CN113881435B - Rare earth doped silver selenide quantum dot and synthesis method thereof - Google Patents

Abstract

The invention provides a rare earth doped silver selenide quantum dot and a synthesis method thereof, belonging to the technical field of material chemistry. The synthesis method comprises the following steps: adding selenium powder into the organic phosphine solution, and stirring and mixing uniformly under the condition of keeping out of the sun to obtain a selenium-organic phosphine solution; adding rare earth metal salt into an organic phosphine solution to obtain a rare earth element precursor; mixing octadecylene, mercaptan and silver acetate, and heating in inert gas for reaction to obtain a clear reaction solution; adding the selenium-organic phosphine solution and a chiral ligand into the reaction solution, uniformly mixing, heating and reacting in an inert atmosphere, adding the rare earth element precursor after the reaction is finished, and heating and reacting to obtain the rare earth element doped silver selenide quantum dots. The invention utilizes the means of transmission electron microscope, absorption spectrum, chiral circular dichroism analysis and the like to carry out corresponding physical characterization and deep research on the optical fiber. The quantum dots obtained by the method can be well compatible with cells, and have good application prospects in the biological field.

Description

A kind of rare earth doped silver selenide quantum dot and its synthesis method

technical field

The invention belongs to the technical field of material chemistry, in particular to a method for synthesizing chiral near-infrared second-region fluorescent silver selenide quantum dots.

Background technique

Due to the low scattering and good penetration depth of long-wavelength light in living tissue, NIR II (1000-1700 nm) imaging has obvious advantages over traditional NIR I (650-950 nm) imaging in in vivo imaging , making near-infrared quantum dots a hot spot in the field of optical imaging because they can overcome the defects of visible light quantum dots that are susceptible to interference in deep tissue imaging, and can obtain higher-resolution images. Moreover, with the rapid development of research in the field of bioimaging, more and more near-infrared quantum dots have been widely used in biological macromolecules and cell labeling, tissue and living cell imaging, tumor model localization, clinical diagnosis and other fields. breakthrough progress.

As a new type of near-infrared binary silver-containing quantum dots, silver selenide (Ag ₂ Se) has been paid more and more attention by researchers due to its low toxicity, small size and excellent near-infrared optical properties. . The emergence of such quantum dots is a favorable supplement to the limitations of alloy quantum dots in the biological field. On the one hand, it makes up for the problem that quantum dots containing heavy metal elements (cadmium or lead) are highly toxic to the environment and biological systems, and can effectively reduce the biological toxicity of quantum dots. On the other hand, because it is a quantum dot in the near-infrared band, it can be well distinguished from the autofluorescence of biological tissue itself, improve the cell resolution ability, and has a deep penetration depth, which can be better for biological applications. . The preparation of chiral near-infrared second-region fluorescent silver selenide quantum dots is technically challenging and has attracted considerable attention in different interdisciplinary fields. At present, most of the near-infrared quantum dots involved are alloy quantum dots CdSeS, CdHgTe, CdSexTe1 and other structures, which have been reported by many scholars. The application has certain limitations. However, the chiral near-infrared silver selenide quantum dot structure is cadmium-free fluorescent quantum dots, which is very necessary to expand the application of near-infrared quantum dots in the field of biomarkers.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a rare earth doped silver selenide quantum dot and a synthesis method thereof.

A method for synthesizing rare earth doped silver selenide quantum dots, comprising the following steps:

(1) adding the selenium powder to the organic phosphine solution, stirring and mixing evenly under the dark condition to obtain a selenium-organophosphine solution;

(2) adding the rare earth metal salt into the organic phosphine solution to react to obtain the rare earth element precursor;

(3) mixing octadecene (ODE), mercaptan and silver acetate, heating to 160-180 DEG C in an inert gas for 10-40min to obtain a clear reaction solution;

(4) adding the selenium-organophosphine solution and the chiral ligand described in the step (1) into the reaction solution described in the step (3) and mixing evenly, heating at 160-180° C. for 1-4 hours under an inert atmosphere, After the reaction is completed, the rare earth element precursor in step (2) is added, and the rare earth element doped silver selenide quantum dots are obtained by heating at 160-180° C. for 1-2 hours and reacting for 1-2 hours.

In an embodiment of the present invention, in step (1), the organic phosphine is one or more of trioctylphosphine, tri-n-octylphosphine oxide and tributylphosphorus oxide.

In an embodiment of the present invention, in step (2), the rare earth metal salt is selected from neodymium chloride, ytterbium chloride and erbium chloride.

In an embodiment of the present invention, the molar ratio of neodymium chloride, ytterbium chloride and erbium chloride is 1:3-5:4-5.

In an embodiment of the present invention, in step (3), the volume ratio of octadecene (ODE) to thiol is 15-5:17-3.

In an embodiment of the present invention, in step (3), the concentration of silver acetate is 0.2mM-1mM.

In an embodiment of the present invention, in step (3), the thiol is dodecanethiol or/and tert-dodecanethiol.

In an embodiment of the present invention, in step (4), the chiral ligand is one or more of binaphthylamine, binaphthol and naphthylethylamine.

In an embodiment of the present invention, in step (4), the concentration of the chiral ligand is 2mM-10mM.

The invention also provides the rare earth element-doped silver selenide quantum dots prepared by the synthesis method.

The above-mentioned technical scheme of the present invention has the following advantages compared with the prior art:

According to the present invention, Ag ₂ Se quantum dots are prepared by a high temperature oil phase synthesis method, Ag ₂ Se quantum dots of different sizes are obtained by changing the Ag:Se ratio, and the optical properties and structural properties of the prepared quantum dots are analyzed from the perspective of optical properties and structural properties. In order to find the optimal Ag:Se ratio for preparing the quantum dots, a comparative analysis was carried out. After that, the fluorescence intensity was greatly enhanced by doping rare earth elements and the position of the fluorescence emission peak was red-shifted. It has chirality, and the physicochemical properties of the modified quantum dots are characterized and analyzed to verify the feasibility of applying Ag ₂ Se to the field of biomarkers, and to provide a reliable basis for the application of this quantum dot in the biological field.

Description of drawings

In order to make the content of the present invention easier to understand clearly, the present invention will be described in further detail below according to specific embodiments of the present invention and in conjunction with the accompanying drawings, wherein

Fig. 1 is the flow chart of the preparation method of chiral near-infrared second region fluorescent silver selenide quantum dots of the present invention.

Figure 2 is a transmission electron microscope photograph of the chiral near-infrared second region fluorescent silver selenide quantum dots of the present invention.

3 is a circular dichroism (CD) diagram of the chiral near-infrared second region fluorescent silver selenide quantum dots of the present invention.

FIG. 4 is an ultraviolet image of the chiral near-infrared second-region fluorescent silver selenide quantum dots of the present invention.

5 is a graph showing the fluorescence enhancement effect of the chiral near-infrared second region fluorescent silver selenide quantum dots of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

Example 1

1. Add 191 mg of selenium powder to 2 mL of tributylphosphine solution, and stir in the dark for 3 hours to obtain a selenium-tributylphosphine solution. In addition, 0.5 mmol of neodymium chloride, ytterbium chloride and erbium chloride were added to each of 5 mL of tributylphosphine chloride. A neodymium-tributylphosphine solution, a ytterbium-tributylphosphine solution, and an erbium-tributylphosphine solution were obtained from the butylphosphine solution.

2. Add 16 mL of octadecene, 4 mL of dodecanethiol and 60 mg of silver acetate into a three-necked flask, heat up to 160° C. under nitrogen protection, and continue the reaction at the preset temperature for 10 min to obtain a clear reaction solution.

3. Inject 200 μL of selenium-tributylphosphine solution and binaphthol into the reaction solution, raise the temperature to 160° C. under nitrogen protection, and continue the reaction at the preset temperature for 30 min.

4. Inject 20 μL of neodymium-tributylphosphine solution, 80 μL of ytterbium-tributylphosphine solution, and 120 μL of erbium-tributylphosphine solution into the reaction solution, and continue the reaction for 2 hours at the preset temperature under nitrogen protection.

5. After the reaction, cool to room temperature and add chloroform to prevent solidification.

6. Perform centrifugal washing treatment with acetone.

Trichloromethane is added to the reaction solution to obtain a solution of silver selenide fluorescent quantum dots dispersed in chloroform.

Example 2

1. Add 179 mg of selenium powder to 3 mL of tributylphosphine solution, and stir in the dark for 4 h to obtain a selenium-tributylphosphine solution.

2. Add 17 mL of octadecene, 3 mL of dodecanethiol and 65 mg of silver acetate into a three-necked flask, heat up to 170° C. under nitrogen protection, and continue to react for 8 min at the preset temperature to obtain a clear reaction solution.

3. Inject 200 μL of selenium-tributylphosphine solution and binaphthol into the reaction solution, raise the temperature to 160° C. under nitrogen protection, and continue the reaction at the preset temperature for 20 min.

4. Inject 10 μL of neodymium-tributylphosphine solution, 100 μL of ytterbium-tributylphosphine solution, and 100 μL of erbium-tributylphosphine solution into the reaction solution, and continue the reaction for 2 hours at the preset temperature under nitrogen protection.

5. After the reaction, cool to room temperature and add chloroform to prevent solidification.

6. Perform centrifugal washing treatment with acetone.

7. Add chloroform to the reaction solution to obtain a solution of silver selenide fluorescent quantum dots dispersed in chloroform.

Example 3

1. Add 188 mg of selenium powder to 2 mL of tributylphosphine solution, and stir in the dark for 4 h to obtain a selenium-tributylphosphine solution.

2. Add 16 mL of octadecene, 3 mL of dodecanethiol and 67 mg of silver acetate into a three-necked flask, heat up to 165° C. under nitrogen protection, and continue to react for 8 min at the preset temperature to obtain a clear reaction solution.

3. Inject 200 μL of selenium-tributylphosphine solution and binaphthol into the reaction solution, raise the temperature to 160° C. under nitrogen protection, and continue the reaction at the preset temperature for 20 min.

4. Inject 20 μL of neodymium-tributylphosphine solution, 90 μL of ytterbium-tributylphosphine solution, and 90 μL of erbium-tributylphosphine solution into the reaction solution, and continue the reaction for 2 hours at the preset temperature under nitrogen protection.

5. After the reaction, cool to room temperature and add chloroform to prevent solidification.

6. Perform centrifugal washing treatment with acetone.

7. Add chloroform to the reaction solution to obtain a solution of silver selenide fluorescent quantum dots dispersed in chloroform.

Performance Testing

The doped material has passed the fluorescence test. Under the excitation of 808nm with the same power, it can achieve a stronger fluorescence intensity, the intensity can be enhanced by 120 times, and the position of the emission peak is red-shifted from 1100nm to 1500nm, which can have a stronger infrared Two-zone fluorescence imaging effect. (The experimental results are shown in Figure 5).

In summary, Ag ₂ Se quantum dots were prepared by high temperature oil phase synthesis method, Ag ₂ Se quantum dots of different sizes were obtained by changing the Ag:Se ratio, and the optical properties and structural properties of the prepared quantum dots were analyzed. In order to find the optimal Ag:Se ratio for preparing the quantum dots, a comparative analysis was carried out. After that, doping the optimal ratio of Nd ³⁺ , Yb ³⁺ , Er ³⁺ greatly enhanced the luminous efficiency of fluorescence, and then used binaphthylamine, binaphthol, naphthylethylamine, etc. to chiral the quantum dots The modification makes it chirality, and the physicochemical properties of the modified quantum dots are characterized and analyzed to verify the feasibility of applying Ag ₂ Se to the field of biomarkers, and to provide a reliable basis for the application of this quantum dot in the biological field.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, other different forms of changes or modifications can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. However, the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (9)

1. a synthetic method of rare earth doped silver selenide quantum dots, is characterized in that, comprises the following steps: (1) adding selenium powder into the organic phosphine solution, stirring and mixing evenly under the dark condition, to obtain a selenium-organophosphine solution; (2) adding a rare earth metal salt into an organic phosphine solution to react to obtain a rare earth element precursor; the rare earth metal salt is a mixture of neodymium chloride, ytterbium chloride and erbium chloride; (3) mixing octadecene, mercaptan and silver acetate, heating and reacting in an inert gas to obtain a clear reaction solution; (4) Add the selenium-organophosphine solution and the chiral ligand described in step (1) into the reaction solution described in step (3) and mix evenly, heat the reaction in an inert atmosphere, and add step (2) after the reaction is completed ), the rare earth element precursor is heated and reacted to obtain the rare earth element doped silver selenide quantum dots. 2 . The synthesis method according to claim 1 , wherein in step (1), the organic phosphine is one or more of trioctylphosphine, tri-n-octylphosphine oxide and tributylphosphine oxide. 3 . kind. 3. synthetic method according to claim 1 is characterized in that, the mol ratio of described neodymium chloride, ytterbium chloride and erbium chloride is 1:3-5:4-5. 4 . The synthetic method according to claim 1 , wherein, in step (3), the volume ratio of the octadecene to thiol is 15-5:17-3. 5 . 5 . The synthesis method according to claim 1 , wherein, in step (3), the silver acetate concentration is 0.2 mM-1 mM. 6 . 6 . The synthesis method according to claim 1 , wherein, in step (3), the thiol is dodecanethiol or/and tert-dodecanethiol. 7 . 7. The synthetic method according to claim 1, wherein in step (4), the chiral ligand is one or more of binaphthylamine, binaphthol and naphthylethylamine . 8 . The synthesis method according to claim 1 , wherein, in step (4), the concentration of the chiral ligand is 2mM-10mM. 9 . 9 . The rare earth element-doped silver selenide quantum dots are prepared by the synthesis method according to any one of claims 1 to 8 .

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