Lanthanide series MOFs two-dimensional nanosheet constructed by single ligand and preparation method and application of lanthanide series MOFs two-dimensional nanosheet
By preparing single-ligand-constructed lanthanide MOFs two-dimensional nanosheet materials, the excitation ratio fluorescence detection strategy was adopted to solve the environmental interference and false positive problems in the detection of Bacillus anthrax, and an efficient and sensitive 2,6-pyridine dicarboxylic acid detection was achieved, with the detection limit as low as 0.1 μmol/L.
Patent Information
- Application Number
- CN202510876218.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-08-19
AI Technical Summary
The prior art is difficult to achieve efficient and sensitive detection of Bacillus anthrax, especially in extreme environments, and traditional fluorescence detection is susceptible to environmental interference, and there is a risk of false positives and concentration dependence.
The lanthanide MOFs two-dimensional nanosheet material constructed with a single ligand was prepared by coordination with pentaamino isophthalic acid and Eu3+. The excitation ratio fluorescence detection strategy was used to measure the fluorescence intensity ratio of 614nm and 402nm to achieve the detection of 2,6-pyridine dicarboxylic acid.
It significantly improves the detection response speed and sensitivity, effectively eliminates environmental interference, reduces the risk of false positives, and achieves efficient and accurate detection of 2,6-pyridine dicarboxylic acid, with the detection limit as low as 0.1μmol/L.
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Figure CN120504845A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of biomarker fluorescence detection, and specifically relates to a lanthanide MOFs two-dimensional nanosheet constructed with a single ligand, and a preparation method and application thereof. Background Art
[0002] Bacillus anthracis is the pathogen that causes anthrax and is a potential bioremediation agent, capable of surviving extreme environments. Among the various components of B. anthracis, 2,6-pyridinedicarboxylic acid (DPA), a specific component in anthrax spores, accounts for approximately 5-15% of the dry weight of bacterial spores and is considered a biomarker for B. anthracis. Given the high pathogenicity of B. anthracis, the development of a sensitive and cost-effective method for the efficient detection of this biomarker is crucial.
[0003] Fluorescent chemical sensors constructed based on lanthanide metal-organic frameworks (Ln-MOFs) materials not only have unique luminescence characteristics of lanthanide elements, such as stable and narrow luminescence peaks, long luminescence lifetimes, and high quantum yields, but also take into account the many advantages of MOFs nanomaterials, such as flexible structure, ordered and adjustable pores, large specific surface area, and multiple active sites. They have become a research hotspot in the field of fluorescence detection.
[0004] Compared to common quenching fluorescence detection, excitation detection can better reduce environmental interference and avoid false responses during the detection process. Ratiometric fluorescence detection, which measures the ratio of fluorescence signals at two or more wavelengths, offers advantages over single-wavelength fluorescence detection, such as being able to offset background signals and avoid concentration dependence. Summary of the Invention
[0005] To solve the problems existing in the prior art, the present invention provides single-ligand constructed lanthanide MOFs two-dimensional nanosheets and their preparation method and application. The present invention constructs single-ligand coordinated Ln-MOFs by selecting special ligand molecules to realize the excitation ratio fluorescence detection of 2,6-pyridinedicarboxylic acid in water system.
[0006] The technical solution adopted is as follows: A method for preparing lanthanide MOFs two-dimensional nanosheets constructed by a single ligand, comprising: dissolving europium nitrate hexahydrate and 5-aminoisophthalic acid in a solvent and mixing them for reaction, and obtaining a lanthanide MOFs two-dimensional nanosheet material constructed by a single ligand after post-treatment.
[0007] Preferably, the molar ratio of europium nitrate hexahydrate to 5-aminoisophthalic acid is 1:1-1:2.
[0008] Preferably, the solvent is water or N,N-dimethylformamide.
[0009] Preferably, the reaction temperature is 120-180° C., and the reaction time is 12-24 h.
[0010] Preferably, the post-processing includes: cooling, crushing and centrifugal collection and fixation.
[0011] Preferably, the steps are as follows: S1, dissolving europium nitrate hexahydrate in a solvent until it is completely dissolved to obtain a first solution; S2, dissolving 5-aminoisophthalic acid in a solvent until it is completely dissolved to obtain a second solution; S3, mixing the second dissolving solution with the first dissolving solution, transferring the mixture into a high pressure reactor for reaction at a temperature of 120-180° C. for 12-24 h; S4. After the reaction is completed, the reactor is cooled to room temperature, a solvent is added, ultrasonically crushed and washed, the solid is collected by centrifugation, and vacuum dried to obtain a flaky material.
[0012] The lanthanide MOFs two-dimensional nanosheet constructed with a single ligand is prepared by the above method. The lanthanide MOFs two-dimensional nanosheet has a fluorescence peak emitted by an independent ligand at a wavelength of 402 nm.
[0013] Preferably, the thickness of the lanthanide MOFs two-dimensional nanosheet material is 10-50 nm.
[0014] The application of single-ligand constructed lanthanide MOFs two-dimensional nanosheets prepared by the above method in the detection of anthrax Bacillus.
[0015] The application of single-ligand constructed lanthanide MOFs two-dimensional nanosheets prepared by the above method in the excitation ratio fluorescence detection of 2,6-pyridinedicarboxylic acid.
[0016] Mechanism explanation: The present invention uses 5-aminoisophthalic acid as a single ligand and Eu 3+ Eu-5-aip nanosheets with two-dimensional structure were prepared by coordination. The ligand molecule 5-aminoisophthalic acid, although with the lanthanide metal Eu 3+ It has strong ligand ability, but its excited state energy is similar to Eu 3+ Mismatch cannot sensitize Eu 3+ Therefore, the prepared Eu-5-aip material has a fluorescence emission peak only at 402nm. When detecting DPA, due to the appropriate energy radiation range of the selected ligand, when the Eu-5-aip material contacts the 2,6-pyridinedicarboxylic acid molecule, the 5-aminoisophthalic acid ligand molecule and the 2,6-pyridinedicarboxylic acid molecule cooperate to regulate the fluorescence properties of the Eu-5-aip material through the "antenna effect", stimulating Eu 3+The fluorescence emission of Eu-5-aip material causes a new fluorescence peak to appear at 614nm, while the fluorescence peak at 402nm remains unchanged, thereby realizing the excitation ratio fluorescence detection of 2,6-pyridinedicarboxylic acid.
[0017] Compared with the prior art, the present invention has the following beneficial effects: the single-ligand constructed lanthanide MOFs two-dimensional nanosheet material prepared by the present invention has a high specific surface area and exposed active sites, which significantly improves the detection response speed and sensitivity. At the same time, the excitation-type dual-emission ratio detection strategy effectively eliminates environmental interference, reduces the risk of false positives, avoids concentration dependence, and improves detection performance. In the present invention, the 5-aminoisophthalic acid ligand molecule and 2,6-pyridinedicarboxylic acid synergistically regulate the fluorescence properties of the Eu-5-aip material, excite the 614nm emission peak, and realize fluorescence ratio detection, which is applied to the detection of anthrax Bacillus and the excitation-type ratio fluorescence detection of 2,6-pyridinedicarboxylic acid. The experimental results show that by measuring the fluorescence intensity ratio of the wavelength 614nm and the wavelength 402nm (I 614 / I 402 ), a linear relationship with the concentration of 2,6-pyridinedicarboxylic acid (0-90μmol / L) was established (R²=0.994), and the detection limit was as low as 0.1μmol / L. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is the SEM image of Eu-5-aip prepared in Example 1 of the present invention.
[0019] Figure 2 This is a fluorescence spectrum diagram of Eu-5-aip prepared in Example 1 of the present invention before and after adding 2,6-pyridinedicarboxylic acid.
[0020] Figure 3 This is a fluorescence response spectrum diagram of Example 2 of the present invention under different concentrations of 2,6-pyridinedicarboxylic acid.
[0021] Figure 4 This is a linear relationship curve diagram under different concentrations of 2,6-pyridinedicarboxylic acid in Example 2 of the present invention.
[0022] Figure 5 The selective detection of 2,6-pyridinedicarboxylic acid by Eu-5-aip in Example 3 of the present invention Figure 1 .
[0023] Figure 6 The selective detection of 2,6-pyridinedicarboxylic acid by Eu-5-aip in Example 3 of the present invention Figure 2 . DETAILED DESCRIPTION
[0024] To facilitate understanding of the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the present invention more thorough and comprehensive.
[0025] The method for preparing single-ligand constructed lanthanide MOFs two-dimensional nanosheets comprises: first dissolving europium nitrate hexahydrate in a solvent, preferably N,N-dimethylformamide (DMF), preferably ultrasonically dissolving the solution for 10-15 minutes; then dissolving 5-aminoisophthalic acid in a solvent, preferably water, and mixing the solution with the europium nitrate hexahydrate solution for reaction after complete dissolution; the reaction temperature is preferably 120-180°C, and the reaction time is preferably 12-24 hours. After post-treatment, the single-ligand constructed lanthanide MOFs two-dimensional nanosheet material is obtained.
[0026] In one embodiment, the post-treatment process is preferably as follows: after the reaction is completed, the reactor is cooled to room temperature, DMF is added for ultrasonic washing, and the solid is collected by centrifugation. This process is repeated three times. The above process is then repeated three times with H2O, and the flaky material, namely Eu-5-aip, is obtained after vacuum drying.
[0027] In one embodiment, the molar ratio of europium nitrate hexahydrate to 5-aminoisophthalic acid is 1:1-1:2.
[0028] The present invention also provides a lanthanide MOFs two-dimensional nanosheet material constructed with a single ligand obtained by the above preparation method. The nanosheet material has a fluorescence peak emitted by an independent ligand at a wavelength of 402 nm. The thickness of the lanthanide MOFs two-dimensional nanosheet material constructed with a single ligand is 10-50 nm.
[0029] The present invention also provides the use of the above-mentioned single-ligand constructed lanthanide MOFs two-dimensional nanosheet material in the excitation ratio fluorescence detection of anthrax markers.
[0030] The present invention also provides an application of the above-mentioned single-ligand constructed lanthanide MOFs two-dimensional nanosheet material in the excitation ratio fluorescence detection of 2,6-pyridinedicarboxylic acid.
[0031] The present invention is further described in detail below with reference to specific examples, in which the raw materials involved are all commercially available.
[0032] Example 1: Preparation of Eu-5-aip.
[0033] Weigh 1 mmol of 5-aminoisophthalic acid and dissolve it in 14 mL of N,N-dimethylformamide (DMF) solvent. Ultrasonicate for 10 minutes to dissolve the mixture. Then, weigh 1 mmol of europium nitrate hexahydrate and dissolve it in 6 mL of water. Once completely dissolved, mix the mixture thoroughly with the previous solution and transfer the mixture to a 50 mL autoclave for 120°C to react for 12 hours. After the reaction is complete, cool the autoclave to room temperature, collect the solid by centrifugation, add 35 mL of DMF, ultrasonically crush and wash the solid, and collect the solid by centrifugation. Repeat this process three times. Repeat this process three more times with 35 mL of H2O. Dry the mixture under vacuum at 60°C to obtain Eu-5-aip flakes.
[0034] Figure 1 This is the SEM image of Eu-5-aip prepared in Example 1 of the present invention. Figure 1 It can be seen that the Eu-5-aip prepared in the present invention is a two-dimensional nanosheet structure.
[0035] The fluorescence spectra of Eu-5-aip prepared in Example 1 of the present invention before and after adding 2,6-pyridinedicarboxylic acid are shown in FIG. Figure 2 , demonstrating its ratiometric excitation detection characteristics. The horizontal axis is wavelength, and the vertical axis is fluorescence intensity.
[0036] Mechanism explanation: The present invention uses 5-aminoisophthalic acid as a single ligand and Eu 3+ Eu-5-aip nanosheets with two-dimensional structure were prepared by coordination. The ligand molecule 5-aminoisophthalic acid, although with the lanthanide metal Eu 3+ It has strong ligand ability, but its excited state energy is similar to Eu 3+ Mismatch cannot sensitize Eu 3+ Therefore, the prepared Eu-5-aip material has a fluorescence emission peak only at 402nm. When detecting DPA, due to the appropriate energy radiation range of the selected ligand, when the Eu-5-aip material contacts the 2,6-pyridinedicarboxylic acid molecule, the 5-aminoisophthalic acid ligand molecule and the 2,6-pyridinedicarboxylic acid molecule cooperate to regulate the fluorescence properties of the Eu-5-aip material through the "antenna effect", stimulating Eu 3+ The fluorescence emission of Eu-5-aip material causes a new fluorescence peak to appear at 614nm, while the fluorescence peak at 402nm remains unchanged, thereby realizing the excitation ratio fluorescence detection of 2,6-pyridinedicarboxylic acid.
[0037] Example 2: Detection of 2,6-pyridinedicarboxylic acid.
[0038] 100 μL of Eu-5-aip (2 mg / mL) prepared in Example 1 was added to 1800 μL of Hepes buffer solution (50 mmol, pH = 6.8). Then, 100 μL of 2,6-pyridinedicarboxylic acid solution of varying concentrations (0-1800 μM) was added. The mixture was incubated for 2 hours, and fluorescence spectra were collected in the 350-750 nm region at an excitation wavelength of 278 nm. Spectral data are shown in Figure 1. Figure 3-4 As shown, Figure 3 It is the fluorescence response spectrum, the horizontal axis is the wavelength and the vertical axis is the fluorescence intensity; Figure 4 The linear relationship curve is plotted against the DPA concentration on the horizontal axis and the ratio of the fluorescence peaks at 614 nm to 402 nm on the vertical axis. As the concentration of the 2,6-pyridinedicarboxylic acid solution increases, the fluorescence peak at 402 nm gradually decreases, while the fluorescence peak at 614 nm attributed to Eu metal gradually increases. The change in the ratio of the two peaks (y) and the concentration of the 2,6-pyridinedicarboxylic acid solution (x) follows a linear relationship: y = 0.0461x + 0.0299, with an R² = 0.994, and a detection limit as low as 0.1 μmol / L.
[0039] Example 3: Selective detection of 2,6-pyridinedicarboxylic acid by Eu-5-aip.
[0040] In order to investigate the selective detection of 2,6-pyridinedicarboxylic acid by Eu-5-aip prepared in Example 1, the reaction of 2,6-pyridinedicarboxylic acid with Fe 3+ 、Zn 2+ 、Ni 2+ 、Ba 2+ 、Fe 2+ Mg 2+ , Ca 2+ 、Cu 2+ 、Co 2+ 、Cd 2+ , K + 、Na + 、Cl – Br – 、S2O3 2– 、SO4 2– 、HCO3 – 、CO3 2–, 3,5-dicarboxyphenylboronic acid (5-bop), terephthalic acid (BDC), cysteine (Csy), PMA, BTC and citric acid (CA) coexisted interference experiment, the specific process is: 100 μL of Eu-5-aip (2 mg / mL) was added to 1700 μL of Hepes buffer solution (50 mmol, pH = 6.8), and then 100 μL of 2,6-pyridinedicarboxylic acid solution with a concentration of 1200 μM and 100 μL of the above other ions with a concentration of 1200 μM were added. After the mixture solution was incubated for 2 hours, the fluorescence spectrum in the 350-750 nm region was collected at an excitation wavelength of 278 nm. Figure 5-6 As shown, the horizontal axis is the wavelength and the vertical axis is the fluorescence intensity. It can be seen that in the presence of other impurity ions, the prepared Eu-5-aip material can still achieve targeted recognition of 2,6-pyridinedicarboxylic acid.
[0041] Example 4: Detection of actual water samples.
[0042] Eu-5-aip was tested for 2,6-pyridinedicarboxylic acid in laboratory tap water and corridor drinking water. Before the experiment, the tap water was centrifuged at 4000 rpm for 10 minutes, and the supernatant was collected. The collected tap water sample was then treated with a 0.22 μm syringe filter to remove impurities. The drinking water was not pretreated before use. Hepes buffer solution was prepared using the treated tap and drinking water samples. 100 μL of Eu-5-aip (2 mg / mL) prepared in Example 1 was added to 1800 μL of Hepes buffer solution prepared with tap water and drinking water samples, respectively. Then, 100 μL of 2,6-pyridinedicarboxylic acid solution of different concentrations (200-1200 μM) was added. After the mixture solution was incubated for 2 h, the fluorescence spectrum in the 350-750 nm region was collected at an excitation wavelength of 278 nm. The fluorescence spectrum and the fluorescence peaks at wavelengths of 402 nm and 614 nm were recorded, and the ratio of the two (I 614 / I 402 ), substitute Figure 3 The concentration of 2,6-pyridinedicarboxylic acid was calculated from the obtained linear equation y=0.0461x+0.0299. The results are shown in Table 1. The calculated concentration is close to the true value, with a recovery rate of 97.5-115% and a small relative standard deviation (<5%). This confirms that the material can realize the fluorescence detection of 2,6-pyridinedicarboxylic acid with high accuracy and precision.
[0043] Table 1 Detection results of 2,6-pyridinedicarboxylic acid in real water samples
[0044] The test result refers to the concentration of 2,6-pyridinedicarboxylic acid; the addition amount refers to the amount of 2,6-pyridinedicarboxylic acid added to the water sample; uM = micromoles per liter. Recovery refers to the ratio of the result obtained by adding a certain amount of standard substance to a sample matrix without the analyte and analyzing it according to the sample processing steps to the theoretical value. The relative standard deviation (RSD) is the ratio of the standard deviation to the arithmetic mean of the measurement results and is generally used to indicate the precision of the analytical test results. Five experiments were conducted, so the test results, recovery rates, and relative standard deviations in the table represent the average of multiple experiments.
[0045] The single-ligand lanthanide MOFs two-dimensional nanosheets prepared by this invention possess a high specific surface area and exposed active sites, significantly improving detection response speed and sensitivity. Furthermore, an excitation-based dual-emission ratiometric detection strategy effectively eliminates environmental interference, reduces the risk of false positives, avoids concentration dependence, and enhances detection performance. In this invention, the 5-aminoisophthalic acid ligand molecule and 2,6-pyridinedicarboxylic acid synergistically regulate the fluorescence properties of the Eu-5-aip material, stimulating the 614nm emission peak and enabling fluorescence ratiometric detection.
[0046] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
Claims
1. A method for preparing lanthanide MOFs two-dimensional nanosheets constructed with a single ligand, characterized in that: include: Europium nitrate hexahydrate and 5-aminoisophthalic acid are dissolved in a solvent and mixed for reaction, and after post-treatment, a lanthanide MOFs two-dimensional nanosheet material constructed with a single ligand is obtained.
2. The method for preparing the single-ligand constructed lanthanide MOFs two-dimensional nanosheets according to claim 1, characterized in that: The molar ratio of europium nitrate hexahydrate to 5-aminoisophthalic acid is 1:1-1:
2.
3. The method for preparing the single-ligand constructed lanthanide MOFs two-dimensional nanosheets according to claim 1, characterized in that: The solvent is water or N,N-dimethylformamide.
4. The method for preparing the single-ligand constructed lanthanide MOFs two-dimensional nanosheets according to claim 1, characterized in that: The reaction temperature is 120-180° C., and the reaction time is 12-24 hours.
5. The method for preparing the single-ligand constructed lanthanide MOFs two-dimensional nanosheets according to claim 1, characterized in that: Post-processing includes: Cool down, crush and collect by centrifugation.
6. The method for preparing the single-ligand constructed lanthanide MOFs two-dimensional nanosheets according to claim 1, characterized in that: Here are the steps: S1, dissolving europium nitrate hexahydrate in a solvent until it is completely dissolved to obtain a first solution; S2, dissolving 5-aminoisophthalic acid in a solvent until it is completely dissolved to obtain a second solution; S3, mixing the second dissolving solution with the first dissolving solution, transferring the mixture into a high pressure reactor for reaction at a temperature of 120-180° C. for 12-24 h; S4. After the reaction is completed, the reactor is cooled to room temperature, a solvent is added, ultrasonically crushed and washed, the solid is collected by centrifugation, and vacuum dried to obtain a flaky material.
7. Lanthanide MOFs two-dimensional nanosheets constructed with a single ligand, characterized by: The lanthanide MOFs two-dimensional nanosheets are prepared by the method according to any one of claims 1 to 6, and have a fluorescence peak emitted by an independent ligand at a wavelength of 402 nm.
8. The lanthanide MOFs two-dimensional nanosheet constructed with a single ligand according to claim 1, characterized in that: The thickness of the lanthanide MOFs two-dimensional nanosheet material is 10-50 nm.
9. Use of the single-ligand constructed lanthanide MOFs two-dimensional nanosheets prepared by the method according to any one of claims 1 to 6 in the detection of Bacillus anthracis.
10. Use of a single-ligand constructed lanthanide MOFs two-dimensional nanosheet prepared by the method according to any one of claims 1 to 6 in the excitation ratiometric fluorescence detection of 2,6-pyridinedicarboxylic acid.