Dual-network hydrogel sensor as well as preparation method and application thereof

Abstract

The invention discloses a dual-network hydrogel sensor as well as a preparation method and application thereof, and belongs to the field of functional biopolymer materials. The invention provides a detection probe for a dual-network hydrogel sensor, which is characterized in that a core-shell up-conversion fluorescent nano material modified by a complementary chain of a nucleic acid aptamer of a target detection object is used as a signal probe, and a metal organic framework material modified by the nucleic acid aptamer of the target detection object is used as a capture probe; the signal probe and the capture probe are incubated together to obtain a detection probe. The capture probe is doped with Cu < 2 + > and modified with-NH2. The capture probe with a high specific surface area-hydrophilic interface composite structure is constructed through co-modification and cooperation, and a structural foundation is further laid for stable construction and high-sensitivity detection of a dual-network hydrogel sensor. The detection probe provided by the invention is prepared into a dual-network hydrogel sensor, and the dual-network hydrogel sensor is used for detecting AFB1 in a grain sample, so that the detection sensitivity and reliability can be improved.

Description

Technical Field

[0001] The present invention relates to the field of functional biopolymer materials, and in particular to a double-network hydrogel sensor and a preparation method and application thereof. Background Art

[0002] Aflatoxin B1 (AFB1) is a naturally occurring, highly toxic fungal metabolite with strong carcinogenic and teratogenic properties, easily contaminating wheat and other grains and their products. Improper temperature and humidity control or a lack of mold prevention measures in some agricultural production and storage processes significantly increases the risk of AFB1 contamination. Once contaminated grain enters the human body through the food processing chain, it can induce diseases such as cancer, acute hepatitis, hemorrhagic necrosis, hepatocellular steatosis, and bile duct hyperplasia, posing a serious threat to public health and safety.

[0003] Conventional methods for detecting AFB1 currently include gas chromatography, liquid chromatography, high-performance liquid chromatography, and enzyme-linked immunosorbent assay (ELISA). While these methods offer advantages such as low detection limits and high specificity, they generally rely on large instruments, specialized operators, and complex pretreatment processes. These methods also suffer from long detection cycles and high costs, making them difficult to meet the needs of rapid screening in the field or at processing sites. Therefore, there is an urgent need to develop a method for detecting AFB1 in grain that combines high sensitivity, rapid response, and portability to meet the needs of rapid, on-site detection of AFB1 in grain. Summary of the Invention

[0004] The present invention aims to provide a dual-network hydrogel sensor, its preparation method, and application, to address the aforementioned problems of the prior art. The present invention provides a detection probe for a dual-network hydrogel sensor. The sensor comprises a core-shell upconversion fluorescent nanomaterial modified with a complementary strand of a nucleic acid aptamer to the target analyte, serving as a signal probe, and a metal-organic framework modified with a nucleic acid aptamer to the target analyte, serving as a capture probe. The signal probe and capture probe are co-incubated to obtain the detection probe. A dual-network hydrogel sensor prepared using the detection probes provided by the present invention and used to detect AFB1 in food samples can improve detection sensitivity and reliability.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a detection probe suitable for a double-network hydrogel sensor, wherein the detection probe consists of a capture probe and a signal probe;

[0007] The capture probe is a metal-organic framework material modified with a nucleic acid aptamer of the target detection object;

[0008] The signal probe is a core-shell upconversion fluorescent nanomaterial modified with a complementary chain of a nucleic acid aptamer of the target detection object;

[0009] The metal organic framework material is Cu 2+ Doping and -NH2 co-modification.

[0010] Optionally, the target detection substance includes aflatoxin B1.

[0011] The present invention also provides a double-network hydrogel sensor comprising the detection probe.

[0012] Optionally, the double-network hydrogel sensor is composited with the detection probe and a double-network hydrogel precursor containing acrylamide and sodium alginate, and covalent cross-linking of acrylamide and N,N'-methylenebisacrylamide is initiated by free radical polymerization. At the same time, a second physical cross-linking network is formed by the coordination effect of calcium ions and carboxyl groups of sodium alginate, thereby finally obtaining the double-network hydrogel sensor.

[0013] The present invention also provides a method for preparing the dual-network hydrogel sensor, comprising the following steps:

[0014] a. Preparation of signal probe:

[0015] Preparation of core structure: Rare earth doped NaYF4 core structure upconversion nanomaterials were synthesized by high temperature pyrolysis method, and then dispersed in organic solvent after purification;

[0016] Encapsulating shell: epitaxially growing a NaYF4 inert shell on the surface of the NaYF4 core structure upconversion nanomaterial to form a core-shell upconversion nanomaterial, which significantly improves the luminous efficiency of the material;

[0017] Aptamer complementary chain modification: After surface hydroxylation modification, the core-shell upconversion fluorescent nanomaterial is covalently coupled with the aptamer complementary chain of the target detection object to obtain a signal probe;

[0018] b. Preparation of capture probe:

[0019] 2-Methylimidazole and 2-aminobenzimidazole were used as mixed ligands and self-assembled with copper-zinc bimetallic salts by room temperature coprecipitation method to prepare amino-functionalized NH2-ZIF-8@Cu 2+ Nanoparticles;

[0020] The nucleic acid aptamer of the target detection object was covalently fixed on the NH2-ZIF-8@Cu 2+ The capture probe is prepared on the surface of the nanoparticle;

[0021] c. Preparation of detection probes:

[0022] Mixing the signal probe with the capture probe, and incubating at 37° C. to obtain a detection probe;

[0023] d. Preparation of double network hydrogel sensors:

[0024] Precursor preparation: using acrylamide as a monomer and sodium alginate as a natural polymer additive, together with the detection probe, a chemical crosslinker and an ionic crosslinker to form a uniform mixed solution;

[0025] Double network construction: free radical polymerization is initiated by ammonium persulfate and TEMED, and simultaneously synergistically cross-linked with calcium ions to solidify at 40°C to form a double network hydrogel, thereby obtaining the double network hydrogel sensor.

[0026] Optionally, when preparing the capture probe, the rare earth includes rare earth chlorides, and the rare earth chlorides include yttrium chloride hexahydrate, ytterbium chloride hexahydrate, and thulium chloride hexahydrate.

[0027] Optionally, when preparing the capture probe, CuCl2·2H2O and Zn(CH3COO)2 are dissolved in water to form a metal salt solution, which is then reacted with the mixed ligand.

[0028] Optionally, the target detection substance includes aflatoxin B1.

[0029] The present invention also provides the use of the detection probe, the double-network hydrogel sensor or the double-network hydrogel sensor obtained by the preparation method in preparing a product for detecting aflatoxin B1 in grain.

[0030] Optionally, the grain includes wheat.

[0031] The present invention discloses the following technical effects:

[0032] The present invention discloses a detection probe for a double-network hydrogel sensor, comprising a core-shell upconversion fluorescent nanomaterial modified with a nucleic acid aptamer complementary chain of a target detection object as a signal probe, and a metal-organic framework material modified with a nucleic acid aptamer of the target detection object as a capture probe. The signal probe and the capture probe are incubated together to obtain the detection probe.

[0033] Aptamer-modified NH2-ZIF-8@Cu 2+ It is an effective quencher that can effectively quench the fluorescence of CSUCNPs-cDNA through fluorescence resonance energy transfer. It can quench the fluorescence of CSUCNPs-cDNA in a short time, thereby improving the detection efficiency. 2+ As a capture probe, the Apt on the capture probe surface specifically recognizes AFB1, making the constructed double-network hydrogel sensor have good specificity and anti-interference properties, and can accurately identify AFB1 and improve the accuracy of detection.

[0034] The present invention uses Cu2+ The structure of ZIF-8 was optimized by doping and -NH2 modification. 2+ Doping ZIF-8 increases the specific surface area of ZIF-8 to enhance the target detection aptamer loading capacity and target detection capture efficiency. At the same time, by modifying ZIF-8@Cu with -NH2 2+ The surface of the capture probe is modified to enhance the specific binding of the target aptamer and improve the dispersion stability of the capture probe in the double-network hydrogel through hydrophilic modification. The dual modification synergistically constructs a capture probe with a high specific surface area and hydrophilic interface composite structure, further laying the structural foundation for the stable construction and high-sensitivity detection of the double-network hydrogel sensor.

[0035] The double network gel sensor was prepared by using the detection probe provided by the present invention and used to detect AFB1 in food samples. By precisely controlling the 1.4 mg / mL AFB1 aptamer modified NH2-ZIF-8@Cu 2+ The detection probe was prepared by mixing the core-shell upconversion fluorescent nanomaterial modified with 2 mg / mL AFB1 aptamer complementary chain in a volume ratio of 1:1, which can improve the sensitivity and reliability of the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a transmission electron microscope image of the core-shell upconversion fluorescent nanomaterial;

[0038] Figure 2 The fluorescence spectrum of the core-shell upconversion fluorescent nanomaterial modified with the complementary chain of the AFB1 aptamer;

[0039] Figure 3 NH2-ZIF-8@Cu 2+ Scanning electron microscope images of

[0040] Figure 4 The fluorescence standard curve of different concentrations of AFB1 is shown. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] The present invention provides a detection probe suitable for a double-network hydrogel sensor, wherein the detection probe consists of a capture probe and a signal probe;

[0047] The capture probe is a metal-organic framework material modified with a nucleic acid aptamer of the target detection object;

[0048] The signal probe is a core-shell upconversion fluorescent nanomaterial modified with a complementary chain of a nucleic acid aptamer of the target detection object;

[0049] The metal organic framework material is Cu 2+ Doping and -NH2 co-modification.

[0050] In a specific embodiment of the present invention, the target detection substance includes aflatoxin B1.

[0051] The detection probe provided by the present invention can be used to prepare a double-network hydrogel sensor, and the preparation method includes the following steps:

[0052] a. Preparation of signal probe:

[0053] (1) Preparation of core structure: Rare earth doped NaYF4 core structure upconversion nanomaterials were synthesized by high temperature pyrolysis method and dispersed in organic solvent after purification.

[0054] Optionally, the rare earth includes rare earth chlorides, and the rare earth chlorides include yttrium chloride hexahydrate, ytterbium chloride hexahydrate and thulium chloride hexahydrate.

[0055] In a specific embodiment of the present invention, preparing the core structure includes dissolving yttrium chloride hexahydrate, ytterbium chloride hexahydrate, and thulium chloride hexahydrate in methanol, adding oleic acid and 1-octadecene, and reacting at high temperature under nitrogen protection to obtain a mixed solution A; dissolving ammonium fluoride and sodium hydroxide in methanol, and then mixing with the mixed solution A, pre-reacting at 70°C for 90 minutes, and then introducing nitrogen, and reacting at 160°C for 30 minutes under nitrogen protection to obtain a mixed solution B; the mixed solution B is purified and dispersed in cyclohexane to obtain a cyclohexane solution of NaYF4 core structure upconversion nanomaterial.

[0056] Wrapping shell: epitaxially growing a NaYF4 inert shell on the surface of the NaYF4 core structure upconversion nanomaterial to form a core-shell upconversion nanomaterial, which significantly improves the luminous efficiency of the material.

[0057] In a specific embodiment of the present invention, the shell layer comprises dissolving ammonium fluoride and sodium hydroxide in methanol, and then mixing with a cyclohexane solution of the NaYF4 core structure upconversion nanomaterial, pre-reacting at 70°C for 90 minutes, then introducing nitrogen, and reacting at 300°C for 80 minutes under nitrogen protection to obtain a core-shell upconversion fluorescent nanomaterial.

[0058] Modification of nucleic acid aptamer complementary chain: After surface hydroxylation modification, the core-shell upconversion fluorescent nanomaterial is covalently coupled with the nucleic acid aptamer complementary chain of the target detection object to obtain a signal probe.

[0059] b. Preparation of capture probe:

[0060] 2-Methylimidazole and 2-aminobenzimidazole were used as mixed ligands and self-assembled with copper-zinc bimetallic salts by room temperature coprecipitation method to prepare amino-functionalized NH2-ZIF-8@Cu 2+ Nanoparticles;

[0061] The nucleic acid aptamer of the target detection object was covalently fixed on the NH2-ZIF-8@Cu 2+ The capture probe is prepared on the surface of the nanoparticle.

[0062] Optionally, when preparing the capture probe, CuCl2·2H2O and Zn(CH3COO)2 are dissolved in water to form a metal salt solution, which is then reacted with the mixed ligand.

[0063] In a specific embodiment of the present invention, the steps of preparing the capture probe include: dissolving 2-methylimidazole and 2-aminobenzimidazole in water to form a ligand solution; dissolving CuCl2·2H2O and Zn(CH3COO)2 in water to form a metal salt solution; mixing the ligand solution and the metal salt solution, stirring, standing and reacting to obtain a precipitate, washing, centrifuging, and drying to obtain NH2-ZIF-8@Cu2@C12O. 2+ Nanoparticles; Activate the NH2-ZIF-8@Cu using glutaraldehyde solution 2+ The amino groups on the surface of the nanoparticles enable them to be covalently coupled with the nucleic acid aptamer of the target detection object. After centrifugation and washing, they are dispersed in PBS buffer to obtain capture probes.

[0064] c. Preparation of detection probes:

[0065] Mixing the signal probe with the capture probe, and incubating at 37° C. to obtain a detection probe;

[0066] d. Preparation of double network hydrogel sensors:

[0067] Precursor preparation: using acrylamide as a monomer and sodium alginate as a natural polymer additive, together with the detection probe, a chemical crosslinker and an ionic crosslinker to form a uniform mixed solution;

[0068] Double network construction: free radical polymerization is initiated by ammonium persulfate and TEMED, and simultaneously synergistically cross-linked with calcium ions to solidify at 40°C to form a double network hydrogel, thereby obtaining the double network hydrogel sensor.

[0069] Optionally, the chemical crosslinking agent includes N,N'-methylenebisacrylamide, which forms a covalent crosslinking network with acrylamide through free radical polymerization; the ionic crosslinking agent includes CaCl2·2H2O, which forms a covalent crosslinking network with acrylamide through CaCl2·2H2O. 2+ It forms an ionic cross-linked network with the carboxylate ions in sodium alginate.

[0070] The system is cross-linked by chemical cross-linking (acrylamide-MBA network) and ionic cross-linking (sodium alginate-Ca 2+ The double network structure is constructed together, which gives the hydrogel excellent mechanical properties and stability. Ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) form a redox initiation system to initiate the polymerization reaction.

[0071] The present invention will be further illustrated by the following specific examples.

[0072] Example

[0073] 1. Preparation of core-shell upconversion fluorescent nanomaterials

[0074] 241.5 mg of yttrium chloride hexahydrate, 77.5 mg of ytterbium chloride hexahydrate, and 3.83 mg of thulium chloride hexahydrate were dissolved in 10 mL of methanol, 8 mL of oleic acid and 16 mL of 1-octadecene were added, nitrogen was introduced, and the mixture was heated to 160°C and stirred for 30 minutes at a stirring rate of 400 rpm under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature to obtain a mixed solution A; 0.1482 g of ammonium fluoride and 0.1 g of sodium hydroxide were dissolved in 10 mL of methanol, mixed with the mixed solution A, heated to 70°C and stirred continuously for 90 minutes, and then nitrogen was introduced, heated to 300°C under a nitrogen atmosphere and maintained for 80 minutes, and cooled to room temperature to obtain a mixed solution B; the mixed solution B was washed with a mixed solution of ethanol and cyclohexane, collected by centrifugation, and dispersed in 10 mL of cyclohexane for storage to obtain a cyclohexane solution of nuclear upconversion fluorescent nanomaterials.

[0075] 121 mg of yttrium chloride hexahydrate was dissolved in 10 mL of methanol, 3 mL of oleic acid and 8 mL of 1-octadecene were added, nitrogen was introduced, and the mixture was heated to 160 ° C and stirred for 30 min under a nitrogen atmosphere at a stirring rate of 400 rpm. After the reaction was completed, it was cooled to room temperature to obtain a mixed solution C; subsequently, 55.5 mg of ammonium fluoride and 40 mg of sodium hydroxide were dissolved in 5 mL of methanol to form a solution, and 9 mL of a core-upconversion fluorescent nanomaterial cyclohexane solution were added to the mixed solution C in sequence, heated to 70 ° C and stirred for 90 min, then nitrogen was introduced, heated to 300 ° C under a nitrogen atmosphere and maintained for 80 min, and cooled to room temperature to obtain a mixed solution D; the mixed solution D was washed with a mixed solution of ethanol and cyclohexane, collected by centrifugation, and dried to obtain a core-shell upconversion fluorescent nanomaterial ( Figure 1 ), the prepared core-shell upconversion fluorescent nanomaterials are evenly dispersed and of uniform size, with a diameter of about 30 nm.

[0076] 2. Preparation of core-shell upconversion fluorescent nanomaterial (CSUCNPs-cDNA) signal probe modified with AFB1 aptamer complementary chain

[0077] 50.0 mg of the core-shell upconversion fluorescent nanomaterial was added to a round-bottom flask containing 6.0 mL of toluene and 4.0 mL of chloroform and thoroughly dissolved by sonication. The mixture was then added to 20.0 mL of a 15 mg / mL aqueous solution of polyacrylic acid and stirred vigorously for 48 hours in the dark. Finally, the excess polyacrylic acid was removed by centrifugation and washing to obtain the carboxylated core-shell upconversion fluorescent nanomaterial. 20 mg of the carboxylated core-shell upconversion fluorescent nanomaterial was weighed and dissolved in 10 mL of MES buffer. 1 mL of a 1 mg / mL aqueous solution of N-hydroxysulfosuccinimide and 1 mL of a 2 mg / mL aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added, and the mixture was incubated with shaking for 2 hours. Then, 60 μL of a 100 μM AFB1 aptamer complementary strand (5′-TGTGGGCCTAGCGAAGGGCACGA-C6-NH2-3′, SEQ ID NO. 1) solution was added and shaken for 12 hours. After centrifugation and washing to remove surface impurities, the solution was resuspended in 5 mL of PBS buffer to obtain a core-shell upconversion fluorescent nanomaterial (CSUCNPs-cDNA) solution modified with the complementary chain of the AFB1 aptamer ( Figure 2 ), which is used as a signal probe, has good luminescence performance, can avoid the interference of background fluorescence, and is conducive to improving the accuracy of detection.

[0078] 3. Preparation of Apt-ZIF-8@Cu 2+ Capture probe

[0079] 10.3 g of 2-methylimidazole and 7.18 g of 2-aminobenzimidazole were dissolved in 68 mL of water to obtain a mixed solution E. 0.836 g of CuCl 2· 2H2O and 0.9g Zn(CH3COO)2 were dissolved in 45mL water to obtain mixed solution F. Then, mixed solution E and F were mixed in a volume ratio of 45:57.6 and stirred for 20min. After standing for 6 hours, the precipitate was washed three times with water and ethanol respectively, collected by centrifugation, and dried in an oven to obtain NH2-ZIF-8@Cu 2+ The obtained NH2-ZIF-8@Cu 2+ It has a regular dodecahedral structure, and the nanoparticles have a smooth surface, complete morphology, and uniform size ( Figure 3 ). Then, 10 mg NH2-ZIF-8@Cu was weighed. 2+1.25 mL of glutaraldehyde solution and 5 mL of PBS buffer were added, and the mixture was shaken at 25 ° C in the dark for 2 h. The solution was then centrifuged, the resulting precipitate was washed three times, and then 5 mL of PBS solution was added. Next, 30 μL of 100 μM AFB1 aptamer (5′-COOH-GCTGAGTCTGAGTCGGTTGGGCACGTGTTGTCTCTCTGTGTC TCGTGCCCTTCGCTAGGCCCACA-3′, SEQ ID NO. 2) was added and the mixture was slowly shaken at 37 ° C overnight. Finally, the above solution was centrifuged, the resulting precipitate was washed with PBS buffer and resuspended in 5 mL of PBS buffer to obtain Apt-ZIF-8@Cu 2+ solution, serving as a capture probe.

[0080] 4. Synthetic detection probes

[0081] 2 mg / mL CSUCNPs-cDNA and 1.4 mg / mL Apt-ZIF-8@Cu 2+ The mixture was mixed at a volume ratio of 1:1 and incubated at 37°C for 18 minutes to obtain the detection probe.

[0082] 5. Preparation of dual-network hydrogel sensors

[0083] Dissolve 10g of acrylamide in 48.5mL of deionized water, then add 1.5mL of a 1mg / mL sodium alginate solution and stir until homogeneous. Subsequently, add 3mL of the detection probe, 0.125g of N,N'-methylenebisacrylamide, and 0.13g of CaCl2·2H2O, and stir until homogeneous. Then, add 1.5g of ammonium persulfate and 15μL of a 1mg / mL N,N,N',N'-tetramethylethylenediamine solution and stir until homogeneous to obtain a precursor solution. Finally, the double-network hydrogel precursor solution was injected into a mold and transferred to a 40°C incubator. After 3 hours of gelation, the mold was removed after gelation was complete to obtain the double-network hydrogel sensor.

[0084] 6. Draw a standard curve related to AFB1 concentration

[0085] AFB1 standard solutions of different concentrations (0.1, 0.5, 1, 2, 5, 10, 25, 50, 100 ng / mL) were prepared and added to the dual-network hydrogel sensor to detect the characteristic value of the fluorescence intensity signal of the dual-network hydrogel sensor. A standard curve related to AFB1 concentration was drawn with the logarithm of the AFB1 standard solution concentration as the horizontal axis and the characteristic value of the fluorescence intensity signal as the vertical axis ( Figure 4 ).

[0086] 7. Application of actual detection

[0087] Three wheat samples were randomly selected for testing. AFB1 content was measured using both the national standard method (high-performance liquid chromatography) and the dual-network gel sensor prepared by the present invention. The steps for detecting AFB1 in samples using the dual-network gel sensor prepared by the present invention are as follows:

[0088] A 5g grain sample was added with various concentrations of AFB1 standard solution. The sample was then mixed with 20mL of methanol-water solution, vortexed for 3 minutes, shaken on a shaker for 20 minutes, and centrifuged at 6000 rpm for 10 minutes. The supernatant was then collected for later use. Large particles were then removed with filter paper and filtered through a 0.22μm microporous membrane to obtain a sample solution. The fluorescence intensity signal characteristic value of the sample solution was measured, and the AFB1 content in the grain sample was calculated based on the AFB1 detection standard curve.

[0089] The sample test results are shown in Table 1.

[0090] Table 1 Results of the detection of AFB1 content in grain samples by the method of the present invention and high performance liquid chromatography

[0091]

[0092] It can be seen from the data in Table 1 that the method of the present invention has good accuracy in actual samples and has good application prospects.

[0093] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A detection probe suitable for a double network hydrogel sensor, characterized in that: The detection probe consists of a capture probe and a signal probe; The capture probe is a metal-organic framework material modified with a nucleic acid aptamer of the target detection object; The signal probe is a core-shell upconversion fluorescent nanomaterial modified with a complementary chain of a nucleic acid aptamer of the target detection object; The metal organic framework material is Cu 2+ Doping and -NH2 co-modification.

2. The detection probe according to claim 1, characterized in that The target detection substance includes aflatoxin B1.

3. A dual-network hydrogel sensor, characterized in that: The method comprises the detection probe according to claim 1 or 2.

4. The dual-network hydrogel sensor according to claim 3, characterized in that: The double-network hydrogel sensor is composited with the detection probe according to claim 1 or 2 and a double-network hydrogel precursor containing acrylamide and sodium alginate. The covalent cross-linking of acrylamide and N,N'-methylenebisacrylamide is initiated by free radical polymerization, and a second physical cross-linking network is formed by the coordination effect of calcium ions and the carboxyl groups of sodium alginate, thereby finally obtaining the double-network hydrogel sensor.

5. A method for preparing the double-network hydrogel sensor according to claim 3 or 4, characterized in that: The following steps are involved: a. Preparation of signal probe: Preparation of core structure: Rare earth doped NaYF4 core structure upconversion nanomaterials were synthesized by high temperature pyrolysis method, and then dispersed in organic solvent after purification; Encapsulating the shell layer: epitaxially growing a NaYF4 inert shell layer on the surface of the NaYF4 core structure upconversion nanomaterial to form a core-shell upconversion nanomaterial; Aptamer complementary chain modification: After surface hydroxylation modification, the core-shell upconversion fluorescent nanomaterial is covalently coupled with the aptamer complementary chain of the target detection object to obtain a signal probe; b. Preparation of capture probe: 2-Methylimidazole and 2-aminobenzimidazole were used as mixed ligands and self-assembled with copper-zinc bimetallic salts by room temperature coprecipitation method to prepare amino-functionalized NH2-ZIF-8@Cu 2+ Nanoparticles; The nucleic acid aptamer of the target detection object was covalently fixed on the NH2-ZIF-8@Cu 2+ The capture probe is prepared on the surface of the nanoparticle; c. Preparation of detection probes: Mixing the signal probe with the capture probe, and incubating at 37° C. to obtain a detection probe; d. Preparation of double network hydrogel sensors: Precursor preparation: using acrylamide as a monomer and sodium alginate as a natural polymer additive, together with the detection probe, a chemical crosslinker and an ionic crosslinker to form a uniform mixed solution; Double network construction: free radical polymerization is initiated by ammonium persulfate and TEMED, and simultaneously synergistically cross-linked with calcium ions to solidify at 40°C to form a double network hydrogel, thereby obtaining the double network hydrogel sensor.

6. The preparation method according to claim 5, characterized in that When preparing the capture probe, the rare earth includes rare earth chlorides, and the rare earth chlorides include yttrium chloride hexahydrate, ytterbium chloride hexahydrate and thulium chloride hexahydrate.

7. The preparation method according to claim 5, characterized in that When preparing the capture probe, CuCl2·2H2O and Zn(CH3COO)2 are dissolved in water to form a metal salt solution, which is then reacted with the mixed ligand.

8. The preparation method according to claim 5, characterized in that The target detection substance includes aflatoxin B1.

9. Use of the detection probe according to claim 1 or 2, the double-network hydrogel sensor according to claim 3 or 4, or the double-network hydrogel sensor obtained by the preparation method according to any one of claims 5 to 8 in the preparation of a product for detecting aflatoxin B1 in grain.

10. The use according to claim 9, characterized in that The food grains include wheat.

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