Quantum dot, quantum dot composition and detection reagent and medicine containing quantum dot composition

Abstract

The invention provides a quantum dot, a quantum dot composition, and a detection reagent and a drug containing the quantum dot composition. A surface ligand of the quantum dot is pyrrolidone carboxylic acid metal salt, the content of the ligand is 5wt%-20wt% of that of a core layer and a shell layer, and the ligand is coordinated by embedding metal salt ions into defect vacancies of the shell layer of the quantum dot. Through the coordination effect of the pyrrolidone carboxylic acid metal salt, the quantum dot can be dissolved in water and can be combined with a hydrophilic biocompatible polymer, the problem that the luminous efficiency is reduced after the oil-soluble quantum dot is subjected to water phase conversion is solved, and the application of the quantum dot in the biological field is greatly expanded.

Description

Technical Field

[0001] The present invention relates to the field of quantum dots, and in particular to a quantum dot, a quantum dot composition, and a detection reagent and a drug containing the same. Background Art

[0002] Quantum dots are a new type of semiconductor fluorescent nanomaterials, mainly composed of II-VI elements (such as CdSe, CdTe) or III-V elements (such as InP), with a particle size generally between 1 and 30 nm. Since electrons and holes are quantum confined, the continuous energy band structure becomes a discrete energy level structure with molecular characteristics, which can emit fluorescence after being stimulated. Quantum dots have excellent fluorescence properties such as wide and continuous excitation spectrum, adjustable color, high photochemical stability, and long fluorescence lifetime. Therefore, quantum dots have a larger specific surface area and are easier to modify. These advantages enable quantum dots to be widely used in biomedical fields such as targeted drug delivery, disease diagnosis, and bioimaging.

[0003] However, high-quality quantum dots (high luminous efficiency, narrow half-peak width, stable photochemical properties, etc.) are generally synthesized in oil phase by hot injection. Quantum dots are oil-soluble and can be monodispersed in non-polar solvents such as toluene, n-octane, and cyclohexane. Biological applications generally require materials to be water-soluble and biocompatible. This greatly limits the application of such high-quality quantum dots in biological detection and medicine. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a pyrrolidone carboxylic acid metal salt-modified quantum dot, a quantum dot composition, and a detection reagent and a drug containing the same.

[0005] In order to solve the above technical problems, the first aspect of the present application provides a quantum dot, wherein the surface ligand of the quantum dot is a pyrrolidone carboxylic acid metal salt (PCA-M for short), and the ligand is coordinated by embedding metal salt ions into defect vacancies in the quantum dot shell; the metal salt includes but is not limited to one or more of zinc (Zn), cadmium (Cd), magnesium (Mg), calcium (Ca), barium (Ba), copper (Cu), sodium (Na), potassium (K), gallium (Ga), indium (In), lead (Pb), silver (Ag), etc.

[0006] Furthermore, the compound of the core or shell of the quantum dot is a selenide or sulfide metal salt, the sulfide includes but is not limited to zinc sulfide (ZnS), cadmium sulfide (CdS), indium sulfide (InS), etc., the selenide includes but is not limited to zinc selenide (ZnSe), cadmium selenide (CdSe), indium selenide (InSe), etc.

[0007] Furthermore, the content of pyrrolidone carboxylic acid metal salt ligands on the surface of the quantum dots is 5wt% to 20wt% of the core layer and the shell layer.

[0008] Furthermore, the surface ligand contains the same metal ion as the quantum dot shell.

[0009] The second aspect of the present application provides a quantum dot composition, comprising any of the above-mentioned quantum dots and a hydrophilic biocompatible polymer. The hydrophilic biocompatible polymer includes but is not limited to polyvinyl alcohol (PVA), polyethylene glycol (PEG), etc. The quantum dots account for 0.01wt% to 20wt% in the quantum dot composition.

[0010] The third aspect of the present application provides a detection reagent and a drug, comprising the above-mentioned quantum dots or quantum dot compositions.

[0011] The beneficial effects of the present invention are:

[0012] Pyrrolidone carboxylic acid metal salts have good water solubility and biocompatibility, making the original oil-soluble high-quality quantum dots water-soluble. Furthermore, the quantum dots coordinated by the pyrrolidone carboxylic acid metal salts can be well dispersed in water-soluble polymers, further improving the biocompatibility and stability of the quantum dots. Furthermore, the quantum dots coordinated by the pyrrolidone carboxylic acid metal salts can be combined with hydrophilic biocompatible polymers, and the resulting quantum dot composition solves the problem of reduced luminous efficiency of oil-soluble quantum dots after water phase conversion, and can be widely used in the preparation of biological detection reagents and the development of related drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 These are photos of quantum dots in aqueous solution before and after modification with PCA-Zn ligands in Example 1.

[0014] Figure 2 These are transmission electron microscope (TEM) images of the quantum dots in Example 1 before and after modification with PCA-Zn ligands.

[0015] Figure 3-Figure 7 PL emission spectra of Examples 1-4 and Comparative Example 1. DETAILED DESCRIPTION

[0016] It should be noted that the embodiments described in detail below are exemplary and are intended to provide further explanation of the present invention, but should not be construed as limiting the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the art to which this application belongs. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work belong to the scope of protection of the present invention.

[0017] The quantum dots involved in the present invention can be CdSe / ZnS, CdS / ZnS, ZnSe / ZnS, CdSe / CdS, CdTe / ZnS, CdSe / CdS / ZnS, CdTe / CdSe / ZnS core-shell nanocrystals, or doped ZnO nanocrystals and CdZnS, CdZnSe, CdZnSeS alloy nanocrystals, or other non-Cd series PbSe quantum dots, PbTe quantum dots, PbS quantum dots, ZnSe quantum dots, CuInS quantum dots, InP quantum dots, InAs quantum dots, CuZnSe quantum dots, ZnMnSe quantum dots, etc. One or at least two combinations, but not limited thereto. The synthesis of quantum dots refers to the traditional synthesis method and is not described in detail here.

[0018] The selected quantum dots are dissolved in a high-boiling non-polar organic solvent such as octadecene (ODE), squalane or paraffin oil, and the coordination modification of pyrrolidone carboxylic acid metal salts is achieved by surface cation exchange under high temperature conditions. In some embodiments, the ligand exchange modification of pyrrolidone carboxylic acid metal salts can be performed in the later stage of quantum dot synthesis. The specific technical route is as follows (taking CdSe / ZnS quantum dots modified by pyrrolidone carboxylic acid zinc (PCA-Zn) ligand as an example):

[0019]

[0020] The advantage of using zinc pyrrolidone carboxylate ligands for modification is that, because the ligands themselves contain the same metal ions as the quantum dot shell, sufficient cation exchange can be carried out under high temperature conditions, and the water-soluble organic part of the ligand can well replace the original ligand to achieve a change in water solubility. More importantly, because zinc pyrrolidone carboxylate is a metal cation ligand, it can not only exchange with the original surface metal ions but also passivate the defective parts of the surface, so that the water-transferred quantum dots still have high efficiency and stability in the oil phase.

[0021] After modification with zinc pyrrolidonecarboxylate, the quantum dots are converted from oil-soluble quantum dots to water-soluble quantum dots. On this basis, various water-soluble biocompatible polymer coating treatments can be performed, and the required fluorescent dye / drug loading can be further performed. The specific technical route is as follows (taking CdSe / ZnS@PCA-Zn quantum dots loaded with Sulfo-Cy5 fluorescent dye as an example):

[0022]

[0023] The beneficial effects of the present invention will be further illustrated below in combination with embodiments and comparative examples.

[0024] Example 1

[0025] The first step, the quantum dot synthesis method refers to CN201510219791.1, in which the chemical structure is CdSeS / CdZnSeS / ZnS core-shell quantum dots, and the quantum dot intermediate layer is a wide bandgap quaternary alloy material, which has the advantages of high fluorescence quantum efficiency and continuously adjustable luminescence spectrum, and can maintain a certain photochemical stability. It is a typical hot injection method for synthesizing oil-soluble high-quality quantum dots. In addition to its oil-soluble disadvantage, the optical properties are particularly suitable for biomarker detection and drug tracing applications. The fluorescence emission half-peak width of the synthesized quantum dots is 26nm, and the fluorescence emission wavelength of the quantum dots is 528nm. The quantum dots are dispersed in toluene to obtain a toluene solution of the original quantum dots. The specific synthesis is not repeated here.

[0026] In the second step, add 2g of undiluted quantum dot toluene stock solution (10wt%) to 48g ODE to prepare a quantum dot ODE solution with a concentration of 0.4wt%. Protect with nitrogen and raise the temperature to 150°C under continuous magnetic stirring. Quickly add 1g PCA-Zn powder, and immediately raise the temperature to 200°C and continue stirring for 2h. At the end of the reaction, it can be observed that the originally clear quantum dot ODE solution turns into a turbid state. Slowly cool to room temperature, centrifuge and discard the supernatant, collect the precipitate, and obtain the pure product CdSeS / CdZnSeS / ZnS@PCA-Zn, and finally disperse and dissolve it in an aqueous solution for use. Figure 1 As shown, before the exchange, the quantum dots were dissolved in toluene and phased with water; after the exchange, the quantum dots were transferred to the water phase. Figure 2 The TEM images of CdSeS / CdZnSeS / ZnS quantum dots before and after PCA-Zn ligand transfer are shown. It can be seen that the morphology of quantum dots has not changed significantly. Figure 3 The PL spectra together prove that the luminescence performance of quantum dots has not undergone any qualitative change before and after ligand exchange, and the high luminescence efficiency characteristics of the original alloy quantum dots have been well maintained.

[0027] Step 3: Take 10 mL (2 wt%) of the PCA-Zn modified quantum dot aqueous solution, add 0.4 g of PEG-2000, and stir at room temperature in the dark for 12 h to obtain a water-soluble quantum dot aqueous solution coated with PEG on the surface.

[0028] Step 4: Prepare 10 ml of 0.5 wt% aqueous solution of CdSeS / CdZnSeS / ZnS@PCA-Zn@PEG, add 0.1 g (1 wt%) Sulfo-Cy5 aqueous solution, stir for 12 h at room temperature in the dark. Finally, centrifuge at 18000 rpm for 10 min, discard the upper liquid, and obtain the Cy5-loaded CdSeS / CdZnSeS / ZnS@PCA-Zn@PEG water-soluble quantum dot detection reagent.

[0029] Dispersing the final product into aqueous solution allows for relevant characterization and application.

[0030] Example 2

[0031] The difference from Example 1 is that the selected quantum dots are replaced with heavy metal-free InP / ZnS quantum dots, whose luminescence peak is 530nm. Although it is not as good as Cd-based quantum dots in optical indicators such as luminescence efficiency, it has better biocompatibility. Finally, InP / ZnS@PCA-Zn quantum dots, PEG-coated InP / ZnS@PCA-Zn@PEG quantum dot compositions, and Cy5-loaded InP / ZnS@PCA-Zn@PEG quantum dot detection reagents are obtained. Figure 4 The PL spectra of InP quantum dots before and after PCA-Zn ligand exchange and after one week of storage are shown, indicating that PCA-Zn ligands have a certain universality and are suitable for quantum dots composed of various elements. The reason is that the exchange principle is to exchange cations between the Zn ions of PCA-Zn and the Zn ions on the surface of quantum dots, directly replacing them in situ, and passivating surface defects, so that the efficiency of quantum dots is well maintained and the stability is improved to a certain extent.

[0032] Example 3

[0033] The difference from Example 1 is that copper pyrrolidone carboxylate is used, and copper metal salt can be used to dope copper ions on the surface of the exchanged quantum dots, resulting in a blue shift in the peak position of the quantum dots, and regulating the luminescence peak position to a certain extent. Finally, CdSeS / CdZnSeS / ZnS@PCA-Cu quantum dots, PEG-coated CdSeS / CdZnSeS / ZnS@PCA-Cu@PEG quantum dot compositions, and CdSeS / CdZnSeS / ZnS@PCA-Cu@PEG quantum dot detection reagents loaded with Cy5 are obtained. Figure 5 As shown, through PCA-Cu ligand exchange, part of the Zn ions on the original quantum dot surface were replaced by PCA-Cu, thereby completing partial Cu doping. Due to lattice compression, the PL spectrum underwent an obvious blue shift, and the stability of the quantum dots could be maintained after storage for one week.

[0034] Example 4

[0035] The difference from Example 1 is that the PCA-Zn ligand modification is carried out in the later stage of quantum dot synthesis, and the quantum dots used are unpurified quantum dot reaction liquid, which has the advantage that it does not require multiple solvent washing and purification, reduces the process steps, and is easier to operate. The ratio of PCA-Zn and quantum dots used remains unchanged. Finally, CdSeS / CdZnSeS / ZnS@PCA-Zn quantum dots, PEG-coated CdSeS / CdZnSeS / ZnS@PCA-Zn@PEG quantum dot compositions, and Cy5-loaded CdSeS / CdZnSeS / ZnS@PCA-Zn@PEG quantum dot detection reagents are obtained. Figure 6 As shown, it is feasible to carry out PCA-Zn ligand exchange in the quantum dot synthesis stock solution, and its stability can also be maintained.

[0036] Comparative Example 1

[0037] The type of quantum dots used is the same as that in Example 1, i.e., CdSeS / CdZnSeS / ZnS quantum dot toluene stock solution (10wt%). 2g of quantum dot toluene stock solution was added to 48g of ODE, and 0.1mol of mercaptopropionic acid (MPA) was added under continuous stirring, stirred at room temperature in the dark for 12h, and finally centrifuged at 12000rpm, and the supernatant was discarded to obtain water-soluble CdSeS / CdZnSeS / ZnS@PMA quantum dots. The operation of PEG coating and loading of Cy5 was the same as in Example 1, and finally a CdSeS / CdZnSeS / ZnS@MPA@PEG quantum dot composition coated with PEG and a CdSeS / CdZnSeS / ZnS@MPA@PEG quantum dot detection reagent loaded with Cy5 were obtained.

[0038] Although the prior art solution MPA can indeed complete the water phase transfer, Figure 7 As shown, the quantum dots have undergone a certain degree of red shift, especially after being stored in the water phase for a week. It can be clearly seen that the luminescence efficiency has decreased, and the red shift is obvious, indicating that water and oxygen etching has occurred on the surface of the quantum dots and the structure has been destroyed.

[0039] The test method for comparing the luminescence efficiency and luminescence peak position of quantum dots before and after ligand modification is to take a certain amount of quantum dots before and after ligand modification to prepare a toluene / water solution with the same concentration (0.01% wt).

[0040] Table 1 Luminous efficiency Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Before ligand modification 96.5％ 85.4％ 96.5％ 96.5％ 96.5％ After ligand modification 97％ 86％ 95.5％ 96.3％ 84.5％ Store for 1 week after modification 95.8％ 84.7％ 93.4％ 95.1％ 67.4％

[0041] From the results in Table 1, it can be seen that the efficiency can be well maintained after modification with PCA-M ligands, while the efficiency of the quantum dots after exchange with MPA ligands used in the conventional general technology in the comparative example is significantly reduced. The reason is that the thiol ligands produce defects in the process of exchanging the original trioctylphosphine, which increases the defects and significantly reduces the stability in water. However, when using PCA-M ligands, not only the efficiency is well maintained after exchange, but also the stability in water is improved.

[0042] Table 2 Luminescence peak Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Before ligand modification 528nm 530nm 528nm 528nm 528nm After ligand modification 528nm 530nm 526nm 528nm 529nm Store for 1 week after modification 528nm 530nm 526nm 528nm 530nm

[0043] As can be seen from Table 2, Examples 1, 2, and 4 use PCA-Zn modified ligands with the same metal as the surface, and the luminescent position remains unchanged and can remain stable in water. However, Example 3 using PCA-Cu shows a blue shift, which shows that PCA-Cu does achieve coordination through ion exchange, and Cu ions are successfully doped into the surface of quantum dots. Due to the change in the lattice, the luminescent peak position shows a blue shift, but because it is a cation exchange coordination, and the defective parts are well passivated, the same luminescent peak position can still be maintained after being stored in water for a week, indicating that the PCA-M ligand not only enables the quantum dots to achieve the oil-water phase transition, but also improves the stability of the quantum dots in the water phase, making a critical breakthrough in the field of biological applications of quantum dots.

[0044] The present invention fills a key link in the biological application of quantum dots, not only expanding the method of transferring high-quality oil-phase quantum dots to water-phase, but also solving the problem of changes or even degradation of the luminescence characteristics of quantum dots after water transfer that has long plagued the industry. With the continuous maturity of quantum dot synthesis technology, especially the development of environmentally friendly quantum dots such as heavy metal-free InP and AIGS, combined with the pyrrolidone carboxylic acid metal salt ligand of the present invention, quantum dots will surely shine in the field of biopharmaceuticals.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A quantum dot, characterized in that: The surface ligand of the quantum dot is a pyrrolidone carboxylic acid metal salt, and the chemical formula structure of the pyrrolidone carboxylic acid metal salt is: The M metal ions are one or more of zinc (Zn), cadmium (Cd), magnesium (Mg), calcium (Ca), barium (Ba), copper (Cu), sodium (Na), potassium (K), gallium (Ga), indium (In), lead (Pb) or silver (Ag).

2. The quantum dot according to claim 1, characterized in that The compound of the core or shell layer is a selenide or a sulfide metal salt, the sulfide is zinc sulfide (ZnS), cadmium sulfide (CdS) or indium sulfide (InS), and the selenide is zinc selenide (ZnSe), cadmium selenide (CdSe) or indium selenide (InSe).

3. The quantum dot according to claim 1, characterized in that The content of pyrrolidone carboxylic acid metal salt ligands on the surface of the quantum dots is 5wt% to 20wt% of the core layer and the shell layer.

4. The quantum dot according to claim 1, characterized in that The surface ligands contain the same metal ions as the quantum dot shell.

5. A quantum dot composition, characterized in that: The invention comprises the quantum dots according to any one of claims 1 to 3 and a hydrophilic biocompatible polymer, wherein the hydrophilic biocompatible polymer is polyvinyl alcohol (PVA) or polyethylene glycol (PEG).

6. The quantum dot composition according to claim 5, characterized in that The quantum dots account for 0.01 wt% to 20 wt% of the quantum dot composition.

7. A quantum dot detection reagent, characterized in that: It comprises the quantum dots described in any one of claims 1 to 4, or the quantum dot composition described in claim 5 or 6.

8. A quantum dot drug, characterized in that: It comprises the quantum dots described in any one of claims 1 to 4, or the quantum dot composition described in claim 5 or 6.

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