4-Aminophenol functionalized carbon quantum dots and their preparation method and application

Abstract

The 4-aminophenol functionalized carbon quantum dots provided by the present disclosure embodiments and their preparation method and application, the preparation method includes: preparing sulfur and nitrogen co-doped carbon quantum dots by a hydrothermal method; the sulfur and nitrogen co-doped carbon quantum dots are mixed with solvent A, and amidation reaction is carried out under the action of a catalyst and 4-aminophenol, and the product obtained by amidation reaction is dialyzed, dried to obtain the 4-aminophenol functionalized carbon quantum dots. This preparation method is simple, and raw materials are easy to obtain at low cost, and the synthesized carbon quantum dots have low toxicity and are suitable for mass production. The application is the application of 4-aminophenol functionalized carbon quantum dots in the detection of nitroolefin structural compounds, according to the generation of hydrogen bond interactions between phenolic hydroxyl groups on the surface of carbon quantum dots containing nitroolefin structural compounds, resulting in fluorescence quenching of the fluorescent sensor, which has a high sensitivity to detection containing nitroolefin structural compounds.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of carbon quantum dots, and particularly relates to 4-aminophenol functionalized carbon quantum dots and a preparation method and application thereof. Background Art

[0002] Environmental pollutants are a major factor contributing to environmental problems, directly impacting human health and ecosystems. Because environmental pollutants often present health and ecological risks despite low concentrations in the environment, accurate analysis of trace pollutants is crucial.

[0003] Nitenpyram is a neonicotinoid insecticide that poses environmental residue issues and ecological risks. In a survey of neonicotinoids in Chinese rivers, nitenpyram residues were found to be relatively common among neonicotinoid pesticides, and the residual amounts were high. Nitenpyram is also acutely toxic to non-target organisms such as bees, earthworms, and silkworms. Nizatidine and ranitidine, medications that inhibit gastric acid secretion, have been recalled in some countries due to the presence of carcinogenic impurities. These compounds all contain nitroolefin structures in their molecules, making their detection essential.

[0004] Carbon quantum dots are a type of zero-dimensional carbon nanomaterial that has been widely studied. They have the characteristics of stable chemical properties, good water solubility, good biocompatibility, and excellent fluorescence properties. The surface of carbon quantum dots usually has rich functional groups, which also provides abundant sites for further modification to improve selectivity. The amide bond is a relatively stable chemical bond. The amidation reaction catalyzed by N-hydroxysuccinimide (NHS) / 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) can be carried out at room temperature and has a wide range of applications. In the interaction between nitenpyram and its target enzyme, tyrosine residues play a certain role. This interaction mode can also provide certain ideas for the development of fluorescent sensors. Summary of the Invention

[0005] The present disclosure aims to solve at least one of the technical problems existing in the prior art.

[0006] To this end, the method for preparing 4-aminophenol functionalized carbon quantum dots provided in the first embodiment of the present disclosure has mild reaction conditions, cheap and readily available raw materials, and the obtained product has good stability and excellent fluorescence properties. The method for preparing 4-aminophenol functionalized carbon quantum dots provided in the first embodiment of the present disclosure comprises:

[0007] Sulfur-nitrogen co-doped carbon quantum dots were prepared by hydrothermal method;

[0008] The sulfur-nitrogen co-doped carbon quantum dots are mixed with solvent A, and an amidation reaction is carried out under the action of a catalyst and 4-aminophenol. The product obtained by the amidation reaction is dialyzed and dried to obtain 4-aminophenol functionalized carbon quantum dots.

[0009] In some embodiments, sulfur-nitrogen co-doped carbon quantum dots are prepared by a hydrothermal method, comprising:

[0010] Dissolving a carbon source, a nitrogen source, and a sulfur source in solvent B and performing ultrasonic treatment to form a uniform solution A;

[0011] Performing a hydrothermal reaction on the solution A to obtain a solution B;

[0012] The solution B is dialyzed and dried to obtain the sulfur-nitrogen co-doped carbon quantum dots.

[0013] Furthermore, the carbon source is citric acid or isocitric acid.

[0014] Furthermore, the nitrogen source and sulfur source are selected from a mixture of any one or more of L-cysteine, D-cysteine ​​and N-acetylcysteine.

[0015] Furthermore, the solvent B is deionized water.

[0016] Furthermore, the temperature of the hydrothermal reaction is 160° C. to 220° C., and the reaction time is 1 h to 4 h.

[0017] Furthermore, the dialyzation time of the solution B is 48 hours to 96 hours.

[0018] Furthermore, during the dialysis of the solution B, the solvent B is regularly replaced to obtain a sulfur-nitrogen co-doped carbon quantum dot solution after dialysis.

[0019] Furthermore, the sulfur-nitrogen co-doped carbon quantum dots solution is subjected to rotary evaporation to remove most of the solvent and then freeze-dried to obtain the sulfur-nitrogen co-doped carbon quantum dots.

[0020] In some embodiments, the molar ratio of the carbon source, the nitrogen source and the sulfur source, and the solvent B is 1:0.2-0.8:500-2000.

[0021] In some embodiments, the solvent A is a mixture of one or more of deionized water, ethanol, dichloromethane and dimethylformamide.

[0022] In some embodiments, the catalyst is selected from a mixture of any one or more of N,N'-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, dicyclohexylcarbodiimide, 4-dimethylaminopyridine, carbodiimide hydrochloride, 1-hydroxybenzotriazole and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate.

[0023] In some embodiments, the molar ratio of the sulfur-nitrogen co-doped carbon quantum dots, the solvent A, the catalyst and the 4-aminophenol is 1:5000-200000:1-20:1-10.

[0024] In some embodiments, the sulfur-nitrogen co-doped carbon quantum dots are mixed with solvent A and subjected to an amidation reaction in the presence of a catalyst and 4-aminophenol, comprising:

[0025] The sulfur-nitrogen co-doped carbon quantum dots, the solvent A and the catalyst are activated for 10 to 30 minutes to obtain an activated product;

[0026] The activated product is mixed with the 4-aminophenol, and an amidation reaction is carried out at room temperature for 3 hours to 24 hours.

[0027] In some embodiments, the product is dialyzed for 12 hours to 48 hours.

[0028] Furthermore, the solvent A is regularly replaced during the dialysis process of the product, and a 4-aminophenol functionalized carbon quantum dot solution is obtained after dialysis.

[0029] Furthermore, the 4-aminophenol functionalized carbon quantum dots solution is subjected to rotary evaporation to remove most of the solvent and then freeze-dried to obtain the 4-aminophenol functionalized carbon quantum dots.

[0030] The method for preparing 4-aminophenol functionalized carbon quantum dots provided in the first embodiment of the present disclosure has the following characteristics and beneficial effects:

[0031] The disclosed embodiments utilize a hydrothermal method to react citric acid with L-cysteine ​​to form highly conjugated carbon quantum dots. The incorporation of heteroatoms further enhances the fluorescence of the carbon quantum dots by altering their molecular energy levels, resulting in an extremely high quantum yield. Furthermore, the raw materials used are readily available and extremely low-cost. The product exhibits excellent water solubility and is non-toxic.

[0032] The 4-aminophenol functionalized carbon quantum dots provided in the embodiment of the second aspect of the present disclosure are prepared using the preparation method provided in any embodiment of the first aspect of the present disclosure.

[0033] The 4-aminophenol functionalized carbon quantum dots provided in the second embodiment of the present disclosure have the following characteristics and beneficial effects:

[0034] In the disclosed embodiment, 4-aminophenol is covalently linked to carbon quantum dots through an amidation reaction. This modification of the surface of the carbon quantum dots can produce conjugation with the carbon quantum dots without destroying the fluorescence properties. At the same time, it also allows a large number of phenolic hydroxyl groups to exist on the surface of the carbon quantum dots, which can provide a structural basis for the subsequent hydrogen bond formation.

[0035] The third aspect of the present disclosure provides an embodiment of the application of 4-aminophenol functionalized carbon quantum dots in the detection of nitroolefin structure compounds.

[0036] In some embodiments, the application provided by the third aspect of the present disclosure includes:

[0037] Mixing the 4-aminophenol functionalized carbon quantum dots, solvent C, and a standard solution containing a nitroolefin structure compound at different concentrations to obtain a plurality of homogeneous solutions D, performing fluorescence excitation on each homogeneous solution D, and determining a functional relationship between the concentration of the nitroolefin structure compound and the fluorescence intensity;

[0038] The 4-aminophenol functionalized carbon quantum dots, the solvent C and the test sample extract containing the nitroolefin structure compound are mixed to obtain a homogeneous solution E. The solution E is subjected to fluorescence excitation, and the concentration of the nitroolefin structure compound contained in the test sample is obtained using the functional relationship between the concentration of the nitroolefin structure compound and the fluorescence intensity.

[0039] Furthermore, the solvent C is a mixture of any one or more of water, methanol, ethanol, isopropanol, acetonitrile and dimethyl sulfoxide.

[0040] Furthermore, the standard substance is nitenpyram, ranitidine or nizatidine.

[0041] Furthermore, the test article extract is selected from water samples of rice, orange, cabbage, serum, urine or river water.

[0042] Furthermore, the mass ratio of the 4-aminophenol functionalized carbon quantum dots, the solvent C and the standard solution is 1:10000:0.2-100.

[0043] Furthermore, the mass ratio of the 4-aminophenol functionalized carbon quantum dots, the solvent C and the test sample extract is 1:100-100000:0.01-1000.

[0044] Furthermore, the excitation wavelength is 345 nm.

[0045] The application of 4-aminophenol functionalized carbon quantum dots in the detection of nitroolefin structure compounds provided in the third embodiment of the present disclosure has the following characteristics and beneficial effects:

[0046] The disclosed embodiments utilize active groups such as phenolic hydroxyl groups on the surface of 4-aminophenol-functionalized carbon quantum dots, enabling the 4-aminophenol-functionalized carbon quantum dots to interact with compounds containing nitroolefin structures through hydrogen bonds, and quench the fluorescence of the 4-aminophenol-functionalized carbon quantum dots through a static quenching mechanism, thereby achieving highly sensitive detection of compounds containing nitroolefin structures using 4-aminophenol-functionalized carbon quantum dots as fluorescence sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a transmission electron microscope lattice diffraction image of 4-aminophenol functionalized carbon quantum dots prepared in Example 1 of the present disclosure. The morphology and lattice spacing of the carbon quantum dots can be seen.

[0048] Figure 2 This is a transmission electron microscope image of 4-aminophenol functionalized carbon quantum dots prepared in Example 1 of the present disclosure. The morphology of the carbon quantum dots can be seen.

[0049] Figure 3 This is the X-ray diffraction spectrum of the 4-aminophenol functionalized carbon quantum dots prepared in Example 1 of the present disclosure.

[0050] Figure 4 This is the infrared spectrum of 4-aminophenol functionalized carbon quantum dots prepared in Example 1 of the present disclosure. Figure 4 Medium 1654cm -1 and 1566cm -1 The absorption at corresponds to the amide I peak and the amide II peak, indicating that the formation of amide bonds enables 4-aminophenol to be covalently bound to carbon quantum dots.

[0051] Figure 5 This is a working curve of Example 5 of the present disclosure using 4-aminophenol functionalized carbon quantum dots to detect the nitroolefin structure compound nitenpyram.

[0052] Figure 6 This is the working curve of Example 6 of the present disclosure using 4-aminophenol functionalized carbon quantum dots to detect nizatidine, a compound containing a nitroolefin structure.

[0053] Figure 7 This is the working curve of Example 6 of the present disclosure using 4-aminophenol functionalized carbon quantum dots to detect ranitidine, a compound containing a nitroolefin structure. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0055] On the contrary, this application covers any alternatives, modifications, equivalents, and solutions made within the spirit and scope of this application as defined by the claims. Furthermore, to facilitate a better understanding of this application, certain specific details are described in detail below in the detailed description of this application. Those skilled in the art will be able to fully understand this application without these details.

[0056] The embodiments of the present application are described in detail below.

[0057] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes various applications of using the phenolic hydroxyl structure for identifying compounds containing nitroolefin structures.

[0058] Example 1:

[0059] The preparation method of 4-aminophenol functionalized carbon quantum dots provided in this embodiment 1 specifically includes the following steps:

[0060] 1. Preparation of sulfur-nitrogen co-doped carbon quantum dots: 2 g of citric acid, 1 g of L-cysteine ​​and 5 mL of deionized water were mixed to obtain a uniform solution A, which was added to a hydrothermal reactor with a reaction time of 3 h and a temperature of 200°C. After the reaction was completed, the solution was cooled to room temperature and filtered through a microporous filter membrane to obtain a yellow-brown solution B. The solution was dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain sulfur-nitrogen co-doped carbon quantum dots as a black powder.

[0061] 2. Preparation of 4-aminophenol functionalized carbon quantum dots: 3 mg of sulfur-nitrogen co-doped carbon quantum dots obtained in step 1 were dissolved in 30 mL of deionized water, 50 mg of each of the catalyst N,N'-diisopropylcarbodiimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were added, and the reaction was continued for 15 min. Then 100 mg of 4-aminophenol was added and the reaction was continued for 24 h. The product was filtered through a 0.22 μm microporous filter membrane to obtain a yellow-brown solution; dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain 4-aminophenol functionalized carbon quantum dots as a black powder.

[0062] Figures 1 to 4 is the characterization result of carbon quantum dots, where Figure 1 This is a high-resolution transmission electron microscope image, which shows that the functionalized carbon dots have obvious lattice characteristics. The lattice spacing is about 0.21nm, and they have obvious graphite structure characteristics. Figure 2This is a transmission electron microscope image of carbon quantum dots. It can be seen that the morphology of carbon quantum dots is irregular, with a particle size of 2.0-5.2nm and an average particle size of 3.3nm. Figure 3 This is the X-ray diffraction pattern of carbon quantum dots, which shows a broad diffraction peak with its center at 23.9°, which is the diffraction peak of graphite, and can also indicate that it has the structural characteristics of graphite. Figure 4 This is the infrared spectrum of carbon quantum dots. The main information is 1654cm -1 and 1566cm -1 The absorption at corresponds to the amide I peak and the amide II peak, indicating that the formation of amide bonds enables 4-aminophenol to be covalently bound to carbon quantum dots.

[0063] Example 2:

[0064] The preparation method of 4-aminophenol functionalized carbon quantum dots provided in Example 2 specifically includes the following steps:

[0065] 1. Preparation of sulfur-nitrogen co-doped carbon quantum dots: 0.5 g of citric acid, 0.3 g of D-cysteine ​​and 10 mL of water were mixed to obtain a uniform solution A, which was added to a hydrothermal reactor with a reaction time of 1 h and a temperature of 220°C. After the reaction was completed, the solution was cooled to room temperature and filtered through a microporous filter membrane to obtain a yellow-brown solution B. The solution was dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain sulfur-nitrogen co-doped carbon quantum dots as a black powder.

[0066] 2. Preparation of 4-aminophenol functionalized carbon quantum dots: 1 mg of sulfur-nitrogen co-doped carbon quantum dots obtained in step 1 was dissolved in 100 mL of dichloromethane solution, 130 mg of catalyst was added (the catalyst was 30 mg of dicyclohexylcarbodiimide and 100 mg of 4-dimethylaminopyridine), the reaction was carried out for 10 minutes, and then 30 mg of 4-aminophenol was added and the reaction was carried out for 24 hours. The product was filtered through a 0.22 μm microporous filter membrane to obtain a yellow-brown solution; dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain 4-aminophenol functionalized carbon quantum dots as a black powder.

[0067] Example 3:

[0068] The preparation method of 4-aminophenol functionalized carbon quantum dots provided in Example 3 specifically includes the following steps:

[0069] 1. Preparation of sulfur-nitrogen co-doped carbon quantum dots: 1.5 g of citric acid, 0.8 g of N-acetylcysteine ​​and 3 mL of water were mixed to obtain a uniform solution A, which was added to a hydrothermal reactor with a reaction time of 4 h and a temperature of 160°C. After the reaction was completed, the solution was cooled to room temperature and filtered through a microporous filter membrane to obtain a yellow-brown solution B. The solution was dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain sulfur-nitrogen co-doped carbon quantum dots as a black powder.

[0070] 2. Preparation of 4-aminophenol functionalized carbon quantum dots: Dissolve 10 mg of sulfur-nitrogen co-doped carbon quantum dots obtained in step 1 in 10 mL of water, add 140 mg of catalyst (the catalyst is 70 mg of carbodiimide hydrochloride and 70 mg of 1-hydroxybenzotriazole), react for 30 minutes, then add 200 mg of 4-aminophenol, react for 8 hours, and filter the product through a 0.22 μm microporous filter membrane to obtain a yellow-brown solution; dialyze through a dialysis bag (3500 Da), concentrate by rotary evaporation, and freeze-dry the dialyzate to obtain 4-aminophenol functionalized carbon quantum dots as a black powder.

[0071] Example 4:

[0072] The preparation method of 4-aminophenol functionalized carbon quantum dots provided in this embodiment 4 specifically includes the following steps:

[0073] 1. Preparation of sulfur-nitrogen co-doped carbon quantum dots: 3 g of isocitric acid, 0.5 g of L-cysteine ​​and 5 mL of water were mixed to obtain a uniform solution A, which was added to a hydrothermal reactor with a reaction time of 2 h and a temperature of 180°C. After the reaction was completed, the solution was cooled to room temperature and filtered through a microporous filter membrane to obtain a yellow-brown solution B. The solution was dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain sulfur-nitrogen co-doped carbon quantum dots as a black powder.

[0074] 2. Preparation of 4-aminophenol functionalized carbon quantum dots: 1 mg of sulfur-nitrogen co-doped carbon quantum dots obtained in step 1 was dissolved in 50 mL of dimethylformamide solution, 50 mg of catalyst was added (the catalyst was 50 mg of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate), the reaction was carried out for 10 minutes, and then 20 mg of 4-aminophenol was added and the reaction was carried out for 4 hours. The product was filtered through a 0.22 μm microporous filter membrane to obtain a yellow-brown solution; dialyzed through a dialysis bag (3500 Da), concentrated by rotary evaporation, and the dialyzate was freeze-dried to obtain 4-aminophenol functionalized carbon quantum dots as a black powder.

[0075] Example 5:

[0076] This embodiment 5 is a method for detecting nitenpyram, a compound containing a nitroolefin structure, using 4-aminophenol functionalized carbon quantum dots, which specifically includes the following steps:

[0077] 1. Detection of the concentration of nitenpyram in the standard: Take 900 μL of acetonitrile solution of nitenpyram with different concentrations, add 100 μL of 4-aminophenol functionalized carbon quantum dot solution with a concentration of 1 mg / mL, and record the fluorescence spectra of nitenpyram with different concentrations and the fluorescence intensity at 417 nm at an excitation wavelength of 345 nm. Among them, the fluorescence intensity when nitenpyram is not added is recorded as F0, and the fluorescence intensity when nitenpyram is added is F. Based on the results measured after the interaction between nitenpyram at different concentrations and carbon dots, draw a graph of the concentration x of nitenpyram versus y = F0-F (difference in fluorescence intensity), and obtain the standard curve based on the fitting results, see Figure 5 The equation of the standard curve is: y = 347.51x-1.9402, and the linearity of the curve is R 2 Greater than 0.99, high detection sensitivity and good response.

[0078] 2. Detection of Nitenpyram Concentration in Actual Samples: Take 2g of rice (orange or cabbage can be substituted) and extract with 2mL of acetonitrile. Add 900μL of the resulting extract to 100μL of a 1mg / mL solution of 4-aminophenol-functionalized carbon quantum dots. Test the sample using the nitenpyram concentration method described in Step 1 above. Calculate the nitenpyram concentration in the actual sample using the standard curve method.

[0079] Example 6:

[0080] This Example 6 is a method for detecting ranitidine and nizatidine containing nitroolefin structure compounds using 4-aminophenol functionalized carbon quantum dots, which is specifically completed by the following steps:

[0081] 1. Detection of ranitidine and nizatidine concentrations in standard samples: Take 900 μL of acetonitrile solutions of ranitidine or nizatidine with different concentrations, add 100 μL of 4-aminophenol functionalized carbon quantum dot solution with a concentration of 1 mg / mL, and record the fluorescence spectra of ranitidine or nizatidine with different concentrations at an excitation wavelength of 345 nm and the fluorescence intensity at 417 nm. Among them, the fluorescence intensity when no ranitidine or nizatidine is added is recorded as F0, and the fluorescence intensity when ranitidine or nizatidine is added is F. According to the results measured after the interaction between different concentrations of nitenpyram and carbon dots, a graph of concentration versus F0-F (difference in fluorescence intensity) is made. According to the fitting results, the standard curves for the detection of ranitidine and nizatidine concentrations by 4-aminophenol functionalized carbon quantum dots are obtained, respectively, see Figure 6 、 7The equations of the standard curves are: y = 433.16x-7.305, y = 373.26x + 40.531. The linearity of the curve is R 2 All are greater than 0.99.

[0082] 2. Detection of Ranitidine and Nizatidine Concentrations in Actual Samples: Take a 2g river water sample (the river water sample can be replaced with a urine sample or serum sample) and extract it with 2mL of acetonitrile. Take 900μL of the resulting extract and add 100μL of a 1mg / mL 4-aminophenol-functionalized carbon quantum dot solution. The sample is then tested according to the method for detecting the concentrations of ranitidine and nizatidine compounds in step 1 above. The concentrations of ranitidine and nizatidine in the actual sample are calculated using the standard curve method.

[0083] In summary, the present invention uses common organic small molecules as raw materials, synthesizes sulfur-nitrogen co-doped carbon quantum dots by a hydrothermal method, and synthesizes 4-aminophenol functionalized carbon quantum dots by an amidation reaction, which are used as fluorescent sensors to achieve highly sensitive detection of compounds containing nitroolefin structures.

[0084] The 4-aminophenol functionalized carbon quantum dot fluorescence sensor prepared by this method has uniform size, ranging from 2.0 to 5.2 nm, an average particle size of 3.3 nm, and good dispersibility in aqueous solution.

[0085] This method is mainly based on the hydrogen bond interaction between nitroolefin structure compounds and phenolic hydroxyl groups on the surface of carbon quantum dots, which leads to fluorescence quenching of the fluorescence sensor. The sensor has high detection sensitivity for nitroolefin structure compounds, with a detection limit of up to 0.02 mg / L and a good linear relationship in the range of 0.05-10 mg / L.

[0086] The method has a simple synthesis method, the raw materials are readily available and the cost is low, the synthesized carbon quantum dots have low toxicity, and are suitable for mass production.

[0087] This method is used in the highly sensitive detection of nitroolefin compounds in pesticides and medicines, and has broad application prospects in the detection of pesticide residues and environmental pollutants.

[0088] In the description of this specification, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms must refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0089] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing 4-aminophenol functionalized carbon quantum dots, characterized in that: include: Sulfur-nitrogen co-doped carbon quantum dots were prepared by a hydrothermal method; the carbon source for preparing the sulfur-nitrogen co-doped carbon quantum dots was citric acid or isocitric acid, the nitrogen source and the sulfur source were L-cysteine, D-cysteine ​​or N-acetylcysteine, and the molar ratio of the carbon source, the nitrogen source and the sulfur source was 1:0.2-0.8; The sulfur-nitrogen co-doped carbon quantum dots are mixed with solvent A, and an amidation reaction is carried out in the presence of a catalyst and 4-aminophenol. The product obtained by the amidation reaction is dialyzed and dried to obtain the 4-aminophenol functionalized carbon quantum dots; the molar ratio of the sulfur-nitrogen co-doped carbon quantum dots to the 4-aminophenol is 1:1-10; The particle size of the 4-aminophenol functionalized carbon quantum dots ranges from 2.0 to 5.2 nm, with an average particle size of 3.3 nm; and the 4-aminophenol functionalized carbon quantum dots have amide bonds.

2. The preparation method according to claim 1, characterized in that The method for preparing sulfur-nitrogen co-doped carbon quantum dots by a hydrothermal method comprises: Dissolving the nitrogen source, sulfur source and carbon source in solvent B and performing ultrasonic treatment to form a uniform solution A; subjecting the solution A to a hydrothermal reaction to obtain a solution B; The solution B is dialyzed and dried to obtain the sulfur-nitrogen co-doped carbon quantum dots.

3. The preparation method according to claim 2, characterized in that The solvent B is deionized water, and the molar ratio of the carbon source to the solvent B is 1:500-2000.

4. The preparation method according to claim 1, characterized in that The solvent A is selected from a mixture of any one or more of deionized water, ethanol, dichloromethane and dimethylformamide.

5. The preparation method according to claim 1, characterized in that The catalyst is selected from a mixture of any one or more of N,N'-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, dicyclohexylcarbodiimide, 4-dimethylaminopyridine, carbodiimide hydrochloride and 1-hydroxybenzotriazole or 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate.

6. The preparation method according to claim 1, characterized in that The molar ratio of the sulfur-nitrogen co-doped carbon quantum dots, the solvent A and the catalyst is 1:5000-200000:1-20.

7. The preparation method according to claim 1, characterized in that The sulfur-nitrogen co-doped carbon quantum dots are mixed with solvent A, and an amidation reaction is carried out under the action of a catalyst and 4-aminophenol, comprising: The sulfur-nitrogen co-doped carbon quantum dots, the solvent A and the catalyst are activated for 10 min to 30 min to obtain an activated product; The activated product is mixed with the 4-aminophenol to carry out an amidation reaction, and the reaction time is 3 hours to 24 hours.

8. A 4-aminophenol functionalized carbon quantum dot, characterized in that The method is prepared according to any one of claims 1 to 7.

9. An application of the 4-aminophenol functionalized carbon quantum dots according to claim 8 in the detection of nitroolefin structure compounds; characterized in that, The nitroolefin structure compound is nitenpyram, ranitidine or nizatidine.

10. The use according to claim 9, characterized in that include: Mixing the 4-aminophenol functionalized carbon quantum dots, solvent C, and a standard solution containing a nitroolefin structure compound at different concentrations to obtain a plurality of homogeneous solutions D, performing fluorescence excitation on each homogeneous solution D, and determining a functional relationship between the concentration of the nitroolefin structure compound and the fluorescence intensity; The 4-aminophenol functionalized carbon quantum dots, the solvent C, and the test sample extract containing the nitroolefin structure compound are mixed to obtain a homogeneous solution E, the solution E is subjected to fluorescence excitation, and the concentration of the nitroolefin structure compound contained in the test sample is obtained using the functional relationship between the concentration of the nitroolefin structure compound and the fluorescence intensity; The solvent C is selected from a mixture of any one or more of water, methanol, ethanol, isopropanol, acetonitrile and dimethyl sulfoxide; The standard solution is selected from nitenpyram, ranitidine or nizatidine; The test product extract is selected from water samples of rice, orange, cabbage, serum, urine or river water.

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