Method for preparing functionalized lead halide perovskite quantum dot material stable in physiological buffer solution and application of functionalized lead halide perovskite quantum dot material

Abstract

The invention belongs to the technical field of novel materials, and particularly relates to a method for preparing a functionalized lead halide perovskite quantum dot material stable in a physiological buffer solution and application of the functionalized lead halide perovskite quantum dot material. The preparation method comprises the following steps: S01, dissolving PbX2 and CsX in a hydrophilic organic solvent according to an equal molar ratio; S02, further adding a ligand solution and a hydrophilic polymer, and reacting to obtain a mixed solution; s03, further adding double distilled water into the mixed solution to obtain a precursor solution; and S04, adding the precursor solution into a toluene solution, carrying out stirring reaction, centrifuging, and collecting the precipitate to obtain the functionalized lead halide perovskite quantum dot material stable in the physiological buffer solution.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and in particular relates to a method for preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer solution and an application thereof. Background Art

[0002] In recent years, the molecular formula CsPbX3 (X = Cl - Br - or I - All-inorganic lead halide cesium perovskite quantum dots (CsPbX3QDs) have attracted great attention. Compared with traditional II-VI and III-V quantum dots (such as CdS, CdSe and InP), CsPbX3QDs have excellent optoelectronic properties and are ideal materials for designing optoelectronic devices. However, due to its low formation energy and inherent defects such as dynamic ligand binding to the crystal surface, CsPbX3QDs show poor stability when exposed to moisture or heat, which seriously hinders its application in the biological field. In addition to having unique optical, electrical or magnetic properties and large specific surface area, optoelectronic materials used in the biological field also need to have 1) excellent water dispersibility, 2) buffer compatibility and stability, 3) optoelectronic and electromagnetic stability, and 4) surface functionalization.

[0003] At present, the mainstream methods for preparing CsPbX3 QDs include hot injection method, ligand-assisted reprecipitation method, aqueous emulsion method, etc. In order to improve the water stability and light stability of CsPbX3 QDs, the following strategies are often used: 1) embedding CsPbX3 QDs into inert materials such as silica shell, mesoporous silica or aluminum oxide encapsulation; 2) passivation with polymers such as polystyrene; 3) surface ligand exchange; 4) element doping, etc. However, the above strategies all have problems such as complicated processes or high preparation costs.

[0004] The patent with publication number CN113265249A and invention name "Preparation and biosensing application of a functionalized hydrophilic lead halide perovskite quantum dot" discloses a one-step preparation of surface functionalized water-dispersible lead halide perovskite quantum dots (CsPbBr3QDs), which are coupled with biomolecules and molybdenum disulfide nanosheets to construct a "turn on" fluorescence resonance energy transfer biosensor system. The CsPbBr3QDs synthesized by this patented method are hydrophilic and dispersible and can be stable in water for more than 8 days. However, subsequent experiments found that the CsPbBr3QDs were unstable in chloride-containing physiological buffers, and when used to label recognition molecules and sensor construction, the centrifugal separation of bound and unbound recognition molecules was complicated and unstable, affecting the detection mode, feed ratio and binding rate, resulting in higher detection limits or false negatives and lower repeatability.

[0005] There are many attempts to synthesize stable lead halide cesium perovskite quantum dots in physiological buffers, but the quantum dot materials obtained by the current methods require additional functional groups to be prepared in the later stage before they can be coupled with biological molecules for sensing detection. Therefore, the synthesis steps are cumbersome, the operation is complicated, and the cost is high. Therefore, it is necessary to propose new methods and strategies for improvement. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a method for preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer solution and its application, so as to partially solve or alleviate the above-mentioned deficiencies in the prior art. Specifically, the present invention adopts the following technical scheme.

[0007] A method for preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer comprises the following steps: S01: dissolving PbX2 and CsX in an equal molar ratio or a corresponding molar ratio of molecular formula (see Examples 8 and 9) in a hydrophilic organic solvent, wherein X represents Br, Cl or I; S02: further adding a weakly basic ligand solution and a hydrophilic polymer to react to obtain a mixed solution; the weakly basic ligand solution is composed of an alkyl acid and an alkylamine (adjusted to be weakly basic in a specific ratio); one end of the hydrophilic polymer contains a quantum dot stabilizing coordination group and the other end contains an easily extendable functional group; the quantum dot stabilizing coordination group includes an amino group, a carboxyl group, a thiol group or a sulfonic acid group; the easily extendable functional group includes an amino group or a carboxyl group; the volume ratio of the alkyl acid, the alkylamine and the hydrophilic organic solvent is 1:(0.4-0.7):(30-80); S03: further adding double distilled water to the mixed solution to obtain a precursor solution; the volume ratio of the double distilled water to the mixed solution is 0.1-0.2:1; S04: Add the precursor solution to the toluene solution and stir to react, the volume ratio of the precursor solution to the toluene solution is 1:5-20; centrifuge, collect the precipitate to obtain the functionalized lead halide perovskite quantum dot material that is stable in the physiological buffer solution; the surface of the lead halide perovskite quantum dot material is coated with a hydrophilic polymer layer and a deposited passivation layer. It can be understood that the role of the deposited passivation layer is to protect the quantum dot material and make it stable in the physiological solution environment; however, the deposited passivation layer cannot affect the extension of the functional group. Therefore, preferably, the deposited passivation layer is a discontinuous deposited passivation layer.

[0008] It can be understood that the discontinuous deposition includes point deposition, block deposition and / or discontinuous sheet deposition.

[0009] In some preferred embodiments, X represents Br and Cl.

[0010] In some preferred embodiments, the volume ratio of the alkyl acid, the alkylamine and the hydrophilic organic solvent includes 1:(0.4-0.5):(30-80), 1:(0.5-0.6):(30-80) or 1:(0.6-0.7):(30-80).

[0011] In some preferred embodiments, the volume ratio of the precursor solution to the toluene solution includes 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20.

[0012] Furthermore, the weakly alkaline hydrophilic organic solvent includes N,N-dimethylformamide or dimethyl sulfoxide.

[0013] Furthermore, the alkyl acid is selected from oleic acid, n-octanoic acid or n-hexanoic acid.

[0014] Furthermore, the alkylamine is selected from oleylamine or octylamine.

[0015] Preferably, the hydrophilic polymer is aminopolyethylene glycol carboxyl or polyacrylic acid, and the molecular weight of the hydrophilic polymer ranges from 2000 to 8000 Daltons.

[0016] One end of the hydrophilic polymer is anchored to the lead halide perovskite quantum dot, and the other end extends out a functional group.

[0017] Furthermore, the concentration of the hydrophilic polymer is 1.25-5 mg / mL.

[0018] Furthermore, the precursor solution and the toluene solution are stirred for a reaction time of 5-10 min, and then centrifuged at 6000 rpm-9000 rpm for 2 min-8 min.

[0019] The functionalized lead halide perovskite quantum dot material prepared by the above method is stable in a physiological buffer solution, wherein the lead halide perovskite quantum dot comprises CsPbBr3 or CsPbBr n Cl3-n, n=1 or 2; the surface of the lead halide perovskite quantum dot material is coated with a hydrophilic polymer layer; the surface of the hydrophilic polymer layer has extendable functional groups; the hydrophilic polymer layer contains a (discontinuous) deposited passivation layer; the deposited passivation layer is PbBrOH.

[0020] It can be understood that the PbBrOH passivation layer is mainly deposited in a water reaction system assisted by an alkyl acid and an alkylamine.

[0021] It can be understood that the hydrophilic polymer layer and the passivation layer are simultaneously coated on the surface of the lead halide perovskite quantum dots, and the deposition of the passivation layer does not affect or hardly affects the outward extension of the functional groups in the hydrophilic polymer layer.

[0022] The above functionalized lead halide perovskite quantum dot material stable in physiological buffer is used in the preparation of biosensors for biomolecule detection.

[0023] Application of the above method in preparing biosensors for biomolecule detection.

[0024] The above-mentioned quantum dot materials are activated and coupled with biological molecules, including nucleic acids, peptides, aptamers, antibodies, antigens, and haptens, through surface functional group activation, and can be used as recognition probes and reporter probes for cells, microorganisms, and proteins, and for specific detection of biological molecules; at the same time, the special physicochemical effects of the quantum dots with small molecules and their own catalase activity can be used directly for the detection of related small molecules and the biochemical reactions in which they participate.

[0025] Beneficial technical effects (1) The present invention adopts a one-pot synthesis method to prepare a lead halide perovskite quantum dot material that is stable in a physiological buffer and has surface functional groups. The lead halide perovskite quantum dot material can be used directly, for example, for preparing a biosensor. The synthesis method provided by the present invention is simple, efficient, and has prospects for industrial preparation.

[0026] (2) The present invention achieves stability in a physiological buffer by simultaneously coating / depositing a hydrophilic polymer layer and a passivation layer on the surface of lead halide perovskite quantum dots through the ratio and optimization of multiple substances / ingredients. It is noted that the thickness of the passivation layer is appropriate, so that after deposition, it does not affect or hardly affects the outward extension of the functional groups in the hydrophilic polymer layer; at the same time, the passivation layer is not too thin, so it can remain stable in a physiological buffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without paying creative labor.

[0028] Figure 1 The photoluminescence spectrum of the quantum dot material prepared in one embodiment of the present invention; Figure 2A transmission electron microscope image of a quantum dot material prepared in one embodiment of the present invention; Figure 3 This is a particle size characterization diagram of a quantum dot material prepared in one embodiment of the present invention; Figure 4 This is an infrared spectrum of a quantum dot material prepared in one embodiment of the present invention; Figure 5 This is an investigation on the stability of the quantum dot material prepared in one embodiment of the present invention in a PBS environment; Figure 6 The fluorescence of the quantum dot material prepared in one embodiment of the present invention after being shaken in PBS with different pH values ​​at room temperature for 2 hours; Figure 7 Fluorescence stability test of the quantum dot material prepared in one of the embodiments of the present invention; Figure 8 The fluorescence stability test of the quantum dot material prepared in one of the embodiments of the present invention; Fig. 9 It is to verify the performance of the quantum dot material prepared in one of the comparative examples of the present invention; Fig.10 It is to verify the performance of the quantum dot material prepared in one of the comparative examples of the present invention; Fig.11 To verify the performance of the quantum dot material prepared by changing the ratio of n-hexanoic acid and n-octylamine in one of the embodiments of the present invention; Fig.12 The fluorescence of the quantum dot material prepared by changing the ratio of double distilled water in different solutions in one embodiment of the present invention; Fig.13 This is a performance verification of a quantum dot material synthesized by changing the organic amine and acid to oleylamine and oleic acid in one of the embodiments of the present invention; Fig.14 This is a performance verification of a quantum dot material synthesized by changing the organic amine and acid to n-octanoic acid and n-octylamine in one of the embodiments of the present invention; Fig.15 This is the performance verification of the quantum dot material prepared with a PEG concentration of 5 mg / mL in one of the embodiments of the present invention; Fig.16 This is a performance verification of the quantum dot material prepared with a PEG concentration of 10 mg / mL in one of the embodiments of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0031] Herein "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0033] As used in this specification, the term "about" typically means + / - 5% of the stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically + / - 2% of the stated value, even more typically + / - 1% of the stated value, and even more typically + / - 0.5% of the stated value.

[0034] In this specification, some embodiments may be disclosed in a format of being in a range. It should be understood that this description of "being in a range" is only for convenience and brevity, and should not be interpreted as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and independent numerical values ​​within this range. For example, the description of the range 1-6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within this range, such as 1, 2, 3, 4, 5 and 6. Regardless of the breadth of the range, the above rules apply.

[0035] Definition of noun: The "functionalization" mentioned in the present invention means that the lead halide perovskite quantum dot material synthesized by the method of the present invention has functional groups on its surface, which can be directly coupled with other biological small molecules for subsequent preparation of biosensors.

[0036] The "functionalized lead halide perovskite quantum dot material stable in physiological buffer" described in the present invention refers to a surface functionalized lead halide perovskite quantum dot material stable in physiological buffer.

[0037] The "physiological buffer" described in the present invention refers to a mixed solution composed of weak acids and their salts, weak bases and their salts, which can offset and reduce the effect of external strong acids or strong bases on the pH of the solution to a certain extent, thereby keeping the pH value of the solution relatively stable. It includes but is not limited to phosphate buffer, Tris-HCl buffer, acetate buffer, etc.

[0038] Example 1 This embodiment provides an overview of a method for preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer. This embodiment adopts a one-pot method, and the specific steps are as follows.

[0039] S01: PbX2 and CsX in equal molar ratios are dissolved in a hydrophilic organic solvent, wherein X represents Br, Cl or I; the hydrophilic organic solvent is N , N -Dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).

[0040] S02: further adding weakly basic ligand solution and hydrophilic polymer to obtain a mixed solution; the ligand solution includes alkyl acid and alkyl amine; one end of the hydrophilic polymer contains a quantum dot stabilizing coordination group and the other end contains a functional group that is easy to extend; the quantum dot stabilizing coordination group includes an amino group, a carboxyl group, a thiol group or a sulfonic acid group. In some specific embodiments, the hydrophilic polymer is an amino glycol carboxyl group or a polyacrylic acid; the volume ratio of the alkyl acid, the alkyl amine and the hydrophilic organic solvent is 1: (0.4-0.7): (30-80). Wherein, the alkyl acid is selected from one or more of oleic acid, n-octanoic acid and / or n-hexanoic acid; the alkyl amine is selected from one or more of oleylamine or octylamine.

[0041] S03: further adding double distilled water to the mixed solution to obtain a precursor solution; the volume ratio of the double distilled water to the mixed solution is 0.1-0.2:1.

[0042] S04: adding the precursor solution to the toluene solution and stirring for reaction, the stirring reaction time is 5-10 min, and the volume ratio of the precursor solution to the toluene solution is 1:5-20; centrifuging at 6000 rpm-9000 rpm for 2 min-8 min, collecting the precipitate to obtain the functionalized lead halide perovskite quantum dot material that is stable in the physiological buffer.

[0043] The surface of the lead halide perovskite quantum dot material is coated with a hydrophilic polymer layer and a deposited passivation layer, and the passivation layer is PbBrOH.

[0044] As a preferred embodiment, the concentration of lead ions and cesium ions in the precursor solution is 0.04 M-0.05 M.

[0045] As a preferred embodiment, the concentration of the hydrophilic polymer in the mixed solution is 1.25-5 mg / mL.

[0046] Example 2 This embodiment provides a specific example of preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer.

[0047] The hydrophilic polymer used in this embodiment is amino polyethylene glycol carboxyl (PEG, MW.5000), which is used to encapsulate the prepared CsPbBr3.

[0048] (1) (0.05 mmol) CsBr and (0.05 mmol) PbBr2 were ultrasonically dissolved in 1 mL DMF, and 12.5 µL of hexanoic acid, 9 µL of n-octylamine and 5 mg of PEG 5000 were added successively under stirring, and stirred for 5 min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF was 1:0.7:80, and the concentration of PEG 5000 in the mixed solution was 5 mg / mL.

[0049] (2) Add double distilled water to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water is added and the mixed solution is 1021 μL. The volume ratio of double distilled water to the mixed solution is 0.125:1.

[0050] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene (volume ratio of 1:5) under vigorous stirring and stirred for 5 min; centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PEG5000@PbBrOH. Its fluorescence, particle size and infrared spectroscopy characterization are shown in the attached figure. Figure 1-4 The results show that the CsPbBr3@PEG5000@PbBrOH prepared in this example emits fluorescence in the wavelength range of approximately 475 nm-550 nm (see Appendix Figure 1 ); the particle size range is concentrated between 500 nm and 700 nm, with a maximum of 600 nm (see Appendix Figure 2 ,3). Infrared spectra showed the presence of PEG (attached Figure 4 ).

[0051] Example 3 This embodiment provides another specific example of preparing functionalized lead halide perovskite quantum dot materials that are stable in physiological buffer.

[0052] The hydrophilic polymer used in this embodiment is amino polyethylene glycol carboxyl (PEG, MW.4000), which is used to encapsulate the prepared CsPbBr3.

[0053] (1) (0.05 mmol) CsBr and (0.05 mmol) PbBr2 were ultrasonically dissolved in 1 mL DMF, and 12.5 µL of hexanoic acid, 9 µL of n-octylamine and 5 mg of PEG 4000 were added successively under stirring, and stirred for 5 min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF was 1:0.7:80, and the concentration of PEG 4000 was 5 mg / mL.

[0054] (2) Double distilled water was added to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water was added, the mixed solution was 1021 μL, and the volume ratio of double distilled water to the mixed solution was 0.125:1.

[0055] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene (volume ratio of 1:5) under vigorous stirring and stirred for 5 min. The mixture was centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PEG4000@PbBrOH.

[0056] Example 4 This embodiment provides another specific example of preparing functionalized lead halide perovskite quantum dot materials that are stable in physiological buffer.

[0057] The hydrophilic polymer used in this embodiment is amino polyethylene glycol carboxyl (PEG, MW.2000), which is used to encapsulate the prepared CsPbBr3.

[0058] (1) (0.05 mmol) CsBr and (0.05 mmol) PbBr2 were ultrasonically dissolved in 1 mL DMF, and 12.5 µL of hexanoic acid, 9 µL of n-octylamine and 5 mg of PEG 2000 were added successively under stirring, and stirred for 5 min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF was 1:0.7:80, and the concentration of PEG 4000 was 5 mg / mL.

[0059] (2) Double distilled water was added to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water was added, the mixed solution was 1021 μL, and the volume ratio of double distilled water to the mixed solution was 0.125:1.

[0060] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene (volume ratio of 1:5) under vigorous stirring and stirred for 5 min. The mixture was centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PEG2000@PbBrOH.

[0061] Example 5 This embodiment provides another specific example of preparing functionalized lead halide perovskite quantum dot materials that are stable in physiological buffer.

[0062] The hydrophilic polymer used in this embodiment is polyacrylic acid (PAA, MW.2000), which is used to encapsulate the prepared CsPbBr3.

[0063] (1) (0.05mmol) CsBr and (0.05mmol) PbBr2 were ultrasonically dissolved in 1mL DMF, and 12.5µL hexanoic acid, 9µL n-octylamine and 1.25mg PAA2000 were added successively under stirring, and stirred for 5min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF was 1:0.7:80, and the concentration of PAA2000 was 1.25mg / mL.

[0064] (2) Double distilled water was added to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water was added, the mixed solution was 1021 μL, and the volume ratio of double distilled water to the mixed solution was 0.125:1.

[0065] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene (volume ratio of 1:5) under vigorous stirring and stirred for 5 min. The mixture was centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PAA2000@PbBrOH.

[0066] Example 6 Verification of the stability of CsPbBr3@PEG5000@PbBrOH in chloride-containing buffer.

[0067] CsPbBr3@PEG5000@PbBrOH was dispersed in chlorine-containing buffer PBS (10 mM, pH 7.2-7.4), stored away from light, and monitored continuously for 7 days. It can be seen that the fluorescence remained basically constant in the first 4 days. Although it decreased slightly after the 4th day, the relative fluorescence intensity remained about 80% after 7 days (see Appendix). Figure 5 ), which proves that CsPbBr3@PEG5000@PbBrOH has good resistance to halogen anions.

[0068] Example 7 Verification of the stability of CsPbBr3@PEG5000@PbBrOH in different pH environments.

[0069] A certain amount of CsPbBr3@PEG5000@PbBrOH was added to solutions of different pH values ​​(5.5, 6.5, 7.5, 8.5 or 9.5), shaken at 25°C for 2h, and the fluorescence was measured. The results show that the fluorescence intensity of CsPbBr3@PEG5000@PbBrOH did not change significantly in solutions of different pH values, and the fluorescence was strongest at pH 7.5; the fluorescence did not decrease significantly at the lowest pH value of 5.5 and the highest pH value of 9.5 (see Appendix). Figure 6 ), proving its stability.

[0070] Example 8 This embodiment provides another specific example of preparing functionalized lead halide perovskite quantum dot materials that are stable in physiological buffer.

[0071] The hydrophilic polymer used in this embodiment is aminocarboxyl PEG5000, which is used to encapsulate the prepared CsPbBr2Cl.

[0072] (1) (0.05mmol, 0.0084g) CsCl and (0.05mmol, 0.0184g) PbBr2 were added to 1mL DMF and dissolved by ultrasonication for 5 min. 12.5µL hexanoic acid, 9.04µL n-octylamine and 5mg aminocarboxyl PEG5000 were added successively under stirring at a rate of more than 1000 rpm and stirred for 5 min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF was 1:0.7:80, and the concentration of PEG5000 was 5 mg / mL.

[0073] (2) Add double distilled water to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water is added, and the volume ratio of double distilled water to the mixed solution is 0.125:1.

[0074] (3) Immediately, inject 400 µL of the precursor solution into 2 mL of toluene under vigorous stirring (at least 1500 rpm) and stir at least 1000 rpm for 5 min.

[0075] (4) The product has blue-purple fluorescence and is transferred to an EP tube. It is centrifuged at 9000 rpm for 10 min and precipitated with nitrogen for 5 min to obtain CsPbBr2Cl@PEG5000@PbBrOH.

[0076] The results are attached Figure 7As shown, the fluorescence emission peak of the synthesized quantum dot material is at 448 nm (320 nm excitation), showing blue fluorescence; after being placed in PBS solution for 3 days, the fluorescence decreased by about 37%. The stability is not as good as that of CsPbBr3@PEG5000@PbBrOH, but it is significantly improved compared with similar quantum dots without PbBrOH precipitation protection (see Example 10), and meets the test requirements.

[0077] Example 9 This embodiment provides another specific example of preparing functionalized lead halide perovskite quantum dot materials that are stable in physiological buffer.

[0078] The hydrophilic polymer used in this embodiment is aminocarboxyl PEG5000, which is used to encapsulate the prepared CsPbBrCl2.

[0079] (1) Add 0.05mmol CsBr and 0.05mmol PbCl2 into 1mL DMF, dissolve under ultrasonic for 5min (no obvious particles), add 12.5µL hexanoic acid, 9.04µL n-octylamine and 5mg aminocarboxyl PEG5000 successively under stirring at a rate of more than 1000rpm, and stir for 5min to obtain a mixed solution. The volume ratio of hexanoic acid, n-octylamine and DMF is 1:0.7:80, and the concentration of PEG5000 is 5mg / mL.

[0080] (2) Add double distilled water to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water is added, and the volume ratio of double distilled water to the mixed solution is 0.125:1.

[0081] (3) Immediately, inject 400 µL of the precursor solution into 2 mL of toluene under vigorous stirring (at least 1500 rpm) and stir at least 1000 rpm for 5 min.

[0082] (4) The solution had a blue-purple fluorescence and was transferred to an EP tube. It was centrifuged at 9000 rpm for 10 min and precipitated with nitrogen for 5 min to obtain CsPbBrCl2@PEG5000@PbBrOH.

[0083] The results are attached Figure 8 The fluorescence emission peak of the synthesized quantum dot material is at 425 nm (320 nm excitation), which shows a weaker blue fluorescence than CsPbBr2Cl@PEG5000@PbBrOH; after being placed in PBS solution for 3 days, the fluorescence decreased by about 14%, and the stability was slightly better than that of CsPbBr2Cl@PEG5000@PbBrOH.

[0084] Example 10 (Comparative Example 1) This example provides a stability study of a functionalized lead halide perovskite quantum dot material prepared by a control method in a physiological buffer solution. (1) Add CsBr (0.4 mmol), PbBr2 (0.4 mmol) and amino-polyethylene glycol 5000-carboxyl (40 mg) into 10 mL of dimethylformamide and stir at 90 °C for 40 min. (2) Cool the mixture to room temperature, add 0.5 mL of oleylamine, and stir at 700 rpm for 12 h. Add 0.4 mL of perfluorooctyltriethoxysilane and stir at 90 °C for 1 h.

[0085] (3) 0.5 mL of the obtained solution was quickly added into 10 mL of toluene solution and stirred vigorously for 30 seconds. Bright green CsPbBr3 quantum dots were visibly precipitated. The obtained CsPbBr3 quantum dot toluene solution was centrifuged at 8000 rpm at 4 °C for 5 min, washed with toluene, and dried with nitrogen to obtain CsPbBr3@PEG5000 quantum dots.

[0086] As attached Fig. 9 As shown in the figure, it can be seen that CsPbBr3@PEG5000 is relatively stable when dispersed in water, but when dispersed in PBS, the fluorescence is very weak and disappears instantly. This proves that the quantum dot material prepared by this method is unstable in physiological buffer.

[0087] Example 11 (Comparative Example 2) CsPbBr3@PbBrOH was synthesized with the assistance of n-octylamine and n-hexanoic acid and verified.

[0088] (1) (0.05 mmol) CsBr and (0.05 mmol) PbBr2 were ultrasonically dissolved in 1 mL DMF. 12.5 µL of hexanoic acid and 9.04 µL of n-octylamine were added successively under stirring and stirred for 5 min to obtain a mixed solution.

[0089] (2) Add double distilled water to the mixed solution to obtain a precursor solution, wherein 125 μL of double distilled water is added, and the volume ratio of double distilled water to the mixed solution is 0.125:1.

[0090] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene under vigorous stirring and stirred for 5 min. The mixture was centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PbBrOH.

[0091] As attached Fig.10As shown, CsPbBr3@PbBrOH was dispersed in PBS (concentration of 0.125 mg / mL) and the fluorescence intensity was measured (365 nm excitation, 510 nm emission). It was close to that of CsPbBr3@PEG5000@PbBrOH (see Appendix Fig.10 a); but the stability is worse than the latter (attached Fig.10 b) It is proved that the synergy between the hydrophilic polymer layer and the deposited passivation layer can better improve the stability of the quantum dot material in the physiological buffer.

[0092] Example 12 (Comparative Example 3) CsPbBr3@PbBrOH was synthesized by changing the ratio of n-octylamine, n-hexanoic acid and organic solvent.

[0093] (1) (0.05 mmol) CsBr and (0.05 mmol) PbBr2 were ultrasonically dissolved in 1 mL DMF. 25 µL of hexanoic acid and 18.08 µL of n-octylamine (hexanoic acid: n-octylamine: DMF: 1:0.7:40) were added successively under stirring. The mixture was stirred for 5 min to obtain a mixed solution.

[0094] (2) Add double distilled water to the mixed solution to obtain a precursor solution, wherein 100 µL of double distilled water is added (the ratio of double distilled water to mixed solution is 0.1:1).

[0095] (3) Immediately, 400 μL of the precursor was injected into 2 mL of toluene (precursor: toluene was 1:5) under vigorous stirring and stirred for 5 min. The mixture was centrifuged at 7000 rpm for 5 min, the precipitate was collected, and the solvent was evaporated to obtain CsPbBr3@PbBrOH.

[0096] The product was dispersed in toluene and the fluorescence was measured. Fig.11 a, it can be seen that its fluorescence intensity is weaker than that of CsPbBr3@PbBrOH, as shown in the transmission electron microscopy image (Attached Fig.11 b).

[0097] Example 13 CsPbBr3@PbBrOH was prepared by referring to the method of Example 11, wherein different proportions of double distilled water were used, as shown in Table 1.

[0098] Table 1 The results are as follows Fig.12 As shown, Fig.12 a is the fluorescence of different groups of products dispersed in toluene, where the left picture is under sunlight and the right picture is under UV. Fig.12 b is the fluorescence of the product in PBS with a volume of 125 μL and 150 μL of double distilled water, which proves that the most preferred volume ratio of double distilled water to mixed solution is 0.15:1.

[0099] Embodiment 14 The organic amine and acid were changed to oleylamine and oleic acid to assist in the synthesis of CsPbBr3@PbBrOH.

[0100] (0.05mmol, 0.0106g) CsBr and (0.05mmol, 0.0184g) PbBr2 were added to 0.5mL DMF respectively, ultrasonicated for 15min, mixed the two, added oleic acid (ρ: 0.89g / mL, 31.5µL) and oleylamine (ρ: 0.813g / mL, 16.5µL) (converted according to the same molar number as n-hexanoic acid and n-octylamine) (oleic acid: oleylamine: organic solvent = 1:0.5:33) under stirring at 800 rpm, and stirred for about 5min to obtain a mixed solution. 100µL of water (the ratio of water to the mixed solution is 0.1:1) was added to the mixed solution, and immediately stirred vigorously (2000rpm). 400µL of the precursor was injected into 2mL toluene and stirred for 5min. Centrifuged at 7000rpm for 5min, washed once with toluene, purged with nitrogen, and then dispersed in water and PBS.

[0101] The fluorescence of the product dispersed in water and PBS is shown in the attached Fig.13 It can be seen that oleylamine and oleic acid can also assist in the synthesis of CsPbBr3@PbBrOH, which exhibits strong fluorescence in PBS, but the fluorescence decreases in water.

[0102] Embodiment 15 Changing the organic amine and acid to n-octanoic acid and n-octylamine assisted the synthesis of CsPbBr3@PbBrOH.

[0103] (0.05mmol, 0.0106g) CsBr and (0.05mmol, 0.0187g) PbBr2 were dissolved in 1mL DMF, ultrasonicated for 5min, and 19.9µL n-octanoic acid and 9.04µL n-octylamine (n-octanoic acid: n-octylamine: organic solvent = 1:0.45:50) were added, and stirred for about 2min to obtain a mixed solution. 125µL water was added to the mixed solution (the ratio of water to the mixed solution was 0.125:1). 400 µL was injected into 2mL toluene and stirred at 1000 rpm for 5min.

[0104] The fluorescence of the product dispersed in toluene is shown in the attached figure. Fig.14 , the fluorescence is weak.

[0105] Example 16 CsPbBr3@PEG8000@PbBrOH was synthesized by changing the molecular weight and dosage of PEG.

[0106] (1) The concentration of NH2-PEG-COOH (8000) is 5 mg / mL.

[0107] 0.05mmol CsBr and 0.05mmol PbBr2 were ultrasonically dissolved in 1mL DMF, and 12.5µL hexanoic acid and 9.04µL were added and stirred for 5min (hexanoic acid: n-octylamine: organic solvent = 1:0.7:80); (0.625µmol, 5mg) PEG8000 was added and dissolved at a concentration of 5mg / mL, and stirred for 5min to obtain a mixed solution.

[0108] Take 0.5mL of the mixed solution and mix it with 62.5µL of water to obtain the precursor (the ratio of water to the mixed solution is 0.125: 1); a) take 400uL of the precursor and inject it into 2mL of toluene (precursor toluene = 1: 5); b) take 400µL of the precursor and inject it into 4mL of toluene (precursor toluene = 1: 10); stir for 5min; centrifuge at 7000rpm for 5min; blow dry the toluene.

[0109] The product was dispersed in water and PBS and the fluorescence was measured. The results are shown in the attached Fig.15 : a) has green fluorescence, b) has blue fluorescence, indicating that the relative amount of toluene in the precursor is reduced and the emission peak of the product is shifted.

[0110] (2) The concentration of NH2-PEG-COOH (8000) is 10 mg / mL.

[0111] 0.05mmol CsBr and 0.05mmol PbBr2 were ultrasonically dissolved in 1mL DMF, and 12.5µL hexanoic acid and 9.04µL were added and stirred for 5min (hexanoic acid: n-octylamine: organic solvent = 1:0.7:80); (1.25µmol, 10mg) PEG8000 was added, with a concentration of 10mg / mL, and stirred for 5min to obtain a mixed solution; 0.5mL of the mixed solution was mixed with 62.5µL water to obtain a precursor solution (the ratio of water to the mixed solution was 0.125: 1); 400µL of the precursor was injected into 2mL of toluene; stirred for 5min; centrifuged at 7000rpm for 5min; and the toluene was blown dry.

[0112] When the precursor is just injected into toluene, it has blue-green fluorescence. Fig.16 (a), after stirring for 5 min, the fluorescence turns purple. Fig.16 (b) Therefore, it can be seen that the increase in the amount of PEG8000 will also cause the emission peak of the product to blue shift and the fluorescence to weaken.

[0113] The embodiments of the present invention are described in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A method for preparing a functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer, characterized in that: The following steps are involved: S01: dissolving PbX2 and CsX in an equal molar ratio in a hydrophilic organic solvent, wherein X represents Br, Cl or I; S02: further adding a weakly basic ligand solution and a hydrophilic polymer to react to obtain a mixed solution; the weakly basic ligand solution is composed of an alkyl acid and an alkylamine; the hydrophilic polymer has a quantum dot stabilizing coordination group at one end and an easily extendable functional group at the other end; the quantum dot stabilizing coordination group includes an amino group, a carboxyl group, a thiol group or a sulfonic acid group; the easily extendable functional group includes an amino group or a carboxyl group; the volume ratio of the alkyl acid, the alkylamine and the hydrophilic organic solvent is 1:(0.4-0.7):(30-80); S03: further adding double distilled water to the mixed solution to obtain a precursor solution; the volume ratio of the double distilled water to the mixed solution is 0.1-0.2:1; S04: adding the precursor solution to a toluene solution and stirring for reaction, wherein the volume ratio of the precursor solution to the toluene solution is 1:5-20; centrifuging and collecting the precipitate to obtain the functionalized lead halide perovskite quantum dot material that is stable in a physiological buffer solution; the surface of the lead halide perovskite quantum dot material is coated with a hydrophilic polymer layer and a passivation layer is deposited.

2. The method according to claim 1, characterized in that The hydrophilic organic solvent includes N , N -dimethylformamide or dimethyl sulfoxide.

3. The method according to claim 1, characterized in that The alkyl acid includes oleic acid, n-octanoic acid or n-hexanoic acid.

4. The method according to claim 1, characterized in that The alkylamine includes oleylamine or octylamine.

5. The method according to claim 1, characterized in that The hydrophilic polymer includes amino polyethylene glycol carboxyl or polyacrylic acid, and the molecular weight of the hydrophilic polymer ranges from 2000 to 8000 Daltons.

6. The method according to claim 1, characterized in that The concentration of the hydrophilic polymer is 1.25-5 mg / mL.

7. The method according to claim 1, characterized in that The precursor solution and the toluene solution are stirred for a reaction time of 5-10 min, and then centrifuged at 6000 rpm-9000 rpm for 2 min-8 min.

8. A functionalized lead halide perovskite quantum dot material stable in a physiological buffer prepared by the method according to any one of claims 1 to 7, characterized in that: The lead halide perovskite quantum dots include CsPbBr3 or CsPbBr n Cl3-n, n=1 or 2; the surface of the lead halide perovskite quantum dot material is coated with a hydrophilic polymer layer; the surface of the hydrophilic polymer layer has extendable functional groups; the hydrophilic polymer layer contains a deposited passivation layer; the deposited passivation layer is PbBrOH.

9. Use of the functionalized lead halide perovskite quantum dot material stable in a physiological buffer as claimed in claim 8 in the preparation of a biosensor for biomolecule detection.

10. Use of the method according to any one of claims 1 to 7 in the preparation of a biosensor for biomolecule detection.

Images