A polymer probe, its preparation method and application

Abstract

The application discloses a polymer probe and a preparation method and application thereof, and belongs to the technical field of chemical probes.The structural formula of the polymer probe provided by the application is shown as formula (I): in the formula (I), x and y are each independently selected from any integer in 1-3000.The polymer probe has good water solubility, obvious visual color change for sulfur dioxide and derivatives thereof, and can be used for qualitative or quantitative detection of sulfur dioxide and derivatives thereof in water; meanwhile, the polymer probe has thermal response performance, can be recycled and reused by heating after a reaction of the polymer probe with sulfur dioxide and derivatives thereof in an aqueous solution is completed, is used for secondary analysis and identification of sulfur dioxide and derivatives thereof, has good reusability, is favorable for cost reduction, and has wide application in detection of sulfur dioxide and derivatives thereof.

Description

Technical Field

[0001] This invention belongs to the field of chemical probe technology, and particularly relates to a polymer probe, its preparation method, and its application. Background Technology

[0002] Sulfur dioxide (SO2) and its derivatives (sulfites and bisulfites, etc.) are commonly found in most food additives, used as food processing aids and color stabilizers. They slow down browning of fruits and seafood by inhibiting enzymatic reactions and also act as antibacterial agents to inhibit microbial growth during food storage. However, epidemiological data shows that SO2 and its derivatives are weak mutagens. At high concentrations, they can cause cell and gene mutations, directly damaging the respiratory tract and causing damage to multiple organs and systems, including the stomach, intestines, liver, and kidneys. Furthermore, SO2 is difficult to eliminate externally; the body can only clear residues through its own regulatory mechanisms. Until the body's SO2 levels return to normal, varying degrees of pain will continue to bother patients. Therefore, SO2 and its derivatives are also one of the main sources of toxicity in food additives.

[0003] Current methods for detecting SO2 and its derivatives suffer from drawbacks such as high cost, the need for large-scale instruments, slow response times, and the inability to achieve rapid on-site detection. Chemical probes can overcome these shortcomings and represent an important direction for the detection of sulfur-containing gases and their derivatives. However, current SO2-based chemical probes suffer from low contrast, poor biocompatibility and selectivity, and difficulty in reusing them. Therefore, developing a biocompatible, highly specific, and reusable visualized polymer probe for detecting SO2-like substances is crucial for achieving accurate and visualized monitoring of excess SO2 additives. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a polymer probe that can achieve visual identification of sulfur dioxide and its derivatives through color change, and the polymer probe can be recycled and reused by heating.

[0005] The second objective of this invention is to provide a method for preparing the aforementioned polymer probe.

[0006] The third objective of this invention is to provide a method for detecting sulfur dioxide and its derivatives.

[0007] The third objective of this invention is to provide a detection kit for sulfur dioxide and its derivatives.

[0008] The inventive concept of this invention is as follows: This invention utilizes N-isopropylacrylamide and oxazoline monomers to generate covalent bonds through a copolymerization reaction, thereby producing a copolymeric polymer probe. Since SO2 and its derivatives can alter the conjugated structure of the oxazoline molecule through the reaction site, causing a significant change in the probe's color, the oxazoline monomer can respond to sulfur dioxide and its derivatives, enabling qualitative and quantitative detection of SO2 and its derivatives. N-isopropylacrylamide is a thermosensitive polymer monomer; its addition not only improves the water solubility and recyclability of the oxazoline monomer probe but also facilitates its reuse. After the polymer probe reacts with SO2 and its derivatives in an aqueous solution and completes one detection, the polymer probe can be recovered and reused by heating. The color restoration effect after heating is higher than that of the oxazoline monomer, allowing for further analysis and identification of sulfur dioxide derivatives.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A first aspect of the present invention provides a polymer probe, characterized in that the polymer probe has the structural formula shown in formula (I):

[0011]

[0012] In equation (I), x and y are each independently selected from any integer from 1 to 3000.

[0013] A second aspect of the present invention provides a method for preparing the polymer probe described in the first aspect of the present invention, comprising the following steps: copolymerizing N-isopropylacrylamide and oxazoline monomers to obtain the polymer probe;

[0014] The structural formula of the oxazoline monomer is shown in formula (II):

[0015]

[0016] The monomer name of the oxazoline molecule shown in formula (II) is: (E)-N-(9a-(4-dimethylaminostyryl)-9,9-dimethyl-2,3,9,9a-tetrahydrooxazolo[3,2-a]indol-7-yl)-acrylamide.

[0017] Preferably, in the method for preparing the polymer probe, the copolymerization reaction is carried out in a thermal polymerization initiator and an organic solvent.

[0018] Preferably, in the method for preparing the polymer probe, the thermal polymerization initiator is selected from azobisisobutyronitrile (AIBN).

[0019] Preferably, in the method for preparing the polymer probe, the organic solvent is selected from alcohol-based organic solvents; more preferably, the alcohol-based organic solvent includes at least one of methanol, ethanol, propanol, isopropanol, n-butanol, or isobutanol.

[0020] Preferably, in the preparation method of the polymer probe, the molar ratio of the oxazoline monomer to the N-isopropylacrylamide is 1:(100-1000); more preferably 1:(200-700); and even more preferably 1:(300-400).

[0021] Preferably, in the preparation method of the polymer probe, the molar ratio of the oxazoline monomer to the thermal polymerization initiator is 1:(1500-5000); more preferably 1:(2000-4000); and even more preferably 1:(2500-3500).

[0022] Preferably, in the method for preparing the polymer probe, the ratio of the oxazoline monomer to the organic solvent is 1 mmol:(150-1000) mL; more preferably, 1 mmol:(180-700) mL; and even more preferably, 1 mmol:(200-400) mL.

[0023] Preferably, in the method for preparing the polymer probe, the molar ratio of the oxazoline monomer, N-isopropylacrylamide and the thermal polymerization initiator is 1:(100-1000):(1500-5000); more preferably 1:(200-700):(2000-4000); and even more preferably 1:(300-400):(2500-3500).

[0024] Preferably, in the method for preparing the polymer probe, the temperature of the copolymerization reaction is 50–120°C; more preferably 55–100°C; and even more preferably 60–80°C.

[0025] Preferably, in the method for preparing the polymer probe, the copolymerization reaction time is 10-36 h; more preferably 12-30 h; and even more preferably 15-24 h.

[0026] Preferably, in the method for preparing the polymer probe, the oxazoline monomer is obtained by a preparation method comprising the following steps:

[0027] 1) 2,3,3-trimethyl-5-nitroindole was subjected to a substitution reaction with bromoethanol to obtain the intermediate 2,3,3-trimethyl-5-nitroindole bromide.

[0028] 2) The intermediate 2,3,3-trimethyl-5-nitroindole bromide obtained in step 1) is reacted with p-(N,N-dimethyl)benzaldehyde to obtain intermediate product A;

[0029] 3) The intermediate product A obtained in step 2) is reacted under the catalysis of carbonate to obtain intermediate product B;

[0030] 4) The intermediate product B obtained in step 3) is reduced by ammonium chloride and iron powder to obtain intermediate product C;

[0031] 5) The intermediate product C obtained in step 4) is reacted with acryloyl chloride under the catalysis of triethylamine to obtain the oxazoline monomer.

[0032] Preferably, in the method for preparing the oxazoline monomer, in step 1), the molar ratio of 2,3,3-trimethyl-5-nitroindole to bromoethanol is 1:(1-5); more preferably 1:(1.2-3).

[0033] Preferably, in the method for preparing the oxazoline monomer, in step 1), the substitution reaction is carried out in an organic solvent; more preferably, in step 1), the organic solvent includes one of methanol, ethanol, acetonitrile, or toluene.

[0034] Preferably, in the method for preparing the oxazoline monomer, in step 1), the ratio of 2,3,3-trimethyl-5-nitroindole to organic solvent is 1 mmol:(1-20) mL; more preferably, it is 1 mmol:(3-15) mL.

[0035] Preferably, in the method for preparing the oxazoline monomer, in step 1), the temperature of the substitution reaction is 60–120°C; more preferably 80–100°C.

[0036] Preferably, in the method for preparing the oxazoline monomer, in step 1), the substitution reaction time is 12–48 h; more preferably 18–36 h.

[0037] Preferably, in the method for preparing the oxazoline monomer, in step 2), the molar ratio of 2,3,3-trimethyl-5-nitroindole bromide to p-(N,N-dimethyl)benzaldehyde is 1:(0.8-3); more preferably 1:(1-2).

[0038] Preferably, in the method for preparing the oxazoline monomer, in step 2), the reaction is carried out in an organic solvent; more preferably, in step 2), the organic solvent includes at least one of ethanol, acetonitrile, or toluene.

[0039] Preferably, in the method for preparing the oxazoline monomer, in step 2), the ratio of 3,3-trimethyl-5-nitroindole bromide to organic solvent is 1 mmol:(3-20) mL; more preferably, it is 1 mmol:(4-10) mL.

[0040] Preferably, in the method for preparing the oxazoline monomer, in step 2), the reaction temperature is 75–120°C; more preferably, it is 80–100°C.

[0041] Preferably, in the method for preparing the oxazoline monomer, in step 2), the reaction time is 4 to 24 hours; more preferably 6 to 12 hours.

[0042] Preferably, in the method for preparing the oxazoline monomer, in step 3), the carbonate includes at least one of sodium carbonate, potassium carbonate, or lithium carbonate.

[0043] Preferably, in the method for preparing the oxazoline monomer, in step 3), the carbonate participates in the reaction in the form of an aqueous solution; more preferably, in step 3), the carbonate participates in the reaction in the form of a saturated aqueous solution.

[0044] Preferably, in the method for preparing the oxazoline monomer, in step 3), the ratio of intermediate product A to saturated carbonate aqueous solution is 1 mmol:(5-20) mL; more preferably, it is 1 mmol:(6-15) mL.

[0045] Preferably, in the method for preparing the oxazoline monomer, step 3) further includes an organic solvent; more preferably, in step 3), the organic solvent is selected from ethyl acetate.

[0046] Preferably, in the method for preparing the oxazoline monomer, in step 3), the ratio of intermediate product A to organic solvent is 1 mmol:(5-20) mL; more preferably, it is 1 mmol:(6-15) mL.

[0047] Preferably, in the method for preparing the oxazoline monomer, in step 3), the ratio of intermediate product A, saturated aqueous solution of carbonate, and organic solvent is 1 mmol:(5-20) mL:(5-20) mL; more preferably, it is 1 mmol:(6-15) mL:(6-15) mL.

[0048] Preferably, in the method for preparing the oxazoline monomer, in step 3), the reaction temperature is 20–30°C; more preferably, it is 24–26°C.

[0049] Preferably, in the method for preparing the oxazoline monomer, in step 4), the reduction reaction is carried out in a mixed solvent of water and organic solvent; more preferably, in step 4), the volume ratio of water to organic solvent in the mixed solvent is 1:(2-10); even more preferably, it is 1:(3-6).

[0050] Preferably, in the method for preparing the oxazoline monomer, in step 4), the organic solvent includes at least one of methanol, ethanol, or acetonitrile.

[0051] Preferably, in the method for preparing the oxazoline monomer, in step 4), the ratio of intermediate product B to mixed solvent is 1 mmol:(100-200) mL; more preferably, it is 1 mmol:(140-180) mL.

[0052] Preferably, in the method for preparing the oxazoline monomer, in step 4), the molar ratio of intermediate product B, ammonium chloride and iron powder is 1:(1-5):(2-7); more preferably 1:(2-4.5):(3-6).

[0053] Preferably, in the method for preparing the oxazoline monomer, in step 4), the temperature of the reduction reaction is 70–140°C; more preferably 80–120°C.

[0054] Preferably, in the method for preparing the oxazoline monomer, in step 4), the reduction reaction time is 2 to 24 hours; more preferably, it is 4 to 12 hours.

[0055] In the preparation method of the oxazoline monomer, after the reduction reaction described in step 4), the nitro group in intermediate product B is reduced to an amino group.

[0056] Preferably, in the method for preparing the oxazoline monomer, in step 5), the reaction is carried out in a halogenated organic solvent; more preferably, in step 5), the halogenated organic solvent includes at least one of dichloromethane, chloroform, or carbon tetrachloride.

[0057] Preferably, in the method for preparing the oxazoline monomer, in step 5), the reaction temperature is -5 to 5°C; more preferably, it is 0°C.

[0058] Preferably, in the method for preparing the oxazoline monomer, in step 5), the reaction time is 1 to 20 hours; more preferably, it is 3 to 10 hours.

[0059] Preferably, in the method for preparing the oxazoline monomer, in step 5), the molar ratio of the intermediate product C, acryloyl chloride and triethylamine is 1:(2-6):(1.5-5); more preferably 1:(2.4-5):(2-4).

[0060] In the preparation method of the oxazoline monomer, after the reaction described in step 5), the amino group in the intermediate product C is converted into an amide group.

[0061] A third aspect of the present invention provides a method for detecting sulfur dioxide and its derivatives, wherein the method uses the polymer probe described in the first aspect of the present invention as a detection reagent to detect the analyte.

[0062] Specifically, the analyte is detected using colorimetry. This method can achieve qualitative or semi-quantitative detection of the analyte, and it is a visual detection method with a simple and easy-to-perform process.

[0063] Preferably, in the detection method, the polymer probe described in the first aspect of the present invention is used as the detection reagent, and the analyte is detected according to the proportional relationship between the luminescence intensity and the concentration of the analyte.

[0064] Specifically, quantitative detection methods rely on the proportional relationship between luminescence intensity and analyte concentration to detect the analyte.

[0065] Preferably, in the detection method, the polymer probe is recovered by heating for use in the next detection of the analyte.

[0066] Preferably, in the detection method, the heating temperature is 30–80°C; more preferably, it is 35–60°C.

[0067] Preferably, in the detection method, the heating time is 10 to 60 minutes; more preferably, it is 20 to 40 minutes.

[0068] Preferably, in the detection method, the recovery rate of the polymer probe is 40-90%; more preferably 50-90%.

[0069] In a specific embodiment of the present invention, the initial recovery rate of the polymer probe is 80-90%; more specifically, it is 82-88%.

[0070] A fourth aspect of the present invention provides a detection kit for sulfur dioxide and its derivatives, the detection kit comprising the polymer probe described in the first aspect of the present invention.

[0071] The beneficial effects of this invention are: the polymer probe exhibits good water solubility and clear visual color changes in sulfur dioxide and its derivatives, enabling qualitative or quantitative detection of sulfur dioxide and its derivatives in water; simultaneously, the polymer probe has thermal response properties, and after a single detection is completed by reacting the polymer probe with sulfur dioxide and its derivatives in an aqueous solution, it can be recovered and reused by heating for further analysis and identification of sulfur dioxide and its derivatives. This polymer probe has good reusability, which helps reduce costs and has wide applications in the detection of sulfur dioxide and its derivatives.

[0072] Specifically, compared with the prior art, the present invention has the following advantages:

[0073] 1. The copolymeric polymer probe prepared by this invention exhibits a significant color change in the detection of sulfur dioxide and its derivatives. During detection, the polymer probe reacts with sulfur dioxide and its derivatives, changing from a magenta color to colorless, enabling the qualitative or quantitative detection of sulfur dioxide and its derivatives in water using colorimetry. After one detection by reacting the polymer probe with sulfur dioxide and its derivatives in an aqueous solution, heating the solution causes the polymer probe to precipitate from the water, turning magenta. Upon separation and subsequent placement in water at room temperature or below, the polymer probe dissolves again, allowing for further analysis and identification of sulfur dioxide derivatives. The polymer probe of this invention is reusable, exhibiting good reusability and reducing costs, and has wide applications in the detection of sulfur dioxide and its derivatives.

[0074] 2. The polymer probe preparation method of the present invention is simple, the raw material sources are diverse, and it is easy to produce and apply on a large scale. Attached Figure Description

[0075] Figure 1 This is a synthetic route diagram of the polymer probe P-1 in Example 1.

[0076] Figure 2 Add 10 equivalents of SO3 to the P-1 probe solution 2- The color change before and after.

[0077] Figure 3 Add different equivalents of SO3 to the P-1 probe solution 2- The UV-Vis absorption differential spectrum.

[0078] Figure 4 The images show the UV-Vis absorption differential spectra of the P-1 probe solution reacting with different ions.

[0079] Figure 5 The graph shows the physical changes of the P-1 probe solution when it reacts with different ions.

[0080] Figure 6 This is a schematic diagram illustrating the changes in the P-1 probe solution after repeated recycling.

[0081] Figure 7 The UV-Vis absorption spectrum changes when the P-1 probe solution is repeatedly cycled.

[0082] Figure 8 Add SO3 to monomer D probe solution 2- The UV-Vis absorption differential spectra before and after.

[0083] Figure 9 Add SO3 to monomer D probe solution 2- UV-Vis absorption spectra after fading and heating at different temperatures for 30 minutes.

[0084] Figure 10 Add SO3 to monomeric D probe solution 2- The image shows the changes in the object after fading and heating at 75°C for 30 minutes. Detailed Implementation

[0085] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0086] Example 1

[0087] In this embodiment, a polymer probe P-1 was prepared, and its synthetic route is shown below. Figure 1 As shown, the specific synthesis process is as follows:

[0088] (1) Step 1: Weigh 5 mmol (1.02 g) of 2,3,3-trimethyl-5-nitroindole and dissolve it in 15 mL of acetonitrile. Then add 6.8 mmol (500 μL) of bromoethanol and stir until homogeneous. Heat the mixture at 90 °C under reflux and stir for 25 h. After the reaction is complete, cool to room temperature, remove excess solvent, filter the precipitate to obtain a filter cake, and wash with ethyl acetate to obtain 0.66 g of brown solid, which is the intermediate 2,3,3-trimethyl-5-nitroindole bromide, with a yield of 40.1%.

[0089] (2) Step 2: Weigh 2.2 mmol (0.33 g) of p-(N,N-dimethyl)benzaldehyde and 2.0 mmol (0.65 g) of the intermediate product 2,3,3-trimethyl-5-nitroindole bromide obtained in Step 1 into 10 mL of ethanol, heat and reflux and stir for 8 h to obtain 0.72 g of dark blue solid, which is intermediate product A, with a yield of 78.3%.

[0090] (3) Step 3: At room temperature, 1.5 mmol (0.69 g) of intermediate product A was mixed with 10 mL of saturated sodium carbonate (Na2CO3) and 10 mL of ethyl acetate and stirred for 1 h. After the reaction, the solution was separated by a separatory funnel. The upper liquid was dried by rotary evaporator to obtain 0.53 g of orange-yellow solid, which was intermediate product B, with a yield of 93.0%.

[0091] (4) Step 4: Weigh 0.9 mmol (0.34 g) of intermediate product B obtained in step 3, dissolve it in a mixed solvent of 120 mL EtOH and 30 mL H2O, add 1.8 mmol (0.096 g) NH4Cl and 2.7 mmol (0.1512 g) Fe, and heat and stir at 85 °C for 6 h. After the reaction is cooled to room temperature, neutralize the solvent with saturated Na2CO3 aqueous solution, and then remove the mixed solvent of ethanol and water. Dissolve the residue in water, extract with ethyl acetate, dry with anhydrous sodium sulfate, and finally remove ethyl acetate to obtain 0.28 g of brown solid, which is intermediate product C, with a yield of 90%.

[0092] (5) Step 5: Weigh 0.3 mmol (0.11 g) of intermediate product C obtained in step 4, dissolve it in 5 mL of CH2Cl2, add 0.66 mmol (0.067 g) of triethylamine, and stir at 0 °C for 20 min; add 0.72 mmol (0.066 g) of acryloyl chloride dropwise to the stirred solution, and continue stirring at 0 °C for 5 h; wash with water and 5% NaOH solution, separate the liquid, dry the organic phase with Na2SO4 solid, and then remove the organic solvent to obtain 0.067 g of purple solid, which is oxazoline monomer D, with a yield of 56.0%.

[0093] (6) Step 6: Weigh 0.026 mmol (0.010 g) of the oxazoline monomer D obtained in Step 5, 8.8 mmol (1.0 g) of N-isopropylacrylamide, and 72.8 mmol (0.012 g) of azobisisobutyronitrile, and dissolve them in 7 mL of n-butanol; degas the solution by three refrigeration pump-thawing cycles, and stir at 70 °C for 18 h under nitrogen protection. The resulting polymer is evaporated and concentrated to remove the solvent, and then purified by precipitation with 3 mL of methanol and 250 mL of diethyl ether to obtain 0.893 g of purple solid, which is the target copolymer probe P-1, with a yield of 86%.

[0094] At 25℃, the oxazoline monomer D and the polymer probe P-1 were dissolved in ethanol / water solution (v / v, 3 / 7), and the absorbance of each was measured at 567nm. Based on the absorbance of the two, the ratio of x to y in the polymer probe P-1 was determined to be 883:1.

[0095] Example 2

[0096] This example uses the polymer probe P-1 obtained in Example 1 as a probe to provide a method for detecting sulfur dioxide derivatives. The detection effect of polymer probe P-1 on sulfur dioxide derivative Na2SO3 solution is tested. The specific process is as follows:

[0097] A solution containing 10 μM (0.57 g / L) of polymer probe P-1 was prepared using sodium phosphate buffer (pH = 7.4) and designated as probe solution P-1. A sulfur dioxide derivative solution, Na2SO3, was added to the probe solution P-1, and the color changes of the solution before and after the reaction with 10 equivalents of Na2SO3 were recorded using a digital camera. Figure 2 Add 10 equivalents of SO3 to the P-1 probe solution 2- Color changes before and after. Figure 2 It can be clearly seen that the P-1 probe solution changes from rose red to colorless. By utilizing the significant color change after the P-1 probe reacts with Na2SO3, it is possible to achieve visual colorimetric detection of sulfur dioxide derivatives and realize the qualitative detection of sulfur dioxide and its derivatives.

[0098] The changes in absorption peaks of polymer probe P-1 were measured using a UV-Vis spectrophotometer after the addition of different concentrations of Na2SO3 (0.01 equivalents to 100 equivalents). The polymer probe P-1 aqueous solution was used as a reference solution, and the polymer probe P-1 aqueous solutions with different concentrations of Na2SO3 were used as test solutions. The changes in the intensity and wavelength of the polymer probe P-1 absorption peaks were investigated and measured using differential spectroscopy. Figure 3 Add different equivalents of SO3 to the P-1 probe solution 2- The UV-Vis absorption differential spectrum. Figure 3 It can be seen that with SO3 2- With increasing concentration, the absolute value of the absorbance of the polymer probe at 567 nm gradually increases, and the absorption intensity of the polymer probe gradually strengthens.

[0099] Example 3

[0100] This example uses the polymer probe P-1 obtained in Example 1 as a probe to provide a method for detecting sulfur dioxide derivatives, and explores the selectivity of polymer probe P-1 for detecting sulfur dioxide derivatives. The specific process is as follows:

[0101] A solution containing 10 μM (0.57 g / L) of polymer probe P-1 was prepared using sodium phosphate buffer (pH = 7.4), and denoted as probe solution P-1, for later use. 1 mM solutions of sodium nitrite (NaNO2), sodium chloride (NaCl), sodium perchlorate (NaClO4), sodium chlorate (NaClO3), sodium fluoride (NaF), sodium nitrate (NaNO3), sodium azide (NaN3), sodium sulfate (Na2SO4), sodium thiosulfate (Na2S2O3), sodium bicarbonate (NaHCO3), sodium sulfite (Na2SO3), sodium bisulfite (NaHSO3), potassium thiocyanate (KSCN), potassium bromide (KBr), potassium iodide (KI), potassium acetate (CH3COOK), and 50 mM tetrabutylammonium cyanide (n-Bu4N) were also prepared. + CN - Prepare a solution of sodium sulfide (Na₂S) for later use. Take 3 mL of the prepared P-1 probe solution and add it to a 10 mL transparent vial. Add 3 μL of each of the prepared ion solutions respectively, and determine the reaction of the polymer probe P-1 to different ions. Figure 4 The images show the UV-Vis absorption differential spectra of the P-1 probe solution reacting with different ions. Figure 5 The graphs show the physical changes of the P-1 probe solution after reacting with different ions. Figure 4 and Figure 5 It is known that polymer probe P-1 has good detection selectivity for sulfur dioxide derivatives and can be used as a probe for detecting sulfur dioxide and its derivatives.

[0102] Example 4

[0103] This example uses the polymer probe P-1 obtained in Example 1 as a probe to provide a method for detecting sulfur dioxide derivatives, and explores the reversible detection of sulfur dioxide derivatives by polymer probe P-1. The specific detection process is as follows:

[0104] A solution containing 10 μM (0.57 g / L) of polymer probe P-1 was prepared using sodium phosphate buffer (pH = 7.4), denoted as P-1 probe solution, for later use. At room temperature, the P-1 probe solution was rose-red in color and was transparent and homogeneous. Upon addition of 20 equivalents of sodium sulfate, the solution color faded, becoming colorless. The solution was heated to 50°C; after 5 minutes, it gradually became turbid, and a rose-red solid precipitated from the solution. After heating for 30 minutes, the solid was obtained by hot filtration and redissolved in sodium phosphate buffer (pH = 7.4) to obtain a homogeneous rose-red aqueous solution. Upon further addition of 20 equivalents of sodium sulfate solution, the solution color faded again. Figure 6 This diagram illustrates the changes in the P-1 probe solution after repeated recycling. The UV-Vis absorption spectrum of the polymer probe P-1 solution was measured during this process. Figure 7 The UV-Vis absorption spectrum changes after repeated cycles of the P-1 probe solution show that the polymer probe P-1 exhibits good reversible detection performance for sulfur dioxide derivatives, and the polymer probe P-1 demonstrates good repeatability. Figure 7 The absorbance data can be used to calculate the recovery rate of the polymer P-1 probe. The recovery rate calculation formula is as follows:

[0105] Recovery rate = Absorbance of the reconstituted PD-1 probe solution / Absorbance of the original PD-1 probe solution × 100%.

[0106] It can be calculated that the color recovery rate of the P-1 probe solution after the first reconstitution is 85.1%, that is, the recovery rate of the polymer P-1 probe after the first heating is 85.1%, while the color recovery rate of the P-1 probe solution after the second reconstitution is 51.6%.

[0107] Example 5

[0108] This example uses the polymer probe P-1 obtained in Example 1 and the oxazoline monomer D as probes to provide a method for detecting sulfur dioxide derivatives, and explores and compares the reversible detection effects of the two probes on sulfur dioxide derivatives. The specific process is as follows:

[0109] Prepare 100 mL of an ethanol / water (v / v, 3 / 7) mixed solution containing 10 μM oxazoline monomer D, designated as the monomer D probe solution, for later use. Take 3 mL of the above monomer D probe solution into two cuvettes, one as the reference solution and the other as the test solution, and measure its absorption spectrum using a UV-Vis spectrophotometer. Then, add 3 μL (10 equivalents) of Na₂SO₃ aqueous solution to the test solution and determine the concentration of SO₃ added to the monomer D probe solution using differential spectroscopy. 2- The changes in absorption peak intensity and wavelength before and after, Figure 8 Add SO3 to monomeric D probe solution 2- The UV-Vis absorption difference spectra before and after. (From...) Figure 8 It can be seen that the oxazoline monomer D has a certain detection effect on sulfur dioxide derivatives.

[0110] Using ethanol / water (v / v, 3 / 7) as the reference solution, SO3 was added. 2- The monomeric D probe solutions were heated at 25, 30, 40, 50, 60, 70, and 75 °C for 30 min, respectively, and used as test solutions. Their UV-Vis absorption spectra were then measured. Figure 9 Add SO3 to monomeric D probe solution 2- UV-Vis absorption spectra after fading and heating at different temperatures for 30 minutes. Figure 9It can be seen that as the temperature increases, the absorption peak at 567 nm is enhanced. For the original monomer D probe solution that has not been copolymerized with isopropylacrylamide, the color recovery rate of the monomer D solution heated at 75 °C is the highest at 28.7%, which means that the recovery rate of the oxazoline monomer D probe after heating at 75 °C is only 28.7%. Figure 10 Add SO3 to monomeric D probe solution 2- The image shows the changes in the product after fading and heating at 75°C for 30 minutes. It can be seen that the addition of SO3... 2 Even after heating to 75°C, the monomeric D probe solution remains nearly colorless and cannot be used for the next detection of sulfur dioxide derivatives.

[0111] As described in Example 4, the recovery rate of the polymer P-1 probe after the first heating can reach 85.1%. This shows that the addition of the thermosensitive polymer monomer N-isopropylacrylamide not only improves the water solubility of the oxazoline monomer probe, but also assists in the reuse of the probe, thereby increasing the probe recovery rate.

[0112] The polymer probe of this invention exhibits good water solubility and clear visual color changes in sulfur dioxide and its derivatives, enabling qualitative or quantitative detection of sulfur dioxide and its derivatives in water. Simultaneously, the polymer probe possesses thermal response properties; after a single detection by reacting the polymer probe with sulfur dioxide and its derivatives in an aqueous solution, it can be recovered and reused through heating for further analysis and identification of sulfur dioxide and its derivatives. This polymer probe demonstrates good reusability, which helps reduce costs and has wide applications in the detection of sulfur dioxide and its derivatives.

Claims

1. A polymer probe, characterized in that, The structural formula of the polymer probe is shown in formula (I): （I）； In equation (I), x and y are each independently selected from any integer from 1 to 3000.

2. The method for preparing the polymer probe according to claim 1, characterized in that, The process includes the following steps: copolymerizing N-isopropylacrylamide and oxazoline monomers to obtain the polymer probe; The structural formula of the oxazoline monomer is shown in formula (II): (II)。 3. The preparation method according to claim 2, characterized in that, The copolymerization reaction is carried out in a thermal polymerization initiator and an organic solvent; The thermal polymerization initiator is selected from azobisisobutyronitrile; And / or, the organic solvent includes at least one of methanol, ethanol, propanol, n-butanol or isobutanol.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the oxazoline monomer to the N-isopropylacrylamide is 1:(100~1000). And / or, the molar ratio of the oxazoline monomer to the thermal polymerization initiator is 1:(1500~5000). And / or, the ratio of the oxazoline monomer to the organic solvent is 1 mmol: (150~1000) mL.

5. The preparation method according to claim 2, characterized in that, The temperature of the copolymerization reaction is 50~120℃; And / or, the copolymerization reaction takes 10 to 36 hours.

6. A method for detecting sulfur dioxide and its derivatives, characterized in that, The detection method uses the polymer probe described in claim 1 as the detection reagent to detect the analyte.

7. The detection method according to claim 6, characterized in that, The detection method uses the polymer probe described in claim 1 as the detection reagent, and detects the analyte based on the proportional relationship between the luminescence intensity and the concentration of the analyte.

8. The detection method according to claim 6, characterized in that, The polymer probe is recovered by heating for use in the next analyte detection.

9. The detection method according to claim 8, characterized in that, The heating temperature is 30~80℃; And / or, the heating time is 10~60 min.

10. A detection kit for sulfur dioxide and its derivatives, characterized in that, The detection kit includes the polymer probe as described in claim 1.

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