NiCo@C HNs enzyme-like activity composite nanomaterial and preparation method thereof

Abstract

The application discloses a kind of NiCo@C HNs enzyme-like activity composite nanomaterial and preparation method thereof, the preparation method of the composite nanomaterial includes dispersing nickel nitrate and sodium citrate in water, adding potassium cyanide aqueous solution, incubation at room temperature, obtain NiCo precursor, NiCo precursor is dispersed into buffer solution, add dopamine, obtain the NiCo precursor with polydopamine coating, pyrolysis at 300 DEG C-500 DEG C, obtain product.The NiCo@C HNs enzyme-like activity composite nanomaterial of the application has the advantages of large specific surface area, regular and ordered pore size, high catalytic activity, its preparation process is simple, low in cost, suitable for large-scale preparation, and the composite nanomaterial can be used as functional nanomaterial for environmental monitoring and other fields, has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of synthetic technology, specifically relating to NiCo@C HNs enzyme-like composite nanomaterials and their preparation methods. Background Technology

[0002] Recently, composite nanomaterials derived from metal-organic frameworks (MOFs) have attracted widespread attention in the field of catalysis due to their tunable morphology and synergistic effects, generating high-density biomimetic sites and thus becoming a novel type of catalyst. MOFs, also known as metal-organic coordination polymers, are emerging porous materials with a three-dimensional structure, high porosity, and ease of design. Calcination in air leads to the formation of metal oxides. Therefore, MOFs have been widely used as sacrificial templates. However, high-temperature calcination in air typically causes the collapse of their 3D framework, disrupting their porous structure, reducing specific surface area, and consequently decreasing their catalytic activity. Therefore, careful design is needed to maintain the original spatial structure of MOFs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a NiCo@C HNs enzyme-active composite nanomaterial with large specific surface area, porous structure and high catalytic activity. It also provides a method for preparing NiCo@C HNs enzyme-active composite nanomaterial with simple process, low cost and large-scale industrial production capability.

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

[0005] A method for preparing NiCo@C HNs enzyme-like composite nanomaterials includes the following steps:

[0006] (1) Disperse nickel nitrate and sodium citrate in water, then add potassium cobalt cyanide aqueous solution, incubate at room temperature, centrifuge and dry to obtain NiCo precursor;

[0007] (2) The NiCo precursor was dispersed in a buffer solution, and then dopamine was added. The reaction was carried out at room temperature to obtain a NiCo precursor with a polydopamine coating.

[0008] (3) The NiCo precursor with polydopamine coating obtained above is subjected to high-temperature pyrolysis at 300℃~500℃ to obtain NiCo@C HNs enzyme-active composite nanomaterials.

[0009] In the preferred method for preparing the above-mentioned NiCo@C HNs enzyme-active composite nanomaterials, in step (1), the molar ratio of nickel nitrate to sodium citrate is 1:1 to 3, and the molar ratio of nickel nitrate to potassium cobalt cyanide is 1:0.5 to 1.

[0010] In the above-mentioned method for preparing NiCo@C HNs enzyme-active composite nanomaterials, preferably, in step (2), the buffer solution is a Tris-HCl buffer solution, and the mass ratio of dopamine to NiCo precursor is 1:1 to 3.

[0011] In the preferred method for preparing the above-mentioned NiCo@C HNs enzyme-active composite nanomaterials, in step (1), the room temperature is 25℃~30℃ and the incubation time is 18h~24h.

[0012] In the preferred embodiment of the above-mentioned method for preparing NiCo@C HNs enzyme-active composite nanomaterials, in step (2), the room temperature is 25℃~30℃ and the reaction time is 4h~6h.

[0013] In the above-mentioned method for preparing NiCo@C HNs enzyme-active composite nanomaterials, preferably, in step (3), the high-temperature pyrolysis time is 2h to 4h.

[0014] As a general technical concept, the present invention also provides a method for preparing the above-mentioned NiCo@C HNs enzyme-active composite nanomaterials, resulting in NiCo@C HNs enzyme-active composite nanomaterials.

[0015] Preferably, the microstructure of the NiCo@C HNs enzyme-active composite nanomaterial described above exhibits a hollow nanobox structure.

[0016] Preferably, the hollow nanobox structure of the aforementioned NiCo@C HNs enzyme-active composite nanomaterial has a porous surface.

[0017] The main design principle of this invention is as follows: a polydopamine (PDA) coating is formed on the surface of the NiCo precursor by utilizing the dopamine self-polymerization reaction. During the pyrolysis process, the PDA is transformed into a porous carbon shell, and the NiCo precursor is transformed into NiCo bimetallic oxide. At the same time, the carbon shell derived from the PDA protects the framework structure of the NiCo precursor. Finally, a NiCo bimetallic oxide porous carbon composite nanomaterial with a hollow nanobox structure is formed.

[0018] The NiCo@C HNs enzyme-like composite nanomaterial provided by this invention has high peroxidase-like activity. It can catalytically oxidize TMB in the presence of H2O2 and generate a blue oxidation product. By utilizing the specific recognition function of nucleic acid aptamers and adjusting enzyme activity, it can be used as a functional nanomaterial in the field of environmental monitoring.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] 1. The preparation method of this invention uses a NiCo Prussian blue analogue as a precursor. After self-assembling a polydopamine coating on its surface, a NiCo@CHNs enzyme-active composite nanomaterial is obtained through a one-step calcination. The applicant discovered that by utilizing the self-polymerization reaction of dopamine in a buffer solution to coat the surface of the NiCo precursor with a layer of polydopamine, it can maintain its original spatial structure during high-temperature pyrolysis. This method is simple, can be carried out spontaneously at room temperature, and greatly saves costs. After high-temperature pyrolysis, PDA is transformed into porous carbon, and the NiCo precursor is transformed into NiCo bimetallic oxide with a unique spatial structure, similar to a hollow nanobox, which will increase the specific surface area of ​​the composite material. In addition, the PDA-coated NiCo precursor, after pyrolysis, is derived into a composite nanomaterial of carbon with excellent conductivity and multivalent NiCo bimetallic oxide, which will significantly improve the catalytic activity of the material.

[0021] In this invention, dopamine is selected as an organic compound rich in carbon and nitrogen, which can spontaneously polymerize in aqueous solution and can grow a polydopamine (PDA) coating on almost any substrate. After pyrolysis, PDA can be transformed into a porous, nitrogen-doped carbon material. Therefore, this invention utilizes a PDA coating to protect the MOF-derived framework structure, forming a composite material with a unique porous structure.

[0022] 2. The preparation method of the present invention is simple, low-cost, and can be used to prepare NiCo@C HNs enzyme-active composite nanomaterials on a large scale.

[0023] 3. The NiCo@C HNs composite nanomaterial of the present invention exhibits a hollow nanobox structure and has the advantages of large specific surface area, regular and ordered pore size, and high catalytic activity.

[0024] 4. The NiCo@C HNs enzyme-active composite nanomaterial of the present invention can be used as a functional nanomaterial in fields such as environmental monitoring, and has good application value and market prospects. Attached Figure Description

[0025] Figure 1 The images show scanning electron microscope (SEM) images of the NiCo@C HNs enzyme-like composite nanomaterial and the comparative sample prepared in Example 1 of this invention. In the images, (A) is the NiCo precursor, (B) is the NiCo precursor with a polydopamine coating, (C) is the calcined product of the NiCo precursor without PDA coating (Nano-NiCo), and (D) is the NiCo@C HNs enzyme-like composite nanomaterial.

[0026] Figure 2 This is a transmission electron microscope image of the NiCo@C HNs enzyme-like composite nanomaterial prepared in Example 1 of this invention.

[0027] Figure 3 The image shows the X-ray photoelectron spectrum of the NiCo@C HNs enzyme-like composite nanomaterial prepared in Example 1 of this invention.

[0028] Figure 4 The image shows the X-ray diffraction pattern of the NiCo@C HNs enzyme-like composite nanomaterial prepared in Example 1 of this invention.

[0029] Figure 5 The UV-vis absorption curves are shown for the solutions obtained after incubating the NiCo@C HNs enzyme-active composite nanomaterial and NiCo precursor prepared in Example 1 of this invention in sodium acetate-acetic acid buffer containing TMB and H2O2.

[0030] Figure 6 The UV-vis absorption curve of the solution obtained after incubating the NiCo@C HNs enzyme-active composite nanomaterial with nucleic acid aptamers in sodium acetate-acetic acid buffer containing TMB and H2O2 in Example 1 of this invention. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the raw materials and instruments used in the following embodiments are commercially available. In the following embodiments, the room temperature conditions are all between 25°C and 30°C.

[0032] Example 1

[0033] A method for preparing NiCo@C HNs enzyme-like composite nanomaterials according to the present invention includes the following steps:

[0034] (1) Disperse nickel nitrate and sodium citrate in water, then add 0.4 mM potassium cobalt cyanide aqueous solution. The molar ratio of nickel nitrate to sodium citrate is 1:2 and the molar ratio of nickel nitrate to potassium cobalt cyanide is 1:1. Incubate at room temperature for 20 h, centrifuge and dry to obtain NiCo precursor.

[0035] (2) The NiCo precursor was dispersed in Tris-HCl buffer solution, and then dopamine was added. The mass ratio of dopamine to NiCo precursor was 1:1. The reaction was carried out at room temperature for 6 hours to obtain NiCo precursor with polydopamine coating.

[0036] (3) The NiCo precursor with polydopamine coating obtained above is pyrolyzed at 350°C for 3 hours to obtain NiCo bimetallic oxide porous carbon composite nanomaterial with hollow nanobox structure, namely NiCo@CHNs enzyme-active composite nanomaterial.

[0037] NiCo precursor is a MOF material with a solid cubic morphology. NiCo@C HNs exhibits a morphology similar to a hollow nanobox (HNs is an abbreviation for hollow nanobox). NiCo@C HNs is derived from the high-temperature pyrolysis of NiCo precursor (MOFs).

[0038] like Figure 1 As shown in Figure A, the NiCo precursor prepared in this embodiment exhibits a uniform cubic structure, as... Figure 1 As shown in Figure B, after PDA coating, the cube size increases and the surface becomes rougher. Direct high-temperature pyrolysis (Nano-NiCo) without PDA coating is as follows... Figure 1 As shown in Figure C, the cubic structure has collapsed, becoming many irregularly shaped cubic structures. After the NiCo precursor is coated with PDA and calcined, as shown in Figure C... Figure 1 As shown in D, NiCo@C HNs still basically maintains a cubic structure, while the surface becomes loose and porous.

[0039] like Figure 2 As shown in the transmission electron microscope image, the NiCo@C HNs enzyme-like composite nanomaterial exhibits a distinct hollow nanobox structure and porous characteristics.

[0040] from Figure 1 Scanning electron microscope and Figure 2 The transmission electron microscope (TEM) image shows that the NiCo@C HNs after pyrolysis has a hollow structure (see...). Figure 2 The white area of ​​the medium-nano cube has a hollow structure that can significantly increase the specific surface area. At the same time, the surface is distributed with some small pores, which further increases the specific surface area of ​​the material.

[0041] like Figure 3 As shown in the X-ray photoelectron spectrum, C, O, Co, and Ni elements can be seen in the NiCo@C HNs enzyme-like composite nanomaterial, indicating that the generated NiCo@C HNs contains NiCo bimetallic oxide and carbon.

[0042] like Figure 4 The X-ray diffraction pattern shows that multiple characteristic peaks of the NiCo precursor match the characteristic peaks of the Ni3[Co(CN)6]2·12H2O standard card. After the NiCo precursor is coated with PDA and directly pyrolyzed at high temperature, peaks of the NiCo@C HNs enzyme-like composite nanomaterial are found at 37.0°, 43.4° and 65.5°, which correspond to the characteristic peaks of NiCo2O4. This indicates that the NiCo precursor is transformed into NiCo bimetallic oxide by high-temperature pyrolysis after PDA coating.

[0043] To test the peroxidase-like activity of the NiCo@CHNs composite nanomaterials prepared in Example 1, NiCo@CHNs were added to 0.2M sodium acetate-acetic acid buffer containing 1mM TMB (3,3',5,5'-tetramethylbenzidine) and 10mM H2O2 and incubated for 3 min. Figure 5 As shown, the NiCo@CHNs enzyme-like composite nanomaterial exhibits a significant absorption peak at 652 nm in the reaction solution. This absorption peak is characteristic of the TMB oxidation product, indicating that NiCo@CHNs possesses peroxidase-like activity. In contrast, the NiCo precursor shows almost no characteristic absorption peak of the TMB oxidation product, indicating that the NiCo precursor has virtually no enzyme activity. However, after high-temperature pyrolysis, its catalytic activity is significantly enhanced, which stems from its unique hollow porous structure and the synergistic effect of Ni, Co bimetallic oxides, and carbon.

[0044] NiCo@C HNs were incubated with nucleic acid aptamers, and then added to 0.2M sodium acetate-acetic acid buffer containing 1mM TMB and 10mM H2O2 and incubated for 3 min. The absorbance value at 652nm was measured.

[0045] The nucleotide sequence of the nucleic acid aptamer is shown in SEQ ID No. 1:

[0046] CCCAT CAGGG GGCTA GGCTA ACACG GTTCG GCTCT CTGAG CCCGG GTTAT TTCAGGGGGA

[0047] like Figure 6 As shown, the absorbance of NiCo@CHNs after aptamer incubation was significantly lower than that without aptamer incubation, indicating that aptamer incubation can inhibit the activity of NiCo@CHNs-type peroxidases. Given the specific recognition effect of aptamers on target analytes, the binding of the target analyte to the aptamer in its presence can alter enzyme activity, thereby achieving the detection of the target analyte. Therefore, the hollow nanobox structured NiCo bimetallic oxide porous carbon (NiCo@CHNs) composite nanomaterial of this invention can be used as a functional nanomaterial in fields such as environmental monitoring.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention. sequence list <110> Hunan University <120> NiCo@C HNs Enzyme-Activated Composite Nanomaterials and Their Preparation Methods <160> 1 <170> SIPOSequenceListing 1.0 <210> 1 <212> DNA <213> Artificial Sequence <220> <221> misc_feature <222> (1)..(60) <223> The nucleotide sequence designed according to experimental requirements to serve as an aptamer probe. <400> 1 cccatcaggg ggctaggcta acacggttcg gctctctgag cccgggttat ttcaggggga 60

Claims

1. A preparation method of a NiCo@C HNs enzyme-like active composite nanomaterial, characterized in that, Includes the following steps: (1) Disperse nickel nitrate and sodium citrate in water, then add potassium cobalt cyanide aqueous solution, incubate at room temperature, centrifuge and dry to obtain NiCo precursor; (2) The NiCo precursor was dispersed in a buffer solution, and then dopamine was added. The reaction was carried out at room temperature to obtain a NiCo precursor with a polydopamine coating. (3) The NiCo precursor with polydopamine coating obtained above is subjected to high-temperature pyrolysis at 300℃~500℃ to obtain NiCo bimetallic oxide porous carbon composite nanomaterial with hollow nanobox structure, namely NiCo@C HNs enzyme-like composite nanomaterial. In step (1), the molar ratio of nickel nitrate to sodium citrate is 1:1 to 3, and the molar ratio of nickel nitrate to potassium cobalt cyanide is 1:0.5 to 1. In step (2), the buffer solution is a Tris-HCl buffer solution, and the mass ratio of dopamine to NiCo precursor is 1:1 to 3. 2.The method for preparing the NiCo@C HNs enzyme-like active composite nanomaterial according to claim 1, characterized in that, In step (1), the room temperature is 25 ℃~30 ℃, and the incubation time is 18 h~24 h. 3.The method for preparing the NiCo@C HNs enzyme-like active composite nanomaterial according to claim 1, characterized in that, In step (2), the room temperature is 25 ℃~30 ℃, and the reaction time is 4 h~6 h.

4. The method for preparing NiCo@C HNs enzyme-like composite nanomaterials according to claim 1, characterized in that, In step (3), the high-temperature pyrolysis time is 2 h to 4 h.

5. The NiCo@C HNs enzyme-active composite nanomaterial prepared by the method described in any one of claims 1 to 4.

6. The NiCo@C HNs enzyme-like composite nanomaterial according to claim 5, characterized in that, The microstructure of the NiCo@C HNs enzyme-like composite nanomaterial is a hollow nanobox structure.

7. The NiCo@C HNs enzyme-like composite nanomaterial according to claim 6, characterized in that, The hollow nanobox structure has porous surfaces.

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