Preparation process of sulfur quantum dots with high fluorescence intensity and high stability and its application

Abstract

The present invention relates to the technical field of the preparation of sulfur quantum dots, and specifically discloses a preparation process and application of sulfur quantum dots with high fluorescence intensity and high stability. The process comprises the following steps: (1) adding sulfur powder to an alkali solution, stirring evenly, then adding a single-stranded DNA fragment, and then reacting under the conditions of continuous stirring and heating insulation. (2) Adding hydrogen peroxide to the reaction solution obtained in the above step (1), and then continuously reacting under the condition of continuous stirring. After completion, dialysis is carried out to obtain a sulfur quantum dot dispersion. The above process of the present invention is not only simple and efficient, but also significantly improves the fluorescence intensity, stability and biocompatibility of sulfur quantum dots, providing new ideas and technical means for the synthesis of sulfur quantum dots.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of sulfur quantum dots, and particularly relates to a preparation process and application of sulfur quantum dots with high fluorescence intensity and high stability. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Sulfur quantum dots (SQDs) are spherical fluorescent sulfur nanoparticles with a size in the nanometer range, having excellent properties such as high fluorescence intensity, high photostability, anti-photobleaching, and low toxicity. These properties enable sulfur quantum dots to have broad application potential in various fields such as detection, catalysis, imaging, and therapy. Currently, there are many reports on converting bulk elemental sulfur into nano-sulfur, including physical methods such as grinding and etching and chemical methods such as oxidation. However, this is mainly limited to non-luminescent sulfur nanoparticles with a size greater than 10 nm, and there is little research on sulfur quantum dots. The synthesis methods of sulfur quantum dots include: (1) the acid etching oxidation method, which includes three main steps: the physical contact process, the phase interface reaction, and the in-situ dissolution precipitation. (2) The assembly-fission method, which requires a reaction time of up to 100 hours to reach the dynamic equilibrium of the fission-dominated assembly process to obtain monodisperse sulfur quantum dots. The traditional preparation methods of sulfur quantum dots have problems such as low quantum yield, cumbersome preparation, and long reaction time, which limit their further application. Summary of the Invention

[0004] In view of this, the present invention provides a preparation process of sulfur quantum dots with high fluorescence intensity and high stability, which is not only simple, efficient, and has a high yield, but also significantly improves the fluorescence intensity and stability of sulfur quantum dots, providing new ideas and technical means for the synthesis of sulfur quantum dots. Specifically, the technical solution of the present invention is as follows.

[0005] First, the present invention provides a preparation process of sulfur quantum dots with high fluorescence intensity and high stability, including the following steps:

[0006] (1) Add sulfur powder to the alkaline solution and stir evenly, then add single-stranded DNA fragments, and then react under continuous stirring and heating insulation conditions.

[0007] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), and then continue to react under continuous stirring conditions. After completion, dialysis is carried out to obtain the sulfur quantum dot dispersion.

[0008] Further, in step (1), the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, etc. Preferably, the solvent of the alkaline solution is any one of ultrapure water and deionized water.

[0009] Further, in step (1), the mass fraction of the alkaline solution is 8-15%. The sulfide formed by the alkaline solution and sulfur powder can further react with sulfur powder to form an unstable intermediate polysulfide (such as Na2S x ), which can further undergo a fission reaction to release sulfur nanoparticles.

[0010] Further, in step (1), the molar ratio of the sulfur powder, the solute in the alkaline solution, and the single-stranded DNA fragment is 400-700:1400-1600:0.01-0.05. Optionally, the particle size of the sulfur powder is in the micron range.

[0011] Further, in step (1), the single-stranded DNA fragment includes at least one of PolyA 11-PolyA 50, PolyC 11-PolyC 50, PolyG 11-PolyG 50, PolyT 11-PolyT 50, etc. Preferably, the single-stranded DNA fragment is PolyA 11-PolyA 50.

[0012] Further, in step (1), the temperature for heating and insulation is 60-90 °C, and the reaction time is 12-24 hours. Optionally, the rate of continuous stirring is 400-700 rpm.

[0013] Further, in step (2), the initial mass fraction of hydrogen peroxide in the reaction solution is 4-10%. In this step, the present invention uses hydrogen peroxide to etch the surface of the sulfur nanoparticles, so that the larger-sized sulfur nanoparticles form smaller-sized sulfur quantum dots and the sulfur quantum dots have stronger fluorescence intensity.

[0014] Further, in step (2), the time for continued reaction is 4-12 hours. Optionally, the rate of continuous stirring is 400-700 rpm.

[0015] Further, in step (2), dialysis is carried out using a dialysis membrane to separate the alkali to obtain the sulfur quantum dots. Optionally, the pH of the sulfur quantum dots is 8-9.

[0016] Further, in step (2), the sulfur quantum dots need to be stored in a low-temperature environment of 2-8 °C and protected from light.

[0017] Secondly, the present invention provides the application of the sulfur quantum dots obtained by the preparation process in the fields of detection, catalysis, imaging, medicine, etc.

[0018] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: The present invention uses single-stranded DNA fragments as passivating agents to prepare sulfur quantum dots. During the synthesis process, the ammonium ions (NH4 + formed by the amino groups (-NH2) on the DNA surface in an alkaline solution interact with the negatively charged groups (such as SO3 2- on the surface of the sulfur quantum dots through electrostatic interaction, enhancing the dispersibility of SQDs. At the same time, the DNA fragments cover the surface of SQDs as capping agents through electrostatic interaction, which can effectively prevent the formed SQDs from aggregating, improve the stability of SQDs, and thus obtain sulfur quantum dots with high fluorescence intensity, high stability and good biocompatibility. In addition, compared with the traditional preparation process of sulfur quantum dots, the preparation process proposed by the present invention significantly shortens the reaction time of the traditional assembly-cleavage method, which takes up to 100 hours, to less than 36 hours, significantly improving the production efficiency. This shows that the sulfur quantum dot preparation process proposed by the present invention is more simple and efficient, and the yield of sulfur quantum dots is higher, providing new ideas and technical means for the synthesis of sulfur quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0020] Figure 1 Transmission electron microscopy image of the sulfur quantum dots prepared in Example 1 below.

[0021] Figure 2 Particle size distribution diagram of the sulfur quantum dots prepared in Example 1 below.

[0022] Figure 3 Fluorescence emission diagram of the sulfur quantum dots prepared in Example 1 below.

[0023] Figure 4 Fluorescence emission diagram of the sulfur quantum dots prepared in Example 1 below after standing for 15 days.

[0024] Figure 5 Transmission electron microscopy image of the sulfur quantum dots prepared in Example 2 below.

[0025] Figure 6 Fluorescence emission diagram of the sulfur quantum dots prepared in Example 2 below.

[0026] Figure 7 Fluorescence emission diagram of the sulfur quantum dots prepared in Example 2 below after standing for 15 days.

[0027] Figure 8 Transmission electron microscopy image of the sulfur quantum dots prepared in Example 3 below.

[0028] Figure 9 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 3 below.

[0029] Figure 10 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 4 below.

[0030] Figure 11 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 5 below.

[0031] Figure 12 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 6 below.

[0032] Figure 13 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 7 below.

[0033] Figure 14 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 7 after standing for 15 days.

[0034] Figure 15 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 8 below.

[0035] Figure 16 Fluorescence emission diagram of the sulfur quantum dots prepared for Example 8 after standing for 15 days.

[0036] Figure 17 Fluorescence emission diagram of the sulfur nanoparticles prepared for Example 9 below. Detailed implementation mode

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0038] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or according to the product instructions.

[0039] In addition, any methods and materials similar or equivalent to the recorded content can be applied to the method of the present invention. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0040] Example 1

[0041] A preparation process for sulfur quantum dots with high fluorescence intensity and high stability includes the following steps:

[0042] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 11.7%. Then add micron-sized sulfur powder. After stirring evenly, add single-stranded DNA fragment PolyA 30 (i.e., 30 adenine lengths: AAAAA AAAAAAAAAA AAAAA AAAAA AA AAA). The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragment is 625:1430:0.02. Then heat the obtained system to 70 °C and continuously stir and react at a rate of 450 rpm for 12 hours.

[0043] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide is 9%. Then continuously stir and react for 8 hours at a stirring rate of 450 rpm. Then dialyze the reaction solution with a 500 Da dialysis membrane to obtain sulfur quantum dots with a pH = 8.7. After completion, store the obtained sulfur quantum dot dispersion at 4 °C.

[0044] The transmission electron microscope image of the sulfur quantum dots prepared in this example is as Figure 1 shown. It can be seen that the sulfur quantum dots are evenly distributed and there is no agglomeration phenomenon.

[0045] The particle size distribution diagram of the sulfur quantum dots prepared in this example is as Figure 2 shown. It can be seen that the average particle size of the sulfur quantum dots is 1.9 nm.

[0046] The fluorescence emission and the fluorescence emission spectrum after standing for 15 days of the sulfur quantum dots prepared in this example are respectively as Figure 3 , Figure 4 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is about 420 nm, indicating that the sulfur quantum dots are successfully synthesized in this example, and the fluorescence intensity of the quantum dots remains basically unchanged after standing for 15 days, proving that the quantum dots have high stability.

[0047] Example 2

[0048] A preparation process for sulfur quantum dots with high fluorescence intensity and high stability, comprising the following steps:

[0049] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 10%. Then add micron-sized sulfur powder. After stirring evenly, add single-stranded DNA fragment PolyA 11 (i.e., 11 adenine lengths: AAAAA AAAAAA). The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragment is 625:1430:0.02. Then heat the obtained system to 60 °C and continuously stir and react at a rate of 700 rpm for 24 hours.

[0050] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide is 9%. Then continuously stir for 4 hours at a stirring rate of 700 rpm. Then dialyze the reaction solution with a dialysis membrane of 500 Da to obtain sulfur quantum dots with a pH of 9. After completion, store the obtained sulfur quantum dot dispersion at 4 °C.

[0051] The transmission electron microscopy image of the sulfur quantum dots prepared in this example is as Figure 5 shown. It can be seen that the sulfur quantum dots are evenly distributed without agglomeration, and the average particle size of the sulfur quantum dots is 2.5 nm.

[0052] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as Figure 6 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is around 410 nm, indicating that sulfur quantum dots are successfully synthesized in this example. Figure 7 This is the fluorescence spectrum of the quantum dots after standing for 15 days, and the intensity remains basically unchanged, proving that the quantum dots have high stability.

[0053] Example 3

[0054] A preparation process for sulfur quantum dots with high fluorescence intensity and high stability includes the following steps:

[0055] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 8%. Then add micron-sized sulfur powder, and after stirring evenly, add a single-stranded DNA fragment PolyA 50 (i.e., 50 adenine lengths: AAAAA AAAAAAAAAA AAAAA AAAAA AAAAA AAAAA AAAAA AAAAA AAAAA). The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragment is 500:1500:0.03. Then heat the obtained system to 70 °C and continuously stir and react at a rate of 400 rpm for 12 hours.

[0056] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide is 5%. Then continuously stir for 7 hours at a stirring rate of 400 rpm. Then dialyze the reaction solution with a dialysis membrane of 500 Da to obtain sulfur quantum dots with a pH of 8. After completion, store the obtained sulfur quantum dot dispersion at 8 °C.

[0057] The transmission electron microscopy image of the sulfur quantum dots prepared in this example is as Figure 8 shown. It can be seen that the sulfur quantum dots are evenly distributed without agglomeration, and the average particle size of the sulfur quantum dots is 2.8 nm.

[0058] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as follows Figure 9 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is around 410 nm, indicating that the sulfur quantum dots have been successfully synthesized in this example.

[0059] Example 4

[0060] A preparation process for sulfur quantum dots with high fluorescence intensity and high stability includes the following steps:

[0061] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 15%. Then add micron-sized sulfur powder, and after stirring evenly, add single-stranded DNA fragment PolyC 30 (i.e., cytosine with 30 lengths: CCCCC CCCCCCCCCC CCCCC CCCCC CCCCC). The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragment is 700:1600:0.05. Then heat the obtained system to 80 °C and continuously stir and react at a rate of 500 rpm for 20 hours.

[0062] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide is 4%. Then continuously stir for 6 hours at a stirring rate of 500 rpm. Then dialyze the reaction solution with a dialysis membrane of 500 Da to obtain sulfur quantum dots with a pH of 8.3. After completion, store the obtained sulfur quantum dot dispersion at 2 °C.

[0063] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as follows Figure 10 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is between 410 and 450 nm, indicating that the sulfur quantum dots have been successfully synthesized in this example.

[0064] Example 5

[0065] A preparation process for sulfur quantum dots with high fluorescence intensity and high stability includes the following steps:

[0066] (1) Add sodium carbonate powder to ultrapure water to form a sodium carbonate solution with a mass fraction of 12%. Then add micron-sized sulfur powder, and after stirring evenly, add single-stranded DNA fragment PolyG 30 (i.e., guanine with 30 lengths: GGGGG GGGGG GGGGGGGGGG GGGGG GGGGG). The molar ratio of the sulfur powder, sodium carbonate powder, and single-stranded DNA fragment is 400:1400:0.01. Then heat the obtained system to 70 °C and continuously stir and react at a rate of 450 rpm for 12 hours.

[0067] (2) Hydrogen peroxide was added to the reaction solution obtained in the above step (1), and the initial mass fraction of hydrogen peroxide was 6.5%. Then, continuous stirring was carried out for 8 hours at a stirring rate of 450 rpm. Then, the reaction solution was dialyzed with a 500 Da dialysis membrane to obtain sulfur quantum dots with a pH of 9. After completion, the obtained sulfur quantum dot dispersion was stored at 5 °C.

[0068] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as Figure 11 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is between 410 and 450 nm, indicating that sulfur quantum dots were successfully synthesized in this example.

[0069] Example 6

[0070] A preparation process of sulfur quantum dots with high fluorescence intensity and high stability, comprising the following steps:

[0071] (1) Potassium hydroxide powder was added to deionized water to form a 10% potassium hydroxide solution, and then micron-sized sulfur powder was added. After stirring evenly, a single-stranded DNA fragment PolyT 30 (i.e., 30 thymine residues: TTTTTTTTTTTTTTTTTTTTTTTTTTTTT) was added. The molar ratio of the sulfur powder, potassium hydroxide powder, and single-stranded DNA fragment was 600:1550:0.04. Then, the obtained system was heated to 70 °C and continuously stirred and reacted at a rate of 450 rpm for 12 hours.

[0072] (2) Hydrogen peroxide was added to the reaction solution obtained in the above step (1), and the initial mass fraction of hydrogen peroxide was 10%. Then, continuous stirring was carried out for 12 hours at a stirring rate of 600 rpm. Then, the reaction solution was dialyzed with a 500 Da dialysis membrane to obtain sulfur quantum dots with a pH of 8.5. After completion, the obtained sulfur quantum dot dispersion was stored at 4 °C.

[0073] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as Figure 12 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is between 410 and 450 nm, indicating that sulfur quantum dots were successfully synthesized in this example.

[0074] Example 7

[0075] A preparation process of sulfur quantum dots, comprising the following steps:

[0076] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 11.7%. Then add micron-sized sulfur powder. After stirring evenly, add single-stranded DNA fragments (GAAGT GAAAA TGACA GAACA CAACA AAAATCGGGC). The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragments is 625:1430:0.02. Then heat the resulting system to 70 °C and continuously stir and react at a rate of 450 rpm for 12 hours.

[0077] (2) Add hydrogen peroxide to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide is 9%. Then continuously stir and react for 8 hours, and the stirring rate is 450 rpm. Then dialyze the reaction solution with a 500 Da dialysis membrane to obtain sulfur quantum dots with a pH of 8.7. After completion, store the obtained sulfur quantum dot dispersion at 4 °C.

[0078] The fluorescence emission spectrum of the sulfur quantum dots prepared in this example is as Figure 13 shown. It can be seen that the fluorescence emission wavelength of the quantum dots is around 410 nm. At the same time, from Figure 13 it can be seen that the fluorescence intensity of the sulfur quantum dots prepared in this example is about 5500, while the fluorescence intensity of the corresponding Example 1 is about 8000. Figure 14 This is the fluorescence intensity of the sulfur quantum dots prepared in this example after standing for 15 days. It can be seen that the fluorescence intensity of the sulfur quantum dots at this time is 3500, which is about 2000 lower than the fluorescence intensity when they were just synthesized, proving that the stability of the quantum dots is poor. This means that the quantum dots synthesized from the mixed-sequence DNA in this example are significantly lower than the quantum dots synthesized from the single base A in Example 1 in terms of fluorescence intensity and stability.

[0079] Example 8

[0080] A process for preparing sulfur quantum dots includes the following steps:

[0081] (1) Add sodium hydroxide powder to ultrapure water to form a sodium hydroxide solution with a mass fraction of 10%. Then add micron-sized sulfur powder. After stirring evenly, add double-stranded DNA (dsDNA: synthesized by annealing two single strands of AAAAA AAAAA A and TTTTT TTTTT T at 95 °C for 2 minutes). The molar ratio of the sulfur powder, sodium hydroxide powder, and double-stranded DNA fragments is 625:1430:0.02. Then heat the resulting system to 60 °C and continuously stir and react at a rate of 700 rpm for 24 hours.

[0082] (2) Hydrogen peroxide was added to the reaction solution obtained in the above step (1), where the initial mass fraction of hydrogen peroxide was 9%. Then, continuous stirring was carried out for 4 hours at a stirring rate of 700 rpm. Then, the reaction solution was dialyzed using a 500 Da dialysis membrane to obtain sulfur quantum dots with a pH of 9. After completion, the obtained sulfur quantum dot dispersion was stored at 4 °C.

[0083] The fluorescence emission graph of the sulfur quantum dots prepared in this example is as Figure 15 shown. It can be seen that the fluorescence emission wavelength of this quantum dot is around 410 nm. At the same time, from Figure 15 it can be seen that the fluorescence intensity of the sulfur quantum dots prepared in this example is around 4000, while the fluorescence intensity of the corresponding Example 2 is around 9500. Figure 16 This is the fluorescence intensity of the sulfur quantum dots prepared in this example after standing for 15 days. It can be seen that the fluorescence intensity of this sulfur quantum dot at this time is 3500, which is about 500 lower than the fluorescence intensity when it was just synthesized, proving that the stability of this quantum dot is average. This means that the quantum dots synthesized from double-stranded DNA in this example are significantly lower than the quantum dots synthesized from single-stranded DNA fragments in Example 2 in terms of fluorescence intensity and stability.

[0084] Example 9

[0085] A preparation process of sulfur quantum dots includes the following steps:

[0086] (1) Sodium hydroxide powder was added to ultrapure water to form a sodium hydroxide solution with a mass fraction of 10%. Then, micron-sized sulfur powder was added. After stirring evenly, single-stranded DNA fragment PolyA 11 (i.e., 11 adenine lengths: AAAAA AAAAAA) was added. The molar ratio of the sulfur powder, sodium hydroxide powder, and single-stranded DNA fragment was 625:1430:0.02. Then, the obtained system was heated to 60 °C and continuously stirred and reacted at a rate of 700 rpm for 24 hours.

[0087] (2) The reaction solution obtained in the above step (1) was dialyzed using a 500 Da dialysis membrane. After completion, the obtained sulfur particle product was stored at 4 °C.

[0088] The fluorescence emission of the sulfur particle product prepared in this example is as Figure 17 shown. It can be seen that without adding hydrogen peroxide, the sulfur particle product synthesized by this method has no fluorescence, which is because this sulfur particle product is not a sulfur quantum dot.

[0089] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A process for preparing sulfur quantum dots with high fluorescence intensity and high stability, characterized in that: The steps include: (1) Add sulfur powder to the alkali solution and stir evenly, then add the single-stranded DNA fragment, and then react under continuous stirring and heating at 60-90°C for 12-24 hours; (2) adding hydrogen peroxide to the reaction solution obtained in the above step (1), and then continuing the reaction for 4 to 12 hours under continuous stirring conditions; after completion, dialyzing is performed to obtain a sulfur quantum dot dispersion; The molar ratio of the sulfur powder, the solute in the alkali solution, and the single-stranded DNA fragment is 400-700: 1400-1600: 0.01-0.05; The single-stranded DNA fragment is selected from at least one of PolyA 11 to PolyA 50, PolyC 11 to PolyC 50, PolyG 11 to PolyG50, and PolyT 11 to PolyT 50.

2. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (1), the alkaline solution includes at least one of a sodium hydroxide solution, a potassium hydroxide solution, and a sodium carbonate solution.

3. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (1), the solvent of the alkali solution is any one of ultrapure water and deionized water.

4. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (1), the mass fraction of the alkali solution is 8-15%.

5. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (1), the particle size of the sulfur powder is in the micrometer level.

6. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: The single-stranded DNA fragment is PolyA 11~PolyA 50.

7. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (1), the continuous stirring rate is 400-700 rpm.

8. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (2), the initial mass fraction of hydrogen peroxide in the reaction solution is 4-10%.

9. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to claim 1, characterized in that: In step (2), the continuous stirring rate is 400-700 rpm.

10. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to any one of claims 1 to 9, characterized in that: In step (2), the sulfur quantum dots are separated by dialysis using a dialysis membrane.

11. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to any one of claims 1 to 9, characterized in that: In step (2), the pH of the sulfur quantum dots is 8-9.

12. The process for preparing sulfur quantum dots with high fluorescence intensity and high stability according to any one of claims 1 to 9, characterized in that: In step (2), the sulfur quantum dots need to be stored in an environment of 2-8°C and protected from light.

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