A fluorescence sensor-based detection system, preparation method and application thereof

Abstract

The application discloses a detection system based on a fluorescent sensor and a preparation method and application thereof, and belongs to the technical field of fluorescent sensors. The detection system based on the fluorescent sensor comprises a fluorescent sensor, and the fluorescent sensor is Pt-MOF. The fluorescent sensor Pt-MOF in the application presents a special fluorescent color after being combined with H2S, and can present different fluorescent colors after being combined with H2S with different concentrations, thereby providing a new direction for visual detection and quantitative detection of H2S. In addition, the fluorescent sensor Pt-MOF in the application can be used to quantitatively and visually detect H2S without complex instruments and processes, and can be used to quickly detect H2S in food, thereby providing a convenient condition for judging whether the food is deteriorated.

Description

Technical Field

[0001] This invention belongs to the field of fluorescence sensor technology, specifically relating to a detection system based on a fluorescence sensor, its preparation method, and its application. Background Technology

[0002] Hydrogen sulfide, as one of the gases produced during food spoilage, can serve as an important indicator of food freshness. The sulfur in hydrogen sulfide has a -2 oxidation state, the lowest valence of sulfur, exhibiting strong reducing properties. Simultaneously, sulfur in the -2 oxidation state possesses strong nucleophilicity, allowing it to undergo a wide range of chemical reactions, such as redox reactions, nucleophilic substitution reactions, nucleophilic addition reactions, and coordination reactions. Utilizing the chemical properties of hydrogen sulfide, specific detection probes for hydrogen sulfide can be constructed.

[0003] Many techniques have been explored to detect the presence of H2S gas, including conductivity impedance methods, potentiometry, amperometry, colorimetry, absorption methods, and fluorescence methods. Currently, research on fluorescent sensors for detecting H2S in food mainly focuses on organic fluorescent molecular probes, with a small number of fluorescent nanoprobes also included.

[0004] (1) Organic fluorescent molecular probes

[0005] Almost all organic fluorescent molecular probes for detecting hydrogen sulfide possess a donor-π-acceptor (D-π-A) structure, with the donor and acceptor linked by conjugated systems such as C=C, C=N, or benzene rings, exhibiting strong fluorescence before or after recognition. For example, modifying a functional group on the fluorescent donor of an organic fluorescent molecule results in a fluorescence "off" state; when H2S is present, HS... − A trigger reaction causes the functional group to detach, releasing a fluorophore. This can eliminate donor-excited photoinduced electron transfer (d-PET) and restore the internal charge transfer (ICT) process, resulting in an "on" fluorescence state. This process is known as the fluorescence "off-on" strategy. Alternatively, the linker in the organic fluorescent molecule is highly reactive. After reacting with H2S, the D-π-A structure is destroyed, the internal charge transfer (ICT) process disappears, and the fluorescence is "off." This process is also known as the fluorescence "on-off" strategy.

[0006] (2) Fluorescent nanoprobes

[0007] Currently, there are relatively few reported fluorescent nanoprobes, such as the NIR775 / Cy7Cl@HyNPs near-infrared ratiometric fluorescent nanoprobe, SnSe2 / WO3 composite nanomaterial fluorescent probe, bismuth oxide nanorod colorimetric sensor, ruthenium nanoparticles (Ru NPs), and functionalized gold and silver nanoparticles. Taking the NIR775 / Cy7Cl@HyNPs near-infrared ratiometric fluorescent nanoprobe as an example, due to resonant energy transfer, it only emits fluorescence at ~810 nm. When H2S is present, the nucleophilicity of H2S can eliminate the resonant energy transfer, resulting in a decrease in fluorescence at ~810 nm and an increase in fluorescence at ~778 nm. H2S can be detected through fluorescence ratio.

[0008] Currently, refrigeration, freezing, vacuum packaging, protective gas packaging, and the use of new packaging materials are the main methods of food preservation. However, these methods can only slow down the spoilage process, which is inevitable. Therefore, developing a specific H2S detection system is both urgent and valuable in order to avoid food waste and the consumption of spoiled food. Summary of the Invention

[0009] In view of the above-mentioned prior art, the present invention provides a detection system based on a fluorescence sensor, a method for its preparation, and its application, so as to provide a sensor and process that can effectively detect H2S.

[0010] To achieve the above objectives, the technical solution adopted by this invention is to provide a detection system based on a fluorescence sensor, including a fluorescence sensor; the fluorescence sensor is Pt-MOFs; the Pt-MOFs are prepared through the following steps:

[0011] S1: Disperse the platinum salt in an organic solvent and stir at 30~60 °C until it is uniformly suspended to obtain a suspension; dissolve 2,2'-bipyridine in ethanol to obtain a 2,2'-bipyridine solution;

[0012] S2: Add the 2,2'-bipyridine solution to the suspension and stir for 10 min to obtain a mixed solution;

[0013] S3: Under an inert atmosphere, heat the mixed solution to 160~200 ℃, maintain the temperature for 5~10 h, then centrifuge and collect the solid;

[0014] S4: After cleaning the collected solids, vacuum dry them to obtain the fluorescent sensor Pt-MOFs.

[0015] Based on the above technical solution, the present invention can be further improved as follows.

[0016] Furthermore, the platinum salt is platinum tetrachloride, and the organic solvent is N,N-dimethylformamide.

[0017] Furthermore, the concentration of the suspension is 0.02~0.03 mol / L; the concentration of the 2,2'-bipyridine solution is 0.2~0.5 mol / L.

[0018] Furthermore, the molar ratio of platinum ions to 2,2'-bipyridine in the mixed solution obtained in S2 is 1:2.

[0019] Furthermore, the heating rate in S3 is 5~10 ℃ / min; the final heating temperature is 180 ℃; and the reaction time is 6 h.

[0020] Furthermore, the solid cleaning method in S4 is as follows: wash the solid with N,N-dimethylformamide 1 to 3 times, and then soak the washed solid in ethanol for 12 to 24 hours each time, for a total of 2 to 3 soakings.

[0021] Furthermore, the vacuum drying temperature in S4 is 80~120 ℃, and the vacuum drying time is 6~12 h.

[0022] This invention also discloses a method for preparing the above-mentioned detection system based on a fluorescence sensor, comprising the following steps:

[0023] (1) Disperse the fluorescence sensor in ethanol and sonicate for 10 min to obtain a dispersion with a concentration of 2 g / L.

[0024] (2) The dispersion is dropped onto a quartz glass slide and the ethanol is evaporated at room temperature to obtain a Pt-MOFs fluorescent film. The Pt-MOFs fluorescent film is a detection system based on a fluorescence sensor.

[0025] The present invention also discloses the application of the above-mentioned detection system based on a fluorescence sensor, specifically, the detection system based on a fluorescence sensor is used to detect H2S.

[0026] Furthermore, a detection system based on a fluorescence sensor is used for quantitative and / or visual detection of H2S; wherein, the quantitative detection of H2S includes the following steps:

[0027] (1) Disperse the H2S-containing sample in PBS buffer to obtain the test solution; then add the fluorescence sensor-based detection system to the test solution and let it stand at room temperature for 5 min; the ratio of the fluorescence sensor-based detection system to the test solution is 2.5 mg: 1 mL.

[0028] (2) Irradiate the test solution after the reaction with light of wavelength 365 nm, measure the fluorescence emission spectrum and record the fluorescence intensity Y at the maximum emission peak;

[0029] (3) Substitute the fluorescence intensity Y into the following equation to calculate the value of X, which is the concentration of H2S in the test solution, and its unit is ng / mL;

[0030] Y = -311.4ln(X) + 849.72

[0031] The visual detection of H2S includes the following steps:

[0032] (1) Disperse the H2S-containing sample in PBS buffer to obtain the test solution; then add the fluorescence sensor-based detection system to the test solution and let it stand at room temperature for 5 min; the ratio of the fluorescence sensor-based detection system to the test solution is 2.5 mg: 1 mL.

[0033] (2) Irradiate the test solution after the reaction with light of wavelength 365 nm and observe the fluorescence color of the test solution; the test solution shows different fluorescence colors as the concentration of H2S changes, so as to realize the visual detection of H2S.

[0034] The beneficial effects of this invention are:

[0035] 1. The fluorescent sensor Pt-MOFs in this invention exhibits a special fluorescent color after combining with H2S, which can specifically identify H2S and provide a new direction for the visual detection of H2S.

[0036] 2. The Pt-MOFs fluorescence sensor in this invention can exhibit different fluorescence colors when combined with different concentrations of H2S, and the fluorescence intensity has a linear relationship with the H2S concentration. Based on this, the Pt-MOFs fluorescence sensor in this invention can be used to quantitatively detect H2S, providing a new approach for detecting the H2S content in food.

[0037] 3. Using the Pt-MOFs fluorescence sensor in this invention, H2S can be quantitatively and visually detected without complicated instruments and processes. It can quickly detect H2S in food and other foods, providing convenient conditions for determining whether food has spoiled. Attached Figure Description

[0038] Figure 1 TEM images of Pt-MOF fluorescent sensors;

[0039] Figure 2 Elemental mapping images of Pt-MOFs fluorescence sensors;

[0040] Figure 3 This is a particle size distribution diagram of Pt-MOFs, a fluorescent sensor.

[0041] Figure 4 The fluorescence emission spectra of Pt-MOFs fluorescent sensors with and without H2S binding are shown.

[0042] Figure 5TEM image of Pt-MOFs fluorescent sensors after binding with H2S;

[0043] Figure 6 The elemental mapping image of Pt-MOFs fluorescent sensors after binding with H2S;

[0044] Figure 7 The fluorescence spectra of H2S at different concentrations after binding with the fluorescent sensor Pt-MOFs are shown.

[0045] Figure 8 The results show the linear fit between fluorescence intensity and H2S concentration.

[0046] Figure 9 The images show the fluorescence colors of different concentrations of H2S after interacting with the Pt-MOF fluorescence sensor. Detailed Implementation

[0047] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0048] Example 1: Fabrication of fluorescent sensor Pt-MOFs

[0049] The fabrication of Pt-MOF fluorescent sensors includes the following steps:

[0050] (1) 67.4 mg of platinum tetrachloride (PtCl4) was dispersed in 9 mL of N,N-dimethylformamide (DMF) and stirred at 40 °C until uniform suspension was obtained to obtain a platinum tetrachloride suspension; 62.5 mg of 2,2'-bipyridine was dissolved in 1 mL of ethanol to obtain a 2,2'-bipyridine solution;

[0051] (2) Slowly add the 2,2'-bipyridine solution to the platinum tetrachloride suspension and stir for 10 min to obtain a mixed solution;

[0052] (3) Transfer the mixed solution to the liner of the reactor, replace the air in the liner with nitrogen and then seal it; then put the liner into the reactor and heat it to 180 ℃ at a heating rate of 5 ℃ / min, and keep it at the temperature for 6 h; after the reaction is completed, let it cool naturally to room temperature, centrifuge (8000 rpm×5 min) and collect the solid.

[0053] (4) Wash the solid twice with fresh DMF; then soak the washed solid in ethanol for solvent exchange, soaking for 12 h each time, for a total of 3 soaks, to remove residual DMF in the pores;

[0054] (5) Place the solvent-exchanged sample in a vacuum drying oven and dry it under vacuum at 100 °C (<10- 2 After drying for 10 hours, the fluorescent sensor Pt-MOFs are obtained.

[0055] Transmission electron microscopy (TEM) images of fluorescent Pt-MOF sensors, such as Figure 1 As shown in the image, the Pt-MOF fluorescent sensors exhibit a rough, spherical structure. The elemental mapping image of the Pt-MOF fluorescent sensors is shown below. Figure 2 As shown in the figure, it can be seen that the fluorescent sensor Pt-MOFs contain representative Pt, O, C, and N elements. The particle size distribution of the fluorescent sensor Pt-MOFs is as follows. Figure 3 As shown, the average particle size of the fluorescent Pt-MOFs is 173.1 nm, which is larger than the 120 nm shown by the transmission electron microscope. This is because the structure measured by the particle size analyzer contains the hydration radius.

[0056] Example 2: Investigating the sensitivity of Pt-MOF fluorescent sensors to H2S concentration

[0057] The Pt-MOF fluorescent sensors were dispersed in PBS buffer (pH 7.4) to obtain a 1 mM dispersion. Two equal volumes of dispersion were taken; one was treated with H2S solution to bring the final H2S concentration to 100 μM, and the other was treated with the same volume of PBS buffer. After 5 min, the fluorescence emission spectra of both samples under a 365 nm laser were measured (emission range 400–750 nm). The results are shown below. Figure 4 As shown. From Figure 4 As can be seen, the Pt-MOF fluorescent sensors produce weak fluorescence in the absence of H2S, but the fluorescence in the presence of H2S becomes stronger. This is because H2S alters the structure of the fluorescent sensor, leading to increased fluorescence. Furthermore, morphological and elemental composition analyses of the H2S-bound Pt-MOF fluorescent sensors were performed, and the results are as follows: Figure 5 and 6 As shown; where, Figure 5 The images are transmission electron microscope (TEM) images of Pt-MOFs combined with H2S, from left to right: DF2, DF6 and HAADF imaging modes. Figure 6 This is an elemental mapping image of Pt-MOFs combined with H2S. From Figure 5 As can be seen, the morphology of the fluorescent Pt-MOF sensors changes significantly after binding with H2S, and the surface becomes smoother; from Figure 6 As can be seen, the key element S is clearly visible in the fluorescent sensor Pt-MOFs; the results show that H2S is indeed effectively bound to the fluorescent sensor Pt-MOFs.

[0058] Example 3: Constructing a standard curve for H2S detection and visualizing H2S detection

[0059] The method for constructing the H2S detection standard curve is as follows:

[0060] (1) 2 mg of fluorescent sensor Pt-MOFs powder was dispersed in 1 mL of ethanol and ultrasonically dispersed for 10 min to obtain a dispersion.

[0061] (2) The dispersion was uniformly dropped onto a clean quartz glass slide and dried at room temperature to prepare a solid Pt-MOFs fluorescent film;

[0062] (3) Dissolve Na2S in PBS buffer (pH 7.4) to prepare a stock solution with a concentration of 1 mM; then dilute the stock solution proportionally to obtain a series of H2S simulation solutions with different concentrations (0.005 ng / mL, 0.01 ng / mL, 0.05 ng / mL, 0.1 ng / mL, 0.5 ng / mL, 1 ng / mL, 5 ng / mL, 10 ng / mL); to ensure concentration stability, all solutions should be prepared fresh and stored under sealed conditions to prevent H2S volatilization;

[0063] (4) Place 5 mg of the prepared Pt-MOFs fluorescent film into a quartz cuvette, add 2 mL of H2S simulated solutions of different concentrations to the cuvette, and let it stand at room temperature for 5 min to allow the H2S to fully react with the Pt-MOFs; then use a fluorescence spectrometer to measure the fluorescence emission spectrum of the sample under a laser with a wavelength of 365 nm (emission range 400~750 nm), and record the fluorescence intensity at the maximum emission peak. The fluorescence spectra of H2S simulated solutions of different concentrations are shown below. Figure 7 As shown; from Figure 7 As can be seen, the fluorescence intensifies with increasing H2S concentration, indicating that the Pt-MOF fluorescence sensor is sensitive to H2S concentration. A standard curve was constructed with the H2S concentration as the x-axis and the fluorescence intensity as the y-axis, and linear fitting was performed. The results are shown below. Figure 8 As shown. From Figure 8 As can be seen, H2S exhibits a good linear relationship with fluorescence intensity within the concentration range of 0.005-10 ng / mL. The linear equation between fluorescence intensity and H2S concentration is as follows:

[0064] Y = -311.4ln(X) + 849.72, R 2 =0.9978,

[0065] Where Y is the fluorescence intensity and X is the H2S concentration.

[0066] (5) Place the prepared Pt-MOFs fluorescent film into a quartz cuvette, add 2 mL of H2S simulated solutions of different concentrations to the cuvette, and let it stand at room temperature for 5 min to allow the H2S to fully react with the Pt-MOFs. Then, under ultraviolet light irradiation at a wavelength of 365 nm, observe and photograph the changes in the fluorescence color of the sample with the naked eye. During the photographing, keep the exposure time, ISO, and aperture consistent. The results are as follows. Figure 9 As shown. From Figure 9 As can be seen, different concentrations of H2S react with the Pt-MOF fluorescence sensor and exhibit different fluorescence colors under ultraviolet light of a specific wavelength. This not only enables the visual detection of H2S, but also allows the concentration of H2S in the sample to be determined based on the displayed color, providing conditions for the qualitative and quantitative detection of H2S in food.

[0067] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. An application of a detection system based on a fluorescence sensor, characterized in that: A fluorescence sensor-based detection system is used to detect H2S; the fluorescence sensor-based detection system includes a fluorescence sensor; the fluorescence sensor is Pt-MOFs; the Pt-MOFs are prepared through the following steps: S1: Disperse the platinum salt in an organic solvent and stir at 30~60 °C until it is uniformly suspended to obtain a suspension; dissolve 2,2'-bipyridine in ethanol to obtain a 2,2'-bipyridine solution; S2: Add the 2,2'-bipyridine solution to the suspension and stir for 10 min to obtain a mixed solution; S3: Under an inert atmosphere, heat the mixed solution to 160~200 ℃, maintain the temperature for 5~10 h, then centrifuge and collect the solid; S4: After cleaning the collected solids, vacuum dry them to obtain the fluorescent sensor Pt-MOFs.

2. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that: The platinum salt is platinum tetrachloride, and the organic solvent is N,N-dimethylformamide.

3. The application of the detection system based on a fluorescence sensor according to claim 2, characterized in that: The concentration of the suspension is 0.02~0.03 mol / L; the concentration of the 2,2'-bipyridine solution is 0.2~0.5 mol / L.

4. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that: The molar ratio of platinum ions to 2,2'-bipyridine in the mixed solution obtained in S2 is 1:

2.

5. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that: The heating rate in S3 is 5~10 ℃ / min; the final heating temperature is 180 ℃; and the reaction time is 6 h.

6. The application of the detection system based on a fluorescence sensor according to claim 2, characterized in that: The solid cleaning method in S4 is as follows: wash the solid with N,N-dimethylformamide 1 to 3 times, and then soak the washed solid in ethanol for 12 to 24 hours each time, for a total of 2 to 3 soakings.

7. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that: The vacuum drying temperature in S4 is 80~120 ℃, and the vacuum drying time is 6~12 h.

8. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that, The fluorescence sensor-based detection system is manufactured through the following steps: (1) Disperse the fluorescence sensor in ethanol and sonicate for 10 min to obtain a dispersion with a concentration of 2 g / L. (2) The dispersion is dropped onto a quartz glass slide and the ethanol is evaporated at room temperature to obtain a Pt-MOFs fluorescent film. The Pt-MOFs fluorescent film is the detection system based on a fluorescence sensor.

9. The application of the detection system based on a fluorescence sensor according to claim 1, characterized in that, A fluorescence sensor-based detection system is used for quantitative and / or visual detection of H2S; wherein, the quantitative detection of H2S includes the following steps: (1) Disperse the H2S-containing sample in PBS buffer to obtain the test solution; then add the fluorescence sensor-based detection system to the test solution and let it stand at room temperature for 5 min; the ratio of the fluorescence sensor-based detection system to the test solution is 2.5 mg: 1 mL. (2) Irradiate the test solution after the reaction with light of wavelength 365 nm, measure the fluorescence emission spectrum and record the fluorescence intensity Y at the maximum emission peak; (3) Substitute the fluorescence intensity Y into the following equation to calculate the value of X, which is the concentration of H2S in the test solution, and its unit is ng / mL; Y = -311.4ln(X) + 849.72; The visual detection of H2S includes the following steps: (1) Disperse the H2S-containing sample in PBS buffer to obtain the test solution; then add the fluorescence sensor-based detection system to the test solution and let it stand at room temperature for 5 min; the ratio of the fluorescence sensor-based detection system to the test solution is 2.5 mg: 1 mL. (2) Irradiate the test solution after the reaction with light of wavelength 365 nm and observe the fluorescence color of the test solution; the test solution shows different fluorescence colors as the concentration of H2S changes, so as to realize the visual detection of H2S.

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