Biomimetic Au@ZnO nano-sea urchins with three-dimensional spiked structure, their preparation methods and applications

Abstract

This invention provides a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure, its preparation method, and its application. The method includes: annealing zinc acetate dihydrate to obtain zinc acetate powder; weighing the annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol, and oleylamine and adding them to a reaction system; reacting in an oil bath at 110-130℃ for a period of time, followed by reaction at 170-190℃ to obtain a biomimetic Au@ZnO nano-sea urchin solution; centrifuging, rotary evaporating, and freeze-drying the biomimetic Au@ZnO nano-sea urchin to obtain a solid powder form. This method employs a two-step synthesis strategy, constructing a core of gold nanoparticles and exposing growth crystal faces, enabling the stable growth of zinc oxide nanoparticles on their surface, successfully synthesizing a three-dimensional nanostructure. Furthermore, this method features mild reaction conditions, low energy consumption, and a simple synthesis process. The synthesized product, dissolved in a solvent, can be used for antibacterial application via spraying.

Description

Technical Field

[0001] This invention belongs to the field of synthetic nanomaterials, specifically relating to a method for preparing a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure. Background Technology

[0002] Bacteria are inextricably linked to modern society and humanity; almost every living organism, object, and environment is teeming with them. A paper published in the prestigious medical journal *The Lancet* on November 21, 2022, pointed out that bacterial infection is one of the leading causes of global health problems, second only to ischemic heart disease. Currently, most treatments for bacterial infections rely on antibiotics, but the overuse of antibiotics leads to the emergence of drug-resistant bacteria and even superbugs, undoubtedly increasing the morbidity and mortality rates of bacterial infections. Therefore, finding ways to combat bacteria without relying on antibiotics has become a crucial research topic that urgently needs to be addressed.

[0003] In nature, physical surface antibacterial agents based on the natural structures of various organisms have attracted widespread attention from researchers. Physical antibacterial agents based on natural structures mainly fall into two categories: one is where the natural structure possesses a certain degree of hydrophobicity (such as lotus leaves) or density (such as filefish and shark skin), which can weaken bacterial adhesion and prevent bacteria from multiplying and invading the surface; the other is where the natural structure has a regular array of sharp structures that can physically pierce bacteria, destroying their structure or even directly killing them. For example, the skin surfaces of cicada wings, cockroaches, and geckos all have a certain regular array of sharp structures, which can kill Gram-negative bacteria with thin cell walls to some extent, but have little effect on Gram-positive bacteria with thicker cell walls.

[0004] Currently, the synthesis of nanoparticles with sharp structures based on biomimetic techniques has been extensively studied. However, the orientation of the sharp structures in most biomimetic antibacterial nanoparticles is difficult to control, or requires cumbersome and complex printing techniques to arrange the sharp structures in an orderly manner on the surface of the prepared material. This greatly reduces the practicality and controllability of these biomimetic antibacterial nanoparticles and also results in some cytotoxicity. To prepare biomimetic nanoparticles with good antibacterial properties, the tip orientation problem of physical antibacterial activity needs to be considered, ideally with a three-dimensional biomimetic antibacterial nanostructure.

[0005] Zinc oxide boasts advantages such as environmental friendliness, good biocompatibility, wide availability, and low cost, leading to its widespread application in production and daily life, particularly in the fields of antibacterial and cosmetic applications. The use of zinc oxide materials in biosafety and medicine has a long history, dating back to pre-Christian times. Zinc oxide exhibits excellent inhibitory or bactericidal effects against a variety of Gram-negative and Gram-positive bacteria. It can also be used to synthesize various nanostructures, providing a basis for physical antibacterial processes, while the exposed crystal faces and oxygen vacancies provide a chemical antibacterial basis for releasing reactive oxygen species. Gold nanoparticles are also a biocompatible nanomaterial and a widely studied antibacterial material. Their stable properties make them ideal as a growth substrate for nanomaterials, providing corresponding crystal faces and growth sites. Summary of the Invention

[0006] To achieve the aforementioned biomimetic nanoparticles with physical antibacterial capabilities and a three-dimensional structure, this invention provides a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure, its preparation method, and its applications. This method employs a two-step synthesis strategy, constructing a core of gold nanoparticles and exposing growth crystal faces, allowing the zinc oxide nanoparticle structure to grow stably on its surface, successfully synthesizing a three-dimensional nanostructure. Furthermore, this method features mild reaction conditions, low energy consumption, and a simple synthesis process. The synthesized product, dissolved in a solvent, can be applied using a spray coating method for antibacterial purposes.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] This invention provides a method for preparing biomimetic Au@ZnO nano-sea urchins, comprising:

[0009] Zinc acetate dihydrate was annealed to obtain zinc acetate powder;

[0010] Weigh out the annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol and oleylamine and add them to the reaction system. React in an oil bath at 110-130℃ for a period of time, and then react at 170-190℃ to obtain a biomimetic Au@ZnO nano sea urchin solution.

[0011] The biomimetic Au@ZnO nano-sea urchins were centrifuged, rotary evaporated, and freeze-dried to obtain solid powdered biomimetic Au@ZnO nano-sea urchins.

[0012] Annealing zinc acetate dihydrate serves several purposes: 1. Improves microstructure: Annealing improves the microstructure of the material, making it more uniform and homogeneous; 2. Reduces residual stress: Annealing reduces residual stress in the material, preventing the formation of cracks and other defects; 3. Improves dimensional stability: Annealing improves the dimensional stability of the material, reducing the chance of deformation or other dimensional changes during the main annealing process. It also allows subsequent reactions to better grow into a spiked structure, as unannealed zinc acetate dihydrate does not readily form this specific structure.

[0013] Benzyl alcohol, as a highly polar solvent, served as the reaction system; oleylamine, as a ligand and reducing agent of chloroauric acid, reduced the [AuCl4] precursor in situ at 110-130℃ in the presence of oleylamine to form gold nanoparticle intermediates, while zinc acetate was used to prepare ZnO nanoparticles by thermal decomposition at 170-190℃.

[0014] Preferably, the molar ratio of zinc acetate dihydrate to chloroauric acid is (4-6):1. More preferably, the molar ratio of zinc acetate dihydrate, chloroauric acid, and oleylamine is (4-6):1:(150-160).

[0015] Preferably, the volume ratio of benzyl alcohol to oleylamine is (1:1) to (3:1).

[0016] Preferably, the method for annealing zinc acetate dihydrate is as follows: place zinc acetate dihydrate in a muffle furnace, set the heating rate of the muffle furnace to 10°C per minute, reach the preset temperature of 110°C, and maintain it for 5-20 minutes, then wait for it to cool naturally before use.

[0017] Preferably, the reaction time is 10-30 minutes at 110-130℃ and 30-60 minutes at 170-190℃.

[0018] Preferably, the specific steps for purifying and drying the biomimetic Au@ZnO nano-sea urchin are as follows: add 2-3 times the volume of anhydrous ethanol to the biomimetic Au@ZnO nano-sea urchin solution, mix thoroughly, centrifuge at high speed to separate the phases, discard the supernatant, dissolve the lower precipitate with chloroform, then evaporate the solution to dryness, disperse with anhydrous ethanol and centrifuge to precipitate, repeat three times, finally dissolve the precipitate in tert-butanol, freeze with liquid nitrogen and vacuum dry to obtain a solid powder sample.

[0019] A biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure is prepared by the preparation method described above.

[0020] Preferably, the gold nucleus in the biomimetic Au@ZnO nano-sea urchin has a particle size of 20-25 nm, and the ZnO nanostructure has a length of 30-120 nm.

[0021] Application of a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure as an antibacterial material.

[0022] Application of a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spiked structure as an antibacterial material for inhibiting Escherichia coli and Staphylococcus aureus.

[0023] Benzyl alcohol is used as an auxiliary solvent.

[0024] The technical solution provided by this invention has the following beneficial effects:

[0025] 1. This invention is the first to prepare a biomimetic Au@ZnO nano-sea urchin with a three-dimensional spike structure.

[0026] 2. The biomimetic Au@ZnO nano-sea urchin composite material prepared by this invention has good dispersibility (the surface has oleylamine as a ligand, which can be dissolved in highly polar solvents), the gold core particle size is 20-25nm (the proportion of oleylamine reduction intermediate and the nucleation time are controlled, thereby controlling the gold core size), and the ZnO nano-straw structure length is 30-120nm (the time of zinc acetate thermal decomposition is controlled).

[0027] 3. The biomimetic Au@ZnO nano-sea urchins prepared by this invention can be uniformly and stably dispersed in n-hexane. They can be easily sprayed directly using a spray bottle for physical antibacterial purposes, exhibiting broad-spectrum, high-efficiency, stable, and non-toxic characteristics, and are applicable to various material surfaces. They can achieve inhibition rates of over 99.99% against Escherichia coli and Staphylococcus aureus. Attached Figure Description

[0028] Figure 1 This is the ultraviolet absorption spectrum of the biomimetic Au@ZnO nano-sea urchin of Example 1 of the present invention.

[0029] Figure 2 This is a transmission electron microscope image of the biomimetic Au@ZnO nano-sea urchin of Example 1 of the present invention.

[0030] Figure 3 This is a transmission electron microscope image of the biomimetic Au@ZnO nano-sea urchin of Example 1 of the present invention.

[0031] Figure 4 This is a STEM image of the biomimetic Au@ZnO nano-sea urchin from Example 1 of the present invention.

[0032] Figure 5 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 EDS mapping image of gold elements.

[0033] Figure 6 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 EDS mapping image of zinc.

[0034] Figure 7 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 EDS mapping image of oxygen in medium.

[0035] Figure 8 The images show data on the antibacterial effects of the biomimetic Au@ZnO nano-sea urchins of Example 1 of this invention on Escherichia coli and Staphylococcus aureus.

[0036] Figure 9 This is a schematic diagram illustrating the antibacterial effect of the biomimetic Au@ZnO nano-sea urchin prepared in this invention using a spray coating method. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, these should not be construed as limiting the present invention and are merely examples.

[0038] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0039] Example 1

[0040] This embodiment provides a method for preparing biomimetic Au@ZnO nano-sea urchins with a three-dimensional spiked structure, including:

[0041] Step 1: Annealing with zinc acetate dihydrate:

[0042] Place zinc acetate dihydrate in a muffle furnace and set the heating rate of the muffle furnace to 10°C per minute. Once the preset temperature of 110°C is reached, maintain it for 15 minutes and allow it to cool naturally before use.

[0043] Step 2: Synthesis of biomimetic Au@ZnO nano-sea urchins:

[0044] The annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol, and oleylamine were weighed and added to the reaction system. The mixture was reacted in an oil bath at 120°C for 25 minutes, and then at 180°C for 45 minutes to obtain a biomimetic Au@ZnO nano-sea urchin solution. The molar ratio of zinc acetate dihydrate, chloroauric acid, and oleylamine was 5:1:150, and the volume ratio of benzyl alcohol to oleylamine was 2:1.

[0045] Step 3: Purification of biomimetic Au@ZnO nano-sea urchins:

[0046] Purification of biomimetic Au@ZnO nano-sea urchins: Add 2-3 times the volume of anhydrous ethanol to the biomimetic Au@ZnO nano-sea urchin solution in step two above, mix thoroughly, centrifuge at high speed to separate the phases, discard the supernatant, dissolve the lower precipitate with chloroform, then evaporate the solution to dryness, disperse with anhydrous ethanol and centrifuge to precipitate, repeat three times, finally dissolve the precipitate in tert-butanol, freeze with liquid nitrogen and vacuum dry to obtain a solid powder sample.

[0047] Example 2

[0048] This embodiment provides a method for preparing biomimetic Au@ZnO nano-sea urchins with a three-dimensional spiked structure, including:

[0049] Step 1: Annealing with zinc acetate dihydrate:

[0050] Place zinc acetate dihydrate in a muffle furnace and set the heating rate of the muffle furnace to 10°C per minute. Once the preset temperature of 110°C is reached, maintain it for 20 minutes and allow it to cool naturally before use.

[0051] Step 2: Synthesis of biomimetic Au@ZnO nano-sea urchins:

[0052] The annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol, and oleylamine were weighed and added to the reaction system. The mixture was reacted in an oil bath at 110°C for 30 minutes, followed by a reaction at 190°C for 30 minutes to obtain a biomimetic Au@ZnO nano-sea urchin solution. The molar ratio of zinc acetate dihydrate, chloroauric acid, and oleylamine was 4:1:155, and the volume ratio of benzyl alcohol to oleylamine was 1:1.

[0053] Step 3: Purification of biomimetic Au@ZnO nano-sea urchins:

[0054] Purification of biomimetic Au@ZnO nano-sea urchins: Add 2-3 times the volume of anhydrous ethanol to the biomimetic Au@ZnO nano-sea urchin solution in step two above, mix thoroughly, centrifuge at high speed to separate the phases, discard the supernatant, dissolve the lower precipitate with chloroform, then evaporate the solution to dryness, disperse with anhydrous ethanol and centrifuge to precipitate, repeat three times, finally dissolve the precipitate in tert-butanol, freeze with liquid nitrogen and vacuum dry to obtain a solid powder sample.

[0055] Example 3

[0056] This embodiment provides a method for preparing biomimetic Au@ZnO nano-sea urchins with a three-dimensional spiked structure, including:

[0057] Step 1: Annealing with zinc acetate dihydrate:

[0058] Place zinc acetate dihydrate in a muffle furnace and set the heating rate of the muffle furnace to 10°C per minute. Once the preset temperature of 110°C is reached, maintain it for 5 minutes and allow it to cool naturally before use.

[0059] Step 2: Synthesis of biomimetic Au@ZnO nano-sea urchins:

[0060] The annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol, and oleylamine were weighed and added to the reaction system. The mixture was reacted in an oil bath at 130°C for 10 minutes, and then at 170°C for 60 minutes to obtain a biomimetic Au@ZnO nano-sea urchin solution. The molar ratio of zinc acetate dihydrate, chloroauric acid, and oleylamine was 6:1:160, and the volume ratio of benzyl alcohol to oleylamine was 3:1.

[0061] Step 3: Purification of biomimetic Au@ZnO nano-sea urchins:

[0062] Purification of biomimetic Au@ZnO nano-sea urchins: Add 2-3 times the volume of anhydrous ethanol to the biomimetic Au@ZnO nano-sea urchin solution in step two above, mix thoroughly, centrifuge at high speed to separate the phases, discard the supernatant, dissolve the lower precipitate with chloroform, then evaporate the solution to dryness, disperse with anhydrous ethanol and centrifuge to precipitate, repeat three times, finally dissolve the precipitate in tert-butanol, freeze with liquid nitrogen and vacuum dry to obtain a solid powder sample.

[0063] This invention will use the biomimetic Au@ZnO nano-sea urchin prepared in Example 1 as an example to characterize and illustrate the preparation results:

[0064] Figure 1 The image shows the ultraviolet absorption spectrum of the biomimetic Au@ZnO nano-sea urchin from Example 1 of this invention, reflecting the ultraviolet-visible light absorption of Au@SPh. It exhibits obvious absorption peaks at 360, 408, and 520 nm, corresponding to the structural characteristic peaks of zinc oxide and gold nanoparticles.

[0065] Figure 2 The image shows a transmission electron microscope (TEM) image of the biomimetic Au@ZnO nano-sea urchin from Example 1 of this invention. The TEM image shows that the biomimetic Au@ZnO nano-sea urchin is about 140 nm in size, with the gold core being 20-25 nm in size and the zinc oxide nanoparticles being 30-120 nm in size.

[0066] Figure 4 This is a STEM image of the biomimetic Au@ZnO nano-sea urchin from Example 1 of the present invention, showing the morphology of the biomimetic Au@ZnO nano-sea urchin.

[0067] Figure 5 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 EDS mapping images of gold elements show that Figure 4 The distribution of gold elements in the nano-bionic sea urchin shows that its core is gold.

[0068] Figure 6 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 EDS mapping image of zinc element shows Figure 4 Distribution of zinc in China.

[0069] Figure 7 The biomimetic Au@ZnO nano-sea urchin of Example 1 of this invention Figure 4 The oxygen element EDS mapping image shows that Figure 4 The distribution of oxygen in the medium shows that the three-dimensional nanostructure is composed of zinc oxide.

[0070] To more easily illustrate how the technical solution of this invention can successfully prepare black phosphorus-supported gold nanoclusters, Example 1 is preferred for illustration. Examples 2 and 3 have also been successfully synthesized, and will not be described in detail here.

[0071] Experimental Example 1

[0072] The biomimetic Au@ZnO nano-sea urchin sample used in this experiment was obtained in Example 1 and applied to the antibacterial experiment:

[0073] The antibacterial activity of biomimetic Au@ZnO nano-sea urchins was studied using the colony-forming unit (CFU) method on Luria-Bertani (LB) agar plates, with *Escherichia coli* (Gram-negative bacteria) and *Staphylococcus aureus* (Gram-positive bacteria) as representative bacteria. *E. coli* or *Staphylococcus aureus* were cultured in LB medium. The original bacterial suspension was incubated overnight in a shaking incubator at 37°C. The bacterial suspension was then diluted with PBS (pH 7.4), and *E. coli* or *Staphylococcus aureus* (1×10⁻⁶) were added to the suspension. 7 CFU mL -1 The bacterial suspension was incubated with control (PBS) or biomimetic Au@ZnO nano-sea urchins at 37°C for 24 hours. For colony counting, the bacterial suspension was spread on agar plates and incubated for another 24 hours to evaluate its antibacterial activity. The bacterial lethality rate was calculated using the following formula:

[0074]

[0075] Figure 8The images show antibacterial data of the biomimetic Au@ZnO nanocomposite material of Example 1 of this invention for Escherichia coli and Staphylococcus aureus. As can be seen from the images, the upper left culture dish is the E. coli control group, where many E. coli colonies grew on the LB plate. However, the upper right plate, after co-incubation with biomimetic Au@ZnO nano-sea urchins, showed no obvious colonies, demonstrating its strong killing effect on E. coli. Similarly, the lower left culture dish is the Staphylococcus aureus control group, where many Staphylococcus aureus colonies grew on the LB plate. The lower right plate, after co-incubation with biomimetic Au@ZnO nano-sea urchins, showed no obvious colonies, demonstrating its strong killing effect on Staphylococcus aureus.

[0076] In some embodiments, such as Figure 9 As shown, the synthesized biomimetic Au@ZnO nano-sea urchin can be dissolved in a solvent and then sprayed for antibacterial treatment.

[0077] To more easily illustrate the antibacterial properties of the biomimetic Au@ZnO nano-sea urchins prepared using the technical solution of this invention, Example 1 is preferred for illustration. The inhibitory effects of Examples 2 and 3 are basically the same as those of Example 1, and will not be described in detail here.

[0078] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A preparation method of biomimetic Au@ZnO nanochalices, characterized in that, The application relates to a preparation method of biomimetic Au@ZnO nanochalk. The zinc acetate dihydrate is annealed to obtain zinc acetate powder, including placing the zinc acetate dihydrate in a muffle furnace, setting the heating speed of the muffle furnace to 10 DEG C per minute, reaching a preset temperature of 110 DEG C and keeping for 5-20 minutes, and waiting for natural cooling to be used; The annealed zinc acetate powder, chloroauric acid powder, benzyl alcohol and oleylamine are weighed and added into a reaction system, reacted in an oil bath at 110-130 DEG C for 10-30 minutes, and then reacted at 170-190 DEG C for 30-60 minutes to obtain a biomimetic Au@ZnO nanochalk solution; The biomimetic Au@ZnO nanochalk is centrifuged, rotary evaporated and freeze-dried to obtain a solid powder of the biomimetic Au@ZnO nanochalk, wherein the gold core particle size of the biomimetic Au@ZnO nanochalk is 20-25 nm, and the ZnO nanostyle structure length is 30-120 nm.

2. The method for preparing biomimetic Au@ZnO nano-sea urchins according to claim 1, characterized in that, The molar ratio of the zinc acetate dihydrate, the chloroauric acid and the oleylamine is (4-6):1: (150-160).

3. The method for preparing biomimetic Au@ZnO nano-sea urchins according to claim 1, characterized in that, The volume ratio of the benzyl alcohol and the oleylamine is (1:1)-(3:1).

4. The method for preparing biomimetic Au@ZnO nano-sea urchins according to claim 1, characterized in that, The purification and drying of the biomimetic Au@ZnO nanochalk are carried out by adding 2-3 times of anhydrous ethanol into the biomimetic Au@ZnO nanochalk solution, mixing thoroughly, high-speed centrifuging, discarding the upper clear night, dissolving the lower precipitate in chloroform, rotary evaporating the solution, dispersing in anhydrous ethanol and centrifuging, repeating three times, dissolving the precipitate in t-butyl alcohol, freezing in liquid nitrogen and vacuum drying to obtain a solid powder sample.

5. A biomimetic Au@ZnO nanochalica with three-dimensional spiny structure, characterized in that, The biomimetic Au@ZnO nanochalk is prepared by the preparation method in any one of claims 1-4. 6.The application of the biomimetic Au@ZnO nanochalk according to claim 5, characterized in that, The biomimetic Au@ZnO nanochalk is applied to antibacterial materials. 7.The application of the biomimetic Au@ZnO nanochacle according to claim 5, characterized in that, The biomimetic Au@ZnO nanochalk is applied to antibacterial materials for inhibiting escherichia coli and staphylococcus aureus.

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