Praseodymium oxide / zirconium-based MOF composite nano-enzyme as well as preparation method and application thereof

Abstract

The invention discloses a praseodymium oxide / zirconium-based MOF composite nano-enzyme preparation method, which comprises: respectively dissolving ZrOCl2. 8H2O and NH2-BDC in a first solvent, mixing to obtain a mixed solution, adding Pr6O11 into the mixed solution, uniformly mixing, carrying out a synthesis reaction under heating, and sequentially carrying out centrifugation, washing and drying after the reaction is finished to obtain the praseodymium oxide / zirconium-based MOF composite nano-enzyme. The praseodymium oxide / zirconium-based MOF composite nano-enzyme is prepared by selecting cheap and easily available praseodymium oxide and zirconium salt as raw materials through a one-step synthesis method, the preparation process is simple, the cost is low, and the prepared praseodymium oxide / zirconium-based MOF composite nano-enzyme has the advantages of good stability and no toxicity, and is suitable for industrial production. And a new insight is expected to be provided for developing a multifunctional nano-enzyme and an integrated multi-mode sensing platform.

Description

Technical Field

[0001] The present invention relates to the technical field of nanozyme sensors, and more specifically, to a praseodymium oxide / zirconium-based MOF composite nanozyme and a preparation method and application thereof. Background Art

[0002] Nanomaterials with enzyme activity (nanozymes) are considered to be excellent substitutes for natural enzymes. Nanozyme sensors have become a research hotspot due to their high stability, high activity, simple preparation, easy operation, and low cost. Nanozymes can be divided into oxidase mimics, peroxidase mimics, superoxide dismutase mimics, catalase mimics, hydrolase mimics, etc. according to the catalytic type. Due to the excellent performance of nanozymes, various nanozymes have been widely studied in biosensors, environmental protection, disease diagnosis and treatment, and antibacterial agents. Praseodymium oxide is a rare earth element oxide with many excellent properties and application fields. It has a high melting point and thermal stability and can maintain its structure unchanged at high temperatures. Due to its Pr 3+ / Pr 4+ It has the potential to become a catalytic artificial enzyme. Studies have found that praseodymium oxide has good performance in catalytic ozonation, oxidation of methanol, methane, CO, photocatalytic degradation of dyes, phenol, 2-naphthol, etc., and is often used as a catalyst additive or carrier.

[0003] In recent years, the development of new multifunctional nanomaterials and the construction of their nanosensors have pointed out the research direction for the development of new technologies and methods for rapid, sensitive and in situ detection of hazardous substances. So far, a large number of nanomaterials with enzyme-like activity have been discovered and designed, including metals, metal oxides, metal organic frameworks (MOFs), and carbon-based materials. In particular, MOFs have clear structures and high tunability, which can precisely regulate catalytic activity and study catalytic mechanisms. In addition, the rich ligand library and the diversity of topological structures give MOF functionality. MOF-based nanomaterials have good prospects in biomedicine / biosensing due to their several unique properties: high specific surface area and high loading capacity porosity; stable but degradable structure, which can be degraded on demand; good dispersibility and biocompatibility to ensure biosafety for medical applications. It can be used as a carrier of fluorescent signals to enhance the stability and sensitivity of fluorescent signals. It has good biocompatibility and is suitable for direct contact with biological samples. Zirconium-based MOF materials, as a porous material formed by zirconium (Zr) ions and organic ligands connected by coordination bonds, have many significant advantages, which make them show broad application prospects in many fields. Zirconium-based MOF materials have a high specific surface area and provide a large number of active sites, which are conducive to surface reactions such as adsorption and catalysis. They can be used as carriers for immobilized metal nanocatalysts, and by loading precious metal nanoparticles (such as Pd nanoparticles), they can form an efficient catalytic system for reactions such as organic synthesis. Compared with other MOFs, zirconium-based MOFs have higher chemical stability. This stability enables zirconium-based MOF materials to maintain the stability of their structure and performance in various chemical environments, thereby extending the service life of the material and expanding its application range.

[0004] Therefore, the rational design and use of praseodymium oxide to prepare enzyme-like luminescent MOFs is an environmentally friendly and sustainable way to address food safety and environmental pollution. Summary of the invention

[0005] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0006] Another object of the present invention is to provide a method for preparing a praseodymium oxide / zirconium-based MOF composite nanozyme, which uses cheap and readily available praseodymium oxide and zirconium salts as raw materials, and obtains the praseodymium oxide / zirconium-based MOF composite nanozyme through a one-step synthesis method. The preparation process is simple and the cost is low. The prepared praseodymium oxide / zirconium-based MOF composite nanozyme has the advantages of good stability and non-toxicity, and is expected to provide new insights for the development of multifunctional nanozymes and integrated multimodal sensing platforms.

[0007] In order to achieve these purposes and other advantages according to the present invention, a method for preparing a praseodymium oxide / zirconium-based MOF composite nanozyme is provided, which comprises: Dissolve ZrOCl2·8H2O and NH2-BDC in the first solvent respectively and mix them to obtain a mixed solution, then add Pr6O 11 After being evenly mixed, the synthesis reaction is carried out under heating. After the reaction is completed, centrifugation, washing and drying are carried out in sequence to obtain praseodymium oxide / zirconium-based MOF composite nanozyme.

[0008] Preferably, the preparation method of the praseodymium oxide / zirconium-based MOF composite nanozyme comprises ZrOCl2·8H2O, NH2-BDC, Pr6O 11 The dosage ratio is 1:2:0.3.

[0009] Preferably, in the method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme, the centrifugal speed is 5000-12000 rad / min and the centrifugal time is 10-20 min.

[0010] Preferably, in the method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme, the conditions for the synthesis reaction are a temperature of 120-180° C. and a reaction time of 12-24 h.

[0011] Preferably, in the preparation method of the praseodymium oxide / zirconium-based MOF composite nanozyme, the washing method is to wash the solid product collected by centrifugation with the first solvent and anhydrous ethanol respectively for 5 to 8 times.

[0012] Preferably, in the method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme, the first solvent is NN-dimethylformamide.

[0013] Preferably, in the preparation method of the praseodymium oxide / zirconium-based MOF composite nanozyme, the drying method is to place the washed solid product in a vacuum dryer and dry it for 12 to 20 hours.

[0014] The present invention provides a praseodymium oxide / zirconium-based MOF composite nanozyme, which is prepared by the above-mentioned praseodymium oxide / zirconium-based MOF composite nanozyme preparation method.

[0015] The present invention provides an application of the above-mentioned praseodymium oxide / zirconium-based MOF composite nanozyme in food detection.

[0016] The present invention provides an application of the above-mentioned praseodymium oxide / zirconium-based MOF composite nanozyme in the detection of organic phosphorus in food.

[0017] The present invention has at least the following beneficial effects: 1. The present invention adopts a solvent thermal method to prepare a composite MOF material (Pr6O 11 / Zr-MOF), the nanozyme catalyst has excellent oxidase performance and good chemical stability. The praseodymium source and zirconium source used in the present invention are rich in sources, low in cost, and simple in preparation process. In addition, the whole preparation process of the present invention is pollution-free, non-toxic, green and environmentally friendly, and can be prepared in large quantities; 2. Pr6O prepared by the present invention 11 / Zr-MOF composite nanozymes have the advantages of stable properties, good dispersibility and high fluorescence brightness, and have important application value in realizing in-situ and visual monitoring of multiple target molecules in environmental food; 3. Pr6O prepared by the present invention 11 / Zr-MOF composite MOF materials further improve the understanding of the precise preparation of nanomaterials and the mechanism of interaction between organic pollutants and their fluorescent luminescence, play an important role in developing a simple, rapid, sensitive, in-situ organic pollutant research and visualization detection platform, and provide effective protection for people's food safety and life health.

[0018] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a comparison chart of the oxidation activity of the composite nanozymes prepared with different amounts of zirconium oxide added in Example 1 of the present invention; Figure 2 Praseodymium oxide and Zr-MOF, Pr6O prepared in Example 1 of the present invention 11 / SEM image of Zr-MOF; Figure 3 The praseodymium oxide standard card, praseodymium oxide and Zr-MOF prepared in Example 1 of the present invention, Pr6O 11 / XRD pattern of Zr-MOF; Figure 4 The Zr-MOF and Pr6O prepared in Example 1 of the present invention 11 / UV spectrum of Zr-MOF; Figure 5 Pr6O 11 , NH2-BDC and Zr-MOF prepared in Example 1 of the present invention, Pr6O 11 / Fluorescence spectrum of Zr-MOF; Figure 6 The Pr6O prepared in Example 1 of the present invention 11 / Analysis of catalytic performance of the simulated oxidase of Zr-MOF; Figure 7 The Pr6O prepared in Example 1 of the present invention11 / Analysis results of different reaction times of Zr-MOF and TMB; Figure 8 It is the UV spectrum of the reaction between the working solution and AChE, ATCh and AChE+ATCh; Fig. 9 This is the UV spectrum of AChE+ATCh+ working solution after acting on dichlorvos; Fig.10 Pr6O 11 Fluorescence changes of / Zr-MOF and dichlorvos. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0021] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0022] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0023] In the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0024] <Example 1> The present invention provides a method for preparing a praseodymium oxide / zirconium-based MOF composite nanozyme, which comprises: Dissolve ZrOCl2·8H2O (zirconium oxychloride octahydrate) (16.1 mg) in 5 mL DMF to obtain a first solution; dissolve NH2-BDC (2-aminoterephthalic acid) (18.1 mg) in 10 mL DMF (NN-dimethylformamide) to obtain a second solution. Mix the first solution and the second solution to obtain a mixed solution. Add 17 mg of Pr6O 11(praseodymium oxide), ultrasonically mixed for 20 minutes, synthesized at 160°C for 18 hours, and after the reaction, centrifuged at a speed of 8500rad / min for 15 minutes to collect the solid product; the solid product collected by centrifugation was washed with NN-dimethylformamide (DMF) and anhydrous ethanol for 7 times respectively; the washed solid product was placed in a vacuum dryer at 60°C for 16 hours to obtain Pr6O 11 / Zr-MOF (praseodymium oxide / zirconium-based MOF composite nanozyme) (17-Pr6O 11 / Zr-MOF is Pr6O prepared in Example 1 11 / Zr-MOF).

[0025] Dissolve ZrOCl2·8H2O (10~20mg) (zirconium oxychloride octahydrate) in 5mL DMF, and dissolve NH2-BDC (2-aminoterephthalic acid) (10~20mg) in 10mL DMF, mix ultrasonically for 20min, and react at 120~180℃ for 12~24h. After the reaction, centrifuge for 10~20min at a speed of 5000~12000rad / min to collect the solid product; wash the solid product collected by centrifugation with NN-dimethylformamide (DMF) and anhydrous ethanol for 5~8 times respectively; dry the washed solid product in a vacuum dryer for 12~20h to obtain Zr-MOF.

[0026] Condition optimization 1. Zirconia addition amount The preparation method of praseodymium oxide / zirconium-based MOF composite nanozyme in Example 1 was adopted. When other industrial parameters and conditions remained unchanged, different masses (7 mg, 12 mg, 17 mg, 22 mg, 27 mg) of Pr6O 11 (praseodymium oxide), a variety of composite nanozymes were prepared, X-Pr6O 11 / Zr-MOF (X = 1, 12, 17, 22, 27, X represents the amount of praseodymium oxide added), and the oxidase activity of various composite nanozymes was tested (the specific test method is the same as the oxidase activity test below). The results are as follows Figure 1 As shown by Figure 1 It can be seen that as the doping amount of praseodymium oxide increases, Pr6O 11 / Zr-MOF has enhanced oxidase activity, 17-Pr6O 11 / Zr-MOF, the oxidase activity of the material reaches the maximum, so the optimal addition amount of praseodymium oxide is 17 mg. Therefore, the ZrOCl2·8H2O, NH2-BDC and Pr6O 11 The optimized dosage ratio is 1:2:0.3.

[0027] Example 2> Material characterization 1. Scanning electron microscope Praseodymium oxide, Zr-MOF prepared in Example 1 of the present invention and Pr6O 11 SEM images of / Zr-MOF Figure 2 The test results are shown in Figure 2 As shown, Figure 2 a is praseodymium oxide, which is a nanorod-like structure. Figure 2 b is Zr-MOF, which presents a block structure. Figure 2 c is Pr6O prepared by the present invention 11 The morphology of / Zr-MOF is similar to that of Zr-MOF, indicating that Zr-MOF grows uniformly on the surface of praseodymium oxide, which is beneficial to increase its specific surface area and improve the oxidase activity.

[0028] 2. X-ray diffraction P6O 11 And the Zr-MOF and Pr6O prepared in Example 1 of the present invention 11 The XRD pattern of / Zr-MOF is as follows Figure 3 As shown, the Pr6O prepared in Example 1 of the present invention 11 / Zr-MOF XRD spectrum, and Pr6O 11 Compared with the standard PDF card (JCPDS card number 41-1219), all diffraction peaks can be completely overlapped, and there are no extra impurity peaks. The diffraction peaks at 28.979, 33.540, 47.962, 56.849, 59.659, and 69.952 correspond to {111}, {200}, {220}, {311}, {222}, and {400} crystal planes, respectively. The characteristic diffraction peaks of Zr-MOF at 2θ=7.5°, 26.1°, and 43.5° respectively represent {111}, {224}, and {400} of Zr-MOF, which shows that Example 1 of the present invention successfully synthesized Zr-MOF, 17-Pr6O 11 Pr6O appeared in the XRD spectrum of Zr-MOF. 11 The characteristic diffraction peaks of Zr-MOF indicate that Pr6O 11 / Zr-MOF, Pr6O 11 / Zr-MOF still shows obvious Zr-MOF diffraction peaks, indicating that Pr6O 11 The addition of did not change the crystal structure of Zr-MOF.

[0029] 3. Ultraviolet spectrum Take 3mL of sample {Pr6O 11 / Zr-MOF (1 mg / mL), Zr-MOF (1 mg / mL)} aqueous solution was spectrally scanned at 200-800 nm on a UV luminescence photometer, and the spectrum is shown in Figure 4 As shown, Depend on Figure 4 It can be seen that Zr-MOF has a UV peak of 340 nm in aqueous solution, and Pr6O 11 / Zr-MOF has a 327nm ultraviolet peak. 11 The doping of NH2-BDC can shift the ultraviolet peak of Zr-MOF; NH2-BDC, as a photoluminescent organic molecule, gives the obtained MOF fluorescent properties. Therefore, it is speculated that Pr6O prepared with NH2-BDC as a ligand 11 / Zr-MOF may have fluorescent properties.

[0030] 4. Fluorescence spectrum In order to study the prepared Pr6O 11 / Zr-MOF luminescence mechanism, tested Pr6O 11 , Zr-MOF, Pr6O 11 Fluorescence spectra of / Zr-MOF and organic ligand NH2-BDC in acetate buffer solution (pH=4). Figure 5 As shown, Zr-MOF, Pr6O 11 / Zr-MOF emits a blue fluorescence at 450 nm in an acetate buffer solution (pH = 4), which is similar to the fluorescence of the organic ligand NH2-BDC. 11 No luminescence, proving that Zr-MOF, Pr6O 11 The fluorescence properties of / Zr-MOF indeed come from its organic linker NH2-BDC.

[0031] 5. Oxidase activity test In order to detect the Pr6O prepared in Example 1 of the present invention 11 / Zr-MOF activity, 50 μL of TMB (3,3′,5,5′-tetramethylbenzidine) (1 mM) solution was mixed with 50 μL of Pr6O 11 / Zr-MOF (1 mg / mL) solution (Pr6O 11 / Zr-MOF was dispersed in deionized water to prepare Pr6O 11 / Zr-MOF aqueous solution) was mixed in 890 μL acetate buffer (0.1M, pH=4), and after reacting for a certain period of time at room temperature, the absorbance change at 652 nm was detected.

[0032] In order to study the Pr6O 11Does Zr-MOF have catalytic activity similar to that of oxidase? Taking TMB as the single substrate and Pr6O 11 / Zr-MOF was used as the catalyst and a typical oxidase enzymatic experiment was carried out to react TMB with Pr6O 11 / Zr-MOF was mixed in acetate buffer (pH = 4), and the colorless mixed solution turned blue, such as Figure 6 ( Figure 6 AC+TMB in the table indicates a blank control group, which is a mixture of TMB and acetate buffer; Pr6O 11 Indicates TMB and Pr6O 11 in acetate buffer (pH=4); Zr-MOF represents a mixture of TMB and Zr-MOF in acetate buffer (pH=4); Pr6O 11 / Zr-MOF represents TMB and Pr6O 11 / Zr-MOF in acetate buffer (pH = 4) as shown in the mixed solution, the absorbance at 652nm increased, containing Pr6O 11 / Zr-MOF nanozyme solution has the highest absorbance, while the solution containing Pr6O 11 The solution absorbance is very small, and Zr-MOF has no change. This phenomenon shows that after the introduction of Zr-MOF, Pr6O 11 The oxidase-like activity of the / Zr-MOF nanozyme was significantly enhanced. The above results show that the Pr6O 11 / Zr-MOF exhibits oxidase-mimicking activity.

[0033] Optimization and control of catalytic reaction time By recording Pr6O 11 The changes in UV absorbance of Zr-MOF and TMB in acetic acid buffer solution at different reaction times were used to optimize the catalytic reaction time. The results are shown in Figure 7 As shown, when Pr6O 11 When / Zr-MOF and TMB reacted in acetate buffer solution for 20 min, the oxidase reaction reached equilibrium, so the Pr6O prepared in Example 1 of the present invention 11 / The optimal catalytic reaction time of Zr-MOF and TMB is 20 min.

[0034] <Example 3> Research on the application of materials in the detection of organic phosphorus Organophosphorus pesticides (OPs) are pesticides commonly used in modern agricultural production. Due to their simple preparation, low cost and high efficacy, they have been used to effectively control pests and increase crop yields. However, due to the high stability of OPs, their half-life in the hydrolysis and degradation process in water exceeds millions of years. Therefore, the large-scale and uncontrolled use of OPs poses a major threat to the ecological environment and human health. In addition, the residues of OPs in water sources and crops can enter the human body through the food chain. Acetylcholinesterase (AChE) is an important nervous system enzyme. OPs can bind to AChE, rapidly and irreversibly block AChE, and cause nervous system diseases. Therefore, the problem of OP residues in environmental and food samples has attracted great attention.

[0035] Nanozyme sensors have become a research hotspot due to their high stability, high activity, simple preparation, convenient operation and low cost. Due to the unique properties of these nanozymes, especially those with peroxidase-mimicking activity, they have become signal generators and target identifiers for OPs sensor applications. The use of organic ligands gives MOFs attractive optical properties, while unsaturated metal nodes enable MOFs to exhibit excellent biomimetic catalytic activity. MOF-based nanozymes have many remarkable properties and have been widely used for a variety of analytical purposes. According to previous reports, the sensing applications of MOF-based nanozymes mainly include colorimetric sensing, fluorescence sensing, chemiluminescence sensing, electrochemical sensing and SERS sensing. In fluorescence detection, luminescent metal-organic framework (LMOF) materials have the inherent advantages of simple operation, high sensitivity and fast response speed of fluorescence sensing methods. In addition, the pore characteristics of LMOF materials can endow the probe with good performance, screening and concentrating analytes according to the size of the analyte substrate to enhance the sensing ability. Due to the Pr 3+ / Pr 4+ Praseodymium oxide has good oxidase properties. Therefore, a new MOF nanozyme sensor is constructed by composite praseodymium oxide with zirconium-based MOF, which provides a new method for rapid, high-resolution, ultra-sensitive, real-time in-situ and visual detection of toxins and pollutants in food safety, environmental pollution and related basic research.

[0036] The present invention provides an application of the above-mentioned praseodymium oxide / zirconium-based MOF composite nanozyme in the detection of organic phosphorus in food.

[0037] 6. AChE activity test A 10 U / mL AChE solution (50 μL) was reacted with ATCh (50 μL, 10 mM) and incubated at 35°C for 10-20 min before the introduction of Pr6O 11 / Zr-MOF (50 μL, 1 mg / mL) (Pr6O prepared in Example 1 11 / Zr-MOF was mixed with deionized water to prepare a mixed solution with a mass concentration of 1 mg / mL) and incubated for 1 min to completely inhibit the activity of the nanozyme. TMB (50 μL, 1 mM) and acetate buffer (890 μL, 100 mM, pH = 4) were added. After incubation at 35 °C for 20-40 min, the absorption of the system was monitored and the changes in UV absorbance were recorded.

[0038] At the same time, two control groups were set up: 10 U / mL AChE solution (50 μL) and ATCh (50 μL, 10 mM) were mixed with the working solution separately, and then TMB (50 μL, 1 mM) and acetate buffer (890 μL, 100 mM, pH = 4) were added. After incubation at 35°C for 20-40 minutes, the absorption of the system was monitored and the changes in UV absorbance were recorded. The results were recorded as follows: Figure 8 As shown, Pr6O 11 / Zr-MOF has oxidase activity and can oxidize colorless TMB solution into blue TMB. The reaction of AChE and ATCh can produce the reducing substance thiocholine (TCh) to reduce and fade the blue TMB. Figure 8 It can be seen that Pr6O 11 The working solution composed of / Zr-MOF (50μL, 1mg / mL), TMB (50μL, 1mM) and acetate buffer 890μL did not change the absorbance at 652nm when reacting with AChE or ATCh alone. Only when the working solution reacted with AChE and ATCh together, the absorbance at 652nm changed, and the colorless solution turned into a blue solution. This proves that the reaction of AChE and ATCh can inhibit Pr6O 11 / Zr-MOF material oxidase activity. AChE is acetylcholinesterase, and ATCh is acetylthiocholine.

[0039] 7. Organic phosphorus UV detection Dichlorvos (OPs) (50 μL, 2 uM) solution was reacted with AChE (50 μL, 10 U / mL) at 35 °C. After incubation for 10 min, ATCh (50 μL, 10 mM) was introduced and incubated for another 10 min. Subsequently, Pr6O 11 / Zr-MOF (50 μL, 1 mg / mL) (Pr6O prepared in Example 1 11 / Zr-MOF was mixed with deionized water to prepare a mixed solution with a mass concentration of 1 mg / mL), TMB (50 μL, 1 mM) and acetate buffer (890 μL, 100 mM, pH = 4) to form a working solution. After incubation at 35°C for 10 min, the UV absorbance of the system was measured; At the same time, a control group was set up: 10 U / mL AChE solution (50 μL) was reacted with ATCh (50 μL, 10 mM), incubated at 35 °C for 10 min, and Pr6O 11 / Zr-MOF (50 μL, 1 mg / mL) (Pr6O prepared in Example 1 11 / Zr-MOF was mixed with deionized water to prepare a mixed solution with a mass concentration of 1 mg / mL), TMB (50 μL, 1 mM) and acetate buffer (890 μL, 100 mM, pH = 4) to form a working solution. After incubation at 35°C for 10 min, the UV absorbance of the system was measured; the results are shown in Fig. 9 As shown in the figure, when the working solution and AChE reacted with ATCh, TMB was reduced due to the reaction of AChE and ATCh to generate thiocholine (TCh) reducing substances, and the absorbance at 652 nm decreased. The addition of dichlorvos can react with AChE to reduce the generation of thiocholine (TCh), thereby restoring the absorbance at 652 nm, proving that Pr6O 11 / Zr-MOF can perform colorimetric detection of dichlorvos.

[0040] 8. Organic phosphorus fluorescence detection Dichlorvos (DDV) (50 μL, 2 uM) solution was mixed with the Pr6O prepared in Example 1. 11 / Zr-MOF (50 μL, 1 mg / mL) was mixed in 3000 μL acetate buffer solution, and the change of fluorescence intensity at 450 nm was detected under excitation at 340 nm, slit: 3 nm.

[0041] At the same time, set up a control group: Mix in 3000 μL acetate buffer solution (AC) and detect the change of fluorescence intensity at 450 nm under excitation at 340 nm; Dichlorvos (50 μL, 2 uM) solution was mixed with 3000 μL acetate buffer solution, and the change of fluorescence intensity at 450 nm was detected under excitation at 340 nm; Pr6O prepared in Example 1 11 / Zr-MOF (50 μL, 1 mg / mL) was mixed with 3000 μL of acetate buffer solution, and the change of fluorescence intensity at 450 nm was detected under excitation at 340 nm; Test results such as Fig.10 As shown ( Fig.10 The black line overlaps with the red line, and the black line is covered by the red line). Fig.10 It can be seen that pure acetate buffer solution ( Fig.10 AC) and dichlorvos in acetate buffer solution ( Fig.10+DDV in the sample) has no fluorescence change at 450 nm under 340 nm excitation. 11 / Zr-MOF in acetate buffer solution ( Fig.10 +Pr6O 11 / Zr-MOF) emits blue fluorescence at 450 nm. When dichlorvos is added to the Pr6O 11 / Zr-MOF acetate buffer solution ( Fig.10 +Pr6O 11 / Zr-MOF+DDV), the blue fluorescence at 450 nm was significantly enhanced, proving that dichlorvos and the Pr6O 11 / Zr-MOF can enhance the blue fluorescence at 450 nm, thus indicating that the Pr6O prepared in Example 1 of the present invention 11 / Zr-MOF can construct a fluorescent signal for detecting dichlorvos.

[0042] In summary, Pr6O 11 / Zr-MOF can react with AChE and ATCh through oxidase activity, and its own fluorescence can be used to construct a colorimetric and fluorescence dual-mode detection platform for detecting dichlorvos.

[0043] The Pr6O prepared by the present invention 11 / Zr-MOF composite MOF material is cheap and easy to obtain, and the preparation process is simple and easy to operate, which greatly reduces the production cost. At the same time, it also realizes the colorimetric and fluorescent dual-mode detection of organophosphorus pesticides, providing a new method for real-time in situ and visual detection of toxins and pollutants in food safety and environmental pollution and related basic research, and providing a scientific basis for the in-depth development and utilization of MOF and other nanoenzyme materials.

[0044] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0045] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing a praseodymium oxide / zirconium-based MOF composite nanozyme, characterized in that: include: Dissolve ZrOCl2·8H2O and NH2-BDC in the first solvent respectively and mix them to obtain a mixed solution, then add Pr6O 11 After being evenly mixed, the synthesis reaction is carried out under heating. After the reaction is completed, centrifugation, washing and drying are carried out in sequence to obtain praseodymium oxide / zirconium-based MOF composite nanozyme.

2. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 1, characterized in that: ZrOCl2·8H2O, NH2-BDC and Pr6O 11 The dosage ratio is 1:2:0.

3.

3. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 2, characterized in that: The centrifugal speed is 5000 ~12000rad / min, and the centrifugal time is 10~20min.

4. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 3, characterized in that: The conditions for the synthesis reaction are a temperature of 120-180°C and a reaction time of 12-24 hours.

5. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 4, characterized in that: The washing method is to wash the solid product collected by centrifugation with the first solvent and anhydrous ethanol respectively for 5 to 8 times.

6. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 5, characterized in that: The first solvent is NN-dimethylformamide.

7. The method for preparing the praseodymium oxide / zirconium-based MOF composite nanozyme according to claim 6, characterized in that: The drying method is to place the washed solid product in a vacuum dryer and dry it for 12 to 20 hours.

8. Praseodymium oxide / zirconium-based MOF composite nanozyme, characterized in that: The nanozyme is prepared by the method for preparing the praseodymium zirconium oxide-based MOF composite nanozyme according to any one of claims 1 to 7.

9. Use of the praseodymium oxide / zirconium-based MOF composite nanozyme as claimed in claim 8 in food detection.

10. Use of the praseodymium oxide / zirconium-based MOF composite nanozyme as claimed in claim 8 in the detection of organic phosphorus in food.

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