White peroxidase simulant manganese-based metal organic framework as well as preparation method and application thereof

Abstract

The invention discloses a white peroxidase simulant manganese-based metal organic framework (Mn-MOF) as well as a preparation method and application thereof, and belongs to the technical field of nano materials and detection. The Mn-MOF is prepared by reacting manganese acetate tetrahydrate with 1, 3, 5-benzene tricarboxylic acid in an ethanol-water mixed system, is of a white three-dimensional microsphere structure, and has excellent simulated peroxidase activity. The perfluorooctane sulfonate can catalyze H2O2-mediated TMB chromogenic reaction, and perfluorooctane sulfonate (PFOS) can inhibit the catalytic activity of the perfluorooctane sulfonate (PFOS) through multiple interactions, so that the blue color of the solution becomes light. The change of absorbance is detected by using an ultraviolet spectrophotometer, or a color developing image is converted into an RGB value through a smart phone and an R / B ratio is calculated, so that high-selectivity, visual and rapid detection of the PFOS can be realized. The method does not need complex pretreatment, is simple and convenient to operate and low in cost, has the detection limit as low as 53.3 nM, and is suitable for quantitative analysis of PFOS in a field environment water sample.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterials and detection technology, and particularly relates to a white peroxidase mimic manganese-based metal organic framework Mn-MOF, a preparation method and application thereof. BACKGROUND

[0002] Perfluorooctanesulfonic acid (PFOS) is a synthetic fluorosurfactant that is well known for its ultra-stable carbon-fluorine bonds and unique amphiphilic properties. It is widely used in industrial and consumer applications, from fire-fighting foams to stain-resistant textiles and agrochemical formulations. Due to its resistance to thermal decomposition, chemical oxidation, and enzymatic degradation, this compound has a strong persistence in the environment, allowing it to be bioaccumulated through the food chain and enriched in human tissues for long periods. Emerging toxicological evidence suggests that long-term exposure to PFOS can pose multi-system health risks, including neurodevelopmental abnormalities, hepatotoxicity, endocrine disruption, and reproductive disorders.

[0003] Although liquid or gas chromatography-mass spectrometry (LC-MS and GC-MS) remains the standard method for PFOS quantification, these traditional chromatographic techniques face key operational challenges such as reliance on complex equipment, time-consuming extraction processes, and limited field applications. These limitations require innovative sensors to strike a balance between precision and practicality for on-site deployment of water analysis, where recent progress highlights the emerging feasibility of colorimetric strategies. This approach is increasingly popular due to its significant advantages, including simplicity, cost-effectiveness, speed, and visual readability, making it particularly suitable for field applications. These inherent advantages highlight the importance of establishing reliable colorimetric protocols to accurately quantify PFOS.

[0004] Anzyme is a kind of non-protein molecule synthesized by organic or inorganic chemical methods, which has similar catalytic activity to natural enzymes. Compared with natural enzymes, anzymes have higher thermal stability, chemical stability, lower preparation cost and adjustable catalytic performance. The colorimetric analysis method based on peroxide anzyme has important application value in the field of analysis and detection due to its visual detection results, simple operation and low cost. The peroxidase-like activity of this kind of anzyme can catalyze the hydrogen peroxide-mediated color reaction, especially the oxidation of colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB, which provides a basic detection mechanism for environmental pollutant detection. The anzyme materials reported so far usually have intrinsic colors, such as black (Fe3O4 and Co3O4, see 1. Fe3O4 magnetic nanoparticles as peroxidase mimetics and their applications in H2O2 and glucose detection[J]. Analytical chemistry, 2008; 2. Co3O4 nanoparticles with multi-enzyme activities and their application in immunohistochemical assay[J]. ACS Applied Materials&Interfaces, 2014), yellow (CeO2 and V2O5, see 1. Dual-mode fluorescence and colorimetric detection of pesticides realized by integrating stimulus-responsive luminescence with oxidase-mimetic activity into cerium-based coordination polymer nanoparticles[J]. Journal of Hazardous Materials, 2022; 2. V2O5 nanowires with an intrinsic peroxidase-like activity[J].Advanced Functional Materials, 2011), red (Au nanoparticles, see Nanozyme-catalyzed cascade reactions for mitochondria--mimicking oxidative phosphorylation [J]. Angewandte Chemie International Edition, 2019) and brown (Pt nanoparticles, MnO2 and CuO, see 1. Ultrasmall Pt nanoclusters as robust peroxidase mimics for colorimetric detection of glucose in human serum [J]. ACS applied materials & interfaces, 2017; 2. One-pot enzyme-and indicator-free colorimetric sensing of glucose based on MnO2 nano-oxidizer [J]. Sensors and Actuators B: Chemical, 2020; 3. Self-cascade reaction catalyzed by CuO nanoparticle-based dual-functional enzyme mimics [J]. Biosensors and Bioelectronics, 2017), respectively. These colors will interfere with the judgment of color development reaction and may affect the absorbance determination of colorimetric analysis. To solve this problem, it is of great significance to develop an enzyme mimetic material with white appearance.

[0005] Based on the above background, the present application aims to provide a white manganese-based metal organic framework material (Mn-MOF) which can be used for colorimetric detection of perfluorooctane sulfonic acid (PFOS).

[0006] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information which does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0007] The purpose of the present application is to provide a white peroxidase mimetic manganese-based metal organic framework and its preparation method, which can be used for on-site rapid detection of perfluorooctane sulfonic acid PFOS.

[0008] In order to achieve the above object, the present application provides a white peroxidase mimic manganese-based metal organic framework Mn-MOF, which is a metal organic framework formed by coordination of manganese salt and 1,3,5-benzenetricarboxylic acid, in the form of white powder, and has peroxidase mimic activity.

[0009] Further, the manganese-based metal organic framework Mn-MOF provided by the present application has a microspherical morphology, with a diameter of 1.5-2.5 μm, and is assembled by nanorods, and the Mn-MOF has an absorption peak at 491 cm -1 in the Fourier infrared spectrum.

[0010] Further, in the manganese-based metal organic framework Mn-MOF provided by the present application, the manganese salt is selected from manganese acetate tetrahydrate.

[0011] The present application also provides a preparation method of the above manganese-based metal organic framework Mn-MOF, comprising the following steps: The manganese salt and polyvinylpyrrolidone are dissolved in an ethanol-water mixed solution to obtain solution A, and 1,3,5-benzenetricarboxylic acid is dissolved in an ethanol-water mixed solution to obtain solution B; Solution B is added dropwise to solution A at room temperature, and then stirred and reacted, and then left to stand; After the precipitate is separated, it is washed and vacuum dried to obtain the manganese-based metal organic framework Mn-MOF.

[0012] Preferably, in the above preparation method, the volume ratio of anhydrous ethanol to water in the ethanol-water mixed solution is 2:1; the manganese salt is preferably manganese acetate tetrahydrate, the polyvinylpyrrolidone is PVP K30, and the concentrations of manganese acetate tetrahydrate and PVP K30 in solution A are 4.9 g / L and 20 g / L, respectively; the concentration of 1,3,5-benzenetricarboxylic acid in solution B is 11.25 g / L; and the volume ratio of solution A to solution B is 5:4.

[0013] Preferably, in the above preparation method, the stirring and reaction time is 20 minutes, and the standing time is 12 hours; the washing is performed by ethanol washing three times, and the vacuum drying is performed at 60°C for 6 hours.

[0014] The Mn-MOF provided by the present application can be used for detecting perfluorooctane sulfonic acid PFOS or preparing a PFOS detection kit.

[0015] The present application also provides a kit for detecting PFOS, which comprises the above Mn-MOF, and further comprises a TMB solution, an H2O2 solution, and a buffer solution with pH=3.6-4.0.

[0016] The present application also provides a colorimetric detection method for detecting PFOS based on the above kit, which comprises the following steps: The prepared Mn-MOF is reacted with the sample to be tested in a buffer solution; TMB and H2O2 are added for color development reaction; The qualitative or quantitative analysis of PFOS is realized by detecting the change of absorbance at 652 nm or the change of solution color.

[0017] Preferably, in the above detection method, the concentration of Mn-MOF in the reaction system of color development reaction is 50 μg / mL, the concentration of H2O2 is 3 mM, and the concentration of TMB is 0.4 mM.

[0018] The application is a visual detection method for perfluorooctane sulfonate based on the characteristics of white manganese-based peroxidase. A white peroxidase mimic manganese metal organic framework is synthesized first. The white peroxidase mimic Mn-MOF can catalyze the conversion of the color developing substrate 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxidation product oxTMB. When perfluorooctane sulfonate (PFOS) is added to the Mn-MOF dispersion, it is combined with the Mn-MOF through various interactions such as electrostatic attraction, manganese-oxygen bond, iron-sulfur bond, and manganese-fluorine bond, which inhibits the mimic peroxidase characteristics of the Mn-MOF and causes the inhibition of the catalytic color development of TMB. Finally, the blue oxidation product in the solution decreases and the color becomes lighter. The absorption spectrum of oxTMB is determined by a UV spectrophotometer, and the detection of perfluorooctane sulfonate is realized according to the change of the characteristic absorption peak intensity. In addition, a smart phone equipped with a color scanning application program can provide a fast visual tool. The color development reaction images under different concentrations of perfluorooctane sulfonate can be converted into RGB values. In the quantitative analysis of perfluorooctane sulfonate, the ratio of the intensity of the red band to the blue band is calculated to evaluate the proportional relationship between the spectral bands, and then accurate hue recognition and analysis are realized for real-time detection of perfluorooctane sulfonate on site.

[0019] The application has the following advantages: Compared with traditional mimic enzymes, the white peroxidase mimic manganese metal organic framework provided by the application has a relatively simple preparation process, easy-to-obtain materials, good specificity, and less influence on detection than other mimic enzymes.

[0020] Compared with the prior art, the application has the advantages that the method does not need complicated sample pretreatment and professional operation, the detection time is shorter, the cost is lower, and the application range is wider. In the application, when H2O2 exists, the white peroxidase mimic Mn-MOF can catalyze the colorless substrate TMB to be converted into the blue oxidation product oxTMB; when PFOS exists, the PFOS is combined to the Mn-MOF through electrostatic attraction, manganese-oxygen bond, iron-sulfur bond and manganese-fluorine bond and the like, the catalytic activity of the Mn-MOF is inhibited, the blue oxidation product (oxTMB) is reduced, and the color is lighter; the absorption spectrum of the oxTMB is determined by the ultraviolet spectrophotometer, and the detection of the PFOS is realized according to the change of the characteristic absorption peak intensity.

[0021] The application can convert the color reaction images under different PFOS concentrations into RGB values on the basis of the disclosed intelligent mobile phone software, in the quantitative analysis of the PFOS, the intensity ratio (R / B) of R and B is calculated, the proportional relationship between the spectral bands is evaluated, the accurate hue identification and analysis are realized, and the high selectivity, visualization and on-site rapid detection of the PFOS are realized. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The application provides white peroxidase mimic manganese-based metal organic framework powder in a dry state and white peroxidase mimic manganese-based metal organic framework dispersed in anhydrous ethanol.

[0023] Figure 2 The application provides a scanning electron microscope image of the white peroxidase mimic manganese-based metal organic framework.

[0024] Figure 3 The application provides a transmission electron microscope image of the white peroxidase mimic manganese-based metal organic framework.

[0025] Figure 4 The application provides an X-ray diffraction spectrum of the white peroxidase mimic manganese-based metal organic framework.

[0026] Figure 5 The application provides a Fourier infrared spectrum of the white peroxidase mimic manganese-based metal organic framework.

[0027] Figure 6 The application provides a diagram of the inhibition effect of PFOS on the peroxidase mimic property of the white peroxidase mimic manganese-based metal organic framework.

[0028] Figure 7 The photo of the solution of different reaction systems in the present application and the ultraviolet verification spectrum of the white peroxidase mimetic manganese-based metal organic framework mimicking the peroxidase characteristics.

[0029] Figure 8 The ultraviolet-visible absorption spectrum of the Mn-MOF / TMB / H2O2 system in the presence of perfluorooctane sulfonic acid.

[0030] Figure 9 The pH optimization results of the Mn-MOF / TMB / H2O2 system provided by the present application.

[0031] Figure 10 The Mn-MOF concentration selection of the Mn-MOF / TMB / H2O2 system provided by the examples of the present application.

[0032] Figure 11 The H2O2 and TMB concentration optimization of the Mn-MOF / TMB / H2O2 system provided by the examples of the present application.

[0033] Figure 12 The inhibition rate of Mn-MOF activity under different time and different pH conditions in combination with perfluorooctane sulfonic acid provided by the examples of the present application.

[0034] Figure 13 The absorption spectrum change and absorption peak intensity difference after the white peroxidase mimetic manganese-based metal organic framework reacts with different concentrations of perfluorooctane sulfonic acid provided by the examples of the present application. Delta A 652 Linear relationship with the concentration of perfluorooctane sulfonic acid.

[0035] Figure 14 The selectivity of the white peroxidase mimetic manganese-based metal organic framework to perfluorooctane sulfonic acid provided by the examples of the present application, perfluorooctane sulfonic acid concentration (20 μM), other interferent concentration (40 μM).

[0036] Figure 15 The reaction system photo under different concentrations of perfluorooctane sulfonic acid, the colorimetric method for determining perfluorooctane sulfonic acid by a smartphone, and the linear relationship between R / B value and perfluorooctane sulfonic acid concentration. DETAILED DESCRIPTION

[0037] The technical solutions in the examples of the present application will be described clearly and completely below. Obviously, the described examples are only a part of the examples of the present application, not all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] Note: The experimental methods in the following examples are all conventional methods, unless otherwise specified, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained commercially.

[0039] Preparation and characterization of white peroxidase mimic manganese-based metal organic framework Preparation of white peroxidase mimic manganese-based metal organic framework: An ethanol-water mixed solution was prepared by mixing 30 mL of anhydrous ethanol and 15 mL of deionized water, and then the solution was divided into two beakers, A and B. The A beaker contained 25 mL of the solution, and the B beaker contained 20 mL of the solution. 0.1225 g of manganese acetate tetrahydrate and 0.5 g of polyvinylpyrrolidone (PVP K30, average molecular weight 58000) were added to the A beaker, and 0.225 g of 1,3,5-benzenetricarboxylic acid was added to the B beaker. Both were stirred until clear. The solution in the B beaker was added dropwise to the A beaker at room temperature, and after stirring for 20 minutes, the mixture was left to stand for 12 hours. After ultrasonic dispersion of the precipitate, centrifugation was performed at 10,000 r / min for 5 min, and ethanol washing was performed three times. After each washing, the same conditions were used for centrifugation. Finally, the product was dried at 60 °C under vacuum for 6 hours to obtain a white powder, as shown in A of Figure 1 , and the white peroxidase mimic manganese-based metal organic framework dispersed in anhydrous ethanol is shown in B of Figure 1 ;

[0040] Characterization of white peroxidase mimic manganese-based metal organic framework: The surface morphology and structural characteristics of the white peroxidase mimic manganese-based metal organic framework were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As shown in Figure 2 and Figure 3 , the white manganese-based mimic enzyme exhibited an ordered three-dimensional microsphere structure with a diameter of about 1.5 to 2.5 μm. These microspheres were intricately assembled from high-density one-dimensional nanorods, and the surface of the microspheres had traces of these nanorods, as shown in Figure 4 . X-ray diffraction analysis of the white manganese-based mimic enzyme showed that it had high crystallinity, as shown in Figure 5 . The characteristic absorption at 491 cm -1 in the Fourier transform infrared spectrum of the white manganese-based mimic enzyme was attributed to manganese-oxygen stretching vibration, which confirmed the successful coordination between manganese and oxygen atoms in the synthesized material. The above results show that the white peroxidase mimic manganese-based metal organic framework Mn-MOF was successfully prepared by the method of the present application. The schematic diagram of the inhibitory effect of perfluorooctanesulfonic acid (PFOS) on the peroxidase mimic properties of the white peroxidase mimic manganese-based metal organic framework is shown in Figure 6 .

[0041] Example 2 This embodiment is to analyze the peroxidase mimetic properties of white peroxidase mimetic Mn-based metal-organic framework, as follows: The peroxidase mimetic properties of white peroxidase mimetic Mn-based metal-organic framework on H2O2-TMB system were investigated by UV-Vis absorption spectroscopy, and the results are shown in Figure 7 From A in Figure 7 , it can be seen that TMB, TMB + H2O2, TMB + Mn-MOF have no obvious characteristic absorption peak change and color change, however, TMB + Mn-MOF + H2O2 solution presents obvious blue color, and the characteristic absorption peak of oxTMB appears at 652 nm, as shown in B in Figure 7 . The above results show that Mn-MOF has good peroxidase mimetic properties, and can effectively catalyze the oxidation of TMB in H2O2-TMB system to generate blue oxTMB. In addition, the inhibitory effect of perfluorooctane sulfonic acid on the peroxidase mimetic properties of Mn-MOF was investigated by UV-Vis absorption spectroscopy, and the results are shown in Figure 8 From Figure 7 , it can be seen that when Mn-MOF is added to H2O2-TMB system after reacting with perfluorooctane sulfonic acid solution for a period of time, the blue color of the solution becomes significantly lighter, and the absorption peak intensity of oxTMB is significantly reduced, indicating that perfluorooctane sulfonic acid greatly inhibits the peroxidase mimetic properties of Mn-MOF, resulting in reduced catalytic efficiency of Mn-MOF. The above results show that based on the inhibitory effect of perfluorooctane sulfonic acid on the peroxidase mimetic properties of Mn-MOF, an absorption spectroscopy method can be constructed for colorimetric analysis of perfluorooctane sulfonic acid.

[0042] Example 3 In the pH optimization experiment, 100 μL of Mn-MOF (1 mg / mL), 100 μL of TMB (5 mM), and 50 μL of H2O2 (0.1 M) were sequentially added to 750 μL of HAc-NaAc buffer solution with different pH values, mixed well, and reacted at 37°C for 30 minutes. The absorbance at 652 nm was measured to evaluate the effect of pH on the catalytic color development reaction, as shown in Figure 9 . In the MOF concentration optimization, different volumes of Mn-MOF (1 mg / mL) were added to the buffer system with pH=3.6, and 40 μL of TMB (5 mM) and 30 μL of H2O2 (0.1 M) were fixedly added. After mixing, the solution was reacted at 37°C for 30 minutes, and the absorbance at 652 nm was measured to determine the optimal amount of Mn-MOF, as shown in Figure 10As shown in the figure. For optimization of TMB and H2O2 concentrations, 50 μL of Mn-MOF (1 mg / mL) and 30 μL of H2O2 (0.1 M) were initially added to a pH 3.6 buffer solution, and the volume of TMB (5 mM) added was varied. The results are shown in the figure. Figure 11 B in the solution; then, 50 μL of Mn-MOF and 80 μL of TMB were fixed, and the amount of H2O2 (0.1 M) added was varied. The results are shown in [the table below]. Figure 11 All A components were mixed thoroughly and reacted at 37°C for 30 minutes before absorbance was measured at 652 nm. The final reaction system parameters were set as follows: pH = 3.6, white manganese-based enzyme concentration = 50 μg / L, hydrogen peroxide concentration = 3 mM, and TMB concentration = 0.4 mM. The reaction mixture was incubated at 37°C for 30 min to ensure complete substrate conversion.

[0043] Example 4 This embodiment provides an absorption spectrometry method for detecting perfluorooctane sulfonic acid based on the peroxidase-mimicking properties of a white peroxidase mimic, manganese-based metal-organic framework, as detailed below: To achieve optimal analysis of perfluorooctane sulfonic acid, the final determination conditions were set as follows using the controlled variable method: PFOS adsorption experiments were conducted at pH 4.0 (see...). Figure 12 The process was carried out under the optimized condition of A), with an equilibration time of 15 min (see [reference]). Figure 12 (B in the middle).

[0044] Under optimized conditions, the analytical performance of the white peroxidase mimic manganese-based metal-organic framework as a colorimetric probe for perfluorooctane sulfonic acid was investigated. The results are as follows: Figure 13 As shown. 50 μL of 1 mg / mL Mn-MOF solution was added to 100 μL of 200 mM pH=4 acetate-sodium acetate buffer solution and mixed thoroughly. Then, different concentrations of perfluorooctane sulfonic acid (PFOS) solutions (0, 0.1, 0.5, 1, 2, 3, 5, 10, 20, 30, 40, 50, 60, 70 μM) were added, and the total volume of the reaction solution was diluted to 300 μL with buffer solution. The reaction was carried out with vigorous shaking on a shaker for 15 min. Then, 80 μL of 5 mM TMB and 30 μL of 0.1 M H2O2 were added sequentially to the resulting solution. The total volume of the solution was diluted to 1 mL with pH=3.6 acetate-sodium acetate buffer solution, and the reaction was carried out at 37℃ for 30 min. As the concentration of PFOS increased, the blue color of the solution gradually lightened, and the absorption peak at 652 nm (A) of the solution was observed. 652 The intensity gradually decreases (see) Figure 13 A in the diagram). The intensity difference of the absorption spectrum at 652 nm ( Delta A 652The concentrations of ) showed a good linear relationship with those of perfluorooctane sulfonic acid in the ranges of 0-3 μM and 3-60 μM (see [link to data]). Figure 13 The lowest detection limit (LOD) is 53.3 nM, which is better than most existing detection methods.

[0045] Simultaneously, the intensity difference of the absorption spectrum at 652 nm ( Delta A 652 The selectivity of Mn-MOF for the detection of perfluorooctane sulfonic acid was investigated using Mn-MOF as the indicator, and the results are as follows: Figure 14 As shown. The system's response to common interfering substances was tested, including perfluorooctanoic acid (PFOA), surfactants (hexadecyltrimethylammonium bromide CTAB), and anions (chloride ions Cl). - Bromide ions (Br) - Sulfate ions SO4 2- carbonate ions CO3 2- phosphate ions PO4 3- ) and metal ions (potassium ions K) + Zinc ions (Zn) 2+ Calcium ions (Ca) 2+ Copper ions Cu 2+ Magnesium ions (Mg) 2+ Iron ions Fe 3+ To evaluate the selectivity of white manganese-based mimic enzymes, perfluorooctanoic acid (PFOA) was used. Experimental results showed that PFOA was the only enzyme specifically targeting white manganese-based mimics. Delta A652 exhibits significant interference, while the effects of other interfering substances are negligible. This selectivity stems from a unique multiple interaction mechanism between Mn-MOF and perfluorooctane sulfonic acid (PFOS). First, there is electrostatic attraction between the two. Second, the synergistic effect of various chemical bonds in Mn-MOF, including the manganese-oxygen bond (Mn-O), iron-sulfur bond (Fe-S), and newly formed manganese-fluorine bond (Mn-F), effectively inhibits the peroxidase-like properties of Mn-MOF. Notably, although the carboxylic acid group in PFOS can coordinate with the metal center of Mn-MOF, reducing its enzymatic activity to some extent and thus interfering with PFOS detection, the detection system still exhibits excellent selectivity. This superior anti-interference capability gives it significant advantages in the detection of PFOS in real-world environmental samples, making it a highly promising analytical tool.

[0046] Example 5 This embodiment provides a method for detecting perfluorooctane sulfonic acid (PFOS) using a smartphone based on a white peroxidase mimicking manganese-based metal-organic framework to simulate the properties of peroxidase. The details are as follows: like Figure 15As shown, the blue color intensity of the Mn-MOF / TMB / H2O2 system exhibits a clear and gradual decreasing trend with increasing perfluorooctane sulfonic acid (PFOS) concentration, thus enabling intuitive visual detection. Based on Example 3, the colorimetric reaction images at different PFOS concentrations were converted to RGB values ​​using a mobile application, see [link to example]. Figure 15 A in [the original text]. See also [the original text]. Figure 15 As shown in Figure B, a strong correlation exists between relative RGB values ​​and perfluorooctane sulfonate (PFOS) concentration, with the R / B pattern exhibiting the highest linear correlation. This relationship is described by the linear equation y = 0.01245x + 0.21461 (R² = 0.9979), which is valid in the range of 0.1 to 60 μM, with a calculated limit of detection (LOD) of 62.4 nM. Therefore, the proposed smartphone-based visualization method provides a simple and effective approach for the determination of PFOS, offering a practical and convenient tool for real-world applications.

[0047] In summary, this invention provides a white peroxidase mimic manganese-based metal-organic framework (Mn-MOF) that can be used to prepare a detection kit for perfluorooctane sulfonic acid (PFOS) for colorimetric detection, offering advantages such as visualization and rapid on-site detection.

[0048] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A white peroxidase mimic manganese-based metal-organic framework (Mn-MOF), characterized in that, The manganese-based metal-organic framework Mn-MOF is a metal-organic framework formed by coordination between manganese salt and 1,3,5-benzenetricarboxylic acid. It is a white powder and has peroxidase-mimicking activity.

2. The manganese-based metal-organic framework Mn-MOF according to claim 1, characterized in that, The Mn-MOF exhibits a microspherical morphology with a diameter of 1.5-2.5 μm. It is grown from nanorods. The Mn-MOF shows a value of 491 cm⁻¹ in Fourier transform infrared spectroscopy. -1 An absorption peak is present at this location.

3. The manganese-based metal-organic framework Mn-MOF according to claim 1, characterized in that, The manganese salt is selected from manganese acetate tetrahydrate.

4. A method for preparing the manganese-based metal-organic framework (Mn-MOF) according to any one of claims 1-3, characterized in that, It includes the following steps: Manganese salt and polyvinylpyrrolidone were dissolved in an ethanol-water mixture to obtain solution A, and 1,3,5-benzenetricarboxylic acid was dissolved in an ethanol-water mixture to obtain solution B. Add solution B dropwise to solution A at room temperature, stir to react, and then let stand. After separation and precipitation, the sample is washed and vacuum dried to obtain the manganese-based metal-organic framework Mn-MOF.

5. The preparation method according to claim 4, characterized in that, The volume ratio of anhydrous ethanol to water in the ethanol-water mixed solution is 2:1; the manganese salt is manganese acetate tetrahydrate, the polyvinylpyrrolidone is PVP K30, and the concentrations of manganese acetate tetrahydrate and PVP K30 in solution A are 4.9 g / L and 20 g / L, respectively; the concentration of 1,3,5-benzenetricarboxylic acid in solution B is 11.25 g / L; wherein the volume ratio of solution A to solution B is 5:

4.

6. The preparation method according to claim 4, characterized in that, The stirring reaction time is 20 minutes, the standing time is 12 hours, the washing is performed three times with ethanol, and the vacuum drying is performed at 60°C for 6 hours.

7. The use of Mn-MOF as described in any one of claims 1-3 in the detection of perfluorooctane sulfonate (PFOS) or in the preparation of PFOS detection kits.

8. A kit for detecting PFOS, characterized in that, The kit contains the Mn-MOF as described in any one of claims 1-3, and also contains a TMB solution, an H2O2 solution, and a buffer solution with a pH of 3.6 to 4.

0.

9. A colorimetric detection method for PFOS based on the kit described in claim 8, characterized in that, Includes the following steps: The Mn-MOF was reacted with the sample to be tested in a buffer solution; TMB and H2O2 were added to initiate a colorimetric reaction; Qualitative or quantitative analysis of PFOS can be achieved by detecting changes in absorbance at 652 nm or changes in solution color.

10. The detection method according to claim 9, characterized in that, In the reaction system of the colorimetric reaction, the concentration of Mn-MOF is 50 μg / mL, the concentration of H2O2 is 3 mM, and the concentration of TMB is 0.4 mM.

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