CN114437713A

CN114437713A - Temperature response type polymer fluorescent probe, preparation method thereof and application of temperature response type polymer fluorescent probe in detection of gold ions

Info

Publication number: CN114437713A
Application number: CN202210025910.XA
Authority: CN
Inventors: 毛艳丽; 管伟民; 顾林彦; 王蕾; 韩娟; 兰会玲; 王赟
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2022-01-11
Filing date: 2022-01-11
Publication date: 2022-05-06
Anticipated expiration: 2042-01-11
Also published as: CN114437713B

Abstract

The invention belongs to the technical field of fluorescent probes, and discloses a temperature response type polymer fluorescent probe and a preparation method and application thereof. The fluorescent probe is made of temperature-sensitive polymer PEG₁₁₃‑b‑P(NIPAM‑co‑GMA)_mThe grafted rhodamine B thiohydrazide is prepared by preparing benzyl trithiocarbonate BTPA, preparing a polyethylene glycol macromolecular transfer agent through esterification reaction with polyethylene glycol monomethyl ether, polymerizing glycidyl methacrylate GMA onto the polyethylene glycol macromolecular transfer agent through polymerization, and finally grafting the rhodamine B thiohydrazide onto the prepared polymer. The obtained temperature response type polymer fluorescent probe solves the need of a small molecule fluorescent probeThe gold ion detection reagent has the advantages of being good in gold ion identification performance after repeated circulation, strong in anti-interference performance, free of interference of common metal ions, sensitive in reaction and convenient and fast to use.

Description

Temperature response type polymer fluorescent probe, preparation method thereof and application of temperature response type polymer fluorescent probe in detection of gold ions

Technical Field

The invention belongs to the technical field of fluorescent probes, and particularly relates to a temperature response type polymer fluorescent probe, a preparation method thereof and application of the temperature response type polymer fluorescent probe in gold ion detection.

Background

Gold is highly chemically stable and is distributed in nature primarily in the elemental state. Gold has been used as a precious metal for thousands of years in the fields of coinage, decoration, and the like. Due to rapid development of science and technology in recent decades, gold has been widely used in the fields of physics, chemistry and medicine due to its unique physicochemical properties. With the large amount of gold used, new problems are brought about. Gold is safe and harmless in its simple substance, but gold in its ionic form causes some damage to the liver, kidneys and nervous system. According to the literature, 200 u M gold ion salt solution can produce 90% of cytotoxicity effect, gold ion can also be associated with DNA, resulting in DNA lysis.

The existing gold ion detection modes mainly comprise an atomic absorption method, an ion mass spectrometry method, an electrochemical method, an inductively coupled plasma atomic emission spectrometry method and the like besides a fluorescent probe. Although these methods are sensitive and specific, they require expensive instruments and complicated operations. The traditional small molecule organic probe has poor water solubility, needs to add an organic solvent as a cosolvent, and may cause secondary pollution, and the traditional probe cannot be recycled, which increases the use cost of the fluorescent probe. The temperature response type polymer fluorescent probe has the advantages of high sensitivity, good selectivity and simple and convenient operation of the fluorescent probe, and also has the advantages of easy recovery of the temperature sensitive polymer and good water solubility, and the reaction between the probe and an analyte is reversible. Therefore, the prepared temperature response type polymer fluorescent probe is sensitive to response of gold ions, strong in anti-interference performance, easy to recycle, environment-friendly, excellent in cycle performance and simple and convenient to operate. Therefore, the development of a temperature response type polymer fluorescent probe is significant.

Disclosure of Invention

The invention aims to provide a temperature response type polymer fluorescent probe, which has a structural formula as follows:

a method for preparing a temperature response type polymer fluorescent probe comprises the following steps:

(1) preparation of rhodamine B hydrazide

Weighing rhodamine B, dissolving the rhodamine B in methanol, uniformly stirring at room temperature, dropwise adding 85 wt% hydrazine hydrate, stirring, heating and refluxing the prepared solution, and cooling to room temperature after the reaction is finished; when a large amount of orange solid is separated out, carrying out reduced pressure distillation; washing the solid with deionized water, then carrying out suction filtration, dissolving the solid in methanol, carrying out reduced pressure distillation again, washing with deionized water, then carrying out suction filtration, and repeating the previous operation twice to obtain pink solid, namely rhodamine B hydrazide;

wherein the dosage ratio of rhodamine B, methanol and hydrazine hydrate is 3-5g, 60-100mL and 9-15 mL. The reflux heating temperature is 60-80 ℃, and the reaction time is 4-6 h.

(2) Preparation of rhodamine B thiohydrazide

Dissolving the rhodamine B hydrazide prepared in the step (1) in toluene, adding a Lawson reagent, heating and refluxing in a nitrogen atmosphere, stopping heating after the reaction is finished, and cooling to room temperature; and (3) carrying out reduced pressure distillation, and removing the solvent to obtain a light purple solid, wherein the obtained light purple solid is the rhodamine B thiohydrazide.

Wherein the dosage ratio of rhodamine B hydrazide, toluene and Lawson reagent is 0.182-0.273 g: 4-6 mL: 0.162-0.243 g. The reflux reaction temperature is 70-90 ℃, and the reaction time is 3-5 h.

(3) Preparation of BTPA reagent

Dropwise adding 3-mercaptopropionic acid into a potassium hydroxide aqueous solution, then stirring vigorously and dropwise adding carbon disulfide, and reacting for a period of time. Adding benzyl bromide for reflux reaction. After the reaction is finished, cooling the mixed solution to room temperature, adding trichloromethane, adding hydrochloric acid to adjust the pH value of the mixed solution, repeatedly washing the organic layer by using a large amount of distilled water, rotationally evaporating the organic layer, and using excessive dichloromethane to obtain a yellow solid, namely BTPA.

Wherein the dosage ratio of potassium hydroxide, 3-mercaptopropionic acid, carbon disulfide, benzyl bromide, trichloromethane and hydrochloric acid is 3.25-3.55 g: 2.5-3.0 mL: 4-6 mL: 5-5.5 g: 70mL of: 8 mL; the reaction temperature is 82-85 ℃, and the reaction time is 12-14 h.

(4) Macromolecular chain transfer agent PEG based on polyethylene glycol monomethyl ether₁₁₃Preparation of (E) -BTPA

Dissolving dried polyethylene glycol monomethyl ether and BTPA prepared in the step (3) in anhydrous dichloromethane, uniformly stirring in an ice-water bath, then adding a dichloromethane solution containing 4-dimethylaminopyridine DMAP and N, N-dicyclohexylcarbodiimide DCC, stirring for reaction, filtering after the reaction is finished, concentrating under reduced pressure, and precipitating the concentrated filtrate by using excessive ethyl glacial ether to obtain a precipitate; dissolving the precipitate in dichloromethane, concentrating under reduced pressure, precipitating with glacial ethyl ether, repeating for several times, and drying to obtain light yellow solid, i.e. PEG-based macromolecular chain transfer agent; wherein the dosage ratio of the polyethylene glycol monomethyl ether, the BTPA and the dichloromethane is 1.0 mmol: 2.0 mmol: 50 mL; adding 4-dimethylamino pyridine, N-dicyclohexyl carbodiimide and dichloromethane into dichloromethane mixed solution, wherein the dosage ratio of the 4-dimethylamino pyridine to the N, N-dicyclohexyl carbodiimide to the dichloromethane mixed solution is 50 mg: 1 g: 20 mL; the reaction temperature is 25 ℃, and the reaction time is 48 h.

(5) Temperature-sensitive block polymer PEG₁₁₃Preparation of (NIPAM-co-GMA)

The macromolecular chain transfer agent PEG of the polyethylene glycol monomethyl ether prepared in the step (4)₁₁₃Dissolving BTPA, N-isopropylacrylamide, glycidyl methacrylate and azobisisobutyronitrile in 1, 4-dioxane, deoxidizing the mixed solution, reacting in a nitrogen atmosphere, quenching the polymerization reaction by using an ice-water bath after the reaction is finished, opening a seal, and exposing the seal to air. Diluting with 1, 4-dioxane, and precipitating with cold diethyl ether. Repeating the dissolving-precipitating steps for three times to obtain the light yellow temperature-sensitive block polymer PEG₁₁₃-b-P(NIPAM-co-GMA)。

Wherein, the polyethylene glycol monomethyl ether macromolecular chain transfer agent PEG₁₁₃-BTPA, N-isopropylacrylamide, glycidyl methacrylate, azobisisobutyronitrile and 1, 4-dioxane in a ratio of 0.32 to 0.53 g: 0.85-1.41 g: 0.6-1 mmol: 6-10 mg: 3-5 mL; the oxygen removal mode is to introduce nitrogen for 30min, the reaction temperature is 70-80 ℃, and the reaction time is 22-24 h.

(6) The temperature-sensitive block polymer PEG prepared in the step (5)₁₁₃Dissolving B-P (NIPAM-co-GMA) and rhodamine B thiohydrazide prepared in the step (2) in 1, 4-dioxane, uniformly mixing, removing oxygen in the mixed liquid, and adding N₂And carrying out oil bath reaction under the atmosphere, quenching the reaction by using an ice water bath after the reaction is finished, and then precipitating by using excessive cold ether to obtain a pink product, namely the temperature response type polymer fluorescent probe.

Wherein the dosage ratio of the temperature-sensitive block polymer, the rhodamine B thiohydrazide and the 1, 4-dioxane is 170-330 mg: 10-20mg, 2-4 mL; the oxygen removal mode is to introduce nitrogen for 30min, the oil bath reaction temperature is 70-80 ℃, and the reaction time is 22-24 h.

The invention also provides Au detection based on the temperature response type polymer fluorescent probe³⁺The use of (1).

Compared with the traditional detection method, the method has the following beneficial effects:

the rhodamine hydrazide is used as a basic raw material, and the rhodamine fluorescent dye has high fluorescence quantum yield, good light stability and other excellent photophysical and photochemical properties. The fluorescent probe is synthesized by using rhodamine hydrazide and a Lawson reagent, the material is easy to obtain, the preparation is simple, the yield is high, and the fluorescent probe has high selectivity on gold ions and is not interfered by other ions in the comparison of several metal ions; the synthetic fluorescent probe P is used for detecting gold ions, so that naked eye detection can be realized, and other instruments are not needed.

The adopted temperature-sensitive block polymer can be polymerized along with the rise of temperature, is easy to separate from the solution, and the temperature-sensitive block polymer PEG₁₁₃the-b-P (NIPAM-co-GMA) has good water solubility.

The rhodamine B fluorescent probe is connected to the temperature-sensitive block polymer PEG in a grafting way₁₁₃b-P (NIPAM-co-GMA). The method can solve the recovery problem of the rhodamine B fluorescent probe. The separation of the fluorescent probe from the solution is facilitated. After the rhodamine B fluorescent probe is combined with the temperature-sensitive block polymer, the fluorescent probe is more soluble in water, and the fluorescent probe is more easy to use and recycle through modification.

Drawings

FIG. 1 is a preparation process of a temperature-responsive polymer fluorescent probe, wherein (a) is a preparation schematic diagram of rhodamine B hydrazide, (B) is a preparation schematic diagram of rhodamine B thiohydrazide, (c) is a preparation schematic diagram of a temperature-sensitive block polymer, and (d) is a preparation schematic diagram of a fluorescent probe prepared by grafting rhodamine B thioamide on the basis of the temperature-sensitive block polymer.

FIG. 2 is a depiction of rhodamine B thiohydrazide as described in example 1¹H NMR chart.

FIG. 3 temperature sensitive Block Polymer PEG₁₁₃-b-P(NIPAM-co-GMA)_mIs/are as follows¹H NMR chart.

FIG. 4 based on a temperature responsive polymer fluorescent probe P¹H NMR chart.

FIG. 5 is an FT-IR plot of rhodamine B hydrazide and rhodamine B thiohydrazide prepared in example 1.

FIG. 6 is a FT-IR plot of the temperature sensitive block polymer prepared in example 1 and a polymer-based fluorescent probe P.

FIG. 7 shows a turbidity plot at different concentrations of the fluorescent probe P prepared in example 1.

FIG. 8 shows the sedimentation separation of the fluorescent probe P prepared in example 1 in an aqueous solution.

FIG. 9 shows a graph of light transmittance of the fluorescent probe P prepared in example 1 by repeated heating and cooling in an aqueous solution.

FIG. 10 is a graph showing the sensitivity of the fluorescent probe P prepared in example 1 to detection of gold ions after multiple cycles.

FIG. 11 shows the following Au³⁺Graph showing the change in UV absorbance of the fluorescent probe P prepared in example 1 was added.

FIG. 12 shows the following Au³⁺(iii) addition of (D), a graph showing the change in fluorescence intensity of the probe P prepared in example 1.

FIG. 13 shows the addition of Au to the fluorescent probe P prepared in example 1³⁺Then adding the fluorescence spectrogram measured by other metal ions.

FIG. 14 is a fluorescent probe P prepared in example 1 with Au added³⁺Then adding ultraviolet absorption spectrogram measured by various metal ions.

Detailed Description

For the purpose of clearly describing the invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, not all embodiments of the present invention, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the protection scope of the present invention. The invention is further illustrated by the following examples in which:

example 1:

FIG. 1 shows a schematic diagram of the synthesis of a temperature-responsive polymer fluorescent probe P, wherein a diagram (a) is a preparation process of rhodamine B hydrazide, a diagram (B) is a preparation process of rhodamine B thiohydrazide, a diagram (c) is a preparation process of a temperature-sensitive block polymer, and a diagram (d) is a preparation process based on the temperature-sensitive block polymer fluorescent probe P. The specific preparation process is as follows:

(1) preparation of rhodamine B hydrazide

Weighing 4g of rhodamine B, adding the rhodamine B into a 250mL three-neck flask, adding 80mL of methanol for dissolving and stirring, dropwise adding 12mL of 85% hydrazine hydrate at room temperature, uniformly stirring, heating and refluxing at 75 ℃ for 5 hours, cooling to room temperature after the reaction is finished, carrying out reduced pressure distillation when a large amount of orange solid precipitates, adding secondary deionized water into the obtained solid for washing, and carrying out suction filtration. The resulting solid was dissolved in methanol, distilled under reduced pressure again, and washed with water. Repeating the operation for 2 times to obtain pink solid rhodamine B hydrazide.

(2) Preparation based on rhodamine B thiohydrazide

Weighing 0.228g of rhodamine B hydrazide prepared in the step (1), adding into 25mL of round bottom bakedIn a bottle, 5mL of toluene was dissolved, and 0.203g of Lawson's reagent was added. Mixing the mixture in N₂Heated to 80 ℃ under atmosphere and refluxed for 4 h. And after the reaction is finished, cooling the solution to room temperature, carrying out reduced pressure distillation, and removing the solvent to obtain a light purple solid, namely the rhodamine B thiohydrazide.

(3) Preparation of BTPA

Dissolving 3.25g of potassium hydroxide in 32mL of deionized water, dropwise adding 2.5mL of 3-mercaptopropionic acid, dropwise adding 4mL of carbon disulfide under vigorous stirring to obtain an orange-yellow liquid, stirring the orange-yellow liquid at room temperature for 5 hours, adding 5g of benzyl bromide after stirring is finished, and placing the mixture in an oil bath kettle at 85 ℃ for reaction for 12 hours.

After the reaction, the mixture solution was cooled to room temperature, and poured into 70mL of chloroform, and acidified by dropwise addition of hydrochloric acid until the organic phase turned yellow, followed by washing the organic phase with an excess amount of deionized water, drying the organic phase with anhydrous sodium sulfate, and concentrating under reduced pressure to obtain a concentrated solution. Adding a proper amount of dichloromethane into the concentrated solution, precipitating product crystals in a refrigerator, washing the product crystals with deionized water, dissolving the product crystals in chloroform, concentrating under reduced pressure, recrystallizing, repeating the operation for three times, and finally drying the obtained product in a vacuum drying oven overnight to obtain a yellow solid.

(4) Macromolecular chain transfer agents (PEG) based on polyethylene glycol monomethyl ether₁₁₃-BTPA) preparation

2g of dried polyethylene glycol monomethyl ether PEG₁₁₃OH and 0.55g of dry BTPA were dissolved in 50mL of anhydrous dichloromethane, and after the solid was completely dissolved, the mixture was stirred in an ice-water bath for 30 min. Subsequently, 20mL of a methylene chloride solution containing 50mg of 4-dimethylaminopyridine DMAP and 1g N, N-dicyclohexylcarbodiimide was dropwise added to the above solution to mix uniformly, the mixed solution was placed in a magnetic stirrer at 25 ℃ to react for 48 hours, then insoluble salts were removed by filtration to collect the filtrate, and then the filtrate was concentrated under reduced pressure and precipitated with an excess of ethyl glacial ether.

The obtained precipitate was dissolved in anhydrous dichloromethane, concentrated under reduced pressure, precipitated with excess of glacial ethyl ether and the above procedure was repeated three times. The resulting light yellow precipitate was placed in a vacuum oven and dried overnight at room temperature to give a light yellow solid.

(5) Temperature sensitive block polymer PEG₁₁₃-b-P(NIPAM-co-GMA)_mPreparation of

The PEG prepared in the step (4)₁₁₃Macromolecular chain transfer agent (0.42g,0.08mmol), N-isopropylacrylamide (NIPAM,1.13g,10mmol), GMA (114mg,0.8mmol) and azobisisobutyronitrile (AIBN,8mg, 48. mu. mol) were dissolved in 1, 4-dioxane (4.0mL) and transferred to a single-neck flask. After being deoxidized by nitrogen for 30min, the mixed solution is sealed in nitrogen atmosphere. The reaction was carried out at 75 ℃ for 24h, the flask was quenched with an ice-water bath and the reaction solution was exposed to air. Diluted with 1, 4-dioxane and the mixture precipitated with an excess of cold diethyl ether. The dissolution-precipitation cycle is repeated for three times to obtain the light yellow temperature-sensitive block polymer PEG₁₁₃-b-P(NIPAM-co-GMA)_m。

(6) Temperature-responsive polymer fluorescent probe P

And (3) dissolving 250mg of the temperature-sensitive block polymer prepared in the step (5) and 15mg of the rhodamine B hydrazide probe P prepared in the step (2) in 3mL of 1, 4-dioxane, introducing nitrogen for 30min to remove oxygen, and carrying out sealing reaction in a nitrogen atmosphere. Reacting at 75 ℃ for 24h, and precipitating with cold ether after the reaction is finished to obtain pink solid, namely the temperature response type polymer fluorescent probe P (PEG)₁₁₃-b-P(NIPAM-co-GMA)_m-P。

FIG. 2 is a scheme of rhodamine B thiohydrazide¹H NMR chart, it can be seen visually that-CH is found at 1.18ppm₃-a characteristic signal of; the-CH was found at 3.36ppm₂-a characteristic signal of; at 3.64ppm is-NH₂A signal; the positions of 6.31,6.47,7.12,7.47 and 7.95ppm are the characteristic peaks of H on a benzene ring, so that the chemical structure of the rhodamine B thiohydrazide can be judged.

FIG. 3 is a diagram of a temperature sensitive polymer¹H NMR chart, it can be seen visually that-CH is found at 2.65,2.80ppm₂-a characteristic signal of; a characteristic signal for-CH-was found at 2.31 ppm; at 4.28ppm is given as-CH₂-a characteristic signal of; at 3.75ppm is-NH₂A signal; the success of the grafting of GMA can be judged by the characteristic signals.

FIG. 4 is a drawingOf temperature-responsive polymeric fluorescent probes P¹H NMR chart can show that at 4.15ppm, a signal of-OH is found, and the success of grafting the temperature-sensitive block polymer on rhodamine B thiohydrazide can be judged.

FIG. 5 is the FT-IR plot of rhodamine B hydrazide and rhodamine B thiohydrazide in example 1, from which it can be seen that 3430cm^-1The absorption peak is enhanced mainly due to the stretching vibration characteristics of N-H on the probe P. 2969cm^-1Is probe P on-CH₂-peak of oscillation. 1692,1770cm^-1The new absorption peak appears at the position of 1420cm, which is the stretching vibration of C ═ O on the hydrazide amide ring^-1There occur C-N stretching vibration and N-H bending vibration. At 1515cm^-1The strong absorption peak is vibration on the benzene ring skeleton. 1236cm^-1And 1392cm^-1The sharp peaks at (a) are vibration absorption peaks of C ═ S and N — C ═ S, respectively. The chemical shift of the characteristic peaks confirms the chemical structure of the probe P. The results are combined to prove that the rhodamine hydrazide and the probe P are successfully prepared.

FIG. 6 is a FT-IR chart of the temperature sensitive polymer and the fluorescent probe P in example 1, as seen from the chart, 847cm^-1，910cm^-1Disappearance of absorption peak, mainly caused by disappearance of oxygen atom in temperature sensitive block polymer, 3384cm^-1Offset to 3306cm^-1And the rhodamine B thiohydrazide is successfully grafted to the temperature-sensitive block polymer from a sharp peak to a broad peak.

Example 2: cloud point analysis based on temperature-responsive polymer fluorescent probe P

The cloud points of the temperature-responsive polymer fluorescent probes P were measured at different concentrations by preparing solutions of the probes at concentrations of 0.002g/mL, 0.005g/mL, 0.008g/mL, 0.01g/mL, 0.02g/mL, 0.03g/mL, 0.04g/mL, 0.05g/mL, 0.06g/mL, 0.07g/mL, 0.08g/mL, 0.09g/mL, and 0.10g/mL and measuring the cloud points.

As shown in fig. 7. As can be seen from the graph, the cloud point decreases as the concentration of the temperature-responsive polymer fluorescent probe increases. When the concentration of the temperature-responsive polymeric fluorescent probe was increased to 0.06g/mL, the cloud point was minimized. With further increase in the concentration of the fluorescent probe, the cloud point increases. Therefore, the lowest critical point temperature (LCST) of the temperature-responsive polymer fluorescent probe P is 25.8 ℃.

Example 3: recovery test of temperature-responsive polymer fluorescent probes

The polymer was dissolved in secondary deionized water to prepare a 60mg/ml solution, and placed in a water bath and heated for 0.5 hours, 1 hour, 1.5 hours, 2 hours. As shown in FIG. 8, when the aqueous polymer solution was heated in a water bath for 0.5 hour, turbidity was generated and a small amount of precipitate was generated, and the polymer precipitate increased with time. After up to 2 hours, the solid and liquid phases were completely separated. The upper layer is clear liquid, and the lower layer is colloidal precipitate. The transmittance of the photosensitive polymer in the aqueous solution of the second deionized water was observed by repeating the heating and cooling, as shown in FIG. 9. As can be seen from the figure, the temperature-sensitive polymer aqueous solution turns turbid from clear three times during the cooling and heating are repeated three times. The aqueous solution of the temperature-sensitive polymer has good cycle reversibility.

Example 4: cyclic detection of temperature-responsive polymer fluorescent probe P

Compared with the common rhodamine B fluorescent probe, the temperature response type polymer fluorescent probe P has the characteristic of cyclic utilization. The polymer fluorescent probe was dissolved in water, recovered by precipitation, and used several times to obtain the following results, as shown in fig. 10, the detection sensitivity of the fluorescent probe P for gold ions was as high as about 78% after five cycles. The temperature-sensitive block polymer has excellent cyclicity.

Example 5: fluorescent probe PEG₁₁₃-b-P (NIPAM-co-GMA) -P vs Au³⁺Selective detection of

The metal ion solution is prepared by metal salt, and the prepared metal ion solution needs to be stored in a dark place. For measuring probe solution to Au³⁺And (3) testing the fluorescence intensity of the fluorescent probe by using different metal ions. Equal amount of fluorescent probe PEG is taken first₁₁₃-b-P (NIPAM-co-GMA) -P solution was placed in a cuvette and then equal amounts of different metal cations (Fe) were added³⁺,Au³⁺，Co²⁺,Cr³⁺,Ag⁺,Fe²⁺,Li⁺,Mg²⁺,Pb²⁺,Zn²⁺,Cd²⁺,Ca²⁺,Mn²⁺,K⁺) Solutions, one of which was untreated as a blank, were measured for fluorescence intensity. As shown in FIG. 11, only Au was added³⁺The fluorescent probe has obvious fluorescence intensity increase phenomenon, and the probe solution added with other metal cations and the blank probe solution do not have obvious change. The addition of Au can be verified by ultraviolet absorption spectrogram (figure 12)³⁺The fluorescent probe has strong absorption peak, and the ultraviolet diagram of the fluorescent probe solution added with other metal cations and the fluorescent probe blank solution does not change drastically. This indicates that the temperature-responsive polymer fluorescent probe is directed to Au³⁺Has stronger selectivity.

Example 6: anti-interference detection of temperature response type polymer fluorescent probe P

Fluorescent probe P pair selective recognition Au³⁺The interference resistance of the process is an important reference standard for detecting the practicability of the probe, and a plurality of representative common cations are selected in the experiment to be combined with Au³⁺Whether to identify Au to the probe P during coexistence³ ⁺Causing interference. When Au is added to the probe P³⁺Then adding other interfering metal ions for fluorescence test, wherein the fluorescence intensity does not change obviously, which shows that the interfering cations do not recognize the Au on the probe P³⁺Interference is generated and the test results are shown in fig. 13. FIG. 14 is a graph comparing the UV absorption of the solution with the metal interference, showing that there is no significant change in absorbance, further illustrating that the interference ions do not interact with the fluorescent probe P and Au³⁺The identification process of (2) causes interference. Therefore, the probe P can be seen to be relative to Au through fluorescence and ultraviolet experiments³⁺The identification has strong anti-interference performance and can meet the requirement of selectivity in practical application.

Claims

1. A temperature response type polymer fluorescent probe is characterized in that the structural formula is as follows:

2. a preparation method of a temperature response type polymer fluorescent probe is characterized by comprising the following steps:

(1) preparation of rhodamine B hydrazide

Weighing rhodamine B, dissolving the rhodamine B in methanol, uniformly stirring at room temperature, dropwise adding hydrazine hydrate, stirring, heating and refluxing the solution, and cooling to room temperature after the reaction is finished; when a large amount of orange solid is separated out, carrying out reduced pressure distillation; washing the solid with deionized water, then carrying out suction filtration, dissolving the solid in methanol, carrying out reduced pressure distillation again, washing with deionized water, then carrying out suction filtration, and repeating the previous operation twice to obtain pink solid, namely rhodamine B hydrazide;

(2) preparation of rhodamine B thiohydrazide

Dissolving the rhodamine hydrazide prepared in the step (1) in toluene, adding a Lawson reagent, heating and refluxing in a nitrogen atmosphere, stopping heating after the reaction is finished, and cooling to room temperature; carrying out reduced pressure distillation, and removing the solvent to obtain a light purple solid, namely the rhodamine B thiohydrazide;

(3) preparation of BTPA

Dripping 3-mercaptopropionic acid into a potassium hydroxide solution, dripping carbon disulfide under vigorous stirring, and stirring at room temperature; then adding benzyl bromide for oil bath reaction, cooling to room temperature after the reaction is finished, adding the reactant into trichloromethane, and dropwise adding hydrochloric acid for acidification; then washing, drying and concentrating, adding dichloromethane to separate out crystals, and washing and drying the crystals to obtain a yellow solid BTPA;

Dissolving dried polyethylene glycol monomethyl ether and BTPA prepared in the step (3) in anhydrous dichloromethane, uniformly stirring in an ice-water bath, then adding a dichloromethane solution containing 4-dimethylaminopyridine DMAP and N, N-dicyclohexylcarbodiimide DCC, stirring for reaction, filtering after the reaction is finished, concentrating under reduced pressure, and precipitating the concentrated filtrate by using excessive ethyl glacial ether to obtain a precipitate; dissolving the precipitate in dichloromethane, concentrating under reduced pressure, precipitating with glacial ethyl ether, repeating for several times, and drying to obtain light yellow solid, i.e. PEG-based macromolecular chain transfer agent;

The macromolecular chain transfer agent PEG prepared in the step (4)₁₁₃Dissolving BTPA, N-isopropylacrylamide NIPA, glycidyl methacrylate GMA and an initiator azobisisobutyronitrile AIBN in 1, 4-dioxane, uniformly mixing, removing oxygen, carrying out oil bath reaction in nitrogen atmosphere, quenching polymerization reaction by using ice water bath after the reaction is finished, opening a seal, exposing in air, diluting by using 1, 4-dioxane, precipitating by using cold ether, repeating the dissolving-precipitating steps for three times to obtain the light yellow temperature-sensitive block polymer PEG₁₁₃-b-P(NIPAM-co-GMA)；

(6) Preparation of temperature-sensitive polymer fluorescent probe

The temperature-sensitive block polymer PEG prepared in the step (5)₁₁₃Dissolving B-P (NIPAM-co-GMA) and rhodamine B thiohydrazide prepared in the step (2) in 1, 4-dioxane, uniformly mixing, removing oxygen in the mixed liquid, and adding N₂And carrying out oil bath reaction under the atmosphere, quenching the reaction by using an ice water bath after the reaction is finished, and then precipitating by using excessive cold ether to obtain a pink product, namely the temperature response type polymer fluorescent probe.

3. The preparation method according to claim 2, wherein in the step (1), the rhodamine B, the methanol and the hydrazine hydrate are used in a ratio of 3-5g:60-100mL:9-15mL, wherein the mass percentage concentration of hydrazine hydrate is 85 wt%; the reflux heating temperature is 60-80 ℃, and the reaction time is 4-6 h.

4. The method according to claim 2, wherein in the step (2), the ratio of the rhodamine B hydrazide to the toluene to the Lawson reagent is 0.182 to 0.273 g: 4-6 mL: 0.162-0.243 g; the reflux reaction temperature is 70-90 ℃, and the reaction time is 3-5 h.

5. The preparation method according to claim 2, wherein in the step (3), the ratio of the amount of potassium hydroxide, 3-mercaptopropionic acid, carbon disulfide, benzyl bromide, chloroform and hydrochloric acid is 3.25 to 3.55 g: 2.5-3.0 mL: 4-6 mL: 5-5.5 g: 70mL of: 8 mL; the reaction temperature is 82-85 ℃, and the reaction time is 12-14 h.

6. The method according to claim 2, wherein in the step (4), the ratio of the amounts of the methoxypolyethylene glycol, BTPA and dichloromethane is 1.0 mmol: 2.0 mmol: 50 mL; adding 4-dimethylamino pyridine, N-dicyclohexyl carbodiimide and dichloromethane into dichloromethane mixed solution, wherein the dosage ratio of the 4-dimethylamino pyridine to the N, N-dicyclohexyl carbodiimide to the dichloromethane mixed solution is 50 mg: 1 g: 20 mL; the reaction temperature is 25 ℃, and the reaction time is 48 h.

7. The process according to claim 2, wherein in the step (5), the polyethylene glycol monomethyl ether macromolecular chain transfer agent PEG₁₁₃-BTPA, N-isopropylacrylamide, glycidyl methacrylate, azobisisobutyronitrile and 1, 4-dioxane in a ratio of 0.32 to 0.53 g: 0.85-1.41 g: 0.6-1 mmol: 6-10 mg: 3-5 mL; the oxygen removal mode is to introduce nitrogen for 30min, the reaction temperature is 70-80 ℃, and the reaction time is 22-24 h.

8. The preparation method according to claim 2, wherein in the step (6), the dosage ratio of the temperature-sensitive block polymer, rhodamine B thiohydrazide and 1, 4-dioxane is 170-330 mg: 10-20mg:2-4 mL.

9. The preparation method according to claim 2, wherein in the step (6), the oxygen removal mode is nitrogen gas introduction for 30min, the oil bath reaction temperature is 70-80 ℃, and the reaction time is 22-24 h.

10. Use of the temperature-responsive polymer fluorescent probe according to claim 1 for detecting Au³⁺The use of (1).