An aptamer sensor based on water-soluble perovskite nanocrystals, its preparation method and its application in peanut allergen detection

Abstract

The present invention relates to an aptamer sensor based on water-soluble perovskite nanocrystals, a preparation method thereof, and an application thereof in peanut allergen detection, belonging to the technical field of food safety analysis and detection. In the present invention, an aptamer is used as an identification molecule for peanut allergen Arah1. Compared with using an antibody as an identification molecule in traditional immunoassay methods, the aptamer used in the present invention has high stability, low preparation cost, and is easy to label, and has high affinity and high selectivity for peanut allergen Arah1 protein. The Apt-PNCs@cDNA-MNPs sensor constructed in the present invention is directly hybridized by an identification probe (Apt-PNCs) and a magnetic separation probe (cDNA-MNPs). The preparation process is simple. After incubation with a sample to be detected and magnetic separation, the fluorescence signal in the supernatant can be measured, which can greatly shorten the detection time, has the advantages of rapidity and economy, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of food safety analysis and detection, and particularly relates to an aptamer sensor based on water-soluble perovskite nanocrystals, a preparation method thereof, and an application thereof in peanut allergen detection. Background Art

[0002] Peanut allergy is a pathological allergic immune reaction, and its incidence has been increasing in the past few decades, gradually becoming one of the public health problems that people pay attention to. The symptoms of peanut allergy include gastrointestinal discomfort, asthma, itching, and even anaphylactic shock, which seriously threaten the physical health and quality of life of allergy-susceptible populations. The most abundant allergen protein Arah1 in peanuts plays a key role in peanut allergic reactions and has been identified as a biomarker for peanut allergens. So far, peanut allergy cannot be completely cured, and the most effective measure is to strictly avoid peanut allergens. Therefore, establishing an effective detection strategy for peanut allergen Arah1 can not only provide a basis for food production enterprises to formulate allergen labels, but also effectively guide the daily diet of allergic people, which is of great significance.

[0003] Traditional detection strategies for peanut allergen Ara h1 include liquid chromatography-mass spectrometry (LC-MS), enzyme-linked immunosorbent assay (ELISA), loop-mediated isothermal amplification (LAMP), and electrochemical analysis methods. However, the LC / MS method relies on specific large-scale instruments and requires complex sample pretreatment processes, which cannot meet the needs of rapid detection of food allergens; the sensitivities of ELISA, LAMP, and electrochemical analysis methods are still lacking and have high requirements for the skills of operators. In order to overcome the above defects, there is an urgent need to develop sensitive, rapid, and economical detection means to quickly analyze allergen Ara h1 in food to ensure the physical health of allergy-prone groups. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides an aptamer sensor based on water-soluble perovskite nanocrystals, a preparation method thereof, and an application thereof in peanut allergen detection. In the present invention, an aptamer is used as a recognition molecule for peanut allergen Ara h1. Compared with using an antibody as a recognition molecule in traditional immunoassay methods, the aptamer has high stability, low preparation cost, is easy to label, and has high affinity and high selectivity for peanut allergen Ara h1 protein. Using water-soluble perovskite nanocrystals as a fluorescent labeling material, compared with traditional fluorescent labeling materials, water-soluble perovskite nanocrystals have the advantages of narrow emission spectra and high fluorescence quantum yields.

[0005] The technical solution of the present invention is as follows:

[0006] The first object of the present invention is to provide a preparation method of an aptamer sensor based on water-soluble perovskite nanocrystals, comprising the following steps:

[0007] (1) After incubating CsPbBr3@SiO2@DA with a bifunctional crosslinking agent, add the peanut allergen Ara h1 aptamer and incubate to obtain the recognition probe Apt-PNCs; the nucleotide sequence of the peanut allergen Ara h1 aptamer is as shown in SEQ ID No.1;

[0008] (2) Mix the amino-functionalized magnetic nanomaterials with a bifunctional crosslinking agent and incubate. After solid-liquid separation, take the solid phase and add the complementary strand cDNA of the peanut allergen Ara h1 aptamer and mix to obtain cDNA-MNPs; the nucleotide sequence of the complementary strand cDNA of the peanut allergen Ara h1 aptamer is as shown in SEQ ID No.2;

[0009] (3) Mix Apt-PNCs and cDNA-MNPs for a reaction to obtain the aptamer sensor Apt-PNCs@cDNA-MNPs based on water-soluble perovskite nanocrystals.

[0010] In one embodiment of the present invention, in step (1), the CsPbBr3@SiO2@DA is prepared by the following method:

[0011] S1: Mix PbBr2 and CsBr in an organic solvent, add ammonia water and a silicate solution for reaction, perform solid-liquid separation and take the solid phase to obtain the water-soluble perovskite nanocrystals CsPbBr3@SiO2;

[0012] S2: Mix the water-soluble perovskite nanocrystals CsPbBr3@SiO2 with hydrochloric acid dopamine in a buffer solution, adjust the solution to alkaline and incubate, perform solid-liquid separation and take the liquid phase to obtain the CsPbBr3@SiO2@DA.

[0013] In one embodiment of the present invention, in step S1, the organic solvent is selected from oleylamine and / or oleic acid.

[0014] In one embodiment of the present invention, in step S1, the silicate solution is toluene containing TMOS.

[0015] In one embodiment of the present invention, in step S3, the pH value of the alkaline solution is 7.5 - 9.5.

[0016] In one embodiment of the present invention, in step (1), the bifunctional crosslinking agent is sodium 4-(N-maleimidomethyl) cyclohexane-1-carboxylate sulfosuccinimide ester.

[0017] In one embodiment of the present invention, in step (1), the mass ratio of CsPbBr3@SiO2@DA to the bifunctional crosslinking agent is 3:1 - 10:1.

[0018] In one embodiment of the present invention, in step (2), the amino-functionalized magnetic nanoparticles MNPs-NH2 are prepared by the following method:

[0019] Dissolve iron salt, sodium acetate anhydrous, and 1,6-hexanediamine in an organic solvent respectively, collect the black precipitate with a magnet after heating and reacting, to obtain the amino-functionalized magnetic nanoparticles MNPs-NH2.

[0020] In one embodiment of the present invention, the iron salt is selected from FeCl3·6H2O.

[0021] In one embodiment of the present invention, the heating temperature is 160°C - 240°C, and the heating time is 4h - 8h.

[0022] In one embodiment of the present invention, in step (2), the mass ratio of MNPs-NH2 to the bifunctional crosslinking agent is 3:1 - 10:1.

[0023] In one embodiment of the present invention, in step (3), the mass ratio of Apt-PNCs to cDNA-MNPs is 2:1 - 4:1.

[0024] The second object of the present invention is to provide an aptamer sensor based on water-soluble perovskite nanocrystals prepared by the described preparation method.

[0025] The third object of the present invention is to provide the application of the aptamer sensor based on water-soluble perovskite nanocrystals in detecting peanut allergens.

[0026] In one embodiment of the present invention, the method of the application specifically includes the following steps:

[0027] Incubate the solution containing peanut allergen Ara h1 with the aptamer sensor Apt-PNCs@cDNA-MNPs of water-soluble perovskite nanocrystals; perform magnetic separation to take the liquid phase, and detect the fluorescence signal intensity value of the obtained liquid phase, to achieve qualitative or quantitative detection of peanut allergen Arah1.

[0028] In one embodiment of the present invention, the concentration of the solution containing peanut allergen Ara h1 is ≥0.04 ng / mL.

[0029] In one embodiment of the present invention, the concentration of the solution containing peanut allergen Ara h1 is 0.04 ng / mL - 100 ng / mL.

[0030] In one embodiment of the present invention, the concentration of the solution containing peanut allergen Ara h1 is 0.1 ng / mL - 100 ng / mL.

[0031] The water-soluble perovskite nanocrystals (water-soluble PNCs) of the present invention are CsPbBr3@SiO2, which are directly prepared by a one-pot method and have excellent dispersion performance and excellent fluorescence stability in the aqueous phase. The fluorescence half-peak width of the water-soluble PNCs is 26 nm, the optimal excitation wavelength of the water-soluble PNCs is 360 nm, and the emission wavelength is 510 nm.

[0032] The recognition probe and signal probe (Apt-PNCs) of the present invention are water-soluble PNCs functionalized with peanut allergen Ara h1 aptamer, which are prepared by connecting thiolated Ara h1 aptamer to water-soluble PNCs through a bifunctional cross-linker. The nucleotide sequence (5’-3’) of the Ara h1 aptamer is: 5’-SH-TCGCACATTCCGCTTCTACCGGGGGGGTCGAGCTGAGTGGATGCGAATCTGTGGGTGGGCTTCGCACACACGGACTTACG-3’.

[0033] The magnetic separation probe of the present invention is magnetic nanomaterial Fe3O4 (MNPs) functionalized with aptamer complementary strand (cDNA), which is prepared by connecting cDNA to amino-functionalized magnetic nanomaterial (MNPs-NH2) through a bifunctional cross-linker. The nucleotide sequence (5’-3’) of the cDNA is: 5’-SH-CGTAAGTCCGTGTGTGCG-3’.

[0034] The Apt-PNCs@cDNA-MNPs sensor based on the water-soluble PNCs fluorescence probe of the present invention is formed by base complementary pairing hybridization between the recognition probe (Apt-PNCs) and the magnetic separation probe (cDNA-MNPs).

[0035] The present invention constructs an aptamer sensor based on water-soluble perovskite nanocrystals, its preparation method and its application in the detection of peanut allergens. The principle is as shown in the appendix Figure 1As shown. For the first time, the present invention synthesizes water-soluble PNCs capable of maintaining stable optical properties in an aqueous phase by using the "one-pot method". Subsequently, the aptamer of Ara h1 is connected to the surface of the water-soluble PNCs as a recognition probe and a signal probe for fluorescence labeling; while the surface of the magnetic nanomaterial Fe3O4 (MNPs) is functionalized with aptamer complementary DNA (cDNA) as a magnetic separation probe. Hybridizing the aptamer-conjugated water-soluble PNCs (Apt-PNCs) with cDNA-functionalized MNPs (cDNA-MNPs) can construct an Apt-PNCs@cDNA-MNPs sensor based on the water-soluble PNCs fluorescence probe. In the presence of Ara h1, the aptamer preferentially binds to the peanut allergen Ara h1, resulting in the dissociation of Apt-PNCs@cDNA-MNPs and the release of Apt-PNCs / Ara h1 and cDNA-MNPs. After magnetic separation, only Apt-PNCs / Ara h1 remains in the solution, showing fluorescence intensity dependent on the concentration of Ara h1. The Apt-PNCs@cDNA-MNPs sensor based on the water-soluble PNCs fluorescence developed in the present invention combines the extraordinary optical properties of perovskite nanocrystals, the efficient magnetic separation ability of the magnetic nanomaterial Fe3O4, and the high specificity of the aptamer.

[0036] The beneficial advantages of the present invention are as follows:

[0037] (1) The present invention synthesizes and prepares water-soluble perovskite nanocrystals by using the "one-pot method", which not only solves the problem of the instability of traditional perovskite nanocrystals in an aqueous phase but also maximally retains the excellent fluorescence optical properties of perovskite nanocrystals.

[0038] (2) The present invention uses water-soluble perovskite nanocrystals as a fluorescence labeling material. After functionalization with polydopamine (DA), it is connected to the Ara h1 aptamer under the mediation of a bifunctional cross-linking agent to construct a recognition probe (signal probe). Compared with traditional fluorescence labeling materials (carboxymethyl fluorescein, rhodamine, and inorganic fluorescent nanomaterials), the water-soluble perovskite nanocrystals have a higher fluorescence quantum yield and a narrower emission bandwidth.

[0039] (3) In the present invention, the aptamer is used as a recognition molecule for the peanut allergen Ara h1. Compared with using antibodies as recognition molecules in traditional immunoassay methods, the aptamer of the present invention has high stability, low preparation cost, is easy to label, and has a high affinity and high selectivity for the peanut allergen Ara h1 protein.

[0040] (4) The present invention provides a simple, sensitive and economical method for detecting peanut allergen Ara h1 using an aptamer sensor. The Apt-PNCs@cDNA-MNPs sensor constructed in the present invention is directly formed by the hybridization of an identification probe (Apt-PNCs) and a magnetic separation probe (cDNA-MNPs). The preparation process is simple. After incubation with the sample to be detected and magnetic separation, the fluorescence signal in the supernatant can be measured, which can greatly shorten the detection time. It has the advantages of rapidity and economy and has broad application prospects. Description of the Drawings

[0041] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in conjunction with the drawings, where

[0042] Figure 1 is the schematic diagram of the aptamer sensor for detecting peanut allergen Ara h1 based on the fluorescent probe of water-soluble perovskite nanocrystals (water-soluble PNCs) in the present invention;

[0043] Figure 2 is the transmission electron microscopy characterization diagram (TEM) of water-soluble perovskite nanocrystals (CsPbBr3@SiO2) in Example 1 of the present invention;

[0044] Figure 3 is the XRD pattern of water-soluble perovskite nanocrystals (CsPbBr3@SiO2) in Example 1 of the present invention;

[0045] Figure 4 is the change in the relative fluorescence intensity of CsPbBr3@SiO2 and CsPbBr3 in the aqueous phase in Example 1 of the present invention;

[0046] Figure 5 is the transmission electron microscopy characterization diagram (TEM) of the amino-functionalized magnetic nanomaterial Fe3O4 (MNPs-NH2) in Example 3 of the present invention;

[0047] Figure 6 is the ultraviolet-visible absorption spectrum of the supernatant before and after the surface modification of cDNA on MNPs-NH2 in Example 4 of the present invention;

[0048] Figure 7 is the fluorescence intensity diagram of the supernatant before and after the hybridization of Apt-PNCs and cDNA-MNPs in Example 5 of the present invention;

[0049] Figure 8-A is the fluorescence spectrum of the aptamer sensor based on the fluorescent probe of water-soluble perovskite nanocrystals (water-soluble PNCs) under different concentrations of Ara h1 in Example 6 of the present invention;

[0050] Figure 8-BThis is the standard curve corresponding to the aptasensor based on water-soluble perovskite nanocrystal (water-soluble PNCs) fluorescent probe in Example 6 of the present invention;

[0051] Figure 8-C This is the specific analysis diagram of the aptasensor based on water-soluble perovskite nanocrystal (water-soluble PNCs) fluorescent probe in Example 6 of the present invention. Detailed implementation manners

[0052] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0054] Example 1: Synthesis of perovskite nanocrystal CsPbBr3

[0055] First, add 0.1468 g of PbBr2, 0.0851 g of CsBr, 0.8 mL of oleylamine (OAm), and 2.4 mL of oleic acid (OA) to 10 mL of dimethylformamide (DMF), stir at 100 °C for 2 h to obtain a transparent precursor solution. Under vigorous stirring, quickly add 0.2 mL of the precursor solution to 10 mL of anhydrous toluene. After the reaction is completed, collect the precipitated product by centrifuging at 11,000 rpm for 10 min at 10 °C, which is CsPbBr3.

[0056] Example 2: Synthesis of water-soluble perovskite nanocrystal CsPbBr3@SiO2

[0057] First, add 0.1468 g of PbBr2, 0.0851 g of CsBr, 0.8 mL of oleylamine (OAm), and 2.4 mL of oleic acid (OA) to 10 mL of DMF, stir at 100 °C for 2 h to obtain a transparent precursor solution. Add 250 μL of ammonia water (2.8%) to the above precursor solution. Then, under violent stirring, quickly add 0.2 mL of the pre-mixed solution to 10 mL of toluene containing 5 μL of tetraethyl orthosilicate (TMOS). Then, stir and keep at 30 °C for 2 h. After the reaction is completed, collect the precipitated product by centrifuging at 11,000 rpm and 10 °C for 10 min to obtain water-soluble perovskite nanocrystal CsPbBr3@SiO2.

[0058] As Figure 2 shown, CsPbBr3@SiO2 shows a core-shell structure, and the XRD pattern shows no obvious difference between CsPbBr3@SiO2 and CsPbBr3 (see Figure 3 for details).

[0059] The fluorescence intensity changes of water-soluble perovskite nanocrystals CsPbBr3@SiO2 and CsPbBr3 during the storage process in an aqueous solution were measured using an F7000 fluorescence spectrometer. Compared with traditional CsPbBr3, CsPbBr3@SiO2 prepared by the "one-pot method" demonstrated better fluorescence stability in water and still retained 80% of the original fluorescence intensity after 25 days of storage (see Figure 4 for details).

[0060] Example 3: Preparation of recognition probe (signal probe) Apt-PNCs

[0061] First, CsPbBr3@SiO2 was functionalized with dopamine hydrochloride (DA). 6 mg of CsPbBr3@SiO2 and 3 mg of DA were dissolved in 6 mL of PBS buffer, the pH value was adjusted to 8.5, and the mixture was incubated at 25 °C on a shaker for 4 h. The black precipitate was removed by centrifugation, and the supernatant was collected to obtain CsPbBr3@SiO2@DA.

[0062] 1.2 mg of bifunctional crosslinker (sodium 4-(N-maleimidomethyl) cyclohexane-1-carboxylate sulfosuccinimide ester, Sulfo-SMCC) was added to 6 mL of CsPbBr3@SiO2@DA. After incubation at 25 °C for 4 h, CsPbBr3@SiO2@DA was linked to Sulfo-SMCC, and 600 μL of 10 μM peanut allergen Ara h1 aptamer was added to obtain a mixture. Then, the mixture was incubated at 25 °C for 12 h to couple the peanut allergen Arah1 aptamer to the surface of CsPbBr3@SiO2, and the recognition probe (signal probe) Apt-PNCs was prepared.

[0063] The nucleotide sequence of the peanut allergen Ara h1 aptamer is: 5’-SH-TCGCACATTCCGCTTCTACCGGGGGGGTCGAGCTGAGTGGATGCGAATCTGTGGGTGGGCTTCGCACACACGGACTTACG-3’.

[0064] Example 4: Synthesis of amino-functionalized magnetic nanomaterials Fe3O4 (MNPs-NH2)

[0065] 1.0 g of FeCl3·6H2O, 4.0 g of anhydrous sodium acetate, and 3.6 g of 1,6 - hexanediamine were respectively dissolved in 30 mL of ethylene glycol. After forming a transparent solution, it was heated at 200 °C for 6 h. After the reaction, the black precipitate was collected with a magnet, and then washed 3 times with deionized water and ethanol respectively. After removing the residual matrix, the amino - functionalized magnetic nanomaterial Fe3O4 (MNPs - NH2) was obtained, and then MNPs - NH2 was dried overnight at 50 °C. The MNPs - NH2 prepared was analyzed by transmission electron microscopy, and the results were as Figure 5 shown, and Figure 5 it was shown that the prepared MNPs - NH2 was a uniform sphere with a diameter of about 200 nm.

[0066] Example 5: Preparation of magnetic separation probe cDNA - MNPs

[0067] 6 mg of MNPs - NH2 and 1.2 g of Sulfo - SMCC were dispersed in 6 mL of PBS buffer. After continuous ultrasonic treatment for 1 h, the obtained mixture was incubated on a shaker at 25 °C for 4 h. Then it was thoroughly washed with PBS buffer, and the obtained black solid was resuspended in 6 mL of PBS buffer. Subsequently, the complementary strand cDNA of the peanut allergen Arah1 aptamer was mixed with MNPs - NH2 at 25 °C for 12 h. After magnetic separation and washing, MNPs - NH2 was successfully modified. The obtained precipitate was redispersed in 6 mL of PBS for use. The immobilization efficiency of cDNA on the surface of MNPs - NH2 was characterized by ultraviolet - visible spectrophotometer, and the results were as Figure 6 shown. The absorbance value of the supernatant at 260 nm decreased significantly after immobilization, indicating that cDNA had been successfully coupled to the surface of MNPs.

[0068] The nucleotide sequence of the complementary strand cDNA of the peanut allergen Ara h1 aptamer is: 5’ - SH - CGTAAGTCCGTGTGTGCG - 3’.

[0069] Example 6: Construction of Apt - PNCs@cDNA - MNPs sensor based on water - soluble PNCs fluorescence probe

[0070] Mix Apt-PNCs (100 μL) and cDNA-MNPs (0.8 mg / mL 200 μL) for hybridization for 4 h. The solid obtained by magnetic separation finally is Apt-PNCs@cDNA-MNPs. After washing with PBS buffer, it is resuspended in 150 μL of PBS buffer. The fluorescence value in the supernatant after hybridization of Apt-PNCs and cDNA-MNPs and magnetic separation decreased significantly compared with that in the supernatant before hybridization. However, the fluorescence intensity value of the supernatant did not change significantly after the simple PNCs and cDNA-MNPs were mixed and incubated, as shown in Figure 7 as follows. The result from Figure 7 indicates the successful hybridization of Apt-PNCs and cDNA-MNPs and the successful construction of the Apt-PNCs@cDNA-MNPs sensor.

[0071] Example 7: Analysis and determination of peanut allergen Ara h1

[0072] Mix 150 μL of the standard solution containing Ara h1 (or the food sample solution to be analyzed) with 150 μL of Apt-PNC@cDNA-MNPs and incubate continuously at 37 °C for 80 min. Then, obtain the supernatant solution by magnetic separation, and use an F-7000 fluorescence spectrometer to measure the fluorescence intensity in the supernatant (excitation wavelength 360 nm, emission wavelength 510 nm, excitation and emission slit widths 10 nm). As shown in Figure 8-A as follows, as the peanut allergen Ara h1 increases from 0.1 ng / mL to 100 ng / mL, the fluorescence signal response gradually increases and shows a good linear relationship with the logarithm of the allergen Ara h1 concentration ( Figure 8-B ). The regression equation is fitted as ΔF = 625.9lgC Ara h1 + 812.7, and the correlation coefficient value R 2 is 0.9988, where ΔF is the change value of the fluorescence signal intensity and C Ara h1 is the concentration of the allergen Ara h1. According to the 3-fold signal-to-noise ratio principle (LOD = 3δ / κ, where δ is the standard deviation of blank parallel determination and κ is the slope of the calibration curve), the detection limit (LOD) is calculated to be 0.04 ng / mL. The relative standard deviation of 11 repeated determinations of 5 ng / mL allergen Ara h1 is 3.2%. Compared with the signal response value caused by the allergen Ara h1, the signal response values generated by β-lactoglobulin, α-lactalbumin, immunoglobulin-E, lysozyme, and bovine serum albumin are negligible ( Figure 8-C ), indicating that the constructed biosensor has excellent specificity for the allergen Ara h1.

[0073] Example 8: Spike recovery experiment of actual samples

[0074] The milk and tea beverages were purchased from a local supermarket. Before sample pretreatment, peanut allergen Ara h1 with final concentrations of 1.0 μg / kg and 5.0 μg / kg was added to the food samples. First, 5 g of milk was defatted, then passed through a 0.22-μm filter membrane and diluted to 10 mL with PBS buffer for further detection. 5 g of tea beverage was directly filtered through a 0.22-μm filter membrane and diluted to 10 mL with ultrapure water for further determination. As shown in Table 1, the spiked recovery rates of allergen Ara h1 ranged from 95.9% to 105.4%. This result indicates that the Apt-PNCs@cDNA-MNPs sensor based on water-soluble PNCs fluorescent probe constructed in the present invention can effectively resist the interference of complex matrices in actual samples and has excellent potential for practical applications.

[0075] Table 1. Analysis results of spiked Ara h1 in food samples a

[0076]

[0077] a ND: Not detected

[0078] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of an aptamer sensor based on water-soluble perovskite nanocrystals, characterized in that, It includes the following steps: (1) After incubating CsPbBr3@SiO2@DA with a bifunctional crosslinker, add the peanut allergen Arah1 aptamer and incubate to prepare the recognition probe Apt-PNCs; the nucleotide sequence of the peanut allergen Arah1 aptamer is shown in SEQ ID No.1; (2) Mix and incubate the amino-functionalized magnetic nanomaterials with the bifunctional crosslinker. After solid-liquid separation and taking the solid phase, add the complementary strand cDNA of the peanut allergen Arah1 aptamer and mix to prepare cDNA-MNPs; the nucleotide sequence of the complementary strand cDNA of the peanut allergen Arah1 aptamer is shown in SEQ ID No.2; (3) Mix and react Apt-PNCs with cDNA-MNPs to prepare the aptamer sensor Apt-PNCs@cDNA-MNPs based on water-soluble perovskite nanocrystals.

2. The preparation method according to claim 1, wherein In step (1), the CsPbBr3@SiO2@DA is prepared by the following method: S1: Mix PbBr2 and CsBr in an organic solvent, then add ammonia water and a silicate solution for reaction. After solid-liquid separation and taking the solid phase, obtain the water-soluble perovskite nanocrystals CsPbBr3@SiO2; S2: Mix the water-soluble perovskite nanocrystals CsPbBr3@SiO2 with hydrochloric acid dopamine in a buffer solution, adjust the solution to alkaline and incubate, then perform solid-liquid separation and take the liquid phase to obtain the CsPbBr3@SiO2@DA.

3. The preparation method according to claim 2, characterized in that, In step S1, the silicate solution is toluene containing TMOS.

4. The preparation method according to claim 1, characterized in that, In step (1), the bifunctional crosslinker is sodium 4-(N-maleimidomethyl) cyclohexane-1-carboxylate sulfosuccinimide ester.

5. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of CsPbBr3@SiO2@DA to the bifunctional crosslinker is 3:1 - 10:

1.

6. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of Apt-PNCs to cDNA-MNPs is 2:1 - 4:

1.

7. An aptamer sensor based on water-soluble perovskite nanocrystals prepared by the preparation method according to any one of claims 1 - 6.

8. Use of the aptamer sensor based on water-soluble perovskite nanocrystals according to claim 7 in detecting peanut allergens.

9. The application according to claim 8, wherein, The method of the above use specifically includes the following steps: Incubate the solution containing peanut allergens with the aptamer sensor Apt-PNCs@cDNA-MNPs of water-soluble perovskite nanocrystals, perform magnetic separation to take the liquid phase, and detect the fluorescence signal intensity value of the obtained liquid phase to achieve qualitative or quantitative detection of peanut allergens.

10. The application according to claim 9, wherein The concentration of the solution containing peanut allergens is ≥0.04 ng / mL.

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