A mesoporous CeO2 nanocomposite material and its preparation method and application

Abstract

The present invention relates to a mesoporous CeO2 nanocomposite material and its preparation method and application, belonging to the field of nanomaterial preparation. The preparation method comprises the following steps: (1) mixing a cerium source solution with ammonium hydroxide overnight to form CeO2NPs; (2) adding a certain amount of ammonium hydroxide to adjust the pH value of the solution to 8-11; (3) sequentially adding a structure directing agent, a pore-enlarging agent and a silicon source solution and stirring evenly; (4) finally washing with a detergent and stirring evenly to obtain a dispersed mesoporous CeO2 nanocomposite material. The method for preparing the mesoporous CeO2 nanocomposite material of the present invention has the advantages of being simple and controllable, green and environmentally friendly, and safe to operate. The prepared mesoporous CeO2 nanocomposite material has uniform particle size, strong antioxidant capacity, and strong stability, and can be applied in anti-inflammatory and antioxidant drugs.

Description

Technical Field

[0001] The present invention belongs to the field of nano material preparation, and particularly relates to a mesoporous CeO2 nano composite material and a preparation method and application thereof. Background Art

[0002] Cerium dioxide (CeO2) is a light yellow, loose rare earth oxide with a cubic crystal system and a fluorite-type structure. It is non-toxic and odorless, with a melting point of 2600°C. It is used as an antioxidant, catalyst, UV absorber, and polishing material. It is also an important component in gas sensors, optical devices, and fuel cells due to its low price and high added value. In the existing technology, there are many methods for synthesizing CeO2, including chemical precipitation, sol-gel, and hydrothermal methods. Precipitation is the most common chemical reaction method for synthesizing high-purity nanometal oxide materials. Precipitation involves reacting various precipitants dissolved in water with metal salts to form insoluble hydroxides, carbonates, acetates, and sulfates. The precipitate is then filtered, dried, and calcined to obtain the target nanoparticles. Precipitation methods are mainly divided into direct precipitation, co-precipitation, and uniform precipitation.

[0003] For example, CN107774269A discloses a method for preparing a copper-ceria catalyst using a coprecipitation method. The method comprises hydrothermally synthesizing a ceria carrier, coprecipitating a copper salt on the ceria, and then calcining the catalyst with the copper salt in a muffle furnace at 300-800°C for 3-7 hours, with a heating rate of 5-20°C / second. Finally, annealing in a reducing atmosphere using a hydrogen-argon mixture (H2:Ar = 3-19, V:V) at 400-600°C for 3-6 hours, with a heating rate of 5-20°C / second. Also disclosed are copper-ceria catalysts prepared using this method and their applications. However, the precipitation method is prone to agglomeration during particle preparation, requires long, high-temperature calcination, and is difficult to filter and wash, which can easily lead to product loss.

[0004] Silica is an inorganic substance with the chemical formula SiO2. Crystalline silica is formed by long-range ordered arrangements of silicon and oxygen atoms, while amorphous silica is formed by short-range or long-range disordered arrangements. In a silica crystal, silicon atoms are located at the center of a regular tetrahedron, with four oxygen atoms located at the corners. Many of these tetrahedrons are connected by oxygen atoms at the corners, with each oxygen atom being shared by two tetrahedrons, meaning each oxygen atom is bound to two silicon atoms. Monodisperse mesoporous silica microspheres have been widely used in catalysis, drug delivery, coatings, cosmetics, optical sensing, plastics, and other fields due to their large surface area, good biocompatibility, stable physicochemical properties, and ease of functionalization of surface hydroxyl groups. There are many methods for synthesizing silica microspheres, including vapor phase and precipitation methods. For example, the vapor phase method uses silicon tetrachloride as the silicon source. By decomposing silicon tetrachloride at high temperatures in the presence of oxygen and hydrogen, the resulting nano-silica is characterized by low density, dense pores, and good dispersion. However, this method requires stringent experimental conditions, has a very low yield, and is also dangerous. The precipitation method uses silicates as the silicon source, which first requires acidification and then calcination to produce silica microspheres. However, this method produces microspheres with low yields and poor dispersibility. All currently used technologies for synthesizing nanosilica microspheres have certain drawbacks. For example, the high-temperature calcination required and the low yield do not align with the principles of contemporary green science.

[0005] During the normal life activities of living organisms, excessive reactive oxygen species can damage nucleic acids, lipids, and proteins, thereby causing some malignant diseases such as cancer, Alzheimer's disease, Parkinson's disease, and diabetes. Therefore, the removal of reactive oxygen species is very important. Common antioxidants include superoxide dismutase (SOD), peroxidase (CAT), ascorbic acid, etc. However, they have disadvantages such as few active sites, limited scavenging efficiency, repeated intake, and excessive toxicity. Therefore, it is particularly important to develop an antioxidant that is highly effective and stable in various physiological environments. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a mesoporous CeO2 nanocomposite material and its preparation method and application. The present invention adopts a more simple and green process, uses nano-SiO2 as a carrier, and loads nano-CeO2. The mesoporous CeO2 nanocomposite material finally synthesized can effectively improve the stability of the nanosystem and may thereby maintain its antioxidant capacity under different physiological environments. Nano-SiO2 is small in size, loose and porous, has a large specific surface area, and has excellent properties such as good light transmittance and biocompatibility. It is a good carrier material that can avoid the aggregation of nanoparticles and improve the stability of nanoparticles. Cerium dioxide nanoparticles can be placed in CeO2 according to different environmental conditions. 3+and Ce 4+ This ability to transform back and forth gives ceria nanoparticles very important biological properties of scavenging oxygen free radicals.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a mesoporous CeO2 nanocomposite material and a preparation method thereof, comprising the following steps:

[0009] (1) mixing a cerium source solution and an ammonium hydroxide solution and stirring them uniformly to form a CeO2 NPs suspension;

[0010] (2) centrifuging the CeO2 NPs suspension obtained in step (1), washing the precipitate with water and resuspending it, then dropping ammonium hydroxide solution to adjust the solution pH to 8-11, adding a structure directing agent and a pore expanding agent, and then adding a silicon source solution and stirring evenly to obtain a precursor;

[0011] (3) The precursor is washed with a washing liquid to obtain a mesoporous CeO2 nanocomposite material.

[0012] When the pH value is in the range of 8-11, CeO2 NPs are relatively stable. This is because the pH of the solution has a significant effect on the crystallization formation and crystal state of the grains. pH is one of the most critical factors affecting the particle morphology. From an electrochemical point of view, CeO2 NPs under different pH conditions 3+ / Ce 4+ The transformation process varies greatly.

[0013] As a preferred embodiment of the present invention, the cerium source includes any one of cerium nitrate hexahydrate, cerium acetate or cerium sulfate tetrahydrate, the volume ratio of the cerium source solution to the ammonium hydroxide solution is cerium source solution: ammonium hydroxide = 50000:173, and the molar concentration ratio of cerium ions in the cerium source solution to ammonium hydroxide solution is cerium ions to ammonium hydroxide = 10:20-28.

[0014] As a more preferred embodiment of the present invention, the molar concentration ratio of cerium ions to ammonium hydroxide solution in the cerium source solution is cerium ions to ammonium hydroxide = 10:27.

[0015] Once ammonium hydroxide is added to the cerium source solution, trivalent Ce(OH)3 precipitates immediately. This is because the solubility product of Ce(OH)3 is quite low. 3+ / Ce 4+The Ce(OH)3 precipitate generated by the transformation law can be easily oxidized into tetravalent Ce(OH)4 precipitate in the air, and finally the Ce(OH)4 precipitate dehydrates to form CeO2NPs. If the concentration of ammonium hydroxide is too low, it is easy to settle and agglomerate to increase the particle size, which will reduce the stability of the generated CeO2NPs.

[0016] As a preferred embodiment of the present invention, the structure directing agent is cetyltrimethylammonium bromide (CTAB), the solvent of the CTAB solution is 20% ethanol, and the weight ratio of the CeO2 NPs to CTAB is CeO2 NPs:CTAB=1.2:3.

[0017] The structure-directing agent is a substance with amphiphilic groups. After exceeding the critical concentration, micelles are formed inside the solution. By controlling the structure of the micelles, CeO2 NPs and SiO2 are connected and deposited on the micelle surface.

[0018] As a preferred embodiment of the present invention, the pore-expanding agent includes decanane and trimethylbenzene, and the molar ratio of decanane, trimethylbenzene and hexadecyltrimethylammonium bromide is decanane: trimethylbenzene: hexadecyltrimethylammonium bromide = 8-11:2:1.

[0019] As a more preferred embodiment of the present invention, the molar ratio of decanane to trimethylbenzene is decanane:trimethylbenzene=10:2.

[0020] Trimethylbenzene and decane are used as pore-enlarging agents to adjust the pore size of SiO2 because the molecules can enter the hydrophobic area in the center of the micelle, increase the micelle diameter and volume, and thus increase the pore size. When the two are mixed, they have a synergistic effect, effectively increasing the pore size, increasing its specific surface area, and improving its stability.

[0021] As a preferred embodiment of the present invention, the silicon source is ethyl silicate solution, and the solvent is CTAB.

[0022] As a preferred embodiment of the present invention, the molar ratio of ethyl silicate to CTAB is ethyl silicate:CTAB = 3.85:1. Ethyl silicate has good stability, which is beneficial to the stability of subsequent reaction products.

[0023] As a preferred embodiment of the present invention, the washing liquid is an ammonium nitrate solution with a concentration of 2 g / L. Washing the nanocomposite material three times with a 2 g / L ammonium nitrate solution is performed to purify and remove CTAB. This is an efficient ion exchange method that ensures complete elimination of CTAB.

[0024] In a second aspect, a mesoporous CeO2 nanocomposite material prepared by the preparation method is provided.

[0025] In a third aspect, the present invention provides the use of the aforementioned mesoporous CeO2 nanocomposite material with stable antioxidant properties under physiological conditions in the preparation of anti-inflammatory and antioxidant drugs. The coordination numbers of cerium and oxygen are 8 and 4, respectively, where each cerium atom is surrounded by eight oxygen atoms, and each oxygen atom is connected to four cerium atoms. In recent years, CeO2 has been widely used in various engineering and biological research fields, making it a research hotspot in the biomedical field. Multiple studies have demonstrated that cerium dioxide nanoparticles can protect various tissues and organs from damage caused by oxygen free radicals, resisting oxygen free radicals and reducing radiation damage to cells.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The method for synthesizing CeO2 NPs in the present invention does not require high-temperature calcination and layer-by-layer filtration. It only requires the reaction of cerium nitrate with ammonia water and a simple centrifugal extraction, which is low in cost and simple to operate.

[0028] (2) During the operation of introducing SiO2 into CeO2 NPs, it is only necessary to adjust the CeO2 NPs solution to the pH range, and then add the pore-expanding agent, the structure-directing agent and the silicon source solution, and mix them evenly to obtain the mesoporous CeO2 nanocomposite material. No calcination or acidification conditions are required, and the product is green and environmentally friendly. The obtained product has the characteristics of high stability and strong antioxidant ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 UV data of the mesoporous CeO2 nanocomposite prepared in Example 1;

[0030] Figure 2 DLS data of the mesoporous CeO2 nanocomposite prepared in Example 1;

[0031] Figure 3 TEM data of the mesoporous CeO2 nanocomposite prepared in Example 1;

[0032] Figure 4 BET data of the mesoporous CeO2 nanocomposite prepared in Example 1;

[0033] Figure 5 The reaction results of the mesoporous CeO2 nanocomposite prepared in Example 1 and TMB after stirring for 1 day in a simulated human physiological environment;

[0034] Figure 6 This is the reaction result of the mesoporous CeO2 nanocomposite prepared in Example 1 with TMB after being stirred in a simulated human physiological environment for 7 days. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0036] The raw materials used in the following examples are all commercially available.

[0037] Example 1

[0038] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention, the preparation method of the mesoporous CeO2 nanocomposite material in this embodiment is as follows:

[0039] (1) 50 ml of 20 mM cerium nitrate hexahydrate solution was mixed with 173 μl of 54 mM ammonium hydroxide solution and stirred overnight to form a CeO2 NPs suspension;

[0040] (2) The CeO2 NPs suspension obtained in step (1) was centrifuged, the precipitate was washed with water and resuspended, and then an ammonium hydroxide solution was added dropwise to adjust the solution pH to 10; 3 mg / ml CTAB solution (solvent is 20% ethanol) and pore expanders (decanedione and trimethylbenzene) were added, and then an ethyl silicate solution with CTAB as solvent was added and stirred overnight; the weight ratio of CeO2 NPs to CTAB was 1.2:3; the molar ratio of decanedione to trimethylbenzene to ethyl silicate to CTAB was 10:2:3.85:1;

[0041] (3) Add 2 g / L ammonium nitrate solution to the solution obtained in step (2) and wash three times to obtain the mesoporous CeO2 nanocomposite material.

[0042] Example 2

[0043] An embodiment of the mesoporous CeO2 nanocomposite material and the preparation method thereof of the present invention is provided. The difference between this embodiment and embodiment 1 is that the concentration of the ammonium hydroxide solution is 40 mM, and the other conditions are the same.

[0044] Example 3

[0045] An embodiment of the mesoporous CeO2 nanocomposite material and the preparation method thereof of the present invention is provided. The difference between this embodiment and embodiment 1 is that the concentration of the ammonium hydroxide solution is 56 mM, and the other conditions are the same.

[0046] Example 4

[0047] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the pH of the solution in step (2) is 8, and the other conditions are the same.

[0048] Example 5

[0049] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the pH of the solution in step (2) is 11, and the other conditions are the same.

[0050] Example 6

[0051] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the molar ratio of decanane to trimethylbenzene in step (2) is 8:2, and the other conditions are the same.

[0052] Example 7

[0053] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the molar ratio of decanane to trimethylbenzene in step (2) is 11:2, and the other conditions are the same.

[0054] Comparative Example 1

[0055] An embodiment of the mesoporous CeO2 nanocomposite material and the preparation method thereof of the present invention is provided. The difference between this embodiment and embodiment 1 is that the concentration of the ammonium hydroxide solution is 29.4 mM, and the other conditions are the same.

[0056] Comparative Example 2

[0057] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the pH of the solution in step (2) is 12, and the other conditions are the same.

[0058] Comparative Example 3

[0059] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the ethanol concentration in step (2) is 22%, and the other conditions are the same.

[0060] Comparative Example 4

[0061] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the molar ratio of decanane to trimethylbenzene in step (2) is 0:7, and the other conditions are the same.

[0062] Comparative Example 5

[0063] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the molar ratio of decanane to trimethylbenzene in step (2) is 10:3, and the other conditions are the same.

[0064] Comparative Example 6

[0065] An embodiment of the mesoporous CeO2 nanocomposite material and its preparation method of the present invention is different from Example 1 in that the molar ratio of ethyl silicate to CTAB in step (2) is 4.5:1, and the other conditions are the same.

[0066] Test example

[0067] 1. The particle sizes of the mesoporous CeO2 nanocomposites prepared in the above examples and comparative examples were measured using an AntonPaar Litesizer 500 instrument. The results are shown in Table 1.

[0068] Table 1 Characterization results of mesoporous CeO2 nanocomposites

[0069] Average particle size / nm PDI Example 1 173.2 0.0756 Example 2 198.2 0.1055 Example 3 204.5 0.0927 Example 4 185.6 0.1156 Example 5 203.7 0.0863 Example 6 165.8 0.0945 Example 7 205.6 0.1243 Comparative Example 1 275.3 0.2734 Comparative Example 2 253.3 0.1846 Comparative Example 3 149.3 0.1942 Comparative Example 4 363 0.2004 Comparative Example 5 249.8 0.2451 Comparative Example 6 256.7 0.1799

[0070] In the process of preparing CeO2 NPs, the molar concentration ratio of cerium ion and ammonium hydroxide solution in the raw material cerium source solution was cerium ion: ammonium hydroxide = 10:20-28, as in Examples 1-3, and the average particle size was small and the dispersion performance was good; while when the raw material ratio was not in this range, such as in Comparative Example 1, where cerium ion: ammonium hydroxide = 10:14.7, the nanocomposite material prepared in this comparative example had a large particle size and reduced stability, which was considered to be due to the fact that the ammonia concentration was in the range of CeO2 NPs. 3+ / Ce 4+ If the concentration of ammonium hydroxide is too low, it is easy to precipitate and agglomerate, making the particle size larger, which will reduce the stability of the CeO2NPs. Similarly, by comparing Examples 1, 4, and 5 with Comparative Example 2, it can be seen that adjusting the pH value by ammonium hydroxide also has a significant effect on the stability of CeO2NPs. 3+ / Ce 4+ The transformation process is greatly affected. In the present invention, when the pH value is between 8 and 11, the average particle size is small, the dispersion performance is good, and the stability is high. When the pH value is 10, the particle size is the smallest, and the stability and dispersion performance are the best.

[0071] By comparing Examples 1, 6, and 7 with Comparative Examples 4 and 5, we found that the type and ratio of the pore-enlarging agent have a significant effect on the particle size and stability of the nanocomposite material of the present invention. When the molar ratio of decanane to trimethylbenzene is within the range of 8-11:2, the combined use of the two has a synergistic effect and can effectively enhance the stability of the nanocomposite material. When the molar ratio of decanane to trimethylbenzene is 10:2, as in Example 1, the effect is best. Comparing Example 1 with Comparative Example 3, it was found that the nanocomposite material synthesized using 20% ​​ethanol dissolved CTAB as a structure-directing agent has a smaller particle size and better dispersibility than that of Comparative Example 3. It is believed that different concentrations of ethanol control the structure of the micelles formed by CTAB, thereby regulating the morphological characteristics of the nanocomposite material. In addition, by comparing Example 1 with Comparative Example 6, we also found that the amount of ethyl silicate used has a significant effect on the synthesis of the nanocomposite material.

[0072] 2. Antioxidant performance test

[0073] This test example uses TMB experiment to prove the antioxidant ability of the mesoporous CeO2 nanocomposite prepared in Example 1 under a simulated human physiological environment, which specifically includes the following steps:

[0074] Prepare TMB buffer solution, mix the nanomaterials under different treatment conditions with TMB and H2O2, and measure the absorption wavelengths at 450 and 652 nm every ten minutes for one hour. The antioxidant properties of the nanomaterials can be observed by observing the changes in wavelength.

[0075] The experimental results are as follows Figure 5 、 6 As shown, Figure 5 、 6 The following table shows the reaction results of the mesoporous CeO2 nanocomposite prepared in Example 1 with TMB after stirring for one day and seven days in a simulated human physiological environment. It can be seen that the mesoporous CeO2 nanocomposite prepared in Example 1 can exhibit stable antioxidant properties in different environments within the human body over a long period of time. Therefore, the mesoporous CeO2 nanocomposite prepared in the present invention possesses both excellent stability and antioxidant properties, making it promising for use in the preparation of anti-inflammatory and antioxidant drugs.

[0076] 3. Morphological Characterization

[0077] Figure 1-4 They are respectively the UV data, DLS data, TEM data and BET data of the mesoporous CeO2 nanocomposite material prepared in Example 1.

[0078] The mesoporous CeO2 nanocomposite material prepared by the method of the present invention was analyzed by transmission electron microscopy and DLS dynamic light scattering. By UV / Vis wavelength scanning, the characteristic absorption peak of the mesoporous CeO2 nanocomposite material was near 250 nm and the particle size was 125 nm. BET data analysis showed that the prepared mesoporous CeO2 nanocomposite material had strong adsorption capacity and large specific surface area.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a mesoporous CeO2 nanocomposite material, characterized in that: The steps include: (1) mixing a cerium source solution and an ammonium hydroxide solution, and stirring them uniformly to form a CeO2 NPs suspension; the molar concentration ratio of cerium ions in the cerium source solution to ammonium hydroxide solution is cerium ions to ammonium hydroxide = 10:20-28; (2) centrifuging the CeO2 NPs suspension obtained in step (1), washing the precipitate with water and resuspending the precipitate, then dropping an ammonium hydroxide solution to adjust the pH of the solution to 8-11, adding a structure directing agent and a pore-enlarging agent, and then adding a silicon source solution and stirring evenly to obtain a precursor; the pore-enlarging agent includes deuterium oxadiene and trimethylbenzene; the molar ratio of deuterium oxadiene to trimethylbenzene is 8-11:2; (3) The precursor is washed with a washing liquid to obtain a mesoporous CeO2 nanocomposite material.

2. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 1, characterized in that: The cerium source includes any one of cerium nitrate hexahydrate, cerium acetate or cerium sulfate tetrahydrate; the volume ratio of the cerium source solution to the ammonium hydroxide solution is cerium source solution: ammonium hydroxide = 50000:

173.

3. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 1, characterized in that: The structure directing agent is a cetyltrimethylammonium bromide solution, the solvent of the cetyltrimethylammonium bromide solution is 20% ethanol; the weight ratio of the CeO2 NPs to the cetyltrimethylammonium bromide is CeO2 NPs: cetyltrimethylammonium bromide = 1.2:

3.

4. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 3, characterized in that: The molar ratio of decanane, trimethylbenzene and hexadecyltrimethylammonium bromide is decanane: trimethylbenzene: hexadecyltrimethylammonium bromide = 8-11:2:

1.

5. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 1, characterized in that: The silicon source solution is an ethyl silicate solution, and the solvent of the ethyl silicate solution is hexadecyltrimethylammonium bromide.

6. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 5, characterized in that: The molar ratio of the ethyl silicate to the hexadecyltrimethylammonium bromide is ethyl silicate: hexadecyltrimethylammonium bromide = 3.85:

1.

7. The method for preparing the mesoporous CeO2 nanocomposite material according to claim 1, characterized in that: The washing liquid is an ammonium nitrate solution with a mass concentration of 2 g / L.

8. The mesoporous CeO2 nanocomposite material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the mesoporous CeO2 nanocomposite material according to claim 8 in the preparation of anti-inflammatory and antioxidant drugs.

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