CN110699072B

CN110699072B - Coumarin functionalized graphene quantum dot fluorescent probe and preparation method and application thereof

Info

Publication number: CN110699072B
Application number: CN201911076612.8A
Authority: CN
Inventors: 马文辉; 喻照川; 问婧; 吴涛; 张永; 王丽艳; 初红涛
Original assignee: Qiqihar University
Current assignee: Qiqihar University
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2022-03-15
Anticipated expiration: 2039-11-06
Also published as: CN110699072A

Abstract

A coumarin functionalized graphene quantum dot fluorescent probe and a preparation method and application thereof relate to a fluorescent probe and a preparation method and application thereof. It is to solve the existing CN detection^‑And ascorbic acid, low sensitivity and high biological toxicity. The structural formula of the coumarin functionalized graphene quantum dot fluorescent probe is as follows:

the preparation method comprises the following steps: adding graphene oxide into mixed acid for reaction, and then dialyzing, freezing and drying to obtain graphene quantum dots; dispersing the graphene quantum dots into a solvent, performing ultrasonic dispersion, adding EDC, NHS and coumarin derivative S for reaction to obtain a product solution, dialyzing, performing rotary evaporation, and freeze-dryingDrying to obtain a probe; the probe is used for detecting CN^‑And ascorbic acid, recognition of CN^‑The detection limit of (2) is 0.41 mu mol/L, the detection limit of identifying ascorbic acid is 4.84 mu mol/L, and the method can be used for CN in water body^‑And the field of ascorbic acid detection.

Description

Coumarin functionalized graphene quantum dot fluorescent probe and preparation method and application thereof

Technical Field

The invention relates to a fluorescent probe and a preparation method and application thereof.

Background

Anions play an important role in life process and ecological environment, and the detection of the ions is a very important research topic for ecological maintenance, health science and national defense construction. Among the plurality of anions, CN^-The product is a pollutant with extremely high toxicity, can kill a small amount of the pollutant, is quick in poisoning speed, and is harmful to human bodies through the skin, respiratory systems or mistaken eating of the human bodies. CN^-The pollution to water quality and environment inevitably causes harm to human and animals. At present, CN is reported to be detected^-The fluorescent probes are relatively more, most of the fluorescent probes mainly use small-molecule fluorescent dyes, and CN is detected^-The number of material probes is relatively small and the detection mode is single. Synthesis of benzindole fluorescent probe and its application to CN in 2018, 37 th article at No. 7, analytical laboratory, pages 835-838^-The naked eye identification of (a), discloses a fluorescent probe, but the structure is complex and the sensitivity is low; an article, pages 889-895 of < organic chemistry > of No. 4, volume 37, 2017, reports a fluorescent probe for identifying cyanide ions by an imidazophenazine lactam reaction type, but the fluorescent probe has high toxicity.

Ascorbic acid (AA, vitamin C, VC) is a water-soluble vitamin, and Vc in nature exists mainly in an oxidized form and a reduced form, is a nutrient substance necessary for the growth and the maintenance of physiological functions of a human body, is easy to cause scurvy when the intake amount is insufficient, and has a certain prevention effect on diseases such as cancer, hepatitis and the like. Ascorbic acid is widely used in the field of food processing due to its unique chemical properties. Examples of methods for measuring ascorbic acid include spectrophotometry, atomic absorption spectrometry, electrochemical analysis, chromatography, and fluorescence spectrometry. At present, relatively few fluorescent probes are reported for detecting ascorbic acid, and most of the fluorescent probes are mainly fluorescent probes. An article, namely trace ascorbic acid determination by a fluorescence quenching method by taking aromatic amino acid as a probe, which is published on pages 645-648 of a spectrum laboratory,

volume

30, 2, 2013 reports a fluorescent probe, wherein the probe is simple and easy to obtain, but the anti-interference capability is poor; an article published by the journal of luminescence 124 and 131 of the No. 01, volume 38, of 2017, reports a fluorescent probe based on graphene quantum dots, wherein the fluorescent probe is low in biotoxicity and sensitivity.

Disclosure of Invention

The invention aims to solve the problem of the existing detection CN^-The fluorescent probe of the coumarin functionalized graphene quantum dot fluorescent probe and the ascorbic acid have the technical problems of low sensitivity and high biotoxicity, and the preparation method and the application of the fluorescent probe of the coumarin functionalized graphene quantum dot fluorescent probe are provided. The coumarin functionalized graphene quantum dot fluorescent probe can detect CN in an 'off-on' mode^-And ascorbic acid.

The structural formula of the coumarin functionalized graphene quantum dot fluorescent probe is as follows:

the synthesis method of the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

firstly, concentrated sulfuric acid with the mass percentage concentration of 98% and concentrated nitric acid with the mass percentage concentration of 68% are mixed according to the volume ratio of (3-3.5): 1 to obtain mixed acid;

adding Graphene Oxide (GO) into the mixed acid, performing ultrasonic dispersion for 2-3 hours, heating to boil, maintaining reflux reaction for 24-30 hours, cooling, diluting with water, and adjusting the pH value to 6-6.5 with alkali liquor to obtain a mixed solution;

thirdly, dialyzing the mixed solution in water for 6-8 days, and freeze-drying to obtain Graphene Quantum Dot (GQDs) dry powder;

dispersing Graphene Quantum Dot (GQDs) dry powder into a solvent, performing ultrasonic dispersion for 2-3 hours, adding EDC, adjusting the pH value of the system to 5-5.5 by using an HCl solution, stirring for 0.5 hour at the temperature of 25-30 ℃, then adding NHS, adjusting the pH value to 9-9.5 by using an alkali solution, continuing stirring for 3-3.5 hours, finally adding a coumarin derivative S solution, and stirring and reacting for 48-50 hours at the temperature of 25-30 ℃ to obtain a product solution; wherein the chemical formula of the coumarin derivative S is as follows:

fifthly, adding water into the product solution, and then adding dichloromethane (CH)₂Cl₂) Washing and extracting until dichloromethane phase is detected to be free of coumarin derivative S by TLC; finally dialyzing the aqueous dispersion for 24-36 h; and (4) freeze-drying after rotary evaporation to obtain the coumarin functionalized graphene quantum dot fluorescent probe, which is represented by S-GQDs, wherein the S-GQDs are black powder.

The application of the coumarin functionalized graphene quantum dot fluorescent probe is to use the coumarin functionalized graphene quantum dot fluorescent probe for detecting CN^-And ascorbic acid.

CN (CN) detection by coumarin functionalized graphene quantum dot fluorescent probe^-The method comprises the following steps:

using DMF and H₂Taking a mixed solution with the volume ratio of O being 1:1 as a dispersing agent, and adding the dispersing agent with the concentration of the coumarin functionalized graphene quantum dot fluorescent probe being 30mg/L to obtain a probe dispersion solution;

secondly, adding a sample to be detected into the probe dispersion liquid, and uniformly mixing to obtain a sample dispersion liquid;

thirdly, testing the fluorescence intensity A of the probe dispersion liquid when the emission wavelength is 507nm by using a fluorescence spectrophotometer₀The fluorescence intensity A of the sample dispersion at an emission wavelength of 507nm was again measured₁If A is₁≤30％A₀Then, it is determined that CN is contained in the sample to be measured^-。

The method for detecting the ascorbic acid by using the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

firstly, according to the concentration of 30mg/L of coumarin functionalized graphene quantum dot fluorescent probe, the concentration of 600-1166 mu mol/L of tetrabutylammonium cyanide, DMF and H₂Taking a mixed solution with the volume ratio of O being 1:1 as a solvent, adding the coumarin functionalized graphene quantum dot fluorescent probe and tetrabutylammonium cyanide into the solvent, and uniformly mixing to obtain a probe dispersion solution;

secondly, adding a sample to be detected into the probe dispersion liquid, and uniformly mixing to obtain a sample solution;

thirdly, testing the fluorescence intensity of the probe dispersion liquid B by using a fluorescence spectrophotometer when the emission wavelength is 507nm₁And the fluorescence intensity of the sample solution is measured as B when the emission wavelength is 507nm₂If B is₁≤30％B₂And judging that the sample to be detected contains the ascorbic acid.

The reaction process for preparing the coumarin functionalized graphene quantum dot fluorescent probe is shown in figure 1. The coumarin functionalized graphene quantum dot fluorescent probe has good water solubility, is nontoxic, has high selectivity and high sensitivity, and can be used for rapidly detecting CN (CN) by using the graphene quantum dot^-And ascorbic acid "off-on" type fluorescent probes. The fluorescent material probe is arranged at V_DMF:V_H2OTo CN in the system^-The recognition has specificity, is not interfered by other anions, and has stronger anti-interference capability. The fluorescent material probe can identify CN in an aqueous environment^-The detection limit is 0.41 mu mol/L (10.69 mu g/L), which is far lower than the national domestic water standard.

The fluorescent material probeNeedle and CN^-At V_DMF:V_H2OIn the system, the ascorbic acid has good selectivity for the identification of ascorbic acid, is not interfered by other analogues in the solution, and has stronger anti-interference capability. The fluorescent material probe can identify ascorbic acid in an aqueous environment, has a detection limit of 4.84 mu mol/L (0.852mg/L) and has a lower detection limit.

The coumarin functionalized graphene quantum dot fluorescent probe can be used for CN in water body^-And the field of ascorbic acid detection.

Drawings

FIG. 1 is a diagram of a synthetic reaction process of a coumarin functionalized graphene quantum dot fluorescent probe;

fig. 2 is a TEM image of coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1;

FIG. 3 is an FT-IR diagram of coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1;

fig. 4 is an XPS spectrum of the coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1;

FIG. 5 shows fluorescent probe of coumarin functionalized graphene quantum dots prepared in example 1 in DMF/H₂In the O (V/V,1:1) system, the fluorescence emission spectrum is dependent on CN^-(0-1833. mu. mol/L) fluorescence spectrum of the change in concentration;

FIG. 6 shows fluorescence intensity at 507nm vs. CN of coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 in the range of 10-90 μmol/L^-A linear regression curve of concentration;

FIG. 7 shows that 30mg/L of coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 is applied to DMF/H₂O (V/V,1:1) at a concentration of 1166. mu. mol/L of different anions (F)^-，Cl^-，Br^-，I^-，HSO4^-，H₂PO₄ ^-，AcO^-And CN^-) Histogram of fluorescence response of;

FIG. 8 shows the coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 in DMF/H₂O (V/V,1:1), adding CN^-High post-fluorescenceDegree (507 nm) versus time, excitation wavelength 450 nm.

FIG. 9 shows the coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 in DMF/H₂O (V/V,1:1) system, and adding CN^-When the concentration is 1166 mu mol/L, the fluorescence emission spectrum causes a fluorescence spectrum change chart along with the change of the concentration of ascorbic acid (0-2333 mu mol/L);

FIG. 10 is a linear regression curve of the fluorescence intensity at 507nm versus ascorbic acid concentration of the coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 in the range of 33-533. mu. mol/L;

FIG. 11 shows the coumarin functionalized graphene quantum dot fluorescent probe prepared in example 1 in DMF/H₂O (V/V,1:1) and adding CN^-At a concentration of 1166. mu. mol/L, S-GQDs are responsible for different substances (ascorbic acid (AA), Citric Acid (CA), lysine (Lys), glycine (Gly), cysteine (Cys), glutamic acid (Tyr), glucose (glucose), fructose (fructose), K⁺、Ca²⁺、Na⁺Or Mg²⁺) Histogram of fluorescence response of;

FIG. 12 shows fluorescence of coumarin functionalized graphene quantum dots in DMF/H prepared in example 1₂O (V/V,1:1) and adding CN^-When the concentration is 1166 mu mol/L, the change curve of the fluorescence intensity (507 nm) along with the time after adding the ascorbic acid, and the excitation wavelength is 450 nm.

Detailed Description

The first embodiment is as follows: the structural formula of the coumarin functionalized graphene quantum dot fluorescent probe is as follows:

the second embodiment is as follows: the synthesis method of the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

dialyzing the mixed solution in water for 6-8 days, and freeze-drying to obtain spongy brown Graphene Quantum Dot (GQDs) dry powder;

dispersing Graphene Quantum Dot (GQDs) dry powder into a solvent, performing ultrasonic dispersion for 2-3 h, adding EDC, adjusting the pH value of the system to 5-5.5 by using an HCl solution, activating for 0.5h at the temperature of 25-30 ℃, adding NHS, adjusting the pH value to 9-9.5 by using an alkali solution, continuing to activate for 3-3.5 h, finally adding a coumarin derivative S solution, and stirring and reacting for 48-50 h at the temperature of 25-30 ℃ to obtain a product solution; wherein the chemical formula of the coumarin derivative S is as follows:

fifthly, adding water into the product solution, and then adding dichloromethane (CH)₂Cl₂) Washing and extracting until dichloromethane phase is detected to be free of coumarin derivative S by TLC; finally dialyzing the aqueous dispersion for 24-30 h; and (4) freeze-drying after rotary evaporation to obtain the coumarin functionalized graphene quantum dot fluorescent probe, which is represented by S-GQDs, wherein the S-GQDs are black powder.

The third concrete implementation mode: the second embodiment is different from the second embodiment in that the alkali liquor in the second step is a NaOH solution with a mass percentage concentration of 30-50%; the rest is the same as the second embodiment.

The fourth concrete implementation mode: the second or third embodiment is different from the second or third embodiment in that the cut-off molecular weight of the dialysis bag used in the dialysis in the second step is 3500 Da; the other is the same as the second or third embodiment.

The fifth concrete implementation mode: the difference between this embodiment and one of the second to fourth embodiments is that in step four, the solvent is DMF, dimethyl sulfoxide, or toluene; the other is the same as one of the second to fourth embodiments.

The sixth specific implementation mode: the difference between the present embodiment and one of the second to fifth embodiments is that in the fourth step, the concentration of the HCl solution is 0.1-0.2 mol/L; the other is the same as one of the second to fifth embodiments.

The seventh embodiment: the difference between the embodiment and the second to the sixth embodiment is that in the fourth step, the alkali solution is 0.1mol/L NaOH solution; the other is the same as one of the second to sixth embodiments.

The specific implementation mode is eight: the difference between this embodiment and one of the second to seventh embodiments is that in step four, the molar ratio of EDC, NHS, coumarin derivative S is 1: (0.5-1): (0.5 to 1); the rest is the same as one of the second to seventh embodiments.

The specific implementation method nine: the embodiment is different from the second embodiment to the eighth embodiment in that in the fourth step, the mass ratio of the Graphene Quantum Dot (GQDs) dry powder to the coumarin derivative S is 1 (1-2); the rest is the same as the second to eighth embodiments.

The detailed implementation mode is ten: the embodiment is different from the second embodiment to the ninth embodiment in that in the fourth step, Graphene Quantum Dot (GQDs) dry powder is dispersed in DMF to obtain graphene quantum dot dispersion liquid, and the concentration of the graphene quantum dots is 2.5-3 g/L; the other is the same as in one of the second to ninth embodiments.

The concrete implementation mode eleven: the difference between this embodiment and the second to tenth embodiments is that in the fourth step, the solvent for preparing the coumarin derivative S solution is DMF, dimethyl sulfoxide, or tetrahydrofuran; the concentration of the coumarin derivative S is 0.02-0.03 mol/L; the rest is the same as in one of the second to tenth embodiments.

The specific implementation mode twelve: this embodiment differs from one of the second to eleventh embodiments in that in step five, the cut-off molecular weight of the dialysis bag used for dialysis is 1000 Da. The other is the same as in one of the second to eleventh embodiments.

The specific implementation mode is thirteen: Detailed DescriptionThe application of the coumarin functionalized graphene quantum dot fluorescent probe is to use the coumarin functionalized graphene quantum dot fluorescent probe for detecting CN^-And ascorbic acid.

The specific implementation mode is fourteen: the difference between the embodiment and the thirteen specific embodiments is that the coumarin functionalized graphene quantum dot fluorescent probe is used for detecting CN^-The method comprises the following steps:

The concrete implementation mode is fifteen: the embodiment is different from the specific embodiment thirteen in that the method for detecting the ascorbic acid by using the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

thirdly, testing the fluorescence intensity of the probe dispersion liquid B by using a fluorescence spectrophotometer when the emission wavelength is 507nm₁And the fluorescence intensity of the sample solution is measured as B when the emission wavelength is 507nm₂If B is₁≤30％B₂Then determine to waitThe test sample contained ascorbic acid.

The following examples are used to demonstrate the beneficial effects of the present invention:

example 1: the synthesis method of the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

firstly, mixing 15mL of concentrated sulfuric acid with the mass percentage concentration of 98% with 5mL of concentrated nitric acid with the mass percentage concentration of 68% to obtain mixed acid;

adding 0.1g of Graphene Oxide (GO) into 15mL of mixed acid, performing ultrasonic dispersion for 2 hours, heating to 100 ℃ for boiling, maintaining reflux reaction for 24 hours, cooling, diluting with water, and adjusting the pH value to 6 by using a NaOH solution with the mass percentage concentration of 40% to obtain a mixed solution;

putting the mixed solution into a dialysis bag with the molecular weight cutoff of 3500Da, dialyzing in water for 7 days, and freeze-drying to obtain spongy brown Graphene Quantum Dot (GQDs) dry powder;

dispersing 50mg of Graphene Quantum Dot (GQDs) dry powder into 20mL of DMF, ultrasonically dispersing for 2h, then adding 76.8mg (0.4mmol) of EDC, adjusting the pH value of the system to 5 by using 0.1mol/L HCl solution, stirring for 0.5h at the temperature of 25 ℃, then adding 23mg (0.2mmol) of NHS, adjusting the pH value to 9 by using 0.1mol/L NaOH solution, continuing stirring for 3h, finally adding 10mL of DMF solution in which 66.6mg (0.2mmol) of coumarin derivative S is dissolved, and stirring for reacting for 48h at the temperature of 25 ℃ to obtain a product solution; wherein the chemical formula of the coumarin derivative S is as follows:

fifthly, adding 100mL of water into the product solution, and then adding dichloromethane (CH)₂Cl₂) Repeatedly washing and extracting until dichloromethane phase is detected to have no coumarin derivative S by TLC; finally putting the water dispersion into a dialysis bag with the molecular weight cutoff of 1000Da for dialysis for 24 h; and (3) freeze-drying after rotary evaporation to obtain 42mg of coumarin functionalized graphene quantum dot fluorescent probe, which is represented by S-GQDs, wherein the S-GQDs are black powder.

A transmission electron microscope photograph of the coumarin functionalized graphene quantum dot fluorescent probe obtained in the embodiment 1 is shown in fig. 2, and as can be seen from fig. 2, S-GQD has good uniformity, the particle size distribution is 2-7 nm, and the average particle size is 3.6 nm; and the lattice spacing is 0.23nm, which is consistent with the crystal face of graphene (110), and the S-GQD has a graphene-like crystal structure.

An FT-IR diagram of the coumarin functionalized graphene quantum dot fluorescent probe obtained in the embodiment 1 is shown in FIG. 3, and as can be seen from FIG. 3, coumarin derivatives S and GQDs are successfully connected, and the S-GQDs contain functional groups such as-OH, -CONH-, and the like.

The XPS spectrum of the coumarin functionalized graphene quantum dot fluorescent probe obtained in this example 1 is shown in fig. 4, and the results in fig. 4 further prove that coumarin derivatives S are covalently linked with GQDs.

From the data, the structure of the coumarin functionalized graphene quantum dot fluorescent probe prepared by the embodiment can be obtained as follows:

the coumarin functionalized graphene quantum dot fluorescent probe prepared in the embodiment 1 is subjected to a spectral performance test, and the steps are as follows:

preparing a main solution: with DMF and H₂The volume ratio of O is 1:1 (i.e. DMF: H)₂And (3) taking a mixed solution of O (V/V) ═ 1:1) as a solvent, and preparing the coumarin functionalized graphene quantum dot fluorescent probe into a main body solution with the concentration of 30mg/L for later use.

Preparing an anion stock solution: an anion solution was prepared using DMSO as a solvent and tetrabutylammonium salt as a solute at a concentration of 0.10 mol/L.

Ascorbic acid analogs and common interferents with H₂O is a solvent, and is prepared into a 0.10mol/L solution for later use.

CN (CN) pair for detecting coumarin functionalized graphene quantum dot fluorescent probe prepared in the embodiment^-The sensitivity of selectivity is specifically as follows: in DMF, H₂In a system with the volume ratio of O being (V/V,1:1), 0-1833 mu mol/L CN is added into a probe solution with the concentration of 30mg/L^-The change of the fluorescence spectrum measured by the fluorescence spectrophotometer is shown as A in FIG. 5, and the fluorescence intensity is measured with CN^-The change in concentration is shown in B of FIG. 5, and it can be seen from (B) of FIG. 5 that with CN^-The amount of (A) is increased, the intensity of the emission peak at 507nm is increased, when CN^-When the concentration of (b) reaches 1166 mu mol/L, the fluorescence intensity reaches the lowest, and CN is continuously increased^-The fluorescence intensity tends to be stable. By F/F₀Is the ordinate (where F is the fluorescence intensity, F)₀To add no CN^-Fluorescence intensity of) with CN^-The concentration is plotted on the abscissa, as shown in FIG. 6, and it can be seen from FIG. 6 that when the concentration is in the range of 10 to 90. mu. mol/L, the fluorescence intensity of S-GQDs is related to CN^-The concentration of the compound shows a good linear relation (R)²0.9916) and the linear fitting equation is that Y is 0.0724X +1.0787, the detection limit is 0.41 mu mol/L (10.69 mu g/L) and is far lower than the national domestic water standard.

The coumarin functionalized graphene quantum dot fluorescent probe prepared by the embodiment is in the CN pair^-The test method for the anti-anion interference ability in the detection is as follows: in DMF, H₂In a system with a volume ratio of O of 1:1, F with a concentration of 0.10mol/L is added to a probe solution with a concentration of 30mg/L^-、Cl^-、Br^-、I^-、HSO₄ ^-、H₂PO₄ ^-、AC^-Or CN^-Anion, fully mixing, standing for 24h, and respectively adding 0.10mol/L CN^-And then mixing uniformly. The fluorescence emission spectrum was measured at an excitation wavelength of 450nm, and the results are shown in FIG. 7,

bars represent the change in fluorescence of S-GQDs (30mg/L) in the presence of these anions alone (1166. mu. mol/L),

bars represent CN^-The fluorescence emission spectra added to the system containing s-GQDs and these anions are graphed; as can be seen from FIG. 7, CN^-In the presence of other anions (F)^-、Cl^-、Br^-、I^-、HSO₄ ^-、H₂PO₄ ^-Or AC^-) When the fluorescent probe exists, the fluorescence intensity of the fluorescent probe does not change obviously, so that the fact that the coumarin functionalized graphene quantum dot fluorescent probe prepared by the embodiment is used for detecting CN (CN) can be proved^-Without interference from other anions.

CN (CN) is detected by using coumarin functionalized graphene quantum dot fluorescent probe prepared in the embodiment^-The response time test method of (2) is as follows: in DMF, H₂In a system with the volume ratio of O being 1:1, CN with the concentration of 0.10mol/L is added into a probe solution with the concentration of 30mg/L^-The fluorescence intensity at different time is detected, when the excitation wavelength is 450nm, the change curve of the fluorescence intensity (507 nm) along with the time is shown in figure 8, the result shows that the fluorescence intensity of S-GQDs is quenched by 71.2% after 1min, and the quenching degree reaches 90.3% at the maximum after 30min, therefore, the probe is used for detecting CN^-The detection time of the ions is about 30 min.

The sensitivity of the coumarin functionalized graphene quantum dot fluorescent probe prepared in the embodiment to ascorbic acid selectivity is detected, and the specific method is as follows: in DMF, H₂In the system with the volume ratio of O being 1:1, the S-GQDs and the CN with the concentration of 30mg/L are respectively added^-Adding 0-2333 mu mol/L ascorbic acid into the probe solution with the concentration of 1166 mu mol/L, and using a fluorescence spectrophotometer to test the change condition of a fluorescence spectrum as shown in A in figure 9; the change of fluorescence intensity with ascorbic acid is shown in B of FIG. 9, and it can be seen from B of FIG. 9 that with CN^-The amount of the compound (A) is increased continuously, the intensity of an emission peak at 507nm is increased continuously, when the concentration of the ascorbic acid reaches 2000 mu mol/L, the fluorescence intensity reaches the maximum value, and the concentration of the ascorbic acid is increased continuously, so that the fluorescence intensity tends to be stable. By F/F₀Is the ordinate (where F is the fluorescence intensity, F)₀Fluorescence intensity without ascorbic acid) was plotted with ascorbic acid concentration as abscissa, as shown in FIG. 10, and it can be seen from FIG. 10 that when ascorbic acid is addedS-GQDs-CN when the concentration of ascorbic acid is in the range of 33-533 mu mol/L^-Shows a good linear relationship (R) between the fluorescence intensity and the concentration of ascorbic acid²0.9914) with a linear fit equation of Y of 0.0062X +0.6241 with a detection limit of 4.84 μmol/L (0.852 mg/L).

The method for testing the anti-interference capability of the coumarin functionalized graphene quantum dot fluorescent probe to ascorbic acid analogues and common ions in ascorbic acid detection comprises the following steps: in DMF, H₂In the system with the volume ratio of O being 1:1, the S-GQDs and the CN with the concentration of 30mg/L are respectively added^-Adding 2000 μmol/L (ascorbic acid (AA), Citric Acid (CA), lysine (Lys), glycine (Gly), cysteine (Cys), glutamic acid (Tyr), glucose, fructose, K) into 1166 μmol/L probe solution⁺、Ca²⁺、Na⁺Or Mg²⁺) And fully mixing the substances to be detected, standing for 24 hours, adding 2000 mu mol/L ascorbic acid respectively, and uniformly mixing. The fluorescence emission spectrum was measured at an excitation wavelength of 450nm, and the results are shown in FIG. 11.

Representing the change in fluorescence of S-GQDs (30mg/L) when these anions were present at a concentration of 2000. mu. mol/L,

means ascorbic acid added to the solution containing S-GQDs, CN^-And the fluorescence emission spectra in these potential interferent systems, with an excitation wavelength of 450 nm; as can be seen in FIG. 11, ascorbic acid is associated with other anions (citric acid (CA), lysine (Lys), glycine (Gly), cysteine (Cys), glutamic acid, glucose, fructose, K⁺、Ca²⁺、Na⁺Or Mg²⁺) When the probe exists, the fluorescence intensity of the fluorescence does not change obviously, so that the probe can be proved to be free from interference of other analogues and common cations when the probe is used for detecting the ascorbic acid.

The method for testing the response time of the coumarin functionalized graphene quantum dot fluorescent probe for detecting ascorbic acid is as follows: in DMF, H₂In a system with the volume ratio of O being 1:1, adding S-GQDs and CN with the concentration of 30mg/L^-The probe solution with the concentration of 1166 μmol/L is added with ascorbic acid with the concentration of 2000 μmol/L to detect the fluorescence intensity at different times, and the result is shown in FIG. 12, and FIG. 12 shows that the fluorescence intensity of S-GQDs is enhanced by 50.3% after 1min, and the enhancement degree reaches 97.3% at the maximum at 60min, so that the detection time of ascorbic acid by the coumarin functionalized graphene quantum dot fluorescence probe prepared in this embodiment is about 60 min.

Example 2: the synthesis method of the coumarin functionalized graphene quantum dot fluorescent probe provided by the embodiment comprises the following steps:

secondly, adding 0.1g of Graphene Oxide (GO) into 15mL of mixed acid, performing ultrasonic dispersion for 2h, then heating to 140 ℃, stirring for 15-45min, cooling, diluting with water, and then using NaHCO with the mass percentage concentration of 40%₃Regulating the pH value of the solution to 6 to obtain a mixed solution;

dispersing 50mg of Graphene Quantum Dot (GQDs) dry powder into 30mL of DMF, performing ultrasonic dispersion for 2h, adding 76.8mg (0.4mmol) of EDC, 23mg (0.2mmol) of NHS and 66.6mg (0.2mmol) of coumarin derivative S, adjusting the pH value to 9 by using 0.01mol/L of NaOH solution, and stirring and reacting for 48h at the temperature of 25 ℃ to obtain a product solution; wherein the chemical formula of the coumarin derivative S is as follows:

fourthly, 100mL of water is added into the product solution, and dichloromethane (CH) is added₂Cl₂) Repeatedly washing and extracting until dichloromethane phase is detected to have no coumarin derivative S by TLC; finally, filling the aqueous dispersion into a reactor with molecular weight cutoffDialyzing in a 1000Da dialysis bag for 24 h; and (4) freeze-drying after rotary evaporation to obtain 45mg of coumarin functionalized graphene quantum dot fluorescent probe, which is represented by S-GQDs, wherein the S-GQDs are black powder.

The coumarin functionalized graphene quantum dot fluorescent probe prepared by the embodiment is nontoxic, has high selectivity and high sensitivity, and can be used for rapidly detecting CN (CN) by using graphene quantum dots^-And ascorbic acid "off-on" type fluorescent probes. The fluorescent material probe is arranged at V_DMF:V_H2OTo CN in the system^-The recognition has specificity, is not interfered by other anions, and has stronger anti-interference capability. The fluorescent material probe can identify CN in an aqueous environment^-Far below the national standard for domestic water. The fluorescent material probe and CN are simultaneously^-At V_DMF:V_H2OIn the system, the ascorbic acid has good selectivity for the identification of ascorbic acid, is not interfered by other analogues in the solution, and has stronger anti-interference capability. Ascorbic acid can be identified in an aqueous environment.

Claims

1. A coumarin functionalized graphene quantum dot fluorescent probe is characterized in that the structural formula of the probe is as follows:

2. the method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe as claimed in claim 1, which is characterized by comprising the following steps:

adding graphene oxide into mixed acid, performing ultrasonic dispersion for 2-3 hours, heating to boil, maintaining reflux reaction for 24-30 hours, cooling, diluting with water, and adjusting the pH value to 6-6.5 with alkali liquor to obtain mixed liquor;

thirdly, dialyzing the mixed solution in water for 6-8 days, and freeze-drying to obtain graphene quantum dot dry powder;

dispersing graphene quantum dot dry powder into a solvent, performing ultrasonic dispersion for 2-3 hours, then adding EDC, adjusting the pH value of the system to 5-5.5 by using an HCl solution, stirring for 0.5 hour at the temperature of 25-30 ℃, then adding NHS, adjusting the pH value to 9-9.5 by using an alkali liquor, continuing stirring for 3-3.5 hours, finally adding a coumarin derivative S solution, and stirring for reacting for 48-50 hours at the temperature of 25-30 ℃ to obtain a product solution; wherein the chemical formula of the coumarin derivative S is as follows:

adding water into the product solution, adding dichloromethane, washing and extracting until dichloromethane phase is detected to have no coumarin derivative S by TLC; finally dialyzing the aqueous dispersion for 24-36 h; and (4) freeze-drying after rotary evaporation to obtain the coumarin functionalized graphene quantum dot fluorescent probe.

3. The method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe according to claim 2, wherein the alkali solution in the second step is a NaOH solution with a mass percentage concentration of 30% -50%.

4. The method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe according to claim 2 or 3, wherein the molecular weight cut-off of a dialysis bag used in the dialysis in the step two is 3500 Da.

5. The method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe according to claim 2 or 3, wherein in the fourth step, the solvent is DMF, dimethyl sulfoxide or toluene.

6. The method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe according to claim 2 or 3, wherein in the fourth step, the molar ratio of EDC, NHS and coumarin derivative S is 1: (0.5-1): (0.5 to 1).

7. The method for synthesizing the coumarin functionalized graphene quantum dot fluorescent probe according to claim 2 or 3, wherein in the fourth step, the mass ratio of the graphene quantum dot dry powder to the coumarin derivative S is 1 (1-2).

8. The application of the coumarin functionalized graphene quantum dot fluorescent probe as claimed in claim 1, wherein the application is to use the coumarin functionalized graphene quantum dot fluorescent probe for detecting CN^-And ascorbic acid.

9. The use of the coumarin-functionalized graphene quantum dot fluorescent probe according to claim 8, wherein the coumarin-functionalized graphene quantum dot fluorescent probe is used for detecting CN^-The method comprises the following steps:

10. The application of the coumarin functionalized graphene quantum dot fluorescent probe according to claim 8, which is characterized in that the method for detecting ascorbic acid by using the coumarin functionalized graphene quantum dot fluorescent probe comprises the following steps:

first, graphene quantum functionalized according to coumarinThe concentration of the point fluorescent probe is 30mg/L, the concentration of tetrabutylammonium cyanide is 600-1166 mu mol/L, and DMF and H are used₂Taking a mixed solution with the volume ratio of O being 1:1 as a solvent, adding the coumarin functionalized graphene quantum dot fluorescent probe and tetrabutylammonium cyanide into the solvent, and uniformly mixing to obtain a probe dispersion solution;