Silver / schiff base-based antibacterial material, preparation method and application thereof

Abstract

The application discloses a silver / schiff base antibacterial material, a preparation method and application, and relates to the field of antibacterial materials.The silver / schiff base antibacterial material, the preparation method and the application are characterized in that, based on the large electron cloud density of the carbon-nitrogen double bond of the schiff base, silver ions in a silver nitrate solution are uniformly adsorbed on a schiff base base through the electrostatic adsorption principle; under the reduction of a reducing agent, the silver ions are reduced to nanosilver ions, and a silver / schiff base antibacterial material is obtained, in which nanosilver ions in the form of nanospheres are uniformly dispersed on the schiff base in the form of a thin sheet layer, thereby greatly improving the dispersibility of the nanosilver ions.The preparation method is simple, low in cost, and capable of batch production, and has no cytotoxicity, and has high antibacterial effects on streptococcus, pseudomonas aeruginosa and staphylococcus aureus, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of antibacterial materials technology, specifically to a silver / Schiff base antibacterial material, its preparation method, and its application. Background Technology

[0002] Bacterial infection, an acute systemic infection caused by pathogenic or opportunistic pathogens invading the bloodstream, multiplying, and producing toxins and other metabolic products, has become the second leading cause of death. In the long and arduous struggle between humans and bacteria, antibiotics have been the most powerful weapon. However, with the increasing resistance of bacteria, antibiotic use has gradually increased, making antibiotic abuse a global public health problem.

[0003] To address these issues, antibacterial agents have been gradually developed. Currently, the types of antibacterial agents that have been developed and applied fall into three main categories: inorganic antibacterial agents, organic antibacterial agents, and composite antibacterial agents. Inorganic antibacterial agents utilize the antibacterial properties of metals such as silver, copper, and zinc, and are made by fixing these metals onto the surface of porous materials such as fluorite and silica gel through methods such as physical adsorption and ion exchange. To improve the antibacterial effect of inorganic antibacterial agents, scientists are dedicated to developing various nanomaterials, including silver nanoparticles, metal oxides, carbon-based nanostructures, and silica nanoparticles. Silver nanoparticles, with their stable chemical properties and excellent performance, have been widely used in the antibacterial field. Currently, many materials can be composited with silver nanoparticles, such as carbon fibers and graphene. However, when carbon fibers and other materials are composited with silver nanoparticles, the problem of silver nanoparticle agglomeration occurs, leading to low antibacterial efficiency. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention proposes the following technical solution:

[0005] This invention provides a silver / Schiff base antibacterial material, the microstructure of which is silver nanospheres uniformly dispersed on a thin sheet of Schiff base; wherein the silver is orthorhombic nanoparticles with a particle size of 1-20 nm.

[0006] This invention provides a method for preparing a silver / Schiff base antibacterial material, the method comprising:

[0007] S01: Add silver nitrate solution and Schiff base material to anhydrous ethanol and stir until completely dispersed to form a mixture.

[0008] Schiff bases are a class of organic compounds containing imine or methylimine characteristic groups, possessing certain pharmacological and physiological activities. Schiff bases have numerous active sites in their carbon-nitrogen double bonds, exhibiting stable properties and good biocompatibility, making them suitable as substrate materials for composites with nanomaterials. In this application, the high electron cloud density of the carbon-nitrogen double bonds in the Schiff base allows for the adsorption of silver ions from silver nitrate solution onto the Schiff base substrate via electrostatic adsorption.

[0009] Appendix Figure 1-3 The structural formulas of the macrocyclic Schiff base substrate materials used in the embodiments of this application are shown respectively. In this application, silver nitrate solution and Schiff base substrate material are added to anhydrous ethanol and stirred until completely dispersed to form a mixture. The solubility of the silver nitrate solution is 0.1-0.3 mol / L. The molar ratio of silver nitrate solution to Schiff base substrate material is 1:1-4:1. The amount of anhydrous ethanol added is 10-20 mL.

[0010] S02: Add a reducing agent to the mixture, stir evenly, and adjust to alkalinity.

[0011] A reducing agent is added to the mixture to reduce the silver ions adsorbed on the Schiff base substrate to nano-silver ions. Since silver nitrate is in solution, the silver ions in the silver nitrate solution can be uniformly adsorbed on the Schiff base substrate. The reduced nano-silver ions are uniformly dispersed on the Schiff base substrate, which greatly improves the dispersibility of the nano-silver ions and thus enhances the antibacterial effect.

[0012] In this application, the molar ratio of the reducing agent to silver nitrate is 2:1-3:1. The reducing agent includes at least one of DMF (N,N-Dimethylformamide), NaBH4 (Sodium borohydride), butanediamine, and α-tocopherol. The pH of the mixture is adjusted to 9-11 using an alkaline solution, such as sodium hydroxide solution. The stirring speed of the mixture and the reducing agent is 100-300 r / min.

[0013] S03: After the mixture, which has been adjusted to alkalinity, is heated to react, cooled to room temperature, the reaction product is filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material.

[0014] The alkaline mixture was heated at 70-100℃ for 3-6 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 60-100℃, and the drying time was 4-12 hours.

[0015] This application also provides an application of a silver / Schiff base antibacterial material that is capable of resisting Streptococcus sanguinis, Pseudomonas aeruginosa, and Staphylococcus aureus.

[0016] The silver / Schiff base antibacterial material, its preparation method, and its application provided in this application utilize the high electron cloud density of the carbon-nitrogen double bond in Schiff bases. Silver ions from silver nitrate solution are uniformly adsorbed onto a Schiff base substrate via electrostatic adsorption. Under the reducing action of a reducing agent, the silver ions are reduced to nano-silver ions, resulting in a silver / Schiff base antibacterial material with nano-spherical silver uniformly dispersed on a thin, layered Schiff base, significantly improving the dispersibility of the nano-silver ions. The preparation method provided in this application is simple, low-cost, and suitable for mass production. It is non-cytotoxic and exhibits highly effective antibacterial activity against Streptococcus sanguinis, Pseudomonas aeruginosa, and Staphylococcus aureus, demonstrating promising application prospects. Attached Figure Description

[0017] Figure 1 The 2+2 type macrocyclic Schiff base structure provided in the embodiments of the present invention;

[0018] Figure 2 The 2+3 type macrocyclic Schiff base structure provided in the embodiments of the present invention;

[0019] Figure 3 The 2+4 type macrocyclic Schiff base structure provided in the embodiments of the present invention;

[0020] Figure 4 The image shows the XRD pattern of the silver / Schiff base antibacterial material provided in the embodiments of the present invention, wherein the silver / Schiff base antibacterial material is represented by Ag@Schiff base;

[0021] Figure 5 A magnified TEM image of the silver / Schiff base antibacterial material provided in an embodiment of the present invention;

[0022] Figure 6 TEM diffraction ring pattern of the silver / Schiff base antibacterial material provided in the embodiments of the present invention;

[0023] Figure 7 SEM image of a 2+3 type macrocyclic Schiff base provided in an embodiment of the present invention;

[0024] Figure 8 SEM images of substrate-free silver nanomaterials prepared using the same method, as provided in embodiments of the present invention;

[0025] Figure 9 The graph shows the test results of antibacterial activity against Streptococcus sanguinis without the addition of silver / Schiff base antibacterial material.

[0026] Figure 10 The image shows the detection results of the silver / Schiff base antibacterial material provided in the embodiments of the present invention against Streptococcus sanguinis.

[0027] Figure 11 The image shows the detection results of the antibacterial activity of the silver / Schiff base-free antibacterial material provided in this embodiment of the invention against Pseudomonas aeruginosa.

[0028] Figure 12 The image shows the detection results of the silver / Schiff base antibacterial material provided in the embodiments of the present invention against Pseudomonas aeruginosa.

[0029] Figure 13 The image shows the detection results of the antibacterial activity of the silver / Schiff base-free antibacterial material against Staphylococcus aureus provided in the embodiments of the present invention.

[0030] Figure 14 The graph shows the detection results of the silver / Schiff base antibacterial material provided in the embodiments of the present invention against Staphylococcus aureus. Detailed Implementation

[0031] The preparation method of the silver / Schiff base antibacterial material provided in the embodiments of this application is described in detail below.

[0032] Example 1

[0033] The preparation method of the silver / Schiff base antibacterial material provided in this application includes:

[0034] S101: Add 10 ml of silver nitrate solution with a concentration of 0.1 mol / L and 0.025 mmol of Schiff base material to 10 mL of anhydrous ethanol, and stir until completely dispersed to form a mixture.

[0035] S102: Add 3 ml of 0.2 mol / L ethanol solution of α-tocopherol to the mixture, stir until homogeneous at a stirring speed of 100 r / min, and adjust the pH of the mixture to 10 using NaOH solution.

[0036] S103: The mixture with pH adjusted to 10 was heated at 80℃ for 3 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 70℃, and the drying time was 6 hours.

[0037] Example 2

[0038] The preparation method of the silver / Schiff base antibacterial material provided in this application includes:

[0039] S201: Add 10 ml of silver nitrate solution with a concentration of 0.1 mol / L and 0.025 mmol of Schiff base material to 20 mL of anhydrous ethanol, and stir until completely dispersed to form a mixture.

[0040] S202: Add 2 ml of ethanol solution of butanediamine with a concentration of 0.2 mol / L to the mixture, stir until homogeneous at a stirring speed of 300 r / min, and adjust the pH of the mixture to 10 using NaOH solution.

[0041] S203: The mixture with pH adjusted to 10 was heated at 90℃ for 4 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 80℃, and the drying time was 4 hours.

[0042] Example 3

[0043] The preparation method of the silver / Schiff base antibacterial material provided in this application includes:

[0044] S301: Add 10 ml of 0.1 mol / L silver nitrate solution and 0.025 mmol of Schiff base material to 20 mL of anhydrous ethanol, and stir until completely dispersed to form a mixture.

[0045] S302: Add 5 ml of 0.2 mol / L ethanol solution of α-tocopherol to the mixture, stir until homogeneous at a stirring speed of 200 r / min, and adjust the pH of the mixture to 11 using NaOH solution.

[0046] S303: The mixture with pH adjusted to 11 was heated at 90℃ for 4 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 90℃, and the drying time was 4 hours.

[0047] Example 4

[0048] The preparation method of the silver / Schiff base antibacterial material provided in this application includes:

[0049] S401: Add 10 ml of 0.1 mol / L silver nitrate solution and 0.1 mmol of Schiff base material to 15 mL of anhydrous ethanol, and stir until completely dispersed to form a mixture.

[0050] S402: Add 3 ml of NaBH4 with a concentration of 0.3 mol / L to the mixture, stir until homogeneous at a stirring speed of 150 r / min, and adjust the pH of the mixture to 9 using NaOH solution.

[0051] S403: The mixture with pH adjusted to 9 was heated at 70℃ for 6 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 60℃, and the drying time was 12 hours.

[0052] Example 5

[0053] The preparation method of the silver / Schiff base antibacterial material provided in this application includes:

[0054] S501: Add 10 ml of 0.3 mol / L silver nitrate solution and 0.075 mmol Schiff base material to 20 mL of anhydrous ethanol, stir until completely dispersed to form a mixture.

[0055] S502: Add 3 ml of DMF with a concentration of 0.6 mol / L to the mixture, stir until homogeneous at a stirring speed of 200 r / min, and adjust the pH of the mixture to 11 using NaOH solution.

[0056] S503: The mixture with pH adjusted to 11 was heated at 100℃ for 3 hours. After the reaction, it was cooled to room temperature. The reaction product, cooled to room temperature, was then filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material. The vacuum drying temperature was 100℃, and the drying time was 5 hours.

[0057] To verify that the silver / Schiff base antibacterial material provided in this application has good dispersibility, the silver / Schiff base antibacterial material prepared in Example 1 was subjected to XRD (x-ray diffraction) and TEM (transmission electron microscope) tests. The test results are shown in the attached figure. Figure 4 , 5 6. Additionally, the embodiments of this application also include appendices. Figure 2 The 2+3 type macrocyclic Schiff base and the substrate-free silver nanomaterial prepared using the same method were tested using SEM (Scanning Electron Microscope). The results are shown in the attached figure. Figure 7 , 8 From the appendix Figure 5-8It can be seen that the 2+3 type macrocyclic Schiff base has a rod-shaped structure, the substrate-free silver nanomaterial has an aggregated particulate structure, while the silver / Schiff base antibacterial material prepared in Example 1 of this application has a structure in which particulate matter is uniformly distributed on a sheet structure. Thus, it can be seen that the microstructure of the silver / Schiff base antibacterial material provided in this application is that the silver nanospheres are uniformly dispersed on the sheet-like Schiff base.

[0058] In addition, the antibacterial properties of the prepared silver / Schiff base antibacterial material were tested in this application embodiment. Specifically, *Streptococcus sanguinis*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* were placed in Luria-Bertani (LB) or Muellerhinton (MH) broth and allowed to grow overnight by shaking at 37°C and 200 rpm. The bacteria were gently separated from the agar plates using a sterile loop and then incubated overnight at 37°C with the culture medium. 0.5 mL of the overnight grown *Streptococcus sanguinis*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* cultures were incubated with 10 mL of LB medium, and the silver / Schiff base antibacterial material prepared in Example 3 of this application was added, followed by incubation at 37°C for 24 hours. As a comparative example, 0.5 mL of overnight cultures of *Streptococcus sanguinis*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* were incubated with 10 mL of LB medium, followed by the addition of 10 μL of 10 mmol / L H₂O₂, and then incubated at 37°C for 24 hours. After eight consecutive dilutions, 10 μL of each sample was placed on an agar plate and incubated for 12 hours to observe the bacterial colony count. The antibacterial activity of the silver / Schiff base antibacterial material prepared in Example 3 of this application was evaluated using the colony-forming unit (CFU) counting method, and the test results are attached. Figure 9-14 As shown. After testing, the silver / Schiff base antibacterial material prepared in Example 3 of this application showed antibacterial effects of 96.2%, 96.4%, and 96.3% against Streptococcus sanguinis, Pseudomonas aeruginosa, and Staphylococcus aureus, respectively, demonstrating high antibacterial efficacy.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A silver / Schiff base antibacterial material, characterized in that, The antibacterial material has a microstructure consisting of nanospheres of silver uniformly dispersed on a thin, layered Schiff base; wherein the silver is orthorhombic nanoparticles with a particle size of 1-20 nm; the structural formula of the Schiff base is shown below: 2+2 type macrocyclic Schiff base structure: ; 2+3 type macrocyclic Schiff base structure: ; 2+4 type macrocyclic Schiff base structure: ; The preparation method of the silver / Schiff base antibacterial material includes: Silver nitrate solution and Schiff base material were added to anhydrous ethanol and stirred until completely dispersed to form a mixture. A reducing agent is added to the mixture, and after stirring evenly, the solution is adjusted to be alkaline. After the mixture, adjusted to alkalinity, is heated to react, cooled to room temperature, and the reaction product is filtered, washed with acetone, and vacuum dried to obtain the silver / Schiff base antibacterial material.

2. The silver / Schiff base antibacterial material according to claim 1, characterized in that, The molar ratio of the silver nitrate solution to the Schiff base substrate material is 1:1-4:1; the molar ratio of the reducing agent to the silver nitrate is 2:1-3:

1.

3. The silver / Schiff base antibacterial material according to claim 1 or 2, characterized in that, The concentration of the silver nitrate solution is 0.1-0.3 mol / L.

4. The method for preparing the silver / Schiff base antibacterial material according to claim 2, characterized in that, The reducing agent includes at least one of DMF, NaBH4, butanediamine, and α-tocopherol.

5. The silver / Schiff base antibacterial material according to claim 1, characterized in that, The amount of anhydrous ethanol added is 10-20 mL.

6. The silver / Schiff base antibacterial material according to claim 1, characterized in that, The pH of the mixture is adjusted to 9-11.

7. The silver / Schiff base antibacterial material according to claim 1, characterized in that, The reaction temperature of the mixture is 70-100℃, and the reaction time is 3-6h.

8. The silver / Schiff base antibacterial material according to claim 1, characterized in that, The temperature for vacuum drying is 60-100℃, and the drying time is 4-12 hours.

9. The silver / Schiff base antibacterial material according to claim 1 is used for antibacterial activity against Streptococcus sanguinis, Pseudomonas aeruginosa, and Staphylococcus aureus.

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