Rare earth loaded aluminum oxide composite antibacterial material, preparation method and application

Abstract

The invention provides a rare earth loaded aluminum oxide composite antibacterial material, a preparation method and application, and belongs to the technical field of antibacterial materials. The antibacterial material shows an excellent antibacterial effect under a dark condition, and the antibacterial rate on staphylococcus aureus and escherichia coli reaches up to 100%. After being repeatedly used for multiple times, the antibacterial agent still keeps strong bactericidal ability, and the minimum antibacterial rate is 90%.

Description

[0001] This application claims the priority of a Chinese patent application titled "Rare Earth Loaded Alumina Composite Antibacterial Material, Preparation Method and Application" with an application number of 2024119329654 and filed with the National Intellectual Property Administration on December 26, 2024. The entire content thereof is incorporated herein by reference. Technical Field

[0002] The present invention belongs to the technical field of antibacterial materials, and particularly relates to a rare earth loaded alumina composite antibacterial material, a preparation method and an application. Background Art

[0003] In today's era, the problem of bacterial infection has posed extremely severe challenges to human health and many industrial fields globally. Therefore, the innovative research and development of antibacterial materials has become one of the core concerns in the fields of scientific research and industrial applications.

[0004] Traditional antibacterial agents mainly include two categories: organic antibacterial agents and inorganic antibacterial agents. Organic antibacterial agents usually exhibit certain antibacterial activity advantages in the initial stage. However, their chemical stability is relatively weak, and volatilization is prone to occur, resulting in a gradual attenuation of their antibacterial activity. In addition, organic antibacterial agents generally have low heat resistance. In some aspects such as packaging materials that require high-temperature sterilization treatment, protective articles used in high-temperature working environments, and antibacterial treatment of industrial products involving high-temperature processing processes, organic antibacterial agents can hardly play their due antibacterial role. Long-term continuous use of organic antibacterial agents will also induce bacteria to gradually develop drug resistance. Among inorganic antibacterial agents, silver-based antibacterial agents are a relatively typical type. However, the natural reserves of silver elements are relatively limited, severely restricting their popularization and application in a wider market and industrial fields.

[0005] The application potential of nanomaterials in the antibacterial field has gradually become a hot topic. Compared with traditional materials, nanomaterials greatly expand the specific surface area, and at the same time, the surface activity and reaction activity have been increased by several orders of magnitude. Many antibacterial agents based on nanomaterials have the ability to generate reactive oxygen species (ROS) with strong bactericidal activity and a non-specific antibacterial mechanism. This non-specificity makes it difficult for pathogenic strains to develop drug resistance to nanomaterials through specific gene mutations or metabolic pathway adjustments. Because nanomaterials interfere with the overall physiological structure and function of bacteria from multiple dimensions and levels, bacteria are difficult to find a single adaptation strategy to evade the antibacterial effect of nanomaterials.

[0006] However, most of the current nano-antibacterial agents capable of generating ROS largely rely on external stimuli such as light irradiation to initiate the ROS generation process. Taking the common TiO2 nano-material as an example, it needs to be irradiated with ultraviolet light to generate electron-hole pairs, which then trigger a series of subsequent redox reactions, and finally generate ROS to achieve the antibacterial effect. This strong dependence on light irradiation greatly limits the applicability and universality of such nano-antibacterial agents in actual application scenarios. In many actual application scenarios, such as indoor enclosed spaces without light or with weak light, the internal environment of light-shielding packaging materials, and deep tissues inside the human body, these nano-antibacterial agents that rely on light irradiation simply cannot fully exert their expected antibacterial performance and are difficult to meet the diverse actual antibacterial needs.

[0007] Therefore, in the current field of antibacterial material research and development, there is an urgent need to develop a nano-system with a simple structure, high performance, and capable of spontaneously releasing ROS without external stimuli such as light irradiation, so as to break through the bottleneck limitations of existing nano-antibacterial agents in the application process. Summary of the Invention

[0008] In view of the technical problems existing in the prior art, the present invention aims to provide a rare earth-loaded alumina composite antibacterial material, a preparation method and an application thereof.

[0009] One of the purposes of the present invention is to provide a rare earth-loaded alumina composite antibacterial material, and the raw materials of the antibacterial material include rare earth oxides and γ-Al2O3.

[0010] Preferably, the mass fraction of the rare earth oxide is 2.3~18%.

[0011] Preferably, the rare earth oxide includes one of La2O3, CeO2, Pr6O 11 and Nd2O3.

[0012] Preferably, the particle size of the antibacterial material is 200~400 nm.

[0013] Another purpose of the present invention is to provide a preparation method of a rare earth-loaded alumina composite antibacterial material, including: Mixing the rare earth oxide and γ-Al2O3 to obtain a mixed powder; Adding the mixed powder into a ball mill and grinding for 12~15 h to obtain the rare earth-loaded alumina composite antibacterial material.

[0014] Preferably, the ball mill includes a wear-resistant nylon tank and zirconia balls, and the ball diameter of the zirconia balls is 10~50 mm.

[0015] Preferably, the mass ratio of the zirconia balls to the mixed powder is 10:1.

[0016] Preferably, the rotation speed of the ball mill is 400 rpm.

[0017] Preferably, the grinding is carried out alternately by continuous grinding for 10 min and stopping for 5 min.

[0018] The third object of the present invention is to provide an application of a rare earth loaded alumina composite antibacterial material in the field of antibacterial protection in a lightless or low-light environment.

[0019] Advantages of the present invention: The rare earth loaded alumina composite antibacterial material provided by the present invention exhibits excellent antibacterial effects under dark conditions, and the antibacterial rates against Staphylococcus aureus and Escherichia coli are up to 100% at most. After repeated use for many times, it still maintains a strong bactericidal ability, and the lowest antibacterial rate is 90%. Detailed implementation manners

[0020] According to the first aspect of the present invention, a rare earth loaded alumina composite antibacterial material is provided, and the raw materials of the antibacterial material include rare earth oxides and γ-Al2O3.

[0021] In the present invention, the introduction of rare earth oxides increases the content of oxygen vacancies on the surface of alumina. Oxygen vacancies are defects formed by the absence of oxygen ions in the lattice, and these defect positions become active sites for electron capture or release, providing necessary conditions for the generation of reactive oxygen species.

[0022] Rare earth oxides have the characteristic of multiple valence states. During the reversible conversion between different valence states of rare earth elements, electrons can transfer between rare earth ions with different valence states, promoting the redox reaction on the surface of the material. This electron transfer process interacts with oxygen vacancies, making it easier for oxygen molecules adsorbed on the surface of the material to obtain electrons, and thus be activated and converted into reactive oxygen species.

[0023] After rare earth oxides are doped into alumina, some rare earth elements replace the main elements in alumina, resulting in lattice expansion, and then increasing the surface active sites. This not only improves the adsorption ability of the material to bacteria, but also enhances the adsorption effect on oxygen molecules. Oxygen molecules adsorbed on the surface active sites are more easily activated under the combined action of oxygen vacancies and rare earth multiple valence states, and then converted into reactive oxygen species. These reactive oxygen species can target and attack biological macromolecules such as the cell wall, cell membrane, nucleic acids, and proteins inside the bacteria, and finally cause the death of bacteria or severely inhibit their growth through a series of complex oxidative damage chain reactions.

[0024] The doping of rare earth elements causes a more significant reduction in the band gap energy of the alumina material relative to Al2O3. The decrease in the band gap energy enables the material to undergo electron transitions at lower energies. After electrons transition from the valence band to the conduction band, they have higher energy and activity in the conduction band, making it easier to react with oxygen molecules adsorbed on the material surface and promoting the generation of reactive oxygen species. This change in the energy band structure, in conjunction with the oxygen vacancy and the characteristics of the multiple valence states of rare earth elements, jointly enhances the ability of the material to generate reactive oxygen species under dark conditions and improves the antibacterial performance.

[0025] In addition, the doping of rare earth elements increases the lattice constant and unit cell volume of alumina, enhancing the rigidity of the crystal structure and maintaining the stability of the surface properties, which will not change significantly due to contact with bacteria or other substances, ensuring the continuous effectiveness of its antibacterial mechanisms such as adsorption and interaction with bacteria.

[0026] In a preferred embodiment of the present invention, the mass fraction of the rare earth oxide is 2.3 - 18%.

[0027] In the present invention, 2.3 - 18% of rare earth oxide can effectively increase the content of oxygen vacancies on the alumina surface, promote the spontaneous generation of reactive oxygen species under dark conditions, and thus achieve excellent antibacterial performance. For example, too little doping of rare earth oxide may not be sufficient to form enough oxygen vacancies, resulting in insufficient generation of reactive oxygen species and poor antibacterial effect; while too much rare earth oxide may damage the crystal structure stability of alumina, affect the reasonable distribution of oxygen vacancies and the generation efficiency of reactive oxygen species, and may also increase costs and introduce unnecessary impurities.

[0028] 2.3 - 18% of rare earth oxide helps to maintain the relative integrity of the alumina crystal structure when doping rare earth oxide. When the mass fraction of rare earth oxide is moderate, some rare earth elements replace the main elements in alumina, which can cause lattice expansion, appropriately increase the lattice constant and unit cell volume, and enhance the rigidity and stability of the crystal structure, which is crucial for the long-term effectiveness of the material in the antibacterial process. If the mass fraction of rare earth oxide is too high, it may lead to excessive lattice distortion, damage the crystal structure, affect the physical and chemical properties of the material, and thus reduce the antibacterial performance and the stability of the material.

[0029] An appropriate mass fraction of rare earth oxide can regulate the surface properties of the material, such as the number of surface active sites, surface charge distribution, etc. In the range of 2.3 - 18%, it can increase the surface active sites, enhance the adsorption ability of the material to bacteria, and at the same time maintain an appropriate Zeta potential, promoting the electrostatic adsorption and interaction between the material and bacteria and improving the antibacterial efficiency. If the mass fraction is too low, it may not effectively change the surface properties, while too high may lead to unstable surface properties or changes that are not conducive to antibacterial.

[0030] In the present invention, the mass fraction of the rare earth oxide is preferably 9%.

[0031] In a preferred embodiment of the present invention, the rare earth oxide comprises one of La2O3, CeO2, Pr6O 11 and Nd2O3.

[0032] In a preferred embodiment of the present invention, the particle size of the antibacterial material is 200 - 400 nm.

[0033] In the present invention, smaller nano - sizes are more likely to enter the interior of bacteria, interact with the internal structure of bacteria, and cause cell lysis and apoptosis.

[0034] According to the second aspect of the present invention, there is provided a method for preparing a rare - earth - loaded alumina composite antibacterial material, comprising: Mixing a rare earth oxide with γ - Al2O3 to obtain a mixed powder; Adding the mixed powder into a ball mill and grinding for 12 - 15 h to obtain a rare - earth - loaded alumina composite antibacterial material.

[0035] In a preferred embodiment of the present invention, the ball mill comprises a wear - resistant nylon tank and zirconia balls, and the ball diameter of the zirconia balls is 10 - 50 mm.

[0036] In the present invention, the wear - resistant nylon tank and zirconia balls have relatively high strength and hardness, and the impurities introduced during the milling process can be ignored.

[0037] In a preferred embodiment of the present invention, the mass ratio of the zirconia balls to the mixed powder is 10:1.

[0038] In a preferred embodiment of the present invention, the rotation speed of the ball mill is 400 rpm.

[0039] In a preferred embodiment of the present invention, the grinding is carried out by alternating continuous grinding for 10 min and stopping for 5 min.

[0040] In the present invention, continuous grinding and stopping are alternated to prevent overheating and rapid wear of the engine.

[0041] According to the third aspect of the present invention, there is provided an application of a rare - earth - loaded alumina composite antibacterial material in the field of antibacterial protection in a light - less or weak - light environment.

[0042] Example 1 Preparation of a rare - earth - loaded alumina composite antibacterial material: Mixing 10 parts of γ - Al2O3 with 1 part of La2O3, 1 part of CeO2, 1 part of Pr6O 11Mix with 1 part of Nd2O3 to obtain four kinds of mixed powders; add the four kinds of mixed powders into a high-energy planetary mill (QM-3SP2, China) ball mill respectively, select wear-resistant nylon jars and zirconia balls with a ball diameter of 10 - 50 mm, and the mass ratio of zirconia balls to the mixed powders is 10:1; continuously grind for 10 min and stop for 5 min alternately for 12 - 15 h to obtain four kinds of rare earth-loaded alumina composite antibacterial materials, namely La / Al, Ce / Al, Pr / Al, and Nd / Al.

[0043] Antibacterial performance test: Select Staphylococcus aureus (S. aureus, CMCC(B) 26003) and Escherichia coli (E. coli, CMCC(B) 44102) for relevant experiments. The two strains are provided by the China Medical Bacteria Preservation Management Center (CMCC(B)). Select the 4th generation of bacteria for the experiment, and use an ultraviolet spectrophotometer to prepare bacterial suspensions with a bacterial concentration of (1.0 - 5.0)×10 8 CFU / mL, and sequentially dilute them by gradient to 10 3 CFU / mL for standby.

[0044] According to the GB / T 21510-2008 standard, the oscillating method is used to detect the antibacterial performance of the rare earth-loaded alumina composite antibacterial materials.

[0045] The experiment is divided into a control group, experimental group 1, and experimental group 2, and the experimental environment is a dark environment.

[0046] The control group is to add 1 mL of Staphylococcus aureus (or Escherichia coli liquid) with a concentration of 10 5 CFU / mL into 19 mL of physiological sodium chloride solution, place it in a constant temperature oscillator at 37°C, and culture it with an oscillation contact at a speed of 150 r / min for 0.5 - 8 h. Set 3 parallel groups at each time point.

[0047] Experimental group 1 is to put 100 mg of γ-Al2O3 into a 50 mL centrifuge tube, add 19 mL of physiological sodium chloride solution and mix well, then add 1 mL of Staphylococcus aureus (or Escherichia coli liquid) with a concentration of 10 5 CFU / mL, place it in a constant temperature oscillator at 37°C, and culture it with an oscillation contact at a speed of 150 r / min for 0.5 - 8 h. Set 3 parallel groups at each time point. Experimental group 2 is to put 100 mg of rare earth-loaded alumina composite antibacterial material into a 50 mL centrifuge tube, add 19 mL of physiological sodium chloride solution and mix well, then add 1 mL of Staphylococcus aureus (or Escherichia coli liquid) with a concentration of 10 5Staphylococcus aureus (or Escherichia coli bacterial solution) at CFU / mL was placed in a constant temperature shaker at 37°C and cultured with shaking at a speed of 150 r / min for 0.5 - 8 h. Three parallel groups were set at each time point.

[0048] After reaching the time point, 100 μL of the control group and the experimental group were respectively spread on blood agar plates and continued to be cultured for 24 - 48 h. After reaching the time point, the plates were taken out, photographed and counted. The antibacterial rate (R, %) was calculated by formula (2). R ≥ 99% indicates that the material has a strong bactericidal effect, and R ≥ 90% indicates that the material has a bactericidal effect. The antibacterial rates against Staphylococcus aureus and Escherichia coli are shown in Table 1 and Table 2.

[0049]

[0050] In formula (1), C represents the average number of colonies on each sample plate; d represents the dilution factor, and in this article, d = 41; l represents the volume of the bacterial solution inoculated on the sample, and in this article l = 100. In formula (2), N control and N material represent the average number of colonies of the control group and the experimental group respectively.

[0051] Table 1 Antibacterial rate against Staphylococcus aureus

[0052] Table 2 Antibacterial rate against Escherichia coli

[0053] Cyclic bactericidal ability test: Take 100 mg of the antibacterial material in experimental group 2 and add it to 20 mL of Escherichia coli or Staphylococcus aureus bacterial solution with a concentration of 10 5 CFU / mL. After acting in a shaker at 37°C for 24 hours under dark conditions, 100 μL of the supernatant was taken out, spread on a blood agar plate and cultured for 24 - 48 hours to calculate the antibacterial rate by counting. Then the material was centrifuged and taken out, washed with absolute ethanol and ultrapure water respectively, and dried and continued to be used for the next antibacterial experiment. Repeat this 6 times. The cyclic bactericidal rates against Staphylococcus aureus are shown in Table 3, and the cyclic bactericidal rates against Escherichia coli are shown in Table 4.

[0054] Table 3 Cyclic bactericidal rate against Staphylococcus aureus

[0055] Table 4 Cyclic bactericidal rate against Escherichia coli

[0056] Example 2 Preparation of rare earth loaded alumina composite antibacterial material: Mix 10.75 parts of γ-Al2O3 with 0.25 parts of La2O3, 0.25 parts of CeO2, 0.25 parts of Pr6O 11 and 0.25 parts of Nd2O3 to prepare four kinds of rare earth loaded alumina composite antibacterial materials, namely La / Al, Ce / Al, Pr / Al and Nd / Al. The remaining steps and parameters are the same as those in Example 1.

[0057] Antibacterial performance test: The test method is the same as that in Example 1. The antibacterial rates against Staphylococcus aureus and Escherichia coli are shown in Table 5 and Table 6.

[0058] Table 5 Antibacterial rate against Staphylococcus aureus

[0059] Table 6 Antibacterial rate against Escherichia coli

[0060] Cyclic bactericidal ability test: The test method is the same as that in Example 1. The cyclic bactericidal rates against Staphylococcus aureus are shown in Table 7, and the cyclic bactericidal rates against Escherichia coli are shown in Table 8.

[0061] Table 7 Cyclic bactericidal rate against Staphylococcus aureus

[0062] Table 8 Cyclic bactericidal rate against Escherichia coli

[0063] Example 3 Preparation of rare earth loaded alumina composite antibacterial material: Mix 9 parts of γ-Al2O3 with 2 parts of La2O3, 2 parts of CeO2, 2 parts of Pr6O 11 and 2 parts of Nd2O3 to prepare four kinds of rare earth loaded alumina composite antibacterial materials, namely La / Al, Ce / Al, Pr / Al and Nd / Al. The remaining steps and parameters are the same as those in Example 1.

[0064] Antibacterial performance test: The test method is the same as that in Example 1. The antibacterial rates against Staphylococcus aureus and Escherichia coli are shown in Table 9 and Table 10.

[0065] Table 9 Antibacterial rate against Staphylococcus aureus

[0066] Table 10 Antibacterial rate against Escherichia coli

[0067] Cyclic bactericidal ability test: The test method is the same as that in Example 1. The cyclic bactericidal rates against Staphylococcus aureus are shown in Table 11, and the cyclic bactericidal rates against Escherichia coli are shown in Table 12.

[0068] Table 11 Cyclic bactericidal rate against Staphylococcus aureus

[0069] Table 12 Cyclic bactericidal rate against Escherichia coli

Claims

1. A rare earth loaded alumina composite antibacterial material, characterized in that: The raw materials of the antibacterial material include rare earth oxides and γ-Al2O3.

2. The rare earth-loaded alumina composite antibacterial material according to claim 1, characterized in that: The mass fraction of the rare earth oxide is 2.3-18%.

3. The rare earth-loaded alumina composite antibacterial material according to claim 1, characterized in that: The rare earth oxides include La2O3, CeO2, Pr6O 11 and one of Nd2O3.

4. The rare earth-loaded alumina composite antibacterial material according to claim 1, characterized in that: The particle size of the antibacterial material is 200-400 nm.

5. A method for preparing an antibacterial material according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Mixing rare earth oxide with γ-Al2O3 to obtain mixed powder; The mixed powder was added into a ball mill and ground for 12 to 15 hours to obtain a rare earth-loaded alumina composite antibacterial material.

6. The preparation method according to claim 5, characterized in that: The ball mill comprises a wear-resistant nylon tank and zirconia balls, and the diameter of the zirconia balls is 10-50 mm.

7. The preparation method according to claim 6, characterized in that: The mass ratio of the zirconia balls to the mixed powder is 10:

1.

8. The preparation method according to claim 5, characterized in that: The rotation speed of the ball mill is 400 rpm.

9. The preparation method according to claim 5, characterized in that: The grinding is performed alternately by continuous grinding for 10 minutes and stopping for 5 minutes.

10. Use of the rare earth-loaded alumina composite antibacterial material according to any one of claims 1 to 4 in the field of antibacterial protection in a lightless or weak light environment.

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