Ce-MOF enzyme antibacterial agent and preparation method thereof

Abstract

The invention discloses a Ce-MOF enzyme antibacterial agent and a preparation method thereof. The preparation method comprises the following steps: dispersing Ce-MOF powder in deionized water to obtain a suspension; adding sodium hydroxide and hydrogen peroxide into the suspension, and mixing and oxidizing for 1-5 minutes; centrifugally washing and freeze-drying to obtain yellow powder in a mixed valence state; the particle size range of the yellow powder is 300 to 700 nm; the concentration range of the sodium hydroxide in the suspension liquid is 0.03 mol / L to 0.05 mol / L; the concentration range of the hydrogen peroxide in the suspension liquid is 2-3 mmol / L; the Ce-MOF is further oxidized, so that the content ratio of Ce < 3 + > to Ce < 4 + > in the Ce-MOF is changed, and the enzyme-like activity of the Ce-MOF is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of materials, and in particular relates to an enzyme-like antibacterial agent and a preparation method thereof. Background Art

[0002] The shipping industry is an important part of global trade and logistics. Most international trade relies on maritime transport. Ships transport goods quickly and at low cost, playing a vital role in the global economy. When a ship is sailing, a large number of fouling organisms will adhere to the underwater hull, forming a biofilm, causing adhesion and biological corrosion on the surface of the facilities. Marine biofouling can cause many hazards to marine facilities and ships. This fouling will increase the resistance of ships and marine facilities, increase fuel consumption, and reduce energy efficiency; it will accelerate corrosion and wear of metal surfaces, shorten the service life of facilities and ships, and increase maintenance costs; in severe cases, it will affect the maneuverability of ships, increase navigation risks, and even cause accidents. Therefore, research on marine anti-fouling is imperative, which is a strong guarantee for the steady implementation of the strategy of building a strong maritime nation, and has great strategic significance for the construction of a strong maritime nation.

[0003] Among the many antifouling methods, enzyme antifouling mainly refers to the antifouling coating method that uses enzymes as fouling inhibitors. Natural enzymes are biological macromolecules with high specificity and catalytic properties. They are extremely important biocatalysts. With the in-depth study of enzymes, it is shown that natural enzymes have certain limitations and are easily inactivated under changes in factors such as pH and temperature, and their potential antifouling applications are limited. As a mimetic of natural enzymes, nanozymes have the unique properties of nanomaterials, with high stability, adjustable enzyme activity, diverse structures, and diversified preparation methods. Compared with natural enzymes, they have great development potential.

[0004] The biofouling prevention method based on haloperoxidase can catalyze halogen elements (such as bromine) to form halogenated substances to kill fouling organisms in the presence of trace amounts of hydrogen peroxide in the ocean; it affects the transmission of fouling organism signal factors and inhibits the formation of biofilms, so it has a strong inhibitory ability against marine fouling organisms. Cerium oxide nanoparticles are ideal mimics of haloperoxidase, but they are prone to agglomeration and reduce enzyme activity, and are difficult to recycle after use. Summary of the invention

[0005] The present invention aims to provide a Ce-MOF enzyme antibacterial agent and a preparation method thereof, by further oxidizing Ce-MOF to change the Ce in Ce-MOF. 3+ / Ce 4+ The content ratio of Ce-MOF can further improve the enzyme-like activity of Ce-MOF.

[0006] In order to achieve the above purpose, the technical solutions adopted are as follows: A Ce-MOF enzyme antibacterial agent is obtained by oxidizing Ce-MOF powder with a mixed aqueous solution of sodium hydroxide and hydrogen peroxide.

[0007] According to the above scheme, the concentration range of the sodium hydroxide is 0.03~0.05mol / L.

[0008] According to the above scheme, the concentration range of hydrogen peroxide is 2~3mmol / L.

[0009] According to the above scheme, the oxidation reaction time is 1-5min.

[0010] The preparation method of the above-mentioned enzyme antibacterial agent comprises the following steps: Ce-MOF powder is dispersed in deionized water to obtain a suspension; sodium hydroxide and hydrogen peroxide are added to the suspension for mixed oxidation reaction for 1-5 minutes; centrifugal washing and freeze-drying are performed to obtain a mixed valence yellow powder.

[0011] According to the above scheme, the particle size range of the yellow powder is 300~700nm.

[0012] According to the above scheme, the concentration range of sodium hydroxide in the suspension is 0.03-0.05 mol / L; the concentration range of hydrogen peroxide in the suspension is 2-3 mmol / L.

[0013] According to the above scheme, the preparation method of the Ce-MOF powder includes the following steps: Dissolve cerium nitrate hexahydrate and benzenetricarboxylic acid in a water-ethanol mixed solution; stir and react at 50-70° C. for more than 1 hour to obtain a white mixed solution; and obtain white powder Ce-MOF through centrifugal washing and freeze drying.

[0014] According to the above scheme, the volume ratio of water to ethanol in the water-ethanol mixed solution is 10:1.

[0015] According to the above scheme, the molar ratio of cerium nitrate hexahydrate to trimesic acid is 1:1; the concentration range of cerium nitrate hexahydrate in the mixed solution is 0.15-0.2 mol / L; the concentration range of trimesic acid in the mixed solution is 0.15-0.2 mol / L.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Cerium oxide nanoparticles are ideal mimics of haloperoxidase, but they are prone to agglomeration, which reduces enzyme activity and is difficult to recycle after use. MOF-based nanozymes have the excellent properties of the parent MOFs, such as large specific surface area, high porosity, and easy chemical modification. Ce-MOF is composed of metal clusters and organic ligands, with abundant surface active sites and regulated pore structures. These properties enable it to exhibit good catalytic activity in catalytic reactions, especially in redox reactions, similar to the active centers of natural enzymes. The present invention further oxidizes the prepared Ce-MOF and controls the oxidation time to change the Ce in Ce-MOF. 3+ / Ce 4+ The content ratio further improved the enzyme-like activity of Ce-MOF. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : XRD patterns of the products obtained in Examples 1, 2, 3 and Ce-MOF.

[0018] Figure 2 : TEM images of the products obtained in Examples 1, 2, 3 and Ce-MOF.

[0019] Figure 3 : XPS graphs of the products obtained in Examples 1, 2, 3 and Ce-MOF.

[0020] Figure 4 : Enzyme activity curves of the products obtained in Examples 1, 2, and 3 and Ce-MOF at pH=8.

[0021] Figure 5 : The antibacterial effect diagram of the products obtained in Examples 1, 2, and 3 and Ce-MOF applied in antifouling experiments. DETAILED DESCRIPTION

[0022] The following examples further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0023] A specific embodiment provides a method for preparing Ce-MOF powder: 4.34 g of cerium nitrate hexahydrate was dissolved in 45 mL of deionized water, called solution A; 2.10 g of benzenetricarboxylic acid was dissolved in 10 mL of deionized water-ethanol (molar ratio 1:1), called solution B; solution B was strongly magnetically stirred while adding solution A dropwise, and reacted in a 60°C water bath for one hour; the reaction mixture was separated in a centrifuge, and then washed several times with ethanol and deionized water; the precipitate was dried in a freeze dryer for 24 hours, and finally a pure white Ce-MOF powder with a particle size range of 300~700 nm was obtained.

[0024] Example 1 20 mg of Ce-MOF was dissolved in 4 mL of deionized water and ultrasonicated for 10 min to form a suspension. 5 mg of sodium hydroxide and 2.5 μL of hydrogen peroxide were added to the suspension and reacted for 1 min.

[0025] The light yellow precipitate was separated by centrifugation at a speed of 12000 rpm for 1 min, and washed several times with deionized water until the pH of the supernatant was ≈ 7. The precipitate was then dried in a freeze dryer for 24 h to obtain a light yellow powder MVCM (Ce-MOF-1).

[0026] Example 2 Example 1 was repeated, the reaction time was 3 min, and the remaining steps were consistent with Example 1, and finally pale yellow powder Ce-MOF-3 was obtained.

[0027] Example 3 Example 1 was repeated, the reaction time was 5 min, and the remaining steps were consistent with Example 1, and finally light yellow powder MVCM (Ce-MOF-5) was obtained.

[0028] The XRD patterns of the products obtained in Examples 1, 2, and 3 and Ce-MOF are shown in the attached Figure 1 After partial oxidation, MVCM still retains the crystal structure of Ce-MOF, and its good crystal structure is conducive to improving catalytic activity.

[0029] The TEM images of the products obtained in Examples 1, 2, and 3 and Ce-MOF are shown in the attached Figure 2 shown. Figure 2 (a) The scanning electron microscopy and transmission electron microscopy images show that Ce-MOF is a nanorod-like structure. Figure 2 (b) shows that after reaction with NaOH, the MVCM still retains its original morphology, but the nanorods become shorter.

[0030] The XPS images of the products obtained in Examples 1, 2, and 3 and Ce-MOF are shown in the attached Figure 3 As shown. From Ce-MOF to MVCM (Ce-MOF-1), Ce 3+ Reduce, Ce 4+ The enzyme activity increased significantly; from Ce-MOF to MVCM (Ce-MOF-3), Ce 3+ Reduce, Ce 4+ The oxygen vacancies are also higher; from Ce-MOF to MVCM (Ce-MOF-5), Ce 3+ Reduce, Ce 4+ The oxygen vacancies are also higher. With the change of oxidation time, the enzyme-like activities of the three Ce-MOFs are significantly improved. When the oxidation time is 3 minutes, the activity is the best and the antibacterial effect is the best.

[0031] The enzymatic activity curves of the products obtained in Examples 1, 2, and 3 and Ce-MOF at pH = 8 are shown in the attached Figure 4 As shown. Phenol red bromination reaction was used to evaluate the catalase activity of Ce-MOFs. The pH of the reaction solution was 8, and the total volume of the solution was 5 mL, consisting of 100 mg / L Ce-MOF nanoparticles, 50 μmol / L phenol red, 25 mmol / L NH4Br and 25 mmol / L H2O2. The absorbance was recorded every half hour using a microplate reader in the wavelength range of 300 nm to 800 nm. According to the absorbance at 432 nm (OD 432 nm ) and 590 nm (OD 590 nm ) to evaluate the progress of the bromination reaction of phenol red. The MVCM products obtained in Examples 1, 2, and 3 have good activity in a neutral environment and in an environment of pH=8. The enzyme-like activity of Ce-MOF-1, Ce-MOF-3, and Ce-MOF-5 obtained after oxidation treatment is significantly improved compared with the initial Ce-MOF.

[0032] The products obtained in Examples 1, 2, and 3 and the antibacterial effect of Ce-MOF in antifouling are shown in the attached Figure 5As shown. In the experiment, Escherichia coli was selected as the model strain, and a single colony was inoculated into the Escherichia coli liquid culture medium and cultured at 37°C and 120 rpm for 24 hours. After culture, the bacteria were centrifuged several times in a 0.9 wt% sterile NaCl solution and then suspended in a sterile NaCl solution. To evaluate the antibacterial properties of Ce-MOF, six groups were established: control group 1 (E. coli concentration was 106 cells / mL), control group 2 (E. coli suspension + 25 mmol / L NH4Br + 0.1 mmol / L H2O2), experimental group 1 (E. coli suspension + 25 mmol / L NH4Br + 0.1 mmol / L H2O2 + 10 mg / LCe-MOF nanoparticles), experimental group 2 (E. coli suspension + 25 mmol / L NH4Br + 0.1 mmol / L H2O2 + 10 mg / LCe-MOF-3 nanoparticles), experimental group 3 (E. coli suspension + 25 mmol / L NH4Br + 0.1 mmol / L H2O2 + 50 mg / LCe-MOF nanoparticles) and experimental group 4 (E. coli suspension + 25 mmol / L NH4Br + 0.1 mmol / L H2O2 + 100 mg / LCe-MOF-3 nanoparticles). H2O2+ 50 mg / LCe-MOF-3 nanoparticles). Each group was incubated at 37°C in a pre-sterilized 24-well plate. After 30 minutes, it was serially diluted with 0.9 wt% sterile NaCl solution, and 100 μL was applied on agar solid medium. After the medium was incubated at 37°C for 24 hours, the agar plate image was collected for antibacterial evaluation.

Claims

1. A Ce-MOF enzyme antibacterial agent, characterized in that The Ce-MOF powder was obtained by oxidation reaction with a mixed aqueous solution of sodium hydroxide and hydrogen peroxide.

2. The Ce-MOF enzyme antibacterial agent according to claim 1, characterized in that The concentration range of the sodium hydroxide is 0.03-0.05 mol / L.

3. The Ce-MOF enzyme antibacterial agent according to claim 1, characterized in that The concentration range of the hydrogen peroxide is 2-3 mmol / L.

4. The Ce-MOF enzyme antibacterial agent according to claim 1, characterized in that The oxidation reaction time is 1-5 min.

5. The method for preparing the enzyme-like antibacterial agent according to claim 1, characterized in that The following steps are involved: Ce-MOF powder is dispersed in deionized water to obtain a suspension; sodium hydroxide and hydrogen peroxide are added to the suspension for mixed oxidation reaction for 1-5 minutes; centrifugal washing and freeze-drying are performed to obtain a mixed valence yellow powder.

6. The method for preparing the enzyme-like antibacterial agent according to claim 5, characterized in that The particle size of the yellow powder ranges from 300 to 700 nm.

7. The method for preparing the enzyme-like antibacterial agent according to claim 5, characterized in that The concentration range of the sodium hydroxide in the suspension is 0.03-0.05 mol / L; the concentration range of the hydrogen peroxide in the suspension is 2-3 mmol / L.

8. The method for preparing the enzyme-like antibacterial agent according to claim 5, characterized in that The preparation method of the Ce-MOF powder comprises the following steps: Dissolve cerium nitrate hexahydrate and benzenetricarboxylic acid in a water-ethanol mixed solution; stir and react at 50-70° C. for more than 1 hour to obtain a white mixed solution; and obtain white powder Ce-MOF through centrifugal washing and freeze drying.

9. The method for preparing the enzyme-like antibacterial agent according to claim 8, characterized in that The volume ratio of water to ethanol in the water-ethanol mixed solution is 10:

1.

10. The method for preparing the enzyme-like antibacterial agent according to claim 8, characterized in that The molar ratio of the cerium nitrate hexahydrate to trimesic acid is 1:1; the concentration range of the cerium nitrate hexahydrate in the mixed solution is 0.15-0.2 mol / L; the concentration range of trimesic acid in the mixed solution is 0.15-0.2 mol / L.

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