Water-soluble N-heterocyclic carbene ligand and water-dispersible gold nano-enzyme as well as synthesis method and application thereof

Abstract

The invention discloses a water-soluble N-heterocyclic carbene ligand and a water-dispersible gold nano-enzyme as well as a synthesis method and application thereof, and belongs to the technical field of nano-material synthesis. The chemical structural formula of the water-soluble N-heterocyclic carbene ligand is # imgabs0 #; in the formula, R comprises alkyl with the carbon atom number of 1-4, and any one of # imgabs 1 #, # imgabs 2 # and # imgabs 3 #. The gold nano-enzyme can be prepared through the one-step reaction of the water-soluble N-heterocyclic carbene ligand, the alkaline substance, the tetrahydrothiophene aurous chloride and the n-tetrabutylammonium chloride, the synthesis process is stable and simple, the yield is high, and the stability is good; the obtained gold nano-enzyme has good water solubility, excellent biocompatibility and relatively uniform size and morphology, and has good photothermal conversion performance and enzyme-like properties like glucose oxidase, peroxidase and glutathione peroxidase.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial synthesis, and in particular to a water-soluble nitrogen heterocyclic carbene ligand and a water-dispersible gold nanozyme, as well as a synthesis method and application thereof. Background Art

[0002] In recent years, gold nanoparticles (AuNPs) have demonstrated tremendous potential in catalysis, biosensing, and medical diagnostics due to their unique physicochemical properties, such as surface plasmon resonance (SPR), high surface area, and tunable surface functionality. Currently, the typical bonding group used to surface-modify gold nanoparticles for biomedical applications is thiol, which has a S-Au bond energy of 126 kJ / mol. However, the stability of the S-Au bond is often affected by the environment, particularly under acidic and alkaline conditions, in the presence of biological oxidants, and at high temperatures.

[0003] Nitrogen heterocyclic carbenes (NHCs), a typical carbon-based ligand, are widely used for surface modification of nanoparticles. NHCs possess strong electron-donating capacity, easily tunable structures, and diverse electronic and steric structures. They can coordinate with a variety of metals (such as silver, gold, palladium, and platinum) to form stable metal-carbon bonds. Under harsh conditions, NHC-stabilized metal nanoparticles are generally more stable than their thiol-modified counterparts. However, current reports on water-dispersible NHC-stabilized gold nanoparticles are limited, and most focus on improving nanoparticle stability, lacking in-depth research on their biocompatibility, biocatalytic properties (nanozymes), and in vivo biomedical applications. Therefore, developing a new method to synthesize NHC-stabilized water-dispersible gold nanozymes with high yield and expand their biomedical applications is of great practical significance. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a water-soluble nitrogen heterocyclic carbene ligand and a water-dispersible gold nanozyme and their synthesis method and application, so as to solve the problems of the existing NHC-stabilized water-dispersible gold nanozyme, such as the single catalytic reaction type and catalytic properties, poor biocompatibility, and complex synthesis method.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: The first aspect of the present invention provides a water-soluble nitrogen heterocyclic carbene ligand, the chemical structure of which is shown in formula (I): Formula (I): ; In formula (I), R includes an alkyl group having 1 to 4 carbon atoms, 、 and Any one of them.

[0006] The present invention provides a water-soluble nitrogen heterocyclic carbene ligand, which can be used to react with an alkaline substance, tetrahydrothiophene gold chloride and n-tetrabutylammonium chloride in one step to prepare gold nanozymes. The process is stable and simple, and there is no need to prepare a nitrogen heterocyclic carbene metal complex.

[0007] The second aspect of the present invention provides a method for synthesizing the above-mentioned water-soluble nitrogen heterocyclic carbene ligand, comprising the following steps: The 1-substituted imidazole derivative and 1,3-propane sultone are subjected to alkylation reaction in a solvent to obtain the product.

[0008] The beneficial effects of the present invention are as follows: the method for synthesizing the water-soluble nitrogen heterocyclic carbene ligand provided by the present invention is stable and simple, has high yield and good stability, and can be functionalized and adjusted by replacing different substituent types on the imidazole N atom to obtain water-soluble nitrogen heterocyclic carbene ligands with different properties.

[0009] Furthermore, the molar ratio of the 1-substituted imidazole derivative to 1,3-propane sultone is 1:8-12.

[0010] Furthermore, the 1-substituted imidazole derivative includes any one of imidazole substituted with an alkyl group having 1 to 4 carbon atoms, 1-phenylimidazole, 1-benzylimidazole and 1-{4-[bis(4-methoxyphenyl)amino]phenyl}imidazole; Further, the solvent includes acetone.

[0011] Furthermore, the alkylation reaction temperature is 35-55°C and the time is 40-50 h.

[0012] The third aspect of the present invention provides a water-dispersible gold nanozyme based on the water-soluble nitrogen heterocyclic carbene ligand, the chemical structure of which is shown in formula (II): Formula (II): ; In formula (II), R includes an alkyl group having 1 to 4 carbon atoms, 、 and Any one of them.

[0013] The beneficial effects of the present invention are as follows: the present invention provides a gold nanozyme synthesized in one step through a water-soluble nitrogen heterocyclic carbene ligand, the gold nanozyme has good water dispersibility, uniform morphology and size, can exist stably in the pH range of 2-13, and can be continuously stable for more than 6 months without agglomeration under deionized water, physiological saline and culture medium conditions.

[0014] A fourth aspect of the present invention provides a method for synthesizing a water-dispersible gold nanozyme, comprising the following steps: The water-soluble nitrogen heterocyclic carbene ligand, alkaline substance, tetrahydrothiophene gold chloride and n-tetrabutylammonium chloride are subjected to reduction reaction in a solvent to prepare the product.

[0015] The beneficial effects of the present invention are as follows: the present invention can prepare gold nanozyme by a one-step reaction of a water-soluble nitrogen heterocyclic carbene ligand with an alkaline substance, tetrahydrothiophene gold chloride and n-tetrabutylammonium chloride. The synthesis process is stable and simple, with high yield and good stability.

[0016] Furthermore, the molar ratio of the alkaline substance to the water-soluble nitrogen heterocyclic carbene ligand is 8-12:1; and the alkaline substance includes potassium carbonate.

[0017] Preferably, the molar ratio of the alkaline substance to the water-soluble nitrogen heterocyclic carbene ligand is 10:1; and the alkaline substance is potassium carbonate.

[0018] Furthermore, the molar ratio of the water-soluble nitrogen heterocyclic carbene ligand to n-tetrabutylammonium chloride is 1:1-1.2; and the solvent includes acetone.

[0019] Preferably, the molar ratio of the water-soluble nitrogen heterocyclic carbene ligand to n-tetrabutylammonium chloride is 1:1.1; and the solvent is acetone.

[0020] Furthermore, the reduction reaction temperature is 25-45° C., and the reaction time is 10-16 h.

[0021] Preferably, the reduction reaction temperature is 35° C. and the reaction time is 12 h.

[0022] A fifth aspect of the present invention provides the use of the water-dispersible gold nanozyme in photothermal conversion and / or enzyme-like catalysis.

[0023] The beneficial effects of the present invention are as follows: the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme prepared by the present invention has excellent near-infrared light conversion properties, and its photothermal conversion efficiency reaches 88.4%. At the same time, the gold nanozyme also has cascade enzyme activity similar to glucose oxidase, peroxidase, and glutathione peroxidase, and photothermal can further enhance its enzyme catalytic properties.

[0024] The present invention has the following beneficial effects: (1) The nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme synthesized by the present invention can replace different substituent types on the nitrogen atom to perform functional and adjustable modification, and has the characteristics of simple synthesis, good stability, and strong biocompatibility; (2) The synthesis method of the present invention has the characteristics of stable and simple process, high yield, good stability, etc., and does not require the preparation of nitrogen heterocyclic carbene metal complexes. The nitrogen heterocyclic carbene ligand can be reacted with potassium carbonate, tetrahydrothiophene gold chloride, etc. in an acetone solution to synthesize nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozymes in one step; (3) The nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme prepared by the present invention has good dispersibility and uniform morphology and size. It can be stably present in the pH range of 2-13 and can be continuously stable for more than 6 months without agglomeration under the conditions of deionized water, physiological saline and culture medium. (4) The nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme prepared by the present invention has excellent near-infrared light conversion properties, and its photothermal conversion efficiency reaches 88.4%. At the same time, the gold nanozyme also has cascade enzyme activities similar to glucose oxidase, peroxidase, and glutathione peroxidase, and photothermal treatment can further enhance its enzyme catalytic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the H NMR spectrum of compound 1; Figure 2 is the C NMR spectrum of compound 1; Figure 3 is the H NMR spectrum of compound 2; Figure 4 is the H NMR spectrum of compound 2; Figure 5 The chemical reaction formula for the synthesis of water-dispersible gold nanozymes stabilized by nitrogen heterocyclic carbenes; Figure 6 Transmission electron micrographs of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozymes prepared in Examples 3 and 4, wherein (a) is Example 3 and (b) is Example 4; Figure 7 Photoelectron spectrum of water-dispersible gold nanozyme stabilized by nitrogen heterocyclic carbene; Figure 8 This is the UV absorption spectrum of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3; Figure 9 This is the hydrated particle size diagram of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3; Figure 10 This is a graph showing the change in hydration radius over time of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3 in water, normal saline, and serum-free DMEM culture medium; Figure 11 The hydrated particle size of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3 under different pH conditions; Figure 12 This is a laser irradiation experiment diagram of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3; Figure 13This is a photothermal stability test diagram of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3; Figure 14 This is a graph showing the glucose oxidase-like activity of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3; Figure 15 This is a graph showing the peroxidase-like activity of the water-dispersible gold nanozyme Au@TPA-NHC NPs stabilized by nitrogen heterocyclic carbene prepared in Example 3; Figure 16 This is a graph showing the glutathione peroxidase-like activity detection of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs prepared in Example 3. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not intended to limit the scope of the invention. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0027] Example 1: A method for synthesizing a water-soluble nitrogen heterocyclic carbene ligand (Compound 1) comprises the following steps: The synthetic chemical reaction formula is as follows: ; Compound 1-{4-[bis(4-methoxyphenyl)amino]phenyl}imidazole (0.50 g, 1.34 mmol) was first weighed into a 50 mL Schlenk reaction tube, and 5 mL of acetone was added and stirred to dissolve, resulting in a light yellow solution. 1,3-propane sultone (1.625 g, 13.4 mmol) was then dissolved in 5 mL of acetone and added to the reaction system, resulting in a light yellow solution. The reaction tube was then heated at 55°C for 48 h and cooled to room temperature to precipitate a white solid. The white solid was collected by filtration and washed three times with acetone. The resulting solid was dried under vacuum to obtain 0.53 g of compound 1 with a yield of 80%.

[0028] The results of NMR are (H and C spectra are as follows Figure 1 and Figure 2 shown): 1 H NMR (400 MHz, DMSO- d 6): δ =9.61 (s, 1H), 8.15 (s, 1H), 7.99 (s, 1H), 7.52 (d, J= 9.0 Hz, 2H), 7.11 (d, J =8.9 Hz, 4H), 6.96 (d, J = 8.9 Hz, 4H), 6.84 (d, J = 9.0 Hz, 2H), 4.36 (t, J = 6.9Hz, 2H), 3.75 (s, 6H), 2.47 (m, 2H), 2.17 (t, J = 6.9 Hz, 2H). 13 C{ 1 H} NMR (100 MHz, DMSO- d 6): δ = 156.5, 149.6, 139.2, 135.0, 127.4,126.4, 123.1, 123.0, 121.2, 118.3, 115.2, 55.3, 48.3, 47.5, 26.0.

[0029] Example 2: A method for synthesizing a water-soluble nitrogen heterocyclic carbene ligand (Compound 2) comprises the following steps: The synthetic chemical reaction formula is as follows: ; First, compound 1-phenylimidazole (0.50 g, 3.47 mmol) was weighed into a 50 mL Schlenk reaction tube, and 5 mL of acetone was added and stirred to dissolve, and the solution turned light yellow. Then, 1,3-propane sultone (4.24 g, 34.7 mmol) was dissolved in 5 mL of acetone and added to the above reaction system, and the solution turned light yellow. The reaction tube was then heated at 55 °C for 48 h and cooled to room temperature to precipitate a white solid. Finally, the white solid was collected by filtration and washed three times with acetone. The resulting solid was vacuum dried to obtain 0.74 g of compound 2 with a yield of 80%.

[0030] The results of NMR are (H and C spectra are as follows Figure 3 and Figure 4 shown): 1 H NMR (400 MHz, DMSO- d 6): δ =9.80 (s, 1H), 8.31 (s, 1H), 8.06 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.65 (t, J=8.0 Hz, 2H), 7.58 (t, J = 7.1 Hz, 1H), 4.39 (t, J = 7.1 Hz, 2H), 2.53 (t, J = 7.1Hz, 2H), 2.20 (p, J = 7.1 Hz, 2H). 13 C{ 1 H} NMR (100 MHz, DMSO- d 6) δ = 135.6, 134.9, 130.2, 129.7, 121.9,121.2, 47.6, 26.0.

[0031] Example 3: A method for preparing water-dispersible gold nanozymes (Au@TPA-NHC NPs) stabilized by nitrogen heterocyclic carbene (synthetic chemical reaction formula is as follows Figure 5 ), including the following steps: First, compound 1 (0.10 g, 0.20 mmol) obtained in Example 1 was weighed into a 25 mL Schlenk reaction tube, and 5 mL of acetone was added and stirred to dissolve, and the solution became colorless. Then, tetrahydrothiophene gold chloride (0.07 g, 0.22 mmol), potassium carbonate (0.28 g, 2.0 mmol), and n-tetrabutylammonium chloride (0.02 g, 0.20 mmol) were added to the above reaction system in sequence, and the mixture was placed in the dark at room temperature for 12 h. Finally, after the reaction was completed, the filtrate was collected by vacuum filtration using a funnel, and the liquid was concentrated to 0.5 mL by rotary evaporation. 0.5 mL of ultrapure water was added, and the solution gradually changed from colorless to purple-black. The precipitate was collected by centrifugation using a high-speed centrifuge (9000 rpm) to obtain Au@TPA-NHC NPs, which were washed with ultrapure water and dispersed in ultrapure water.

[0032] The transmission electron microscopy image of the water-dispersible gold nanozyme Au@TPA-NHC NPs stabilized by nitrogen heterocyclic carbene prepared in this example is as follows: Figure 6 As shown in Figure (a), it is a spherical nanoparticle with a diameter of about 18 nm.

[0033] The X-ray photoelectron spectrum of the water-dispersible gold nanozyme Au@TPA-NHC NPs stabilized by nitrogen heterocyclic carbene prepared in this example is as follows: Figure 7As shown, after the imidazolium salt precursor coordinates with the metal, the nitrogen heterocycle partially deprotonates to form a metal-carbene bond. Due to the redistribution of the electron cloud density, the N 1s signal shifts toward lower energies. The imidazolium salt precursor modified with the triphenylamine functional group exhibits double peaks at 399.2 eV (triphenylamine nitrogen atom) and 401.1 eV (imidazolium salt nitrogen atom), respectively. In the N 1s spectrum of gold nanoparticles Au@TPA-NHC NPs, the characteristic peak shifts 0.9 eV toward lower energies and merges with the N 1s of triphenylamine to form a single peak with a larger half-width, demonstrating the successful coordination of the nitrogen heterocycle carbene ligand with the gold nanoparticles.

[0034] The UV absorption spectrum of the water-dispersible gold nanozyme Au@TPA-NHC NPs stabilized by nitrogen heterocyclic carbene prepared in this example is shown in FIG. Figure 8 As shown in the figure, Au@TPA-NHC NPs exhibit a characteristic absorption peak at 560 nm, which is a surface plasmon resonance unique to gold nanoparticles, proving the successful formation of gold nanoparticles.

[0035] like Figure 9 As shown, the hydrated particle size of Au@TPA-NHC NPs is 23 nm.

[0036] Example 4: A method for preparing water-dispersible gold nanozymes (Au@Bn-NHC NPs) stabilized by nitrogen heterocyclic carbene (synthetic chemical reaction formula is as follows Figure 5 ), including the following steps: First, compound 2 (0.05 g, 0.20 mmol) obtained in Example 2 was weighed into a 25 mL Schlenk reaction tube, and 5 mL of acetone was added and stirred to dissolve, and the solution became colorless. Then, tetrahydrothiophene gold chloride (0.07 g, 0.22 mmol), potassium carbonate (0.28 g, 2.0 mmol), and n-tetrabutylammonium chloride (0.02 g, 0.20 mmol) were added to the above reaction system in sequence, and the mixture was placed in the dark at room temperature for 12 h. Finally, after the reaction was completed, the filtrate was collected by vacuum filtration using a funnel, and the liquid was concentrated to 0.5 mL by rotary evaporation. 0.5 mL of ultrapure water was added, and the solution gradually changed from colorless to purple-black. The precipitate was collected by centrifugation using a high-speed centrifuge (9000 rpm) to obtain Au@Bn-NHC NPs, which were washed with ultrapure water and dispersed in ultrapure water.

[0037] The transmission electron microscopy image of the water-dispersible gold nanozyme Au@Bn-NHC NPs stabilized by nitrogen heterocyclic carbene prepared in this example is shown in FIG. Figure 6 As shown in Figure (b), it is a spherical nanoparticle with a diameter of about 19 nm.

[0038] Experimental Example 1: Characterization of the Photothermal Performance of Nitrogen Heterocyclic Carbene-Stabilized Water-Dispersible Gold Nanozymes Au@TPA-NHC NPs The Au@TPA-NHC NPs prepared in Example 3 were dispersed in ultrapure water to prepare a solution with a concentration of 10 μg / mL, and the photothermal conversion performance was tested.

[0039] At room temperature, 1 mL of 10 μg / mL sample was dispersed in ultrapure water and the sample was detected by 808 nm near-infrared light (1.0 W / cm 2 ) irradiation for 5 minutes, then turn off the power after 5 minutes and let the sample cool naturally at room temperature. The cooling time was recorded and the temperature change of the sample was collected every 30 seconds using a thermal imager. The above heating-cooling process was repeated 8 times. The photothermal stability of Au@TPA-NHC NPs was monitored by monitoring the maximum temperature of the sample after heating. The irradiation time was extended to 10 minutes. After 10 minutes, the laser was turned off and the sample was allowed to cool naturally to room temperature in air. The photothermal conversion efficiency of the sample was calculated ( η ).

[0040] (1) In the formula h is thermal conductivity; s is the surface area of ​​the container; T max is the highest stable temperature during heating; T surr is the ambient temperature; Q dis represents the amount of heat dissipated by the laser mediated by the solvent and the container. I is the laser power, A 808 is the absorbance of gold nanoparticles at 808 nm. hs 、 θ 、 τ s The calculation formula is: (2) Where m and C are the mass (1 g) and specific heat capacity (4.2 J g) of the solvent, respectively. -1 °C -1 ), θ is the dimensionless parameter of the driving force temperature, τ s is the related time constant, according to the linear time parameter t and -ln θ The relationship between the two is calculated to be 219.9 s.

[0041] Q disThe energy loss from the solvent to the sample tube is measured using a sample tube containing deionized water. The formula is: (3) The experimental results are as follows Figure 11 and Figure 12 shown.

[0042] like Figure 12 As shown in the figure, the temperature of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs increased significantly after laser irradiation, and the photothermal conversion efficiency was 88.4%.

[0043] like Figure 13 As shown in the figure, the temperature change trend of the nitrogen heterocyclic carbene-stabilized water-dispersible gold nanozyme Au@TPA-NHC NPs was consistent after 8 cycles of laser irradiation, indicating that it has excellent photostability.

[0044] Experimental Example 2: Characterization of the enzyme-like activity of water-dispersible gold nanozymes Au@TPA-NHC NPs stabilized by nitrogen heterocyclic carbene Glucose oxidase-like assay: The UV absorption spectrum of the reaction between hydrogen peroxide and titanium sulfate was measured at 412 nm. Gold nanoparticles (Au@TPA-NHC NPs) were mixed with glucose solutions of varying concentrations (0.2 mmol / L, 0.5 mmol / L, 1 mmol / L, 2 mmol / L, 5 mmol / L, and 10 mmol / L). After a period of reaction, the mixture was centrifuged. 0.5 mL of the supernatant was mixed with 1.5 mL of a Ti(SO4)2 solution (300 mg of Ti(SO4)2 dissolved in 30 mL of water containing 5 mL of H2SO4), and the absorbance at 412 nm was measured.

[0045] Peroxidase-like assay: 3,3',5,5'-tetramethylbenzidine (TMB) was used as a reactive oxygen species detector, and the post-reaction UV absorbance peak was measured at 652 nm. Gold nanoparticles (Au@TPA-NHC NPs) (10 μg / mL) and 50 μL of H₂O₂ (10 mmol / L) were added to an acetic acid-sodium acetate buffer solution (pH 3.7) to a final volume of 2 mL. After a 5-minute reaction, 50 μL of TMB (2 mmol / L) was added to the reaction system. The mixture was thoroughly mixed to achieve uniform color development, and the absorbance at 652 nm was measured.

[0046] Glutathione peroxidase-like assay: 5,5-Dithiobis(2-nitrobenzoic acid) (DTNB) was used as an indicator for detecting GSH content. To investigate the glutathione peroxidase-like activity of gold nanoparticles, different concentrations of gold nanoparticles (0 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, and 20 μg / mL) were mixed with 50 μL of GSH (1 mmol / L), 200 μL of DTNB (1 mmol / L), and PBS. The mixture was reacted at 37°C for 1 hour, and the supernatant was collected by centrifugation and its absorbance at 412 nm was measured.

[0047] The experimental results are as follows Figure 14-16 shown.

[0048] like Figure 14 As shown in the figure, as the concentration of the reaction substrate glucose increases, the corresponding absorbance at 412 nm increases from 0.04 to 0.32, and the absorbance is positively correlated with the glucose concentration. This demonstrates that the nitrogen heterocyclic carbene-stabilized gold nanoparticles, Au@TPA-NHC NPs, exhibit glucose oxidase-like properties, decomposing glucose into gluconic acid and hydrogen peroxide.

[0049] like Figure 15 As shown in the figure, when only TMB and TMB + H2O2 were added, there was no characteristic absorption peak at 652 nm, but TMB + H2O2 + Au@TPA-NHC NPs showed an obvious characteristic absorption peak of oxTMB at 652 nm, verifying that Au@TPA-NHC NPs had peroxidase-like activity.

[0050] like Figure 16 As shown in the figure, 2-nitro-5-mercaptobenzoic acid produced by the reaction of DTNB and GSH has a clear absorption peak at 412 nm. As the concentration of Au@TPA-NHC NPs increases to 20 μg / mL, the absorption peak at 412 nm gradually decreases, verifying that Au@TPA-NHC NPs have glutathione peroxidase-like activity.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water-soluble nitrogen heterocyclic carbene ligand, characterized in that The chemical structure is shown in formula (I): Formula (I): ; In formula (I), R includes an alkyl group having 1 to 4 carbon atoms, 、 and Any one of them.

2. The method for synthesizing the water-soluble nitrogen heterocyclic carbene ligand according to claim 1, wherein: The following steps are involved: The 1-substituted imidazole derivative and 1,3-propane sultone are subjected to alkylation reaction in a solvent to obtain the product.

3. The method for synthesizing a water-soluble nitrogen heterocyclic carbene ligand according to claim 2, wherein The molar ratio of the 1-substituted imidazole derivative to the 1,3-propane sultone is 1:8-12; The 1-substituted imidazole derivative includes any one of imidazole substituted with an alkyl group having 1 to 4 carbon atoms, 1-phenylimidazole, 1-benzylimidazole and 1-{4-[bis(4-methoxyphenyl)amino]phenyl}imidazole; The solvent includes acetone.

4. The method for synthesizing a water-soluble nitrogen heterocyclic carbene ligand according to claim 2, wherein The alkylation reaction temperature is 35-55° C. and the reaction time is 40-50 h.

5. A water-dispersible gold nanozyme based on the water-soluble nitrogen heterocyclic carbene ligand according to claim 1, characterized in that The chemical structure is shown in formula (II): Formula (II): ; In formula (II), R includes an alkyl group having 1 to 4 carbon atoms, 、 and Any one of them.

6. A method for synthesizing the water-dispersible gold nanozyme according to claim 5, characterized in that: The following steps are involved: The water-soluble nitrogen heterocyclic carbene ligand according to claim 1, an alkaline substance, tetrahydrothiophene gold chloride and n-tetrabutylammonium chloride are subjected to a reduction reaction in a solvent to prepare the product.

7. The method for synthesizing water-dispersible gold nanozyme according to claim 6, wherein: The molar ratio of the alkaline substance to the water-soluble nitrogen heterocyclic carbene ligand is 8-12:1; and the alkaline substance includes potassium carbonate.

8. The method for synthesizing water-dispersible gold nanozyme according to claim 6, wherein: The molar ratio of the water-soluble nitrogen heterocyclic carbene ligand to the n-tetrabutylammonium chloride is 1:1-1.2; and the solvent includes acetone.

9. The method for synthesizing water-dispersible gold nanozyme according to claim 6, wherein: The reduction reaction temperature is 25-45° C., and the reaction time is 10-16 h.

10. Use of the water-dispersible gold nanozyme according to claim 5 in photothermal conversion and / or enzyme-like catalysis.

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