An integrated method for rapid separation and detection of fungal toxins based on nylon-fluorescent metal-organic framework films

Abstract

The present invention discloses a method for rapid separation and detection of mycotoxins based on nylon-fluorescent metal-organic framework film. The nanofilm is cleaned and dried, and microwave-treated to obtain a nanofilm modified with PDA, which is dissolved in a mixed solution composed of metal ions A, organic ligands B and regulator C, and then placed in a microwave oven for high-temperature heating synthesis, and cleaned and dried to obtain a nanocomposite film loaded with fluorescent metal-organic framework materials, and the mycotoxin solution to be tested is filtered, and the change in fluorescence intensity of the nanocomposite film before and after filtration is measured to determine the corresponding concentration. The present invention solves the problem of poor controllability, realizes the preparation of a stable nylon fiber-metal-organic framework composite film, and the nanocomposite film can directly adsorb and detect mycotoxins in a filtered state, and realizes good practical applications in feed, integrates filtration and detection, and simplifies the problem of complex pre-treatment operations.

Description

Technical Field

[0001] The invention relates to a strain separation and detection method, and in particular to a method for rapid separation and detection based on nylon-fluorescent metal organic framework film integration. Background Art

[0002] In recent years, the degree of mycotoxin in food or feed has become increasingly serious under the influence of the greenhouse effect. Mycotoxins can directly cause livestock and poultry poisoning, resulting in decreased immune function and production performance, and even serious death. Mycotoxins are stable and difficult to degrade, and can cause serious harm to human health through the food chain such as meat, eggs, and milk. Therefore, it is urgent to establish a rapid detection method for mycotoxins.

[0003] Traditional large-scale instrumental analysis technologies, including high-performance liquid chromatography (HPLC) and mass spectrometry (MS), are expensive, have high operating requirements, and are difficult to achieve rapid on-site detection. On the other hand, although rapid detection methods such as chemical colorimetry and immunoassay are fast and convenient, they still require tedious pre-treatment (separation, purification, concentration, etc.). The pre-treatment process and detection links are generally relatively independent, which also increases the complexity of on-site detection. Therefore, it is particularly important to develop an integrated on-site detection technology that integrates simple pre-treatment and rapid detection response.

[0004] As an ideal integrated substrate, commercial fiber membranes have the advantages of low cost, mechanical flexibility and easy operation, and show excellent potential in pretreatment. However, they only have separation and interception functions, lack recognition and response functions, and are difficult to be directly applied in the field of integrated rapid detection. Introducing metal organic frameworks into fiber substrates to prepare hybrid fiber membranes can overcome the single function of traditional membranes and show synergistic properties.

[0005] Currently, there are still difficulties in preparing integrated fiber-metal organic framework hybrid detection membranes due to the growth efficiency of the metal organic framework.

[0006] Controllable preparation of hybrid membranes by microwave irradiation instead of traditional hydrothermal synthesis has been considered an important method to improve the quality and yield of hybrid membranes. Compared with conventional hydrothermal synthesis, microwave-assisted synthesis can penetrate deep into the material instead of relying solely on heat conduction on the surface of the material, thereby directly heating the synthetic precursors and providing a more efficient reaction rate. However, the significantly accelerated growth rate in the solution is not conducive to the growth of the metal-organic framework on the substrate surface, resulting in poor preparation efficiency. Summary of the invention

[0007] In order to solve the problems in the background, the present invention proposes a method based on nylon-fluorescent metal organic framework film and its application in the rapid separation, adsorption and detection of fungal toxins. The method of the present invention uses microwave acceleration and biomineralization to grow metal organic frameworks to prepare composite films after biomolecules are modified on the surface of commercial nylon fiber membranes, which are directly used for the rapid separation, adsorption and detection of fungal toxins.

[0008] The present invention accelerates the preparation of metal organic framework materials on the surface of nylon substrates, solves the problem of poor controllability, and realizes the preparation of stable nylon fiber-metal organic framework composite films. The composite film can directly adsorb and detect fungal toxins in a filtered state, and has achieved good practical applications in feed, integrating simple filtration and rapid detection, simplifying the complex problems of pre-treatment operations, and providing a powerful reference for actual on-site detection.

[0009] The technical solution adopted by the present invention is as follows:

[0010] 1) Cleaning and drying the nanofilm;

[0011] 2) treating the nanofilm with microwaves to obtain a nanofilm modified with polydopamine PDA;

[0012] 3) dissolving the PDA-modified nanofilm in a mixed solution consisting of metal ions A, organic ligands B and regulator C, and then placing it in a microwave oven to rapidly synthesize and react for a period of time by high-temperature heating under microwaves of a certain power, and washing and drying after the reaction to obtain a nanocomposite film loaded with fluorescent metal organic framework materials;

[0013] 4) Using a micro-syringe pump to filter a certain amount of the nanocomposite film loaded with fluorescent metal organic framework material at a certain flow rate to treat the mycotoxin solution to be tested, and measuring the change in fluorescence intensity of the nanocomposite film before and after filtration;

[0014] 5) The corresponding mycotoxin concentration is obtained based on the change in fluorescence intensity of the nanocomposite film before and after filtration combined with the pre-calibrated curve relationship between the fluorescence intensity change and the mycotoxin concentration.

[0015] The curve relationship is obtained by setting different mycotoxin concentrations in advance for multiple times to conduct the same experiment to obtain corresponding fluorescence intensity changes, and establishing a curve relationship between the fluorescence intensity changes and the corresponding mycotoxin concentrations by fitting.

[0016] The fluorescence intensity of the nanocomposite film was measured by using an F-7000 fluorescence spectrophotometer to perform fluorescence measurement.

[0017] The nano-film is a fiber membrane, and the types include but are not limited to nylon membrane, polytetrafluoroethylene membrane, polyethersulfone membrane, glass fiber membrane and the like.

[0018] In the step 1), ultrasonic cleaning is performed three times using deionized water, ethanol and deionized water respectively, and the drying time is not less than 30 minutes.

[0019] The step 2) is specifically as follows: heating the dried nanofilm in deionized water, immersing it in a polydopamine (PDA) solution of a certain concentration at room temperature for soaking modification, and heating it in a microwave oven at a certain power for a period of time to accelerate the reaction, thereby obtaining a nanofilm uniformly modified with PDA.

[0020] In step 2), the concentration of polydopamine is specifically 1-10 g L -1 range to fully modify the nanofilm and make the nanofilm completely immersed in the solution; at the same time, the microwave power is set to the range of 80W-320W, which can not only accelerate the polymerization reaction, but also promote the modification to evenly cover the surface of the nanofilm to form a uniform intermediate modification layer.

[0021] Types of microwave ovens include, but are not limited to, household microwave ovens, microwave reactors, and the like.

[0022] In the step 3), the metal ion A is specifically zirconium chloride, the ligand B is specifically 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, the regulator C is specifically benzoic acid, and the mass ratio of the metal ion A, the ligand B and the regulator C is in the range of 1:1:40-1:2:80, so that fluorescent metal organic framework powders and composite films with suitable particle size and thickness can be synthesized.

[0023] In the step 3), the mixed solution is completely immersed in the modified PDA nanofilm during microwave high temperature heating, and the microwave power is set in the range of 80W-400W to avoid damage to the nanofilm.

[0024] In the step 3), after the synthesis is completed, ultrasonic cleaning is performed using methanol and deionized water in sequence to thoroughly clean the excess adhesion on the surface, and the surface is placed in an oven for drying to remove the excess solution.

[0025] In the step 4), a filter is set to seal the nano-membrane so that the mycotoxin solution to be tested is completely filtered through the nano-membrane in the filter.

[0026] The rapid separation of the nano film and the adsorption detection of the fluorescent metal organic framework material of the present invention are both realized by focusing on the nano composite film, and the operation is simple and efficient.

[0027] The present invention heats and dries the washed nylon membrane and then accelerates the modification using a polydopamine-microwave method, then cross-links the polydopamine biomolecules to obtain a polydopamine-modified nylon fiber membrane, which is then dissolved in a solution containing metal ions, organic ligands and regulators for rapid hydrothermal synthesis in a microwave. After the reaction is completed, the polydopamine-promoted metal-organic framework composite nylon membrane is obtained by washing and drying, and is used for the integrated application of rapid enrichment / adsorption / detection of fungal toxins under filtration conditions.

[0028] The fluorescent metal organic framework nylon composite film of the present invention is used for the rapid separation, adsorption and detection of fungal toxins. An example of a separation and detection method of a nylon-fluorescent metal organic framework composite film includes the following specific steps:

[0029] 1) Clean the Nylon membrane, heat it and dry it;

[0030] 2) soaking the Nylon membrane dried in step 1) in PDA, and accelerating the modification of PDA using microwaves after soaking;

[0031] 3) The modified Nylon membrane obtained in step 2) is dissolved in a mixed solution of metal ion A, organic ligand B and regulator C. The metal ion A solution, organic ligand B and regulator C solution are reacted on the PDA-modified Nylon membrane by microwave to generate Zr-MOFs. After the reaction is completed, Nylon@PDA@Zr-MOFs are obtained by washing and drying.

[0032] 4) The Nylon@PDA@Zr-MOFs membrane obtained in step 3) is sealed in a membrane device, and different concentrations of AFB1 are filtered using a micro-syringe pump. After the filtration is completed, the change in fluorescence intensity before and after the reaction is measured, and the corresponding fungal toxin concentration is obtained based on the change in fluorescence intensity of the nanocomposite film before and after filtration.

[0033] In the step 1), the heating time of the Nylon film is 15 minutes.

[0034] In the step 2), PDA was treated with Tris-HCl buffer (3 g L -1 ) dissolved, the concentration after dissolution is 2g L -1 .

[0035] In the step 2), the PDA immersion time is 10 min; and the microwave accelerated reaction time is 10 min.

[0036] In step 3), the concentration of metal ion A in the metal ion A solution is 6.18 mg mL -1 The concentration of ligand B in the ligand B solution is 8.64 mg mL -1 , the concentration of regulator C in the regulator C solution is 333.3 mg mL -1 .

[0037] In the step 3), the microwave reaction time is 10 min; the drying temperature is 60° C., and the drying time is not less than 30 min.

[0038] In step 4), the mass of the Nylon@PDA@Zr-MOF membrane is 5 mg; the concentration range of AFB1 is 1 ng mL -1 -50 μg mL -1 .

[0039] In the step 4), the filtration time is 10 min.

[0040] In the specific implementation of the present invention, the dried nylon-fluorescent metal organic framework film is filtered to separate the adsorbed fungal toxins, and the nylon-fluorescent metal organic framework film adsorbed with fungal toxins is taken out, cleaned, and measured to obtain the performance results of the film. Specifically, the morphology, structure and fluorescence properties of the film are systematically characterized by electron microscopy, thermogravimetric analysis, X-ray diffraction, Fourier infrared spectroscopy and fluorescence spectrophotometer.

[0041] The present invention uses chemical modification-microwave acceleration to achieve PDA modification on the surface of commercial nylon membranes. By adjusting the concentration of the reactant solution and the microwave intensity, the zirconium-based metal organic framework Zr-MOFs with a particle size of 500nm is grown on the surface of the commercial nylon membrane by microwave acceleration-bionic controllable growth. By accelerating the synthesis efficiency through microwaves, artificially giving functional sites to the substrate surface, and exerting controllability while rapidly preparing, a new type of fluorescent composite membrane for rapid separation and detection of fungal toxins in filtering mode is prepared.

[0042] The nylon-fluorescent metal organic framework film prepared by the method of the present invention has the following advantages:

[0043] 1. The present invention adopts a bulk heating method of microwave heating. The high power makes the synthesis of the metal organic framework more efficient and saves preparation time. In addition, this method can be heated by a household microwave oven, which reduces the cost of the instrument and is convenient and fast.

[0044] 2. PDA modification provides a large number of functional sites for the growth of nanomaterials on the surface of commercial Nylon membranes, improving controllability. The in-situ grown nylon-fluorescent metal organic framework film Nylon@PDA@Zr-MO F membrane solves the technical problem of poor controllability of nanomaterial loading under high microwave power.

[0045] 3. The fluorescent metal-organic framework is used, and the detection effect can be determined by naked eyes and instruments, and the fluorescence change of the composite film can be directly used for quantification, avoiding the indirect quantification method of the concentration change before and after the adsorption of the target solution. It has the advantages of being simple, efficient and can be detected on site.

[0046] 4. By integrating the strong stability of commercial Nylon membrane and the excellent adsorption and signal response performance of fluorescent Zr-MOFs, the prepared Nylon@PDA@Zr-MOF membrane can realize the rapid separation and detection of fungal toxins in water samples and feed solutions.

[0047] In summary, the present invention solves the problems of single function of traditional films and poor controllability of film-forming metal-organic framework materials, and realizes the preparation of efficient nylon fiber-metal-organic framework composite films with high loading rate and high fluorescence signal. The composite films can filter and adsorb fungal toxins in water samples and feed solutions, and quantitatively detect fungal toxins by using changes in fluorescence intensity on the membrane surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the present invention;

[0049] Figure 2 It is a characterization diagram of nylon membrane modified with PDA and growth of fluorescent metal organic framework (Zr-MOFs); Figure 2 AD are the scanning electron microscopy images of Nylon, Nylon@PDA, Nylon@PDA@Zr-MOF and Nylon@Zr-MO F, respectively; Figure 2 E is the energy spectrum of Nylon@PDA@Zr-MOF, Figure 2 F is the physical and fluorescence images of Nylon, Nylon@PDA, Nylon@PDA@Zr-MOF and Nylon@Zr-MOF; Figure 2 G is the X-ray diffraction pattern of Zr-MOFs, Nylon, Nylon@PDA, and Nylon@PDA@Zr-MOF; Figure 2 H is the infrared characterization diagram of Zr-MOFs, Nylon, Nylon@PDA, and Nylon@PDA@Zr-MOF.

[0050] Figure 3 It is a graph showing the fluorescence detection performance of Zr-MOFs to AFB1 in the present invention; Figure 3 A is the power of light absorption; Figure 3 B is the fluorescence intensity-time relationship graph; Figure 3 CD are the fluorescence spectrum and standard curve model of AFB1 detection.

[0051] Figure 4 It is the fluorescence detection performance of Nylon@PDA@Zr-MOF membrane for AFB1 in the present invention; Figure 4 A is the standard curve model for detecting AFB1; Figure 4 B is the tolerance of this method to acid and alkaline environment; Figure 4C is the circulating filtration volume of AFB1 by this method; Figure 4 D is an assessment of the specificity of the method.

[0052] Table 1 shows the actual recovery rate of Nylon@PDA@Zr-MOFs membrane for integrated filtration detection of AFB1 in feed. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the method provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0054] The embodiments of the present invention are as follows:

[0055] (1) Preparation of Nylon@PDA@Zr-MOF membrane by microwave method

[0056] Step 1: After ultrasonic cleaning of a 1.3 cm diameter Nylon membrane with deionized water, ethanol and deionized water mixed solution for 5 min, the membrane was placed in an oven and dried at 60°C for 2 h. Then, the Nylon membrane was placed in deionized water and heated at 100°C for 15 min, taken out and placed in an oven and dried at 60°C for 2 h. -1 The PDA solution was modified in a reactor at room temperature for 10 minutes, and then placed in a microwave oven and heated at a power of 160 W (firepower 20%) for 10 minutes. After the reaction was completed, it was washed with deionized water. After washing, the Nylon membrane was dried at 60°C for 2 hours to obtain the PDA-modified nylon membrane Nylon@PDA.

[0057] Step 2: The Nylon@PDA membrane was loaded into a specific support device and vertically immersed in a reactor containing a Zr-MOFs synthesis precursor solution, wherein the concentration of the metal ion zirconium chloride (ZrCl4) aqueous solution in the mixed solution was 6.18 mg mL -1 , N,N-dimethylformamide (DMF) dissolved organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4TCPB) solution concentration is 8.64mgmL -1 The concentration of DMF dissolving regulator benzoic acid is 333.3 mg mL -1 Then, the reactor was placed in a microwave oven and heated at 160 W (firepower 20%) for 10 min. After the reaction was completed, it was washed with methanol and deionized water, and dried in an oven at 60°C to obtain a Nylon@PDA@Zr-MOF membrane, which was then collected for later use.

[0058] (2) Characterization of Nylon, Nylon@PDA and Nylon@PDA@Zr-MOF membranes

[0059] like Figure 2 As shown, the Nylon membrane was modified with PDA by microwave-assisted acceleration as described in the examples. The fibers of the Nylon@PDA membrane still maintained their original curved morphology ( Figure 2 B), and further synthesized Nylon@PDA@Zr-MOF membrane by microwave heating in the growing Zr-MOFs precursor solution. Although the fibers on the membrane polymerized after a violent reaction, a large range of uniform granular Zr-MOFs (500nm) growth coverage can be seen on the polymerized fibers ( Figure 2 C), this is because PDA is rich in amino and other binding sites. However, when pure Nylon membrane and precursor solution are directly heated by microwaves, only a small amount of Zr-MOFs can be found in the gaps between Nylon membrane fibers, and they will not grow along the fiber surface ( Figure 2 D). This is because there are fewer functional sites on the surface of the Nylon membrane, and the controllable growth of Zr-MOFs on the fiber surface is limited.

[0060] Other characterization methods, such as energy dispersive spectroscopy (EDS), physical photography, powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FT-IR), were performed to comprehensively analyze the various film species obtained.

[0061] From the EDS image, it can be seen that the characteristic zirconium Zr element of the synthesized Nylon@PDA@Zr-MOF membrane is uniformly distributed on the surface of the Nylon membrane, further indicating the controllable growth of the microwave-accelerated and biomineralized Nylon@PDA@Zr-MOF membrane ( Figure 2 E).

[0062] Figure 2 F is the physical and fluorescent image of the Nylon membrane after modification and growth of Zr-MOFs. The surface of the original Nylon membrane is white with weak fluorescence. After modification with PDA, the surface of the Nylon@PDA membrane is evenly covered with brown PDA, and the fluorescence is completely blocked. Zr-MO Fs are further grown on the surface of the Nylon@PDA membrane, and the brown membrane surface is covered with a layer of white Zr-MOFs and turns gray. Under the excitation of ultraviolet light of appropriate wavelength, the Nylon@PDA@Zr-MOF membrane shows bright blue fluorescence. The last picture is the structure of the directly grown Nylon@Zr-MOF membrane. Because the surface is also covered with Zr-MOFs, the membrane surface will also turn gray and be accompanied by blue fluorescence.

[0063] Figure 2G is the PXRD result. The characteristic peak (7°) of Nylon film indicates its amorphous structure. Nylon@PDA@Zr-MOF film and Zr-MOFs have obvious corresponding crystal diffraction peak positions, indicating that Zr-MOFs and Nylon@PDA@Zr-MOF film were successfully prepared. FT-IR spectrum qualitatively explains the modification and growth process ( Figure 2 H), compared with Nylon and Nylon@PDA membranes, Nylon@PDA@Zr-MOF membrane has a -1 The characteristic peaks of Zr-O groups of Zr-MOFs appeared at the sites, which proved the successful preparation of Nylon@PDA@Zr-MOF membrane.

[0064] (3) Detection of fungal toxins by Zr-MOFs

[0065] First, by monitoring the rapid fluorescence response of Zr-MOFs to fungal toxins in the aqueous phase, it was determined that the fluorescence quantitative detection of Nylon@PDA@Zr-MOF membranes is feasible, laying the foundation for the subsequent development of fluorescent sensors suitable for integrated detection. As a common highly toxic fungal toxin, aflatoxin (AFB1) was selected as the detection model. AFB1 aqueous solution was identified and enriched by using Zr-MOFs powder.

[0066] The Zr-MOFs powder film was placed in an aqueous solution containing aflatoxin, and a quantitative fluorescence detection of aflatoxin in the solution was performed. The absorbance and fluorescence intensity of AFB1 were read using an ELISA reader. The adsorption capacity of Zr-MOFs for AFB1 was calculated based on the absorbance of the AFB1 solution before and after adsorption, and the fluorescence detection capacity of Zr-MOFs for AFB1 was calculated based on the change in fluorescence intensity before and after the adsorption of AFB1 by Zr-MOFs, and the results were calibrated using the relevant calibration curve.

[0067] Adsorption time and adsorption amount are key factors in evaluating the adsorption effect and are the basis for AFB1 adsorption detection. At the same time, the rapid adsorption and fluorescence response of Zr-MOFs to AFB1 directly affect the rapid and simple effect of Nylon@PDA@Zr-MO Fs membrane. Figure 3 As shown in A, Zr-MOFs (100 μg mL -1 ) can adsorb 65% of AFB1 (50 μg mL -1 ), and can be maintained for at least 4h.

[0068] The fluorescence response time directly affects the rapid detection applicability of Zr-MOFs. Since the LUMO energy state of Zr-MOFs is higher than that of AFB1, there is an effective electron transfer between Zr-MOFs and AFB1, which leads to a decrease in the fluorescence intensity of Zr-MOFs, which is used as the basis for detection (such as Figure 3 A illustration). Based on the rapid adsorption and spatial confinement of the skeleton structure, the fluorescence quenching rate (F0-F) / F0 of Zr-MOFs to AFB1 reached 82.3% in just 5 minutes ( Figure 3 B) and can be stable for at least 40 minutes, making it an ideal choice for rapid on-site quantitative testing.

[0069] By comparing the changes in fluorescence intensity before and after the reaction of Zr-MOFs with AFB1 solution, the fluorescence quantitative detection of AFB1 by Zr-MOFs was achieved. Figure 3 As shown in Figure C, under the excitation of 310 nm ultraviolet light, the fluorescence intensity of Zr-MOFs at 400 nm gradually decreased with the increase of AFB1 concentration. Figure 3 As shown in D, a relationship curve is established with the logarithmic value of AFB1 concentration as the horizontal axis and (F0-F) / F0 at 400nm as the vertical axis. It can be obtained that the linear range of Zr-MOFs for AFB1 detection is 16ng mL -1 -10 μg mL -1 , the linear regression equation is: y = 0.354logx-0.364 (R 2 =0.939), the detection method has a wide linear detection range and has great advantages in practical applications with various detection requirements. It is worth noting that the detection limit of Zr-MOFs for AFB1 is as low as 14.5 ng mL -1 (S / N=3:1), which is lower than the national standard for corn products (20ng mL -1 ). For this analytical sensor, AFB1 is quickly confined to Zr-MOFs, resulting in strong interactions and higher-order π-π interactions, accelerating electron transport, and making the fluorescence quenching effect more obvious. Based on this property, it is feasible to develop Zr-MOFs-based Nylon@PDA@Zr-MOF membranes for rapid filtration / adsorption / detection of AFB1.

[0070] (4) Integrated detection of fungal toxins using Nylon@PDA@Zr-MOF membrane

[0071] The Nylon@PDA@Zr-MOF membrane was sealed in a matching filtration mold, and 1 mL of AFB1 was dynamically filtered at a certain flow rate under the push of a micro-syringe pump. After the Nylon@PDA@Zr-MOF membrane adsorbed AFB1, obvious fluorescence quenching was observed on the membrane. By comparing the changes in fluorescence intensity of the Nylon@PDA@Zr-MOF membrane before and after filtration, the adsorption-detection integration effect of the Nylon@PDA@Zr-MOF membrane was verified. Similarly, a relationship curve was established with the logarithmic value of the AFB1 concentration as the horizontal axis and (F0-F) / F0 at 400 nm as the vertical axis. It can be obtained that the linear range of the Nylon@PDA@Zr-MOF membrane for AFB1 detection is 1 ng mL -1 -500ng mL -1 , the linear regression equation is y = 0.237logx + 0.098 (R 2 =0.986), and the detection limit was 1.7 ng mL -1 (S / N=3)(e.g. Figure 4 A). Compared with Zr-MOFs, the detection limit of Nylon@PDA@Zr-MOF membrane is improved by 8.5 times. This is because more Zr-MOFs can be integrated in the Nylon membrane due to the biomineralization of PDA, which has a greater contact possibility with AFB1 by dynamic filtration, thus reducing the detection limit.

[0072] Applied to naked eye detection, due to the efficient loading of Zr-MOFs, the Nylon@PDA@Zr-MOF membrane presents a uniform white color under sunlight, and exhibits a uniform blue-purple fluorescence under the excitation of 310nm ultraviolet lamp. After filtering and adsorbing different concentrations of AFB1, the blue-purple fluorescence intensity of the Nylon@PDA@Zr-MOF membrane decreases, showing a transition to yellow-green fluorescence. This is because AFB1 can cause the fluorescence intensity of Zr-MOFs on the membrane to decrease, and the adsorbed AFB1 has blue-green fluorescence. The Nylon@PDA@Zr-MOF membrane can qualitatively distinguish high concentrations of AFB1 by the naked eye, and quantitatively detect low concentrations of AFB1 using a fluorescence photometer based on the fluorescence quenching mechanism, providing a new idea for creating an integrated rapid detection sensor based on filter membranes and porous nanoparticles.

[0073] (5) Acid-base environment tolerance

[0074] The effect of Nylon@PDA@Zr-MOF membrane on the integrated detection of AFB1 in acidic and alkaline environments was further evaluated. The pH value of AFB1 aqueous solution can affect the sensitivity of the composite membrane sensor by changing the binding efficiency of Zr-MOFs and AFB1. Figure 4B shows that pH has little effect on the fluorescence quenching effect of Nylon@PDA@Zr-MOF on AFB1. The fluorescence quenching efficiency is 47%-56% in a wide pH range. Due to the high adsorption of AFB1 on Zr-MOFs, the effect of pH is negligible. These results indicate that Nylon@PDA@Zr-MOF membrane provides a robust bifunctional hybrid membrane for the integrated method of rapid filtration / adsorption / detection of AFB1.

[0075] (6) Filtration volume

[0076] This was followed by a study on the reusability of Nylon@PDA@Zr-MOF membrane filtration for detecting AFB1. Figure 4 C shows the adsorption of AFB1 (100 ng mL -1 ) quenching efficiency. After three filtration cycles, the fluorescence quenching efficiency of AFB1 showed a slight upward trend with the increase in the number of cycles (accumulated calculation). After three cycles, the quenching effect of AFB1 increased from 37% to 39% and 40%, respectively. That is, repeatedly increasing the filtration cycle can improve the fluorescence quenching efficiency of AFB1 on Nylon@PDA@Zr-MOF membrane, but the degree of this improvement is very small. It may be due to the small diameter of this economical and convenient hybrid membrane and the relatively limited content of Zr-MOFs on the membrane, so the adsorption of AFB1 reached the platform limit.

[0077] (7) Specificity

[0078] By detecting five common aflatoxin structural analogs, namely AFB1, aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2) and aflatoxin M1 (AFM1) (100ng mL -1 ), and another common mycotoxin deoxynivalenol (DON) (100 ng mL -1 ).like Figure 4 As shown in Figure D, the developed Nylon@PDA@Zr-MOF membrane sensor showed a certain degree of cross-reaction with AFB2, but the cross-reaction with the other four mycotoxins was negligible. In summary, in the presence of other common mycotoxins in agriculture and food, the Nylon@PDA@Zr-MOF membrane has good selectivity for the detection of mycotoxins.

[0079] (8) Practical application ability

[0080] The practical application capability of the proposed Nylon@PDA@Zr-MOF membrane was evaluated by analyzing the feed matrix solutions containing different concentrations of AFB1.

[0081] Table 1

[0082]

[0083] Table 1 shows that the average recoveries of the various determination methods were 70.6%-101.0% and the coefficients of variation were 0.5%-5.3%. These results indicate that the proposed integrated hybrid membrane sensor has good potential for trace pollutant analysis in complex matrix samples, providing a convenient membrane sensor that simplifies complex pretreatment operations and integrates fluorescence detection.

[0084] It can be seen from the above implementation cases that the Nylon@PDA@Zr-MOF membrane grown by microwave and biomineralization in the present invention is easy to prepare and can achieve controllable growth; at the same time, due to the growth of Zr-MOFs on the membrane, the composite membrane has good fluorescence and adsorption capabilities and can be used for integrated enrichment / identification / detection of fungal toxins under filtration.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the method of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for rapid separation and detection of mycotoxins based on nylon-fluorescent metal organic framework film, characterized in that: The method comprises the following steps: 1) Cleaning and drying the nanofilm; 2) treating the nanofilm with microwaves to obtain a nanofilm modified with polydopamine PDA; 3) dissolving the PDA-modified nanofilm in a mixed solution of zirconium chloride, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and benzoic acid, and then placing the nanofilm in a microwave oven to perform a synthesis reaction by high-temperature heating under microwaves, and washing and drying after the reaction to obtain a nanocomposite film loaded with fluorescent metal organic framework materials; 4) Using a micro-syringe pump to filter the mycotoxin solution to be tested through the nanocomposite film loaded with fluorescent metal organic framework materials, and measuring the change in fluorescence intensity of the nanocomposite film before and after filtration; 5) Obtaining the corresponding mycotoxin concentration according to the change in fluorescence intensity of the nanocomposite film before and after filtration; The film is a nylon film; The step 2) is specifically as follows: placing the dried nanofilm in deionized water for heating, immersing it in a polydopamine (PDA) solution for soaking modification at room temperature, and placing it in a microwave oven for medium to high temperature heating to obtain a nanofilm uniformly modified with PDA; In step 2), the concentration of polydopamine is specifically 1-10 g L -1 range, and the nanofilm is completely immersed in the solution; at the same time, the microwave power is set in the range of 80W-320W; In the step 3), the mass ratio of zirconium chloride, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and benzoic acid is in the range of 1:1:40-1:2:80; In the step 3), the mixed solution is completely immersed in the modified PDA nanofilm during microwave high temperature heating, and the power of the microwave is set in the range of 80W-400W.

2. The method for rapid separation and detection of mycotoxins based on nylon-fluorescent metal organic framework film according to claim 1, characterized in that: In the step 1), ultrasonic cleaning is performed three times using deionized water, ethanol and deionized water respectively, and the drying time is not less than 30 minutes.

3. The method for rapid separation and detection of mycotoxins based on nylon-fluorescent metal organic framework film according to claim 1, characterized in that: In the step 4), a filter is set to seal the nano-membrane so that the mycotoxin solution to be tested is completely filtered through the nano-membrane in the filter.

Images