A method for synthesizing nanoscale enzymes and mimetic enzymes with organophosphorus hydrolytic enzyme activity based on cobalt metal organic framework materials

Abstract

The application discloses a method for synthesizing nano-enzymes and mimic enzymes with organic phosphorus hydrolytic enzyme activity based on cobalt metal organic framework materials. The metal organic framework material is a porous coordination polymer crystal formed by coordination of metal ions and organic ligands. The metal organic framework material is rich in active sites, large in specific surface area, controllable in structure, large in porosity, and has significant catalytic performance. On the other hand, the metal organic framework material is used as a precursor to synthesize a new porous material by calcination pyrolysis in an inert gas such as argon or nitrogen, or air, and has a large specific surface area, good thermal stability and chemical stability, and unique catalytic performance. The application discloses a method for synthesizing unique nano-enzymes and mimic enzymes with organic phosphorus hydrolytic enzyme activity by calcining cobalt metal organic framework materials at high temperature. The method has the advantages of simple operation and simple procedure.

Description

Technical Field

[0001] This invention relates to the fields of cobalt metal-organic framework materials and nanozyme synthesis, and specifically to a method for synthesizing nanozymes with organophosphorus hydrolase activity based on cobalt metal-organic framework materials. Background Technology

[0002] Metal-organic frameworks (MOFs) are porous coordination polymer crystals composed of metal ions and organic ligands. MOFs are mainly classified into three categories based on their organic ligands: carboxylic acid MOFs, nitrogen-containing heterocyclic MOFs, and phosphonic acid MOFs. Carboxylic acid MOFs are the most common, often using terephthalic acid or trimellitic acid. Nitrogen-containing heterocyclic MOFs primarily use imidazole esters and bipyridines as organic ligands. Phosphonic acid MOFs are relatively rare due to the difficulty in obtaining ideal structures. MOFs have become a research and development hotspot in the field of catalytic materials due to their numerous advantages, including large specific surface area, high porosity, tunable pore structure, high catalytic activity, open metal active sites, and structural diversity. Furthermore, using MOFs as precursors, new porous materials can be synthesized by calcination and pyrolysis in inert gases such as argon or nitrogen, or in air, exhibiting large specific surface areas, good thermal and chemical stability, and unique catalytic properties. This invention discloses a method for synthesizing unique nanozymes or mimic enzymes with organophosphorus hydrolase activity by calcining cobalt metal-organic framework materials as precursors at high temperatures. Summary of the Invention

[0003] This invention introduces cobalt metal-organic framework materials as precursors, which are calcined at high temperature in an inert gas atmosphere to obtain cobalt nanoparticles ranging from sub-nanometer to over 100 nanometers. These nanoparticles are dispersed in a nitrogen-doped or nitrogen-oxygen-doped carbon matrix generated during the calcination process. The resulting composite material exhibits unique organophosphorus hydrolase activity, namely, the organophosphorus hydrolase-active nanozyme or organophosphorus hydrolase-active enzyme mimicry described in this invention. This synthesis method has the advantages of simple operation and straightforward procedure.

[0004] Furthermore, the synthesis method and related processes described in this patent refer to a synthesis method in which a cobalt metal-organic framework material as a precursor is calcined at high temperature in an inert gas environment, and a nanozyme or a mimic enzyme with organophosphorus hydrolase activity is used as the target material for synthesis.

[0005] Furthermore, the cobalt metal-organic framework material described in this patent refers to a metal-organic framework material synthesized with divalent cobalt metal ions as the metal coordination center, and its ligands are organic compounds containing two or more coordinating nitrogen atoms, including but not limited to imidazoles, bipyridines and other organic amine compounds.

[0006] Furthermore, the calcination temperature of the cobalt metal-organic framework material during the synthesis process described in this patent refers to 300 degrees Celsius or higher.

[0007] Furthermore, the inert gas required in the synthesis process described in this patent refers to pure nitrogen, pure argon, or other pure inert gases, which contain little or no residual oxygen. Attached Figure Description

[0008] Figure 1. (a) TEM image of cobalt metal-organic framework material (ZIF-67); (b) TEM image of nanozyme with organophosphorus hydrolase activity (Co@NOC), which is a composite material (Co@NOC) formed by dispersing cobalt nanoparticles in a nitrogen-oxygen-doped carbon matrix. This nanozyme, using cobalt metal-organic framework material (ZIF-67) as a precursor, was subjected to 800°C in a nitrogen atmosphere. o It is obtained by calcining C.

[0009] Figure 2. (a) Cobalt metal-organic framework material (ZIF-67) and nanozyme with organophosphorus hydrolase activity (Co@NOC) at 25°C, respectively, with paraoxon and phenylthion. o (a) Comparison of UV spectra of reaction supernatant after 6 minutes of reaction C; (b) Cobalt metal-organic framework material (ZIF-67) and nanozyme with organophosphorus hydrolase activity (Co@NOC) at 40 °C with paraoxon and phenylthion, respectively. o Comparison of UV spectra of the reaction supernatant after reaction C for 12 minutes; (c) Nanozymes (Co@NOC) with organophosphorus hydrolase activity, using paraoxon and phenylthion as substrates at 40 °C. o Comparison of specific activities during reaction C. Working buffer: pH 9.0, 0.15 M sodium carbonate; [paraoxonium] and [phenylthionium]: 147 μM Detailed Implementation

[0010] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] Example:

[0012] 2.3 g of 2-methylimidazole and 1.0 g of Co(NO3)2•6H2O were dissolved separately in anhydrous methanol. The two solutions were mixed and stirred at room temperature (22±1℃) for 20 hours. The purple product was centrifuged and washed several times with anhydrous methanol. Then it was dried in a vacuum oven at 60℃ to obtain the purple powder product, cobalt metal-organic framework material ZIF-67. The ZIF-67 material was then spread in a ceramic boat and placed in a tube furnace. It was then heated to 800°C for 2 hours under N2 atmosphere and cooled to room temperature to obtain the material. Characterization confirmed that the cobalt nanoparticles were dispersed in a nitrogen-oxygen-doped carbon matrix generated during calcination. This composite material has unique organophosphorus hydrolase activity (Co@NOC) nanozyme. TEM imaging showed that ZIF-67 exhibited a typical dodecahedral morphology with an average particle size of approximately 500 nm. Figure 1 a). The Co@NOC obtained in ZIF-67 still retains more or less its original size, shape, and morphology ( Figure 1 b), in which Co nanoparticles are combined with N and O-doped carbon matrix materials ( Figure 1 b). The size of Co nanoparticles ranges from a few nanometers to over 100 nanometers. Figure 1 b). Paraoxon and phenoxyphos are typical organophosphorus compounds used as pesticides. One of the hydrolysis products of paraoxon and phenoxyphos is p-nitrophenol, which is yellow and detectable at approximately 400 nm. Notably, the hydrolysis of paraoxon and phenoxyphos using Co@NOC catalysis can be carried out at a low temperature of 25 °C. Figure 2 a) When paraoxon or phenylthion is incubated with 0.44 mg / mL Co@NOC in pH 9.0, 0.15 M sodium carbonate buffer, the color can be observed to become increasingly yellow. Figure 2 Figures a and 2b show the absorbance profiles of the products from the supernatants of paraoxonium and phenoxyphosphonium after incubation with ZIF-67 and Co@NOC at 25°C for 6 minutes and 40°C for 12 minutes, respectively. The absorbance of phenoxyphosphonium was significantly higher than that of paraoxonium, indicating that the OPH mimicry activity of Co@NOC for phenoxyphosphonium was much higher than that for paraoxonium. In contrast, without Co@NOC, the supernatants of both organophosphorus compounds reacting with ZIF-67 did not produce any peak at 400 nm. Figure 2 (a and 2b) indicates that ZIF-67 has no OPH-mimicking activity. The specific activity of Co@NOC with phenylthionine as a substrate is more than twice that with paraoxonine as a substrate. Figure 2 c).

Claims

1. The application of a nanozyme in the catalytic hydrolysis of organophosphorus compounds, characterized in that, The specific preparation method of the nanozyme is as follows: 2-methylimidazole and Co(NO3)2•6H2O are dissolved in anhydrous methanol, the two solutions are mixed and stirred at room temperature, the purple product is centrifuged, washed with anhydrous methanol, and then dried in a vacuum oven to obtain a purple powder product, cobalt metal-organic framework material ZIF-67. Then, the ZIF-67 material is spread in a ceramic boat, placed in a tube furnace, and calcined at 800°C for 2 hours under N2 atmosphere. After cooling to room temperature, a nanozyme Co@NOC with organophosphorus hydrolase activity is obtained, wherein the cobalt nanoparticles are dispersed in the nitrogen-oxygen-doped carbon matrix generated during the calcination process; the organophosphorus is paraoxon or phenylthionine.

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