Highly luminescent water-soluble fluorescent quantum dots and methods for their preparation

Abstract

The application provides a water-phase high-brightness fluorescent quantum dot and a preparation method thereof. 0.07 -Cu 0.03 In 0.1 Se 0.14 Compared with the prior art, the water-phase high-brightness fluorescent quantum dot has high-brightness fluorescent performance, the fluorescent intensity is more than 800, the absolute value of Zeta potential is greater than or equal to 56 mV, the system stability is good, the water-phase high-brightness fluorescent quantum dot can be mutually soluble with water, the interface with oil is clear, the hydrophilicity is high, and the water-phase high-brightness fluorescent quantum dot can be applied to gene detection, medical diagnosis, biological imaging, targeted drug delivery and the like. The preparation method adopts a solvothermal technology, the preparation method is simple and the preparation period is short, and the water-phase high-brightness fluorescent quantum dot obtained by using the preparation method also has the characteristics of non-toxicity, easy operation, high sensitivity and excellent stability.

Description

Technical Field

[0001] This invention relates to the field of biomedicine, and more particularly to an aqueous high-brightness fluorescent quantum dot and its preparation method. Background Technology

[0002] Ternary quantum dots (Cu-In-Se) not only possess properties similar to group II-VI and III-V binary quantum dots, but also exhibit weaker light scattering and attenuation due to their composition of low-toxicity elements, resulting in deeper detection depths and higher spatial resolution. This has attracted widespread attention in the fields of biomedical labeling and sensing. In recent years, they have become an important research tool in gene detection, medical diagnosis, bioimaging, and targeted drug delivery. Clinically, the excellent fluorescence properties of quantum dots hold promise for achieving early and precise diagnosis and targeted therapy of tumors.

[0003] Currently, the main approach is to first prepare oil-phase Cu-In-Se quantum dots using a solvothermal method. If aqueous-phase Cu-In-Se quantum dots are desired, hydrophilic modification is then performed on the oil-phase Cu-In-Se quantum dots. Current methods mainly fall into two categories: one utilizes surface ligand exchange strategies with hydrophilic small molecules such as mercaptopropionic acid, and the other involves surface modification of the quantum dots with amphiphilic biomacromolecules.

[0004] The above-mentioned methods can all achieve the water solubility and biofunctionalization of quantum dots, but they all involve two-step reactions, which are cumbersome and time-consuming. Moreover, due to the surface reconstruction of the oil-phase quantum dots, the long-term stability of the resulting aqueous products is poor. Summary of the Invention

[0005] The main objective of this invention is to provide an aqueous high-brightness fluorescent quantum dot and its preparation method, aiming to solve the problems of complex preparation process and poor stability of aqueous quantum dots in the prior art.

[0006] To achieve the above objectives, the present invention provides an aqueous high-brightness fluorescent quantum dot, wherein the chemical formula of the aqueous high-brightness fluorescent quantum dot is Zn. 0.07 -Cu 0.03 In 0.1 Se 0.14 Furthermore, the absolute value of the Zeta potential of the aqueous high-brightness fluorescent quantum dots is ≥56mV; the aqueous high-brightness fluorescent quantum dots are miscible with water and have a clear interface with the oil phase.

[0007] This invention also provides a method for preparing aqueous high-brightness fluorescent quantum dots, wherein the chemical formula of the aqueous high-brightness fluorescent quantum dots is Zn. 0.07 -Cu 0.03 In 0.1 Se 0.14 The preparation method includes the following steps:

[0008] Selenium powder, oleylamine, n-dodecyl mercaptan, and thioglycerol are mixed and treated in a water bath to obtain a selenium precursor solution; the mass ratio of the selenium powder to the total volume of the oleylamine, n-dodecyl mercaptan, and thioglycerol is 9.2–36.6 g / L; the volume ratio of the n-dodecyl mercaptan to the thioglycerol is 0–900:100–500.

[0009] Provides a cationic solution containing In ions, Zn ions and Cu ions.

[0010] The selenium precursor solution is injected into the cation solution at 160–170°C to react and obtain aqueous high-brightness fluorescent quantum dots; wherein the molar ratio of the selenium powder, the In ions, the Zn ions, and the Cu ions satisfies the chemical formula of the aqueous high-brightness fluorescent quantum dots being Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 The measurement ratio.

[0011] Furthermore, the reaction duration is 40–90 min.

[0012] Furthermore, the volume ratio of the oleylamine, the n-dodecyl mercaptan, and the thioglycerol is 500–1000:100–500:120–250.

[0013] Furthermore, a vacuuming process is included before the water bath insulation treatment step.

[0014] Furthermore, the water bath heat preservation treatment is carried out in an atmosphere of chemically inert gas; and the temperature of the water bath heat preservation treatment is 40-90℃.

[0015] Furthermore, the cationic solution is obtained by mixing indium acetate, cuprous iodide and zinc acetate in a molar ratio of 1:0.3:0.7, adding oleylamine and octadecene in a volume ratio of 75:400, stirring, and heating to 160-170°C.

[0016] Furthermore, the molar volume ratio of zinc acetate to octadecene is 0.7 mol: 40000 mL.

[0017] Furthermore, after the stirring process and before the heating process, a vacuuming process is also included.

[0018] Furthermore, the vacuuming process needs to be repeated three times consecutively, and nitrogen is replenished after each vacuuming.

[0019] The present invention has the following beneficial effects:

[0020] The aqueous high-brightness fluorescent quantum dots provided by this invention have high-brightness fluorescence performance, with a fluorescence intensity exceeding 800; the absolute value of the Zeta potential is ≥56mV, and the system has good stability; they are miscible with water and have a clear interface with the oil phase, high hydrophilicity, and strong biological applicability, and can be applied in gene detection, medical diagnosis, bioimaging, targeted drug delivery, and other fields.

[0021] The aqueous high-brightness fluorescent quantum dots are prepared by solvothermal technology. The preparation method is simple and the preparation cycle is short. The aqueous high-brightness fluorescent quantum dots obtained by this method are also non-toxic, easy to operate, highly sensitive and have excellent stability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 The oil phase Zn obtained in Comparative Example 1 of the present invention 0.07 -Cu 0.03 In 0.1 Se 0.14 The fluorescence performance test results of quantum dots are shown in the figure.

[0024] Figure 2 This is a comparison chart of the fluorescence performance test results of quantum dots prepared under different temperature conditions in Example 1 of the present invention;

[0025] Figure 3 These are UV-lit comparison images of quantum dots prepared under various temperature conditions in Example 1 of the present invention; wherein, (a) is a UV-lit image of quantum dots prepared at 150℃, (b) is a UV-lit image of quantum dots prepared at 160℃, (c) is a UV-lit image of quantum dots prepared at 165℃, and (d) is a UV-lit image of quantum dots prepared at 170℃.

[0026] Figure 4 This is a comparison chart of the fluorescence performance test results of the aqueous high-brightness fluorescent quantum dots prepared at different reaction times in Example 2 of the present invention;

[0027] Figure 5These are comparison images taken under a UV lamp of the high-brightness fluorescent quantum dots prepared in aqueous phase at different reaction times in Example 2 of the present invention; wherein, (a) is an image taken under a UV lamp of the quantum dots prepared at 40 min, (b) is an image taken under a UV lamp of the quantum dots prepared at 60 min, and (c) is an image taken under a UV lamp of the quantum dots prepared at 90 min.

[0028] Figure 6 This is a comparison chart of the fluorescence performance detection results of quantum dots prepared under different DDT / TG ratios in Example 3 of the present invention;

[0029] Figure 7 These are UV-lit comparison images of quantum dots prepared under different DDT / TG ratios in Example 3 of the present invention; wherein, (a) is a UV-lit image of quantum dots prepared with a DDT / TG ratio of 0 μL:246 μL, (b) is a UV-lit image of quantum dots prepared with a DDT / TG ratio of 90 μL:222 μL, (c) is a UV-lit image of quantum dots prepared with a DDT / TG ratio of 270 μL:172 μL, (d) is a UV-lit image of quantum dots prepared with a DDT / TG ratio of 360 μL:147 μL, and (e) is a UV-lit image of quantum dots prepared with a DDT / TG ratio of 450 μL:123 μL.

[0030] Figure 8 The aqueous high-brightness fluorescent quantum dots and oil-phase Zn in Analytical Example 4 of this invention 0.07 -Cu 0.03 In 0.1 Se 0.14 Comparison of the optical properties of quantum dots under natural light and ultraviolet light; where (a) is the optical comparison under natural light and (b) is the optical comparison under ultraviolet light.

[0031] Figure 9 The diagram shows a comparison of the Zeta potential data of each aqueous high-brightness fluorescent quantum dot sample and each thioglycerol-modified aqueous quantum dot sample in Analytical Example 5 of the present invention; wherein, (a) is a comparison of the Zeta potential data of each aqueous high-brightness fluorescent quantum dot sample, and (b) is a comparison of the Zeta potential data of each thioglycerol-modified aqueous quantum dot sample.

[0032] Figure 10 The infrared spectra of aqueous high-brightness fluorescent quantum dots and pure thioglycerol in Analytical Example 6 of the present invention are shown in comparison; where (a) is the infrared spectrum of aqueous high-brightness fluorescent quantum dots and (b) is the infrared spectrum of pure thioglycerol.

[0033] Figure 11The images are TEM (transmission electron microscope) images of the aqueous high-brightness fluorescent quantum dots at different magnifications in Analytical Example 7 of the present invention; wherein, (a) is a TEM image at a scale of 20 nm, (b) is a TEM image at a scale of 10 nm, (c) is a TEM image at a scale of 50 nm, and (d) is a TEM image at a scale of 5 nm.

[0034] Figure 12 The aqueous high-brightness fluorescent quantum dots and oil-phase Zn in Analytical Example 7 of the present invention 0.07 -Cu 0.03 In 0.1 Se 0.14 Comparison of XRD (X-ray diffraction) patterns of quantum dots.

[0035] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of this invention is for describing specific implementations and not for limiting the scope of protection of this invention.

[0038] Wherein, "Wavelength" can represent wavelength; "Intensity" can represent fluorescence intensity; "Apparent Zeta Potential" can represent apparent zeta potential; "Total Counts" can represent total counts; "Wavenumber" can represent wavenumber; "Transmittance" can represent transmittance; "2Theta" can represent diffraction angle; and "Oil phase QDs" can represent oil phase Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 Quantum dots; “Aqueous phase QDs” can be referred to as aqueous phase high-brightness fluorescent quantum dots.

[0039] Unless otherwise defined, all technical and scientific terms used in this invention are consistent with the prior art known to those skilled in the art and the description of this invention. This invention may also be implemented using any prior art methods, devices and materials similar to or equivalent to those described, used or made by means of methods, devices and materials in the embodiments of this invention.

[0040] When numerical ranges are given in the examples, it should be understood that, unless otherwise stated in the invention, both endpoints of each range and any value between the two endpoints may be used. Test methods in the following examples that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers. Unless otherwise specified, all materials or reagents required in the following examples are commercially available.

[0041] To address the problems of complex preparation processes and poor stability in existing technologies for aqueous quantum dots, this invention provides an aqueous high-brightness fluorescent quantum dot with the chemical formula Zn. 0.07 -Cu 0.03 In 0.1 Se 0.14 Furthermore, the absolute value of the Zeta potential of the aqueous high-brightness fluorescent quantum dots is ≥56mV; the aqueous high-brightness fluorescent quantum dots are miscible with water and have a clear interface with the oil phase. It should be noted that the stability of quantum dots is usually evaluated using the numerical value of the Zeta potential. The larger the absolute value of the Zeta potential, the more stable the system. The absolute value of the Zeta potential of the aqueous high-brightness fluorescent quantum dots of this invention is ≥56mV, indicating that the aqueous high-brightness fluorescent quantum dot system is very stable. Moreover, these aqueous high-brightness fluorescent quantum dots are miscible with water and have a clear interface with the oil phase, exhibiting good hydrophilicity, and can be well applied to biomedical sensing and imaging research.

[0042] The aqueous high-brightness fluorescent quantum dots provided by this invention have high-brightness fluorescence performance, with a fluorescence intensity exceeding 800; the absolute value of the Zeta potential is ≥56mV, and the system has good stability; they are miscible with water and have a clear interface with the oil phase, high hydrophilicity, and strong biological applicability, and can be applied in gene detection, medical diagnosis, bioimaging, targeted drug delivery, and other fields.

[0043] This invention also provides a method for preparing aqueous high-brightness fluorescent quantum dots, wherein the chemical formula of the aqueous high-brightness fluorescent quantum dots is Zn. 0.07 -Cu 0.03 In 0.1 Se 0.14 The preparation method includes the following steps:

[0044] Selenium powder, oleylamine, n-dodecyl mercaptan, and thioglycerol were mixed and treated in a water bath to obtain a selenium precursor solution. The mass ratio of selenium powder to the total volume of oleylamine, n-dodecyl mercaptan, and thioglycerol was 9.2–36.6 g / L; the volume ratio of n-dodecyl mercaptan to thioglycerol was 0–900:100–500. When the volume ratio of n-dodecyl mercaptan to thioglycerol was 0–900:100–500, the reducing and hydrophilic properties of thioglycerol were maximized to realize the application of the final product, quantum dots, in biomedicine. Furthermore, because thioglycerol has a high boiling point of 118℃, thermal decomposition during the preparation of this high-brightness fluorescent quantum dot in aqueous phase was avoided.

[0045] Provides a cationic solution containing In ions, Zn ions and Cu ions.

[0046] A selenium precursor solution was injected into a cation solution at 160–170 °C to react and obtain aqueous high-brightness fluorescent quantum dots. The molar ratio of selenium powder, In ions, Zn ions, and Cu ions satisfies the chemical formula of the aqueous high-brightness fluorescent quantum dots as Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 The stoichiometric ratio. Specifically, when the molar ratio of Se, In, Zn, and Cu elements satisfies the condition that the chemical formula of the high-brightness fluorescent quantum dots in the aqueous phase is Zn... 0.07 -Cu 0.03 In 0.1 Se 0.14 At a stoichiometric ratio of 1, the fluorescence intensity of the aqueous high-brightness fluorescent quantum dot is the strongest, with a fluorescence intensity >800.

[0047] It should be noted that current technologies for preparing aqueous quantum dots generally employ a method of first preparing an oil phase and then converting it to water, specifically including two strategies: surface ligand exchange and surface modification with amphiphilic biomolecules. Both methods have significant drawbacks: ligand exchange effectively preserves the original small size and good crystallinity and dispersibility of the oil-phase quantum dots, but the ligand exchange process still needs to be carried out in an organic phase, and the high-temperature reflux operation under an inert atmosphere is cumbersome; furthermore, the quantum yield is significantly reduced due to changes in the surface structure of the quantum dots. Amphiphilic biomolecule modification causes quantum dot aggregation and significantly increases the hydrated particle size, affecting their biological applications.

[0048] This method departs from the conventional practice of using long-chain organic molecular ligands. Breaking with common sense, it utilizes the hydrophilic biomolecule properties of thioglycerol in this oil-phase system. By using this hydrophilic thioglycerol molecule as a ligand and combining it with solvothermal technology, it efficiently prepares high-brightness fluorescent quantum dots in aqueous phase.

[0049] The aqueous high-brightness fluorescent quantum dots provided by this invention are prepared using solvothermal technology. The preparation method is simple and has a short preparation cycle. The aqueous high-brightness fluorescent quantum dots obtained by this method are also non-toxic, easy to operate, highly sensitive, and have excellent stability.

[0050] Furthermore, the reaction time is 40–90 min. Specifically, a reaction time of 40–90 min facilitates the growth of surface ligands in aqueous high-brightness fluorescent quantum dots, resulting in aqueous high-brightness fluorescent quantum dots with good fluorescence intensity.

[0051] Furthermore, the volume ratio of oleylamine, dodecanethiol, and thioglycerol is 500–1000:100–500:120–250. Specifically, experimental results show that adding thioglycerol alone can prepare aqueous quantum dots. Preferably, the coexistence of dodecanethiol can improve the growth rate of quantum dot crystals (red shift in quantum dot emission indicates larger size) and crystal quality (increased fluorescence intensity indicates reduced structural defects, improved luminescence efficiency, and improved crystal quality). Further theoretical analysis shows that during the preparation of the anionic precursor solution, selenium powder is first reduced by thiol compounds (dodecanethiol and thioglycerol) before being complexed with oleylamine and stabilized. In the current solvothermal oily reaction system, dodecanethiol has higher solubility, therefore its coexistence results in higher activation efficiency and higher product quality.

[0052] Furthermore, a vacuum process is included before the water bath insulation step. Specifically, this can be performed in the order of 10 min, 5 min, and 5 min, followed by nitrogen replenishment to remove moisture and oxygen from the selenium precursor solution and avoid interference in subsequent experiments.

[0053] Furthermore, the water bath treatment is carried out in an atmosphere of chemically inert gas; and the temperature of the water bath treatment is 40–90°C. Specifically, since the selenium powder needs to be activated during the preparation of the anionic precursor solution, oleylamine, dodecyl mercaptan, and thioglycerol are added. After the selenium powder is reduced by the mercaptan compounds, it complexes with oleylamine and remains stable. This activation reaction can occur rapidly and more effectively at higher temperatures (40–90°C).

[0054] Furthermore, the cation solution is obtained by mixing indium acetate, cuprous iodide, and zinc acetate in a molar ratio of 1:0.3:0.7, and adding oleylamine and octadecene in a volume ratio of 75:400. The mixture is stirred and heated to 160–170°C. The core of this solvothermal approach is to utilize the heat energy provided by a high-boiling-point solvent at high temperatures to activate the raw materials and initiate the reaction. Specifically, at high temperatures, the raw materials cuprous iodide, indium acetate, and zinc acetate decompose and dissociate into copper, indium, and zinc ions. These cations directly complex with dodecyl mercaptan, achieving a balance of cation activity. Theoretical studies have shown that temperatures above 150°C and below 170°C effectively promote the bonding of Se precursors and initiate the growth of quantum dot crystals, while preventing the decomposition of dodecyl mercaptan and the evaporation of thioglycerol. Experiments have confirmed that the reaction is stable and effective when the temperature is raised to 160–170°C.

[0055] Specifically, indium acetate, cuprous iodide, and zinc acetate can be poured into a clean three-necked flask in a molar ratio of 1:0.3:0.7, and oleylamine and octadecene with a volume ratio of 75:400 can be added using a pipette, followed by stirring.

[0056] Furthermore, the molar volume ratio of zinc acetate to octadecene is 0.7 mol: 40000 mL.

[0057] Furthermore, after stirring but before heating, a vacuum process is also included.

[0058] Furthermore, the vacuuming process needs to be repeated three times consecutively, with nitrogen replenishment after each vacuuming. Specifically, in the preparation of the cation solution, after stirring, the solution is vacuumed for 10 minutes each time, with nitrogen replenishment after each vacuuming, and this process is repeated three times consecutively. After the last vacuuming, the solution is filled with nitrogen and then heated to 160–170°C within 30 minutes.

[0059] To further illustrate the present invention, the following examples are provided:

[0060] Example 1

[0061] Reaction temperature affects the fluorescence intensity of aqueous high-brightness quantum dots (Zn). 0.07 -Cu 0.03 In 0.1 Se 0.14 The impact of

[0062] First, the volumes of dodecanethiol (DDT) and thioglycerol (TG) in the selenium precursor solution were determined to be 450 μL and 123 μL, respectively, with a reaction time of 40 min. Under the condition that other factors remained unchanged, only the reaction temperature was adjusted to 150℃, 160℃, 165℃, and 170℃ to prepare a series of quantum dots. A total of four experiments were conducted.

[0063] ① Preparation of selenium precursor solution: Weigh 0.0220g of selenium powder and pour it into a clean three-necked flask. Add 750μL of oleylamine and 450μL of n-dodecyl mercaptan using a pipette, and finally add 123μL of thioglycerol. Stir the mixture on a stirrer to make the selenium precursor solution evenly mixed. To remove water and oxygen from the selenium precursor solution, vacuum it in the order of 10min, 5min, and 5min. Finally, replenish the nitrogen gas and place it in a 50℃ water bath for stirring and keeping it warm.

[0064] ② Preparation of cation solution: Weigh 0.0292g of indium acetate, 0.0057g of cuprous iodide, and 0.0128g of zinc acetate, pour them into a clean three-necked flask, add 750μL of oleylamine and 4mL of octadecene using a pipette, place the flask in a sand bath and stir. Vacuum the solution for 10 minutes each time, and replenish it with nitrogen after each vacuuming. Repeat this process three times. After the last time the flask is filled with nitrogen, raise the temperature to 150℃, 160℃, 165℃, and 170℃ respectively within 30 minutes.

[0065] ③ When the cation solution is heated to 150℃, 160℃, 165℃, and 170℃ respectively, 661 μL of the prepared selenium precursor solution is rapidly injected into the cation solution. The reaction is allowed to proceed for 40 min. After the reaction is complete, the solution is removed and cooled. Excess ethanol is added, and the solution is centrifuged at 6000 rpm for 5 min. The supernatant is discarded, water is added as a solvent, and the solution is sonicated for 10 min. The solution is then stored in a brown bottle at room temperature. (Note: The total volume of the selenium precursor solution is 750 μL oleylamine + 450 μL n-dodecyl mercaptan + 123 μL thioglycerol = 1323 μL, and the total amount of selenium is 0.28 mmol. The amount of selenium precursor solution added at this time is half of the original volume, 661 μL, which means the molar amount of selenium injected is 0.14 mmol).

[0066] Comparative Example 1

[0067] Preparation of oil phase Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 quantum dots

[0068] ① Preparation of anionic precursor solution (selenium precursor solution): Weigh 0.0220g selenium powder (0.28mmol), pour it into a clean three-necked flask, add 750μL oleylamine and 900μL n-dodecyl mercaptan using a pipette, and stir on a stirrer to mix the selenium precursor solution evenly. To remove water and oxygen from the selenium precursor solution, vacuum treatment is performed in the order of 10min, 5min, and 5min. Finally, nitrogen is added, and then the solution is placed in a 50℃ water bath for stirring and heat preservation.

[0069] ② Preparation of cation solution: Weigh 0.0057 g of cuprous iodide (0.03 mmol), 0.0128 g of zinc acetate (0.07 mmol), and 0.0292 g of indium acetate (0.1 mmol), and pour them into a clean three-necked flask. Add 750 μL of oleylamine and 4 mL of octadecene using a pipette. Place the flask in a sand bath and stir. Vacuum the solution for 10 min each time. After each vacuuming, replenish with nitrogen. Repeat this process three times. After the last filling with nitrogen, heat the solution to 160 °C within 30 min.

[0070] ③ Thermal injection preparation of quantum dots: When the cation solution is heated to 160℃, 825μL of the prepared selenium precursor solution is rapidly injected into the cation solution. The reaction is allowed to proceed for 40 min. After the reaction, the solution is removed and allowed to cool naturally. Excess ethanol is added, and the solution is centrifuged at 6000 rpm for 5 min for purification. The supernatant is discarded, and the precipitate is treated with chloroform as a solvent and sonicated for 10 min. The product is then stored in a brown bottle at room temperature for later use. (Note: The total anion precursor solution is 1650μL, containing 0.28mmol Se. 825μL is used here, equivalent to injecting 0.14mmol Se. Therefore, the oil phase Zn...) 0.07 -Cu 0.03 In 0.1 Se 0.14 Quantum dots are composed of Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 Regarding the Zn in the oil phase 0.07 -Cu 0.03 In 0.1 Se 0.14 The fluorescence properties of quantum dots were detected, and the results are as follows: Figure 1 As shown. According to Figure 1 It can be seen that the oil phase Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 The fluorescence wavelength of the quantum dots is 635 nm, and the fluorescence intensity is approximately 1365.

[0071] Analysis example 1

[0072] The fluorescence properties of the quantum dots prepared under various temperature conditions in Example 1 were detected (fluorescence excitation wavelength was 380 nm), and the detection results are as follows: Figure 2 As shown. According to Figure 2 It can be seen that the fluorescence intensity of the aqueous high-brightness fluorescent quantum dots prepared at reaction temperatures of 160℃, 165℃, and 170℃ is all >1800, which is significantly higher than the fluorescence intensity of the quantum dots prepared at 150℃.

[0073] The quantum dots prepared under various temperature conditions in Example 1 were photographed under a UV lamp. The actual images under the UV lamp are shown below. Figure 3 As shown. Figure 3 In the diagram, (a), (b), (c), and (d) represent the preparation temperature conditions, respectively: 150℃, 160℃, 165℃, and 170℃. From... Figure 3 As can be seen from this, the reaction temperature is 160℃ ( Figure 3 (b) showed the best fluorescence intensity at 170℃. Figure 3 (d) Secondly, the fluorescence intensity at 160℃, 165℃, and 170℃ is significantly different from that at 150℃.

[0074] Example 2

[0075] Reaction time affects the fluorescence of aqueous high-brightness quantum dots (Zn) 0.07 -Cu 0.03 In 0.1 Se 0.14 The impact of

[0076] First, the volumes of DDT and TG in the selenium precursor solution were determined to be 450 μL and 123 μL, respectively, and the reaction temperature was set at 160 °C. With other conditions unchanged, only the reaction time was adjusted to 40 min, 60 min, and 90 min to prepare a series of quantum dots. A total of four experiments were conducted.

[0077] ① Preparation of selenium precursor solution: Weigh 0.0220g selenium powder (0.28mmol) and pour it into a clean three-necked flask. Add 750μL oleylamine and 450μL n-dodecyl mercaptan using a pipette, and finally add 123μL thioglycerol. Stir the mixture on a stirrer to make the selenium precursor solution evenly mixed. To remove water and oxygen from the selenium precursor solution, vacuum it in the order of 10min, 5min, and 5min. Finally, replenish the nitrogen gas and place it in a 50℃ water bath for stirring and keeping warm.

[0078] ② Preparation of cation solution: Weigh 0.0057 g of cuprous iodide (0.03 mmol), 0.0128 g of zinc acetate (0.07 mmol), and 0.0292 g of indium acetate (0.1 mmol), pour them into a clean three-necked flask, add 750 μL of oleylamine and 4 mL of octadecene using a pipette, place the flask in a sand bath and stir. Vacuum the solution for 10 min each time, replenish with nitrogen after each vacuuming, repeat three times. After the last vacuuming, heat to 160 °C for 30 min.

[0079] When the cation solution is heated to 160℃, 661 μL of the prepared selenium precursor solution is taken out (Note: the total volume of the selenium precursor solution is 750 μL oleylamine + 450 μL n-dodecyl mercaptan + 123 μL thioglycerol = 1323 μL, and the total amount of selenium is 0.28 mmol. The selenium precursor solution added at this time is half of the original volume, that is, the molar amount of selenium injected is 0.14 mmol), and it is quickly injected into the cation solution. The mixture is stirred thoroughly, and the reaction times are 40 min, 60 min, and 90 min, respectively. After the reaction is completed, the mixture is taken out and cooled, excess ethanol is added, and the mixture is centrifuged at 6000 rpm for 5 min. The supernatant is discarded, water is added as a solvent, and the mixture is sonicated for 10 min. The mixture is then placed in a brown bottle and stored at room temperature.

[0080] Analysis example 2

[0081] The aqueous high-brightness fluorescent quantum dots (Zn) prepared under various reaction times in Example 2 0.07 -Cu 0.03 In 0.1 Se 0.14 Fluorescence performance was measured (fluorescence excitation wavelength 380nm), and the results are as follows: Figure 4 As shown. According to Figure 4 It can be seen that a reaction time of 60 min showed better fluorescence intensity, indicating that a longer reaction time is conducive to the growth of surface ligands.

[0082] The aqueous high-brightness fluorescent quantum dots (Zn) prepared at various reaction times in Example 2 were compared with those prepared at different reaction times. 0.07 -Cu 0.03 In 0.1 Se 0.14 The image was taken under a UV lamp. The actual photo taken under the UV lamp is shown below. Figure 5 As shown. Figure 5 In the table, (a), (b), and (c) represent the reaction times: 40 min, 60 min, and 90 min, respectively. From... Figure 5 It can also be seen that a reaction time of 60 min shows better fluorescence intensity.

[0083] Example 3

[0084] TG for high-brightness fluorescent quantum dots in aqueous phase (Zn) 0.07 -Cu 0.03 In 0.1 Se 0.14 The impact of

[0085] First, the reaction temperature and time were determined to be 160℃ and 60 min, respectively. Under the premise of keeping other conditions unchanged, only the ratio of DDT to TG in the selenium precursor solution was adjusted to regulate the volume ratio of DDT to TG in the selenium precursor solution to prepare a series of quantum dots. A total of five experiments were conducted.

[0086] ① Preparation of selenium precursor solution: Weigh 0.0220 g of selenium powder (0.28 mmol) and pour it into a clean three-necked flask. Add 750 μL of oleylamine using a pipette. Then add 0 μL of n-dodecyl mercaptan and 246 μL of thioglycerol, 90 μL of n-dodecyl mercaptan and 222 μL of thioglycerol, 270 μL of n-dodecyl mercaptan and 172 μL of thioglycerol, 360 μL of n-dodecyl mercaptan and 147 μL of thioglycerol, and 450 μL of n-dodecyl mercaptan and 123 μL of thioglycerol respectively. Stir each of the five reaction flasks on a stirrer until the selenium precursor solution is thoroughly mixed. To remove moisture and oxygen from the selenium precursor solution, evacuate it under vacuum in the following order: 10 min, 5 min, 5 min. Finally, replenish with nitrogen. After filling with nitrogen, place the selenium precursor solution in a 50°C water bath for stirring and incubation until ready for use.

[0087] ② Preparation of cation solution: Weigh 0.0057 g of cuprous iodide (0.03 mmol), 0.0128 g of zinc acetate (0.07 mmol), and 0.0292 g of indium acetate (0.1 mmol), and pour them into a clean three-necked flask. Add 750 μL of oleylamine and 4 mL of octadecene using a pipette. Place the flask in a sand bath and stir. Vacuum the solution for 10 minutes each time. After each vacuuming, replenish with nitrogen. Repeat this process three times. After the last time, fill the flask with nitrogen and heat it to 160 °C for 30 minutes.

[0088] When the cation solution is heated to 160℃, 498μL of the five prepared selenium precursor solutions (precursor solution: n-dodecyl mercaptan / thioglycerol = 0μL: 246μL), 531μL of the precursor solution: n-dodecyl mercaptan: thioglycerol = 90μL: 222μL), 596μL of the precursor solution: n-dodecyl mercaptan: thioglycerol = 270μL: 172μL), 628μL of the precursor solution: n-dodecyl mercaptan: thioglycerol = 360μL: 147μL), and 662μL of the precursor solution: n-dodecyl mercaptan: thioglycerol = 450μL: 123μL are rapidly injected into the cation solution. The reaction is allowed to proceed for 60 min. After the reaction is complete, the solution is removed and cooled. Excess ethanol is added, and the solution is centrifuged at 6000 rpm for 5 min. The supernatant is discarded, water is added as a solvent, and the solution is sonicated for 10 min. The solution is then stored in a brown bottle at room temperature.

[0089] Analysis example 3

[0090] The fluorescence properties of quantum dots prepared at different DDT / TG ratios in Example 3 were detected (fluorescence excitation wavelength was 380 nm), and the detection results are as follows: Figure 6 As shown. According to Figure 6It was observed that as the DDT / TG ratio increased from 0 μL:246 μL to 360 μL:147 μL, the fluorescence of the product gradually increased, specifically from 830 to 3500, accompanied by a red shift in the emission wavelength. Specifically, when the DDT / TG ratio was 270 μL:172 μL, the fluorescence intensity of the quantum dot reached 1950. However, when the ratio was further increased to 450 μL:123 μL (at which point the fluorescence intensity of the quantum dot was 2600), the fluorescence intensity of the product decreased significantly, but the emission wavelength did not change noticeably.

[0091] The quantum dots prepared under various temperature conditions in Example 3 were photographed under a UV lamp. The actual images under the UV lamp are shown below. Figure 7 As shown. Figure 7 (a), (b), (c), (d), and (e) are real-life images taken under a UV lamp of quantum dots prepared at DDT / TG ratios of 0 μL:246 μL, 90 μL:222 μL, 270 μL:172 μL, 360 μL:147 μL, and 450 μL:123 μL, respectively.

[0092] Analysis example 4

[0093] Aqueous high-brightness fluorescent quantum dots (Zn) were prepared when the ratio of DDT to TG in the selenium precursor solution was 360 μL:147 μL in Example 3. 0.07 -Cu 0.03 In 0.1 Se 0.14 The oil phase Zn prepared in Comparative Example 1 0.07 -Cu 0.03 In 0.1 Se 0.14 The quantum dots were optically compared under natural light and ultraviolet light, and the optical comparison images are shown below. Figure 8 As shown in the figure. Among them, (a) is an optical comparison diagram under natural light; (b) is an optical comparison diagram under ultraviolet light.

[0094] according to Figure 8 (a) It can be seen that the upper layer of the sample vial on the left is deionized water, and the lower layer is the oil phase Zn. 0.07 -Cu 0.03 In 0.1 Se 0.14 Quantum dots (solvent: chloroform), due to the density of chloroform (1.48 g / cm³). 3 The zinc is larger than water, so the water phase is on top and the oil phase quantum dots are on the bottom. The upper layer of the sample vial on the right is a high-brightness fluorescent quantum dot (Zn) aqueous phase modified with thioglycerol. 0.07 -Cu 0.03 In 0.1 Se 0.14 The lower layer is oil (the solvent is chloroform).

[0095] according to Figure 8 (b) It can be clearly seen that the water / oil two-phase interface between the aqueous high-brightness fluorescent quantum dots (sample bottle on the right) and the solvent chloroform is clear and has high brightness, indicating that the oil phase quantum dots prepared according to Example 1 have been successfully converted to water.

[0096] Comparative Example 2

[0097] ① Preparation of anionic precursor solution (Se precursor solution): Weigh 0.0220g selenium powder (0.28mmol), pour it into a clean three-necked flask, add 750μL oleylamine and 900μL n-dodecyl mercaptan using a pipette, and stir on a stirrer to mix the selenium precursor solution evenly. To remove water and oxygen from the selenium precursor solution, vacuum treatment is performed in the order of 10min, 5min, and 5min. Finally, nitrogen is added, and then the solution is placed in a 50℃ water bath for stirring and heat preservation.

[0098] ② Preparation of cation solution: Weigh 0.0057 g of cuprous iodide (0.03 mmol), 0.0128 g of zinc acetate (0.07 mmol), and 0.0292 g of indium acetate (0.1 mmol), and pour them into a clean three-necked flask. Add 750 μL of oleylamine and 4 mL of octadecene using a pipette. Place the flask in a sand bath and stir. Vacuum the solution for 10 min each time. After each vacuuming, replenish with nitrogen. Repeat this process three times. After the last filling with nitrogen, heat the solution to 160 °C within 30 min.

[0099] ③Preparation of oil-phase quantum dots by thermal injection: When the cation solution is heated to 160℃, 825μL of the prepared selenium precursor solution is rapidly injected into the cation solution. The reaction is carried out for 40min. After the reaction is completed, the solution is taken out and cooled naturally. Excess ethanol is added, and the solution is centrifuged at 6000rpm for 5min for purification. The supernatant is discarded, and the precipitate is added to chloroform as a solvent and sonicated for 10min. The product is then placed in a brown bottle for storage at room temperature for later use.

[0100] ④ Add 1.5 mL of the prepared oil-phase Zn-doped Cu-In-Se quantum dots to a two-necked flask, then add 0.15 mL of thioglycerol, 4.0 mL of ethanol, and 4 mL of N,N-dimethylformamide. Mix thoroughly and stir until the solution turns reddish-brown. Heat the solution to 130 °C under nitrogen protection and continue to reflux for 30 min to obtain the final product. Centrifuge at 8000 rpm for 5 min, dry with nitrogen, and dissolve the precipitate in water to obtain the thioglycerol-modified aqueous quantum dot product.

[0101] Analysis example 5

[0102] Different batches of aqueous high-brightness fluorescent quantum dots (Zn) were prepared according to the DDT to TG ratio of 360 μL: 147 μL in the selenium precursor solution in Example 3. 0.07 -Cu 0.03 In 0.1 Se 0.14 The samples were labeled as Sample 1, Sample 2, and Sample 3. The stability of the quantum dot dispersion system of each sample was evaluated using the zeta potential. Specifically, the zeta potential analysis data of Samples 1-3 were measured using a laser particle size analyzer, as shown in the graph. Figure 9 As shown in (a).

[0103] Following the experimental procedure of Comparative Example 2, different batches of thioglycerol-modified aqueous quantum dot products were prepared and labeled as Sample 1, Sample 2, and Sample 3. The stability of the quantum dot dispersion system of each sample was evaluated using the zeta potential. Specifically, the zeta potential analysis data of Samples 1–3 were measured using a laser particle size analyzer, as shown in the graphs. Figure 9 As shown in (b).

[0104] The larger the absolute value of the zeta potential, the more stable the system. Conversely, the smaller the absolute value of the zeta potential, the more the system aggregates. Between 0 and ±5 mV, the system aggregates rapidly; between ±10 and ±30 mV, the system is unstable; between ±30 and ±40 mV, the system has moderate stability; between ±40 and ±60 mV, the system has good stability; and above ±60 mV, the system has excellent stability.

[0105] from Figure 9 It can be seen from this that Figure 9 (a) shows that the potential values ​​of different batches of samples (samples 1-3) are between 56 and 59 mV, indicating that the aqueous high-brightness fluorescent quantum dot system has good stability and its preparation method is stable and reliable.

[0106] Figure 9 (b) shows that the potential values ​​of different batches of samples (samples 1-3) are between 32 and 35 mV, indicating that the stability of the aqueous fluorescent quantum dot system is generally poor and its preparation method is unreliable.

[0107] Analysis example 6

[0108] The aqueous high-brightness fluorescent quantum dots prepared in Example 2 with a reaction time of 60 min and pure thioglycerol were characterized and analyzed by infrared spectroscopy. The analysis results are as follows: Figure 10 As shown; (a) is the infrared spectrum of high-brightness fluorescent quantum dots in aqueous phase; (b) is the infrared spectrum of pure thioglycerol.

[0109] according to Figure 10Observations show that the characteristic functional groups of pure thioglycerol are thiol (-SH) and hydroxyl (-OH), with stretching vibration absorption peaks at 2550–2600 cm⁻¹. -1 3200~3700cm -1 In the infrared spectrum of aqueous high-brightness fluorescent quantum dots, the characteristic absorption peak of the thioglycerol mercapto group (-SH) is significantly weakened and becomes unrecognizable. The hydroxyl (-OH) stretching vibration absorption peak is still present, but it shifts to lower wavenumbers. These changes in characteristic peaks indicate that the surface of the aqueous high-brightness fluorescent quantum dots has been successfully modified with thioglycerol molecules, and that the thioglycerol sulfapy groups are directly bonded to the quantum dot surface.

[0110] Analysis example 7

[0111] The aqueous high-brightness fluorescent quantum dots (Zn) prepared in Example 3 with a DDT to TG ratio of 360 μL:147 μL in the selenium precursor solution 0.07 -Cu 0.03 In 0.1 Se 0.14 The morphology and crystal structure of the samples were analyzed.

[0112] (1) TEM images of high-brightness fluorescent quantum dots in aqueous phase at different magnifications are shown below. Figure 11 As shown; (a) is a TEM image at a scale of 20 nm; (b) is a TEM image at a scale of 10 nm; (c) is a TEM image at a scale of 50 nm; (d) is a TEM image at a scale of 5 nm.

[0113] Depend on Figure 11 It can be seen that the aqueous high-brightness fluorescent quantum dots have relatively uniform particle size and good dispersion under transmission electron microscopy, and there is no obvious agglomeration phenomenon. The average size is about 5 nm. High-resolution transmission electron microscopy characterization shows that the interplanar spacing is 0.33 nm, which is the (112) crystal plane of chalcopyrite.

[0114] (2) The aqueous high-brightness fluorescent quantum dots and the oil-phase Zn prepared in Comparative Example 1 0.07 -Cu 0.03 In 0.1 Se 0.14 XRD comparison images of quantum dots are shown below Figure 12 As shown.

[0115] according to Figure 12 Observation shows that its diffraction peaks (112), (220), and (312) are consistent with the crystal plane of the standard card JCPDS:40-1487, proving that the aqueous high-brightness fluorescent quantum dot has a typical tetragonal crystal phase of chalcopyrite structure and has the same crystal phase as the oil phase product.

[0116] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing high-brightness fluorescent quantum dots in aqueous phase, characterized in that, The preparation method includes the following steps: Selenium powder, oleylamine, n-dodecyl mercaptan, and thioglycerol are mixed and treated in a water bath to obtain a selenium precursor solution; the mass ratio of the selenium powder to the total volume of the oleylamine, n-dodecyl mercaptan, and thioglycerol is 9.2~36.6 g / L; the volume ratio of the n-dodecyl mercaptan to the thioglycerol is 0~900:100~500. Provides cationic solutions containing In ions, Zn ions and Cu ions; The selenium precursor solution is injected into the cation solution at 160-170℃ to react and obtain aqueous high-brightness fluorescent quantum dots; wherein the molar ratio of the selenium powder, the In ions, the Zn ions, and the Cu ions satisfies the chemical formula Zn 0.07 -Cu 0.03 In 0.1 Se 0.14 The measurement ratio; The cationic solution is obtained by mixing indium acetate, cuprous iodide and zinc acetate in a molar ratio of 1:0.3:0.7, adding oleylamine and octadecene in a volume ratio of 75:400, stirring, and heating to 160~170℃. Furthermore, the absolute value of the Zeta potential of the aqueous high-brightness fluorescent quantum dots is ≥56mV; the aqueous high-brightness fluorescent quantum dots are miscible with water and have a clear interface with the oil phase.

2. The preparation method according to claim 1, characterized in that, The reaction lasts for 40 to 90 minutes.

3. The preparation method according to claim 1, characterized in that, The volume ratio of the oleylamine, the n-dodecyl mercaptan, and the thioglycerol is 500~1000:100~500:120~250.

4. The preparation method according to claim 1, characterized in that, The water bath insulation process is preceded by a vacuuming process.

5. The preparation method according to claim 1, characterized in that, The water bath heat preservation treatment is carried out in an atmosphere of chemically inert gas; and the temperature of the water bath heat preservation treatment is 40~90℃.

6. The preparation method according to claim 1, characterized in that, The molar volume ratio of zinc acetate to octadecene is 0.7 mol: 40000 mL.

7. The preparation method according to claim 1, characterized in that, After the stirring process and before the heating process, a vacuuming process is also included.

8. The preparation method according to claim 7, characterized in that, The vacuuming process needs to be repeated three times consecutively, and nitrogen should be replenished after each vacuuming.

9. A high-brightness fluorescent quantum dot in aqueous phase, characterized in that, It was prepared by the preparation method according to any one of claims 1 to 8; The aqueous high-brightness fluorescent quantum dots have a tetragonal crystal phase with a chalcopyrite structure.

Images