Chitosan-based fluorescent probe, preparation method and application thereof in detecting ferric iron

Abstract

The application discloses a chitosan-based fluorescent probe, a preparation method and application thereof in detection of trivalent iron. 3+ The probe can be combined with Fe 3+ in a 33% THF solvent, so that the fluorescence of the probe is quenched.The probe molecule can qualitatively and quantitatively detect Fe 3+ in a real sample.Moreover, the probe CS-Pyr-1 has the characteristics of quick response (110s) and good stability under wide pH (pH=3-10) conditions, and therefore has important application value in the fields of biochemistry and the like.The structural formula of the probe is as follows: CS-Pyr-1

Description

Technical Field

[0001] This invention belongs to the field of fluorescence detection and relates to the application of fluorescent probes for detecting Fe3+, specifically a chitosan-based fluorescent probe, its preparation method, and its application in the detection of trivalent iron. Background Technology

[0002] Fe 3+ It plays a crucial role in metabolic processes. It not only participates in cellular metabolism but is also an essential element in the formation of proteins and various enzymes within organisms. Excessive Fe... 3+ It can cause diseases such as heart disease and cancer. Throughout the food chain, Fe... 3+ It can pose potential health hazards due to its migration and accumulation in environmental water systems. Therefore, Fe 3+ The detection and removal of [the substance] are of great significance.

[0003] Currently, several instrumental methods have been established to identify Fe in aqueous solutions. 3+ Methods include atomic absorption spectrometry, X-ray fluorescence spectrometry, ultraviolet-visible spectrophotometry, and inductively coupled plasma atomic absorption spectrometry. However, these methods suffer from drawbacks such as high cost and complex operation and pretreatment, which limit their potential applications. Therefore, there is a strong need to develop a simple, highly selective, and fast-responding fluorescent probe for the detection of Fe. 3+ . Summary of the Invention

[0004] This invention provides a chitosan-based fluorescent probe, its preparation method, and its application in the detection of ferric iron.

[0005] One objective of this invention is to provide a fluorescent probe with a simple synthetic route, mild reaction conditions, and low cost; another objective is to provide a probe with high sensitivity, good selectivity, strong anti-interference ability, and the ability to accurately detect Fe in complex systems. 3+ The structure is as follows: CS-Pyr-1; Where n represents the degree of polymerization, which is 300 to 500.

[0006] The synthetic route and synthetic idea are as follows: The method for preparing the chitosan-based fluorescent probe includes the following steps: Chitosan was dissolved in an aqueous acetic acid solution. Then, a solution containing compound P3 was added dropwise to the chitosan solution and reacted at 55-75°C for 7-9 hours. After post-treatment, a chitosan-based fluorescent probe was obtained in the form of an aerogel. The structure of the compound P3 is as follows: P3.

[0007] The ratio of chitosan to aqueous acetic acid is 180-220 mg: 5-15 mL; The volume percentage of acetic acid in the acetic acid aqueous solution is 0.5-2%.

[0008] The solvent in the solution containing compound P3 is tetrahydrofuran.

[0009] The post-processing specifically includes: leaving the reaction product exposed for 2-5 days to evaporate the solvent, washing with tetrahydrofuran, and finally freeze-drying to obtain an aerogel containing a chitosan-based fluorescent probe.

[0010] Specific synthesis method: 180-220 mg of chitosan was dissolved in 5-15 mL of 1% acetic acid aqueous solution. Subsequently, different concentrations of P3 (dissolved in 2 mL of THF) were slowly added dropwise to the chitosan solution, and the reaction was carried out at 65°C for 8 hours. The hydrogel was left exposed for 3 days to evaporate the solvent. It was then washed with THF. Finally, the aerogel was freeze-dried to obtain the corresponding aerogel.

[0011] The chitosan-based fluorescent probe prepared by the aforementioned method can be used for qualitative and quantitative detection of Fe. 3+ Applications of the reagent include: The chitosan-based fluorescent probe was dissolved in an aqueous acetic acid solution to prepare the probe solution. Then, the analyte was added, and after the reaction, the fluorescence change was observed by fluorescence detection at an excitation wavelength of 270-275 nm.

[0012] Specifically, the fluorescent probe CS-Pyr-1 was dissolved in a 1% acetic acid aqueous solution to prepare the probe solution. Then, the analyte was added, and after the reaction, the fluorescence change was observed by fluorescence detection at an excitation wavelength of 274 nm.

[0013] The fluorescent probe CS-Pyr-1 was dissolved in a 1% acetic acid aqueous solution to prepare the probe solution. Then, the sample to be tested was added, and the fluorescence intensity was detected. The Fe was quantitatively calculated based on the linear relationship between the fluorescence intensity and the concentration of the added sample. 3+ The content of.

[0014] like Figure 8 As shown, the mechanism of the probe of the present invention is as follows: The mechanism of action of the fluorescent probe of this invention is as follows: In the probe molecule, the hydroxyl group in CS-Pyr-1 undergoes an enol-imine / ketoenamine tautomerism via ESIPT. This tautomerism binds to metal ions, thereby producing strong fluorescence quenching (detection limit: 1.5 × 10⁻⁶). -6 (mol / L). And forms a stable chelating group CS-Pyr-1-Fe. 3+Composite part.

[0015] The fluorescent probe of this invention has the characteristics of simple synthesis route, fast response and low susceptibility to environmental interference.

[0016] The chitosan-based fluorescent probe of the present invention is used to detect Fe 3+ The probe can react with Fe in 33% THF solvent. 3+ Complexation quenches the fluorescence of the probe. The probe molecule described in this invention can qualitatively and quantitatively detect Fe in real samples. 3 + Furthermore, the probe CS-Pyr-1 exhibits a rapid response (110 s) and good stability over a wide pH range (pH=3-10), making it valuable for applications in fields such as biochemistry. Attached Figure Description

[0017] Figure 1 The infrared spectra of chitosan and probe CS-Pyr-1 in this invention are shown, with the horizontal axis representing wavenumber (cm²). -1 The vertical axis represents transmittance (T %).

[0018] Figure 2 The thermogravimetric analysis spectrum of the probe CS-Pyr-1 in the invention, with the horizontal axis representing temperature (°C) and the vertical axis representing weight percentage (wt%). Figure 3 Transmission electron microscopy (TEM) of probe CS-Pyr-1 in this invention.

[0019] Figure 4 Scanning electron microscope (SEM) of probe CS-Pyr-1 in the invention.

[0020] Figure 5 The ultraviolet absorption spectrum of probe CS-Pyr-1 in THF:H2O=1:2 solution in this invention.

[0021] Figure 6 The probe CS-Pyr-1 of this invention, in a THF:H2O=1:2 solution, was compared with a control and Na at room temperature. + , K + , Sr 2+ Al 3+ Cu 2+ Fe 3+ Ag + , Mn 2+ Zn 2+ Pb 2+ Cd 2+ , Cr 3+ Hg 2+ and Fe 2+The fluorescence spectrum recorded during the reaction. Excitation wavelength: 274 nm.

[0022] Figure 7 The probe CS-Pyr-1 of this invention and Fe of different concentrations 3+ The fluorescence intensity after the reaction and its linear relationship.

[0023] Figure 8 This is a diagram illustrating the reaction mechanism of the probe of the present invention.

[0024] Table 1. Fe in actual water samples 3+ Recovery rate data. Detailed Implementation

[0025] The present invention will be further described below with reference to examples and accompanying drawings, but the present invention is not limited to the following embodiments. Unless otherwise specified, all percentages appearing in the embodiments are mass percentages.

[0026] Example 1: Synthesis of CS-Pyr-1 fluorescent probe 180–220 mg of chitosan was dissolved in 5–15 mL of 1% acetic acid aqueous solution. Then, different concentrations of P3 (dissolved in 2 mL of THF) were slowly added dropwise to the chitosan solution, and the reaction was carried out at 65 °C for 8 hours. The hydrogel was left exposed for 3 days to allow the solvent to evaporate. It was then washed with THF. Finally, the aerogel was freeze-dried to obtain the corresponding aerogel. CS-Pyr-1; The degree of polymerization is 3000~500.

[0027] The structure of compound P3 is as follows: P3.

[0028] Example 2: Selectivity of CS-Pyr-1 fluorescent probe for different metal ions The 50 mg CS-Pyr-1 fluorescent probe from Example 1 was dissolved in 200 mL of 1% AcOH.

[0029] Prepare a solution of the following substances: NaCl, KCl, MgCl₂·6H₂O, CuCl₂·2H₂O, FeCl₃·6H₂O, AgNO₃, MnCl₂·4H₂O, ZnCl₂, CoCl₂, SrCl₂, PbCl₂, CdCl₂·2.5H₂O, CrCl₃·6H₂O, FeCl₂·4H₂O, and HgCl₂ to a concentration of 1 × 10⁻⁶. -2 mol / L of mother liquor.

[0030] Take 16 test tubes and add 100 µL of the different metal ion stock solutions to each tube sequentially. Replace the interfering substances with an equal volume of water for the control. Then add 1500 µL of ultrapure water and 1000 µL of THF. Finally, add 400 µL of probe stock solution to each tube. Shake each solution well and perform fluorescence detection (Ex=274 nm). Plot fluorescence intensity on the ordinate and wavelength on the abscissa. Figure 6 ;Depend on Figure 6 Fe can be found 3+ It can significantly quench the fluorescence intensity of CS-Pyr-1, while other metal ions have almost no interference with its fluorescence intensity.

[0031] Example 3: Fe at different concentrations 3+ Fluorescence intensity of CS-Pyr-1 The concentration was set at 1 × 10⁻⁶. -2 mol / L Fe 3+ The final Fe content was controlled by varying the volume of the mother liquor added to the test tube. 3+ The concentration forms 0-60 equivalent Fe. 3+ The content of Fe was determined. After the reaction, fluorescence detection (Ex=274nm) was performed to measure the fluorescence intensity in each system. The fluorescence intensity was plotted on the ordinate. 3+ Plot a curve with the concentration on the x-axis and demonstrate a linear relationship. Figure 7 It can be seen that with Fe 3+ As the concentration of Fe increases, the fluorescence intensity of the probe gradually decreases. 3+ When the content reaches 60 equivalents, the fluorescence of the probe no longer decreases.

[0032] Example 4: CS-Pyr-1 fluorescent probe for Fe in different water samples 3+ Detection Two types of water samples were selected for spiked recovery experiments (West Lake water and lake water from the Moganshan Campus of Zhejiang University of Technology). Six Fe strains were prepared using these water samples. 3+ Concentration of 1×10 -3 A solution of mol / L.

[0033] Add 100 µL of CS-Pyr-1 stock solution to two test tubes, and dilute to 3 mL with 1900 µL of each of the six water samples and 1 mL of THF, respectively. Detect fluorescence at Ex=274 nm. See Table 1.

[0034] Table 1. Fe in actual water samples 3+ Recovery rate data Conclusion: Verified using the national standard method, this invention can recover and detect Fe in actual water samples. 3+ .

Claims

1. A chitosan-based fluorescent probe, characterized in that, It has the following structural formula: CS-Pyr-1; Where n represents the degree of polymerization, which is 300 to 500.

2. The method for preparing the chitosan-based fluorescent probe according to claim 1, characterized in that, Includes the following steps: Chitosan was dissolved in an aqueous acetic acid solution. Then, a solution containing compound P3 was added dropwise to the chitosan solution and reacted at 55-75°C for 7-9 hours. After post-treatment, a chitosan-based fluorescent probe was obtained in the form of an aerogel. The structure of the compound P3 is as follows: P3。 3. The method for preparing the chitosan-based fluorescent probe according to claim 2, characterized in that, The ratio of chitosan to aqueous acetic acid is 180-220 mg: 5-15 mL; The volume percentage of acetic acid in the acetic acid aqueous solution is 0.5-2%.

4. The method for preparing the chitosan-based fluorescent probe according to claim 2, characterized in that, The solvent in the solution containing compound P3 is tetrahydrofuran.

5. The method for preparing the chitosan-based fluorescent probe according to claim 2, characterized in that, The post-processing specifically includes: leaving the reaction product exposed for 2-5 days to evaporate the solvent, washing with tetrahydrofuran, and finally freeze-drying to obtain an aerogel containing a chitosan-based fluorescent probe.

6. The chitosan-based fluorescent probe prepared by the method according to claim 2 can be used as a qualitative and quantitative detector for Fe. 3+ Its application in reagents, characterized in that, include: The chitosan-based fluorescent probe was dissolved in an aqueous acetic acid solution to prepare the probe solution. Then, the analyte was added, and after the reaction, the fluorescence change was observed by fluorescence detection at an excitation wavelength of 270-275 nm.

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