, in S2, the oxidant is oxygen or air, the flame fuel is methane, and the flame temperature is 1000~1500℃.

8. The method for preparing high-entropy iron oxide nanoparticles according to claim 5, characterized in that, The melting reaction includes the following steps: J1. Add the iron source and the precursor of the doped metal element to an organic solvent and ball mill to obtain a slurry; J2. The slurry obtained from J1 is fed into a heating device and calcined and melted under a protective atmosphere.

9. The method for preparing high-entropy iron oxide nanoparticles according to claim 8, characterized in that, In J1, the organic solvent is anhydrous ethanol; And / or, in J2, the heating device is a tube furnace, the protective atmosphere is an inert or reducing atmosphere, the calcination temperature is 700~1000℃, and the calcination time is 4~6 h.

10. The application of the high-entropy iron oxide nanoparticles according to claim 1 or 2, or the high-entropy iron oxide nanoparticles prepared by the method according to any one of claims 3 to 9, as nanozymes; And / or, the application is selected from any one or more of the following I-VII: I. Preparation of reactive oxygen species scavengers and biological microenvironment regulators; II. Preparation of drugs or implantable biomaterials for treating nervous system diseases and repairing nerve damage; III. Preparation of reagents or drugs for the treatment of cardiovascular and metabolic diseases; IV. Prepare dressings or reagents that promote skin and tissue regeneration and repair; V. Prepare reagents or drugs for treating orthopedic-related inflammatory diseases; VI. Fabrication of magnetic target drug delivery systems or micro / nano robot control platforms; VII. Prepare products for tumor synergistic therapy or antibacterial purposes.

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