Fluorescence sensor as well as preparation method and application thereof

Abstract

The invention provides a fluorescence sensor and a preparation method and application thereof, and belongs to the technical field of sensors. The fluorescent material is loaded on the porous carrier, and the interaction between the fluorescent material and the porous carrier can improve the stability of the fluorescent material in a water body; pCN-222, PCN-223 or PCN-224 is used as a fluorescent material, the fluorescent material has sensitive reaction to fluorine ions, when water contains the fluorine ions, the fluorine ions destroy the structure of the fluorescent material, a fluorescence quenching phenomenon occurs, and the fluorescent material can be further used for detecting PFOA in a water body. The result of the embodiment shows that when the fluorescent sensor provided by the invention is used for detecting the PFOA in the water body, the detection limit is as low as 0.5 ppm, and the fluorescent sensor has excellent sensitivity; in addition, the fluorescent sensor provided by the invention does not generate an obvious attenuation effect after detecting PFOA, and has relatively good water stability.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and particularly to a fluorescence sensor, a preparation method thereof, and an application thereof. Background Art

[0002] PFOA is one of the persistent organic pollutants perfluoro- and polyfluoroalkyl substances (PFASs), which has the characteristics of persistence, resistance to degradation, and easy bioaccumulation, and has been widely present in water bodies and organisms. Research shows that long-term or short-term large-scale exposure to PFOA will cause harm to human health. Therefore, the detection of PFOA concentration in various media is crucial.

[0003] Currently, the detection of PFOA in water bodies relies on traditional chromatography-mass spectrometry techniques. Although this method has high sensitivity, it requires professional technicians to guide the operation of large-scale instruments, and the equipment cost is high, and the sample pretreatment time is long. Therefore, the development of a low-cost, highly portable, and reliable detection method is of great significance for the detection of PFOA in water bodies. The fluorescence detection method has advantages such as high sensitivity and simple operation, and has great potential in the detection of PFOA.

[0004] Luminescent metal-organic frameworks (LMOFs) are a class of fluorescent materials with ultra-high porosity and specific surface area, and diverse and adjustable structures. These characteristics have enabled LMOF-based sensors to show advantages in the fields of detecting metal cations, anions, pH values, gases, biomolecules, and drugs. However, due to the relatively weak and reversible coordination bonds of LMOFs, most LMOFs have poor water stability and poor sensitivity to PFOA detection, which hinders the application of LMOFs in detecting PFOA in water bodies. Moreover, the LMOF materials prepared by conventional methods are in powder form, and there are problems such as difficult recovery when detecting PFOA in water bodies, making it difficult to meet the detection of PFOA in water bodies. Summary of the Invention

[0005] The purpose of the present invention is to provide a fluorescence sensor, a preparation method thereof, and an application thereof. The fluorescence sensor provided by the present invention has excellent water stability and sensitivity when detecting PFOA in water bodies.

[0006] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a fluorescence sensor, including a porous carrier and a fluorescent material loaded on the porous carrier, wherein the fluorescent material includes one or more of PCN-222, PCN-223, and PCN-224; the mass of the fluorescent material accounts for 5.0-7.2% of the mass of the fluorescence sensor.

[0008] Preferably, the porous carrier includes sponge or carbon cloth.

[0009] Preferably, the specific surface area of the porous carrier is 17 - 20.5 m 2 / g, and the pore size is 20.1 - 30 nm.

[0010] The present invention also provides a preparation method of the fluorescence sensor according to the above technical solution, including the following steps:

[0011] (1) Mix a zirconium source, an organic ligand, a structure regulator, and a solvent to obtain a precursor solution;

[0012] (2) Mix the precursor solution obtained in step (1) with the porous carrier, and perform a hydrothermal reaction to obtain a fluorescence sensor.

[0013] Preferably, the zirconium source in step (1) is ZrOCl2·8H2O.

[0014] Preferably, the organic ligand in step (1) is porphyrin.

[0015] Preferably, the structure regulator in step (1) is benzoic acid.

[0016] Preferably, the mass ratio of the zirconium source, the organic ligand, and the structure regulator in step (1) is (25 - 35):(0.9 - 1.1):(210 - 230).

[0017] Preferably, the temperature of the hydrothermal reaction in step (2) is 85 - 90 °C, and the time of the hydrothermal reaction is 5 - 6 h.

[0018] The present invention also provides the application of the fluorescence sensor according to the above technical solution or the fluorescence sensor prepared by the preparation method according to the above technical solution in detecting PFOA in water, including: mixing a test solution with the fluorescence sensor to obtain a test sample; observing the test sample under an ultraviolet lamp.

[0019] The present invention provides a fluorescence sensor, which comprises a porous carrier and a fluorescent material loaded on the porous carrier. The fluorescent material comprises one or more of PCN-222, PCN-223 and PCN-224; the mass of the fluorescent material accounts for 5.0-7.2% of the mass of the fluorescence sensor. In the present invention, the fluorescent material is loaded on the porous carrier, and the interaction between the fluorescent material and the porous carrier can improve the stability of the fluorescent material in water; the present invention uses one or more of PCN-222, PCN-223 and PCN-224 as the fluorescent material, which has a sensitive reaction to fluoride ions. When fluoride ions are present in water, the fluoride ions will destroy the structure of the above-mentioned fluorescent material, resulting in fluorescence quenching. Furthermore, this fluorescence sensor can be used to detect PFOA in water. The results of the examples show that when the fluorescence sensor provided by the present invention is used to detect PFOA in water, the detection limit is as low as 0.5 ppm, and it has excellent sensitivity; moreover, the fluorescence sensor provided by the present invention does not show an obvious attenuation effect after detecting PFOA and has good water stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the standard curve drawn by using the standard solution in Test Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention provides a fluorescence sensor, which comprises a porous carrier and a fluorescent material loaded on the porous carrier. The fluorescent material comprises one or more of PCN-222, PCN-223 and PCN-224; the mass of the fluorescent material accounts for 5.0-7.2% of the mass of the fluorescence sensor.

[0022] The fluorescence sensor provided by the present invention comprises a porous carrier. In the present invention, the porous carrier is used to load the fluorescent material, and the interaction between the carrier and the fluorescent material is utilized to improve the stability of the fluorescent material in water.

[0023] In the present invention, the porous carrier preferably comprises sponge or carbon cloth, and more preferably melamine sponge. The porous carrier adopted in the present invention has a porous structure and good stability, and can maintain good stability when loading the fluorescent material.

[0024] The present invention has no special limitation on the size of the porous carrier, and it can be adjusted according to the size of the required sensor.

[0025] In the present invention, the specific surface area of the porous carrier is preferably 17-20.5 m 2 / g, and more preferably 18.55 m 2 / g; The pore size of the porous support is preferably 20.1 - 30 nm, more preferably 24.18 nm. The porous support with the above parameters adopted in the present invention has a relatively high porosity and appropriate pore size, can load more fluorescent materials, and enables the fluorescent materials to be uniformly loaded in the pores, improving the stability and sensitivity of the fluorescence sensor.

[0026] The fluorescence sensor provided by the present invention includes a fluorescent material loaded on the porous support.

[0027] In the present invention, the fluorescent material includes one or more of PCN - 222, PCN - 223, and PCN - 224, more preferably PCN - 224. When the above fluorescent materials are adopted in the present invention, they have a relatively high sensitivity to PFOA, enabling the sensor to have good sensitivity when detecting PFOA.

[0028] In the present invention, the mass of the fluorescent material accounts for 5.0 - 7.2% of the mass of the fluorescence sensor, preferably 5.8%. When the loading amount of the fluorescent material in the fluorescence sensor provided by the present invention is within the above range, it can ensure that the fluorescent material is uniformly loaded in the porous support.

[0029] The present invention also provides a preparation method of the fluorescence sensor described in the above technical solution, including the following steps:

[0030] (1) Mix a zirconium source, an organic ligand, a structure regulator, and a solvent to obtain a precursor solution;

[0031] (2) Mix the precursor solution obtained in step (1) with the porous support and carry out a hydrothermal reaction to obtain the fluorescence sensor.

[0032] In the present invention, a zirconium source, an organic ligand, a structure regulator, and a solvent are mixed to obtain a precursor solution.

[0033] In the present invention, the zirconium source is preferably ZrOCl2·8H2O. The present invention uses the above zirconium source to provide zirconium elements for the fluorescent material, and the zirconium - based fluorescent material is more conducive to improving the water stability of the fluorescence sensor.

[0034] In the present invention, the organic ligand is preferably porphyrin. By adopting the above organic ligand in the present invention, a zirconium - based metal - organic framework with the required structure can be obtained.

[0035] In the present invention, the structure regulator is preferably benzoic acid. The present invention uses the structure regulator to regulate the pore structure, specific surface area, and chemical properties of the zirconium - based metal - organic framework, thereby improving the stability of the fluorescent material.

[0036] In the present invention, the mass ratio of the zirconium source, the organic ligand and the structure regulator is preferably (25 - 35):(0.9 - 1.1):(210 - 230), more preferably (30 - 35):(1.0 - 1.1):(220 - 230). By controlling the molar ratio of the zirconium source, the organic ligand and the structure regulator within the above range, the structure and chemical properties of the zirconium-based metal-organic framework can be optimized, which is more conducive to improving the stability of the fluorescent material.

[0037] In the present invention, the solvent is preferably N,N-dimethylformamide. By using the above solvent, a suitable reaction environment is provided for the hydrothermal reaction. There is no special limitation on the amount of the solvent used in the present invention. It can be adjusted according to the amounts of the zirconium source, the organic ligand and the structure regulator used, as long as it can dissolve the zirconium source, the organic ligand and the structure regulator and enable the hydrothermal reaction to proceed fully.

[0038] There is no special limitation on the method for mixing the zirconium source, the organic ligand, the structure regulator and the solvent in the present invention. A conventional mixing method can be adopted to dissolve the zirconium source, the organic ligand and the structure regulator in the solvent.

[0039] After obtaining the precursor solution, in the present invention, the precursor solution is mixed with the porous support and subjected to a hydrothermal reaction to obtain a fluorescent sensor.

[0040] There is no special limitation on the ratio of the volume of the precursor solution to the mass of the porous support in the present invention, as long as the porous support can be completely immersed in the precursor solution.

[0041] There is no special limitation on the method for mixing the precursor solution and the porous support in the present invention, as long as the pores of the porous support can be fully infiltrated with the precursor solution. In the present invention, the method for mixing the precursor solution and the porous support is preferably ultrasonic treatment. In the examples of the present invention, the ultrasonic treatment time is preferably 10 min.

[0042] In the present invention, the temperature of the hydrothermal reaction is preferably 85 - 90 °C, more preferably 90 °C; the time of the hydrothermal reaction is preferably 5 - 6 h, more preferably 5 h. By carrying out the reaction at the above temperature and time, the organic ligand and the zirconium cluster can form a coordination polymer through coordination. There is no special limitation on the apparatus for the hydrothermal reaction in the present invention, and any conventional hydrothermal reaction apparatus can be used. In the examples of the present invention, the apparatus for the hydrothermal reaction is preferably a reaction kettle.

[0043] In the present invention, when the mass of the fluorescent material in the fluorescent sensor fails to reach 5.0-7.2% of the mass of the fluorescent sensor, the present invention preferably repeats the hydrothermal reaction several times until the mass content of the fluorescent material in the fluorescent sensor reaches 5.0-7.2%. The present invention has no special limitation on the number of repetitions, and it is only necessary to make the mass content of the fluorescent material in the fluorescent sensor reach 5.0-7.2%.

[0044] The present invention preferably washes and dries the solid obtained from the hydrothermal reaction after the hydrothermal reaction to obtain a fluorescent sensor. The present invention has no special limitation on the operation methods of the washing and drying, and by using conventional washing and drying methods, impurities in the fluorescent sensor can be fully removed and the fluorescent sensor can be dried. In the present invention, the washing reagent is preferably N,N-dimethylformamide; the drying temperature is preferably 60-75°C, more preferably 65-70°C; the drying time is preferably 8-12 h, more preferably 10-12 h.

[0045] The method provided by the present invention is simple to operate, can in-situ load the fluorescent material on the porous carrier, make the fluorescent material evenly distributed on the porous carrier, and improve the stability of the fluorescent material by the interaction between the porous carrier and the fluorescent material.

[0046] The present invention also provides the application of the fluorescent sensor described in the above technical solution in detecting PFOA in water bodies, including: mixing the test solution with the fluorescent sensor to obtain a test sample; observing the test sample under an ultraviolet lamp.

[0047] In the present invention, the test solution is preferably an aqueous PFOA solution, and the concentration of the aqueous PFOA solution is preferably ≥0.5 ppm, more preferably 0.5-100 ppm. Since the fluorescent sensor provided by the present invention has a high sensitivity to PFOA, it can detect the above-mentioned test solution with a relatively low concentration.

[0048] The present invention has no special limitation on the mass ratio of the test solution to the fluorescent sensor, and it is only necessary to make the test solution fully infiltrate the pores of the fluorescent sensor. By fully infiltrating the test solution into the pores of the fluorescent sensor, the test solution can be brought into full contact with the fluorescent material in the fluorescent sensor.

[0049] The present invention has no special limitation on the method of mixing the test solution with the fluorescent sensor, and it is only necessary to make the test solution fully infiltrate the pores of the fluorescent sensor.

[0050] Preferably, in the present invention, after the solution to be tested is mixed with the fluorescence sensor and left standing for a period of time, a sample to be tested is obtained. By leaving it standing for a period of time, the solution to be tested can be fully contacted and reacted with the fluorescent material in the fluorescence sensor. In the present invention, the standing time is preferably 3 to 10 minutes, more preferably 5 minutes.

[0051] After obtaining the sample to be tested, the present invention observes the said sample to be tested under an ultraviolet lamp.

[0052] In the present invention, the wavelength of the ultraviolet lamp is preferably 630 - 660 nm, more preferably 654 nm. In the present invention, the fluorescent material has an obvious fluorescence phenomenon in the above wavelength range. When the solution to be tested contains PFOA, it can destroy the structure of the fluorescent material and cause fluorescence quenching. Furthermore, it can accurately judge whether the solution to be tested contains PFOA according to the change of the color of the sample to be tested. In the present invention, when the color of the sample to be tested is grayish green, it indicates that the solution to be tested contains PFOA; when the color of the sample to be tested is red - purple, it indicates that the solution to be tested does not contain PFOA.

[0053] The fluorescence sensor provided by the present invention uses PCN - 222, PCN - 223 and PCN - 224 as fluorescent materials, which have a sensitive reaction to fluoride ions. When the water contains fluoride ions, the fluoride ions will destroy the structure of the above - mentioned fluorescent materials and cause fluorescence quenching. Furthermore, the fluorescence sensor can be used to detect PFOA in water bodies.

[0054] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0055] Example 1

[0056] A fluorescence sensor is composed of a porous carrier and a fluorescent material loaded on the porous carrier. The fluorescent material is PCN - 224; the mass of the fluorescent material accounts for 5.8% of the mass of the fluorescence sensor; the porous carrier is melamine foam (MF), and the BET specific surface area of the MF is 18.55 m 2 / g, and the average pore diameter is 24.18 nm;

[0057] The preparation method of the above - mentioned fluorescence sensor is as follows:

[0058] (1) Dissolve 120 mg of ZrOCl2·8H2O, 40 mg of porphyrin (TCPP) and 880 mg of benzoic acid in 40 mL of DMF to obtain a precursor solution;

[0059] (2) The 100 mg MF block cut into squares was immersed in the uniformly mixed precursor solution obtained in step (1). After ultrasonic mixing for 10 min, it was sealed in a reaction kettle and hydrothermally reacted at 90 °C for 5 h. After cooling to room temperature, the hydrothermal reaction was repeated once. Then, the solid obtained from the hydrothermal reaction was washed with DMF and dried in an oven at 60 °C for 12 h to obtain a fluorescent sensor.

[0060] Example 2

[0061] A fluorescent sensor is composed of a porous support and a fluorescent material supported on the porous support. The fluorescent material is PCN-224; the mass of the fluorescent material accounts for 6.8% of the mass of the fluorescent sensor; the porous support is MF, and the BET specific surface area of the MF is 18.55 m 2 / g, and the average pore diameter is 24.18 nm;

[0062] The preparation method of the above fluorescent sensor is the same as that of Example 1.

[0063] Comparative Example 1

[0064] A fluorescent sensor is PCN-224;

[0065] The preparation method of the above fluorescent sensor is as follows:

[0066] (1) 120 mg of ZrOCl2·8H2O, 40 mg of porphyrin (TCPP), and 880 mg of benzoic acid were dissolved in 40 mL of DMF to obtain a precursor solution;

[0067] (2) The precursor solution obtained in step (1) was sealed in a reaction kettle and hydrothermally reacted at 90 °C for 5 h. After cooling to room temperature, the hydrothermal reaction was repeated once. Then, the solid obtained from the hydrothermal reaction was washed with DMF and dried in an oven at 60 °C for 12 h to obtain a fluorescent sensor.

[0068] Application Example 1

[0069] 1 mL of an aqueous PFOA solution with a concentration of 100 ppm was mixed with the fluorescent sensor prepared in Example 1. After standing for 5 min, a sample to be measured was obtained. The sample to be measured was observed under a blue light cutting gel instrument, and the fluorescence color changed from red-violet to gray-green.

[0070] Application Example 2

[0071] 1 mL of water was mixed with the fluorescent sensor prepared in Example 1. After standing for 5 min, a sample to be measured was obtained. The sample to be measured was observed under an ultraviolet lamp with a wavelength of 654 nm.

[0072] Test Example 1

[0073] (1) Prepare aqueous solutions of PFOA with concentrations of 5 ppm, 10 ppm, 20 ppm, 40 ppm, and 50 ppm respectively to obtain standard solutions with different concentrations;

[0074] (2) Take 1 mL of the standard solutions with different concentrations prepared in step (1) respectively, mix them with the fluorescence sensor prepared in Example 1, and after standing for 5 min, with an excitation wavelength of 522 nm and an emission wavelength of 654 nm, detect their fluorescence intensities, and draw a standard curve as Figure 1 shown. And the linear detection range of the fluorescence sensor prepared in Example 1 for PFOA is 0.75 - 50 ppm, and the linear correlation equation is (F 原始 - F 反应后 ) / F 原始 = 0.2640 (Log C PFOA ) - 0.0.1741, the linear correlation coefficient is 0.9956, and the detection limit is 0.5 ppm.

[0075] Test Example 2

[0076] (1) Mix water with the fluorescence sensor of Example 1, perform fluorescence detection at an excitation wavelength of 522 nm and an emission wavelength of 654 nm, and obtain an initial fluorescence intensity of 195; after standing for 30 min, perform fluorescence detection at an excitation wavelength of 522 nm and an emission wavelength of 654 nm, and obtain a fluorescence intensity of 193;

[0077] (2) Mix water with the fluorescence sensor of Comparative Example 1, perform fluorescence detection at an excitation wavelength of 522 nm and an emission wavelength of 654 nm, and obtain an initial fluorescence intensity of 138; after standing for 30 min, perform fluorescence detection at an excitation wavelength of 522 nm and an emission wavelength of 654 nm, and obtain a fluorescence intensity of 117;

[0078] It can be seen from the above test results that the attenuation of the fluorescence intensity of PCN-224 in the aqueous solution after detection is 15% after 30 min, while the fluorescence intensity of the fluorescence sensor prepared in Example 1 remains stable, thus proving that the fluorescence sensor prepared by the present invention has the characteristic of water stability.

[0079] Test Example 3

[0080] Another common perfluorinated compound, perfluorooctane sulfonic acid (PFOS), was tested. The results show that the effect of PFOS on the fluorescence intensity of the sensor is very different from that of PFOA, indicating that the sensor has a certain specificity. Under the same operation, the quenching rate of 50 ppm PFOS on fluorescence is 4.7%, which is much lower than that of PFOA at the same concentration.

[0081] As can be seen from the above results, the fluorescence sensor provided by the present invention has excellent water stability, a low detection limit, and excellent sensitivity for the detection of PFOA in water bodies. This is because the present invention utilizes the interaction between the fluorescent material and the porous carrier to improve the stability of the fluorescent material in water bodies; the present invention uses PCN-222, PCN-223, and PCN-224 as fluorescent materials, which have a sensitive reaction to fluoride ions, enabling the fluorescence sensor to have excellent sensitivity when detecting PFOA in water bodies.

[0082] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A fluorescence sensor, comprising a porous support and a fluorescent material loaded on the porous support, wherein the fluorescent material comprises one or more of PCN-222, PCN-223 and PCN-224; the mass of the fluorescent material accounts for 5.0-7.2% of the mass of the fluorescence sensor.

2. The fluorescence sensor according to claim 1, characterized in that, The porous support comprises sponge or carbon cloth.

3. The fluorescence sensor according to claim 1 or 2, characterized in that, The specific surface area of the porous carrier is 17-20.5 m 2 / g, and the pore diameter is 20.1-30 nm.

4. A method for preparing the fluorescence sensor according to any one of claims 1 to 3, comprising the following steps: (1) Mixing a zirconium source, an organic ligand, a structure regulator and a solvent to obtain a precursor solution; (2) Mixing the precursor solution obtained in step (1) with the porous support and performing a hydrothermal reaction to obtain the fluorescence sensor.

5. The preparation method according to claim 4, characterized in that, The zirconium source in step (1) is ZrOCl2·8H2O.

6. The preparation method according to claim 4, characterized in that, The organic ligand in step (1) is porphyrin.

7. The preparation method according to claim 4, characterized in that, The structure regulator in step (1) is benzoic acid.

8. The preparation method according to claim 4, characterized in that, The mass ratio of the zirconium source, the organic ligand and the structure regulator in step (1) is (25-35):(0.9-1.1):(210-230).

9. The preparation method according to claim 4, characterized in that, The temperature of the hydrothermal reaction in step (2) is 85-90°C, and the time of the hydrothermal reaction is 5-6 h.

10. Use of the fluorescence sensor according to any one of claims 1 to 3 or the fluorescence sensor prepared by the preparation method according to any one of claims 4 to 9 for detecting PFOA in water bodies, including: Mixing the test solution with the fluorescence sensor to obtain a test sample; Observing the test sample under an ultraviolet lamp.

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