CN111117608B

CN111117608B - Fluorescent probe for quantitatively detecting acidic or basic amino acid based on carbon quantum dot fluorescence quenching or enhancement method and preparation method thereof

Info

Publication number: CN111117608B
Application number: CN201911233090.8A
Authority: CN
Inventors: 弓晓娟; 吴壮壮; 刘洋; 宋胜梅; 董川
Original assignee: Shanxi University
Current assignee: Shanxi University
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2021-09-28
Anticipated expiration: 2039-12-05
Also published as: CN111117608A

Abstract

The invention belongs to the technical field of fluorescent probes, and provides a fluorescent probe for quantitatively detecting acidic or basic amino acid based on a carbon quantum dot fluorescence quenching or enhancing method and a preparation method thereof. And (3) synthesizing carbon quantum dots C-dots by using o-phenylenediamine and p-aminobenzoic acid as substrates through a hydrothermal method, and performing rotary evaporation, centrifugation, freeze drying to obtain fluorescent probe C-dots solid powder. C-dots are sensitive to pH, and when the pH is acidic, the fluorescence of the C-dots is weakened; fluorescence of C-dots increases when the pH is alkaline. Based on this, C-dots were used for amino acid class detection. When the acidic amino acid is added, the fluorescence of C-dots is gradually weakened, when the basic amino acid is added, the fluorescence of C-dots is gradually strengthened, and the C-dots can be used for detecting the acidic and basic amino acids. The method has the advantages of simple operation, good selectivity, high sensitivity, rapid detection, no need of expensive instruments and equipment, and low detection cost, and can be used for qualitative differential detection of acidic and basic amino acids.

Description

Fluorescent probe for quantitatively detecting acidic or basic amino acid based on carbon quantum dot fluorescence quenching or enhancement method and preparation method thereof

Technical Field

The invention belongs to the technical field of fluorescent probes, and particularly relates to a fluorescent probe for quantitatively detecting acidic or basic amino acid based on a carbon quantum dot fluorescence quenching or enhancement method and a preparation method thereof.

Background

Amino acid (amino acid) is one of a plurality of bioactive macromolecules for constructing organisms and is a basic material for constructing cells and repairing tissues. The most common amino acids in the human body are glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), phenylalanine (Phe), proline (Pro), tryptophan (Trp), serine (Ser), tyrosine (Tyr), cysteine (Cys), methionine (Met), asparagine (Asn), glutamine (gin), threonine (Thr), aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), and histidine (His). The amino acids are classified into: neutral amino acids, acidic amino acids, and basic amino acids. Lack of amino acids or amino acid imbalance in the elderly can accelerate cell degeneration and aging, cause resistance decline, and dysfunction of heart, brain, liver, kidney and stomach and intestine, and is also prone to cause senile diseases, such as hypomnesis, visual deterioration, reaction retardation, and even senile dementia. Lack of amino acids or amino acid imbalances in the adult human body can lead to physical disorders such as anorexia, weight loss, growth retardation, renal hypertrophy, liver fibrosis, poor disease resistance, anemia, and the like. Lack of amino acids or imbalance of amino acids in children's bodies can affect the absorption of calcium by the body, resulting in slow growth, dysplasia and mental retardation. Therefore, it is important to develop a method for detecting amino acids.

The methods for detecting amino acids reported so far are: capillary Electrophoresis (CE), High Performance Liquid Chromatography (HPLC), Spectrophotometry (SP), electrochemical methods, immunoassay, fluorescence methods, and the like. The fluorescence method is widely applied to the detection of amino acid due to the advantages of simple operation, good selectivity, high sensitivity and the like.

As a carbon nano material emerging in recent decades, the carbon quantum dot shows great application potential in the fields of sensors, biological imaging, drug delivery, photocatalysts, luminescence and the like. Carbon quantum dots are used to construct chemical and biological sensors for detecting pH, metal ions, amino acids, drugs, etc. Meanwhile, carbon quantum dots have become a new generation of fluorescent reagent for biological imaging, and are used for imaging living cells, mice and zebra fish. The method for efficiently, quickly and quantitatively detecting the amino acid is developed by using the carbon quantum dots as the basis and using a fluorescence enhancement or quenching method, and has important significance and wide application prospect.

Disclosure of Invention

The invention aims to provide a fluorescent probe for quantitatively detecting acidic or basic amino acid based on a carbon quantum dot fluorescence quenching or enhancing method and a preparation method thereof.

The invention is realized by the following technical scheme: a fluorescent probe for quantitatively detecting acidic or basic amino acid based on a carbon quantum dot fluorescence quenching or enhancing method is characterized in that o-phenylenediamine and p-aminobenzoic acid are used as substrates, carbon quantum dots C-dots are synthesized through a hydrothermal method, and C-dots solid powder is obtained through rotary evaporation, centrifugation and freeze drying, namely the fluorescent probe for quantitatively detecting acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method.

The method for preparing the fluorescent probe for quantitatively detecting the acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method comprises the following specific steps:

(1) accurately weighing 0.05 g of o-phenylenediamine and 0.05 g of p-aminobenzoic acid in a beaker, adding 10 mL of absolute ethyl alcohol, carrying out ultrasonic treatment at 200W for 10 min to completely dissolve the o-phenylenediamine and the p-aminobenzoic acid, transferring the mixed solution into a 100 mL polytetrafluoroethylene lining, assembling a reaction kettle, placing the reaction kettle in an oven, and reacting for 12 h at 180 ℃;

(2) after the reaction is finished, cooling the reaction kettle to room temperature, removing absolute ethyl alcohol in the solution by rotary evaporation, adding 10 mL of secondary water into the reaction kettle, performing ultrasonic treatment at 200W for 10 min to fully disperse, centrifuging at 8000 rpm for 10 min, and freeze-drying the supernatant to obtain the C-dots solid powder.

The method for detecting the pH value of the fluorescent probe for quantitatively detecting the acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method comprises the following specific steps:

(1) accurately weighing C-dots solid powder, adding secondary water, performing ultrasonic treatment at 200W for 10 min to fully dissolve the C-dots solid powder, and preparing C-dots stock solution with mass concentration of 10 mg/mL;

(2) accurately weighing Na₂HPO₄Adding secondary water, ultrasonic treating at 200W for 5 min to dissolve completely, and preparing 0.02 mol/L Na₂HPO₄A stock solution; accurately weighing NaH₂PO₄Adding into secondary water, ultrasonic treating at 200W for 5 min to dissolve completely, and preparing 0.02 mol/L NaH₂PO₄A stock solution; accurately weighing NaOH, adding secondary water, and preparing 1mol/L NaOH stock solution; accurately measuring 10 mL of 85% concentrated phosphoric acid for later use;

(3) preparing phosphate buffer solutions with the pH values of 2, 2.5, 3, 3.5, 4, 4.25, 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, 7, 7.25, 7.5, 7.75, 8, 9, 10, 11, 12 and 13 by using the stock solution in the step (2) and an acidimeter for later use;

(4) accurately transferring 2 mL of secondary water, adding 7 muL of C-dots stock solution with the concentration of 10 mg/mL, and testing and recording the fluorescence intensity F of C-dots₀(ii) a Respectively transferring 2 mL of phosphate buffer solution with a plurality of pH values prepared in the step (3), adding 7 muL of C-dots stock solution with the concentration of 10 mg/mL, and testing and recording the fluorescence intensity F;

(5) calculating F/F corresponding to different pH values₀Numerical values, the relationship between different pH and the change in C-dots fluorescence was examined.

The fluorescent probe for quantitatively detecting acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancement method is used for amino acid type detection, and comprises the following specific steps:

(1) preparation of C-dots stock solution: adding the C-dots solid powder into secondary water, and performing ultrasonic treatment at 200W for 10 min to fully dissolve the C-dots solid powder to obtain C-dots stock solution with the mass concentration of 10 mg/mL;

(2) preparation of acidic and basic amino acid stock solutions: respectively weighing aspartic acid, glutamic acid, histidine, arginine and lysine, respectively adding secondary water, performing ultrasonic treatment at 200W for 5 min for full dissolution, and respectively preparing acidic and basic amino acid stock solutions with the molar concentration of 0.01 mol/L;

(3) obtaining a linear equation of the contents of the acidic and basic amino acids and the fluorescence intensity of C-dots: respectively adding amino acid stock solutions with different volumes into a C-dots solution with the concentration of 0.0349 mg/mL, and recording the fluorescence intensity value of C-dots under 561 nm at an excitation wavelength of 410 nm; and linearly and respectively fitting the amino acid concentration and the C-dots fluorescence intensity through Origin software to obtain five linear equations: aspartic acid, (F)₀-F)/F₀ = 0.0080c_(Asp) + 0.0699，R²= 0.9989, linear range is 10.94-29.80 [ mu ] mol/L; glutamic acid, (F)₀- F)/F = 0.0057c_(Glu) + 0.0421，R²= 0.9970, linear range 11.94-47.11 [ mu ] mol/L; histidine, (F-F)₀)/F₀ = 0.0122c_(His) + 0.0155，R²= 0.9975, linear range of 6.47-28.81 mu mol/L; arginine, (F-F)₀)/F₀ = 0.0169c_(Arg) + 0.0460，R²= 0.9982, linear range is 6.97-29.80 μmol/L; lysine, (F-F)₀)/F₀ = 0.0078c_(Lys) + 0.0465，R²= 0.9995, linear range is 7.96-81.54 [ mu ] mol/L; in the formula F₀F is the fluorescence intensity of C-dots before and after amino acid addition.

The method has the advantages that: the hydrothermal method can synthesize the required C-dots stably, and the o-phenylenediamine and the p-aminobenzoic acid are common reagents, are easy to purchase and have low price. The preparation method of the C-dots probe is simple, expensive instruments are not needed, and the amino acid class detection can be realized quickly, efficiently and quantitatively.

In a word, compared with other methods for detecting amino acid, the method has the advantages of simple operation, good selectivity, high sensitivity, high detection efficiency, no need of expensive instruments and equipment, low detection cost and the like, and is an ideal method for detecting amino acid.

Drawings

FIG. 1 is a UV spectrum and a fluorescence spectrum of C-dots prepared in example 1;

FIG. 2 is a graph showing an excitation wavelength-dependent spectrum of C-dots prepared in example 1;

FIG. 3 shows various metal ions (Sn) in example 2²⁺, Fe³⁺, Al³⁺, Cr³⁺, Fe²⁺,Hg²⁺, Ag⁺, Mn²⁺, Ba²⁺, Co²⁺, Cu²⁺, Zn²⁺, Na⁺, Ca²⁺, Ni²⁺, Mg²⁺, Cr(VI), Pb²⁺) Influence graph on C-dots fluorescence intensity;

FIG. 4 is a graph showing the effect of various amino acids (aspartic acid, glutamic acid, tryptophan, phenylalanine, methionine, cysteine, proline, isoleucine, serine, valine, threonine, leucine, glycine, alanine, homocysteine, tyrosine, asparagine, glutamine, histidine, arginine, lysine) on the fluorescence intensity of C-dots in example 2;

FIG. 5 shows various anions (C) in example 2₂O₄ ^2-, ClO^-, Cr₂O^7-, S₂O₈ ^2-, S₂O₃ ^2-, NO₃ ^-, NO₂ ^-, F^-, Cl^-, Br^-, H₂PO₄ ^-, SO₃ ^2-, HPO₄ ^2-, HCO₃ ^-, CO₃ ^2-) Influence graph on C-dots fluorescence intensity;

FIG. 6 is a bar graph of the effect of different pH's (2, 2.5, 3, 3.5, 4, 4.25, 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, 7, 7.25, 7.5, 7.75, 8, 9, 10, 11, 12, 13) on C-dots fluorescence intensity in example 2;

FIG. 7 is a graph showing the effect of different pH values (2, 2.5, 3, 3.5, 4, 4.25, 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, 7, 7.25, 7.5, 7.75, 8, 9, 10, 11, 12, 13) on the fluorescence intensity of C-dots in example 2 (experiment was repeated three times, error bars were obtained);

FIG. 8 is a spectrum of the change in fluorescence intensity of C-dots in secondary water and C-dots solution added at different pH values in example 2;

FIG. 9 is a C-dots solution titrated with aspartic acid in example 3, which shows the spectrum of C-dots fluorescence intensity change;

FIG. 10 is a graph linearly fitting the aspartic acid concentration to the change in C-dots fluorescence intensity in example 3;

FIG. 11 is a C-dots solution titrated with glutamic acid, showing the spectrum of C-dots fluorescence intensity change in example 3;

FIG. 12 is a linear fit of the glutamic acid concentration to the change in C-dots fluorescence intensity in example 3;

FIG. 13 is a graph showing the change in fluorescence intensity of C-dots in the histidine titration C-dots solution of example 3;

FIG. 14 is a graph linearly fitted with the change in fluorescence intensity of C-dots with histidine concentration in example 3;

FIG. 15 is a C-dots solution titrated with arginine in example 3, showing a C-dots fluorescence intensity change spectrum;

FIG. 16 is a linear fit of arginine concentration to changes in C-dots fluorescence intensity in example 3;

FIG. 17 is a C-dots solution titrated with lysine in example 3, showing the spectrum of change in fluorescence intensity of C-dots;

FIG. 18 is a linear fit of lysine concentration to change in C-dots fluorescence intensity in example 3.

Detailed Description

Example 1: preparation and characterization of C-dots

Step one, accurately weighing 0.05 g of o-phenylenediamine and 0.05 g of p-aminobenzoic acid, adding 10 mL of absolute ethyl alcohol, fully dissolving by ultrasonic waves (200W for 10 min), transferring to a 100 mL polytetrafluoroethylene lining, assembling a reaction kettle, placing in an oven, and heating to 180 DEG C^oAnd reacting for 12 hours under the condition of C.

And step two, after the reaction kettle is cooled to the room temperature, carrying out rotary evaporation on the solution in the reaction kettle and removing the absolute ethyl alcohol. Adding 10 mL of secondary water, dissolving the sticky substance by ultrasonic (200W, 10 min) and transferring to a centrifuge tube, centrifuging the solution at 8000 rpm for 10 min, transferring the supernatant to a beaker, and freeze-drying to obtain C-dots solid powder.

Step three, weighing 0.1 g C-dots solid powder in a beaker, adding 10 mL of secondary water, and performing ultrasonic treatment (200W for 10 min) to fully dissolve the secondary water to obtain C-dots stock solution with the concentration of 10 mg/mL.

The properties are characterized in figures 1 and 2. FIG. 1 is a graph of the UV absorption spectrum of C-dots, in which two distinct absorption peaks are located at 274 nm and 438 nm, respectively, n → π of C = O^*Transition and surface-OH, -NH₂Caused by a functional group; the optimal excitation and emission peaks for C-dots in FIG. 1 are at 410 nm and 561 nm, respectively.

FIG. 2 is a spectrum of emission spectra of C-dots at different excitation wavelengths, and the emission wavelength is substantially unchanged when the excitation wavelength is changed from 360 nm to 500 nm, indicating that the C-dots have no excitation wavelength dependence.

Example 2: response of different substances to C-dots

Step one, accurately weighing a certain mass of metal ions (Sn)²⁺, Fe³⁺, Al³⁺, Cr³⁺, Fe²⁺, Hg²⁺, Ag⁺, Mn²⁺, Ba²⁺, Co²⁺, Cu²⁺, Zn²⁺, Na⁺, Ca²⁺, Ni²⁺, Mg²⁺, Cr(VI), Pb²⁺) Adding 10 mL of secondary water into the compound, fully dissolving the compound by ultrasonic waves (200W, 5 min), and preparing a metal ion stock solution with the molar concentration of 0.1 mol/L.

Step two, accurately weighing amino acids (aspartic acid, glutamic acid, tryptophan, phenylalanine, methionine, cysteine, proline, isoleucine, serine, valine, threonine, leucine, glycine, alanine, homocysteine, tyrosine, asparagine, glutamine, histidine, arginine and lysine) with certain mass, adding 10 mL of secondary water, fully dissolving by ultrasound (200W, 5 min), and preparing amino acid stock solution with the molar concentration of 0.01 mol/L.

Step three, accurately weighing a certain mass of anions (C)₂O₄ ^2-, ClO^-, Cr₂O^7-, S₂O₈ ^2-, S₂O₃ ^2-, NO₃ ^-, NO₂ ^-, F^-, Cl^-, Br^-, H₂PO₄ ^-, SO₃ ^2-, HPO₄ ^2-, HCO₃ ^-, CO₃ ^2-) Adding 10 mL of secondary water into the compound, fully dissolving the compound by ultrasonic waves (200W, 5 min), and preparing an anion stock solution with the molar concentration of 0.1 mol/L.

Step four, preparing 0.02 mol/L Na₂HPO₄、0.02 mol/L NaH₂PO₄And 1mol/L NaOH stock solution, and phosphate buffer solutions with different pH values (2, 2.5, 3, 3.5, 4, 4.25, 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, 7, 7.25, 7.5, 7.75, 8, 9, 10, 11, 12 and 13) are prepared by an acidimeter for later use.

Step five, adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL of secondary water, wherein the mass concentration of C-dots is 0.0349 mg/mL (2007 mu L), testing and performingRecording the fluorescence intensity F of C-dots₀. Then adding 10 muL of metal ion stock solution, wherein the molar concentration of the metal ions is 0.496 mmol/L (2017 muL), testing and recording the fluorescence intensity F of C-dots, and calculating F/F₀And drawing a histogram by taking the number as a vertical coordinate and the type of the metal ions as a horizontal coordinate, wherein the experimental result is shown in figure 3.

Step six, adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL of secondary water, wherein the concentration of C-dots is 0.0349 mg/mL (2007 mu L), and testing and recording the fluorescence intensity F of the C-dots₀. Then adding 50 mu L of amino acid stock solution, wherein the concentration of the amino acid is 0.243 mmol/L (2057 mu L), testing and recording the fluorescence intensity F of C-dots, and calculating F/F₀And the column diagram is drawn by taking the amino acid as the ordinate and the kind of the amino acid as the abscissa, and the experimental result is shown in figure 4.

Step seven, adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL of secondary water, wherein the concentration of C-dots is 0.0349 mg/mL (2007 mu L), and testing and recording the fluorescence intensity F of the C-dots₀. Then adding 10 muL of anion stock solution, wherein the anion concentration is 0.496 mmol/L (2017 muL), testing and recording the fluorescence intensity F of C-dots, and calculating F/F₀And the column diagram is drawn by taking the ion as the ordinate and the kind of the anion as the abscissa, and the experimental result is shown in figure 5.

Seventhly, adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL of secondary water, wherein the concentration of C-dots is 0.0349 mg/mL (2007 mu L), and testing and recording the fluorescence intensity F of the C-dots₀. Adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL phosphate buffer solution with different pH values, testing and recording the fluorescence intensity F of C-dots, and calculating F/F₀And drawing a histogram by taking the pH value as a vertical coordinate and different pH values as a horizontal coordinate, wherein the experimental result is shown in figure 6; the experiment was repeated three times, the error bars were calculated, and fig. 7 was plotted; and simultaneously drawing fluorescence spectrograms of secondary water and different pH values, and the experimental result is shown in figure 8.

FIGS. 3-8 are graphs showing the effect of metal ions, amino acids, anions and pH on the fluorescence intensity of C-dots, indicating that C-dots are pH sensitive and are excellent pH fluorescent probes. When the pH is acidic, the fluorescence of C-dots is obviously weakened; when the pH is alkaline, the fluorescence of C-dots is significantly enhanced. Based on the above, the C-dots can be used for detecting the types of amino acids, and the fluorescence of the C-dots is gradually weakened by adding acidic amino acids into the C-dots; when basic amino acids were added to C-dots, the fluorescence of C-dots was gradually increased.

Example 3: c-dots for acidic and basic amino acid titration

Step one, adding 7 mu L C-dots (10 mg/mL) stock solution into 2 mL of secondary water, testing and recording the fluorescence intensity F of the C-dots at the time when the concentration of the C-dots is 0.0349 mg/mL (2007 mu L)₀。

And step two, dropwise adding the aspartic acid stock solution into the solution obtained in the step one, testing and recording the fluorescence intensity F of C-dots, drawing a fluorescence spectrogram of the whole titration process, and showing an experimental result in figure 9. Calculation (F)₀-F)/F₀And using the concentration of aspartic acid as the abscissa and the ordinate to obtain a linear equation by Origin fitting, (F)₀-F)/F₀ = 0.0080c_(Asp) + 0.0699，R²= 0.9989, the linear range is 10.94-29.80 μmol/L, and the lowest detection limit is 0.1925 umol/L. The results of the experiment are shown in FIG. 10.

And step three, dropwise adding the glutamic acid stock solution into the solution obtained in the step one, testing and recording the fluorescence intensity F of C-dots, drawing a fluorescence spectrogram of the whole titration process, and showing an experimental result in figure 11. Calculation (F)₀-F)/F₀And using the concentration of glutamic acid as the abscissa and the ordinate to obtain a linear equation by Origin fitting, (F)₀-F)/F = 0.0057c_(Glu) + 0.0421，R²= 0.9970, the linear range is 11.94-47.11 [ mu ] mol/L, and the lowest detection limit is 0.2702 umol/L. The results of the experiment are shown in FIG. 12.

Step four, dropwise adding histidine stock solution into the solution obtained in the step one, testing and recording the fluorescence intensity F of C-dots, drawing a fluorescence spectrogram of the whole titration process, and showing an experimental result in figure 13. Calculation (F)₀-F)/F₀And using the histidine as a vertical coordinate and the histidine concentration as a horizontal coordinate, and utilizing Origin to fit to obtain a linear equation (F-F)₀)/F₀ = 0.0122c_(His) + 0.0155，R²= 0.9975, the linear range is 6.47-28.81 [ mu ] mol/L, and the lowest detection limit is0.1263 umol/L. The results of the experiment are shown in FIG. 14.

And step five, dropwise adding the arginine stock solution into the solution obtained in the step one, testing and recording the fluorescence intensity F of C-dots, drawing a fluorescence spectrogram of the whole titration process, and showing an experimental result in a figure 15. Calculation (F)₀-F)/F₀And using the arginine as a vertical coordinate and the arginine concentration as a horizontal coordinate, and utilizing Origin to fit to obtain a linear equation (F-F)₀)/F₀ = 0.0169c_(Arg) + 0.0460，R²= 0.9982, the linear range is 6.97-29.80 μmol/L, and the lowest detection limit is 0.0911 umol/L. The results of the experiment are shown in FIG. 16.

Step six, dropwise adding the lysine stock solution into the solution obtained in the step one, testing and recording the fluorescence intensity F of C-dots, drawing a fluorescence spectrogram of the whole titration process, and showing an experimental result in figure 17. Calculation (F)₀-F)/F₀And using the concentration of lysine as the abscissa and the ordinate to obtain a linear equation (F-F) by Origin fitting₀)/F₀ = 0.0078c_(Lys) + 0.0465，R²= 0.9995, the linear range is 7.96-81.54 μmol/L, and the lowest detection limit is 0.1975 umol/L. The results of the experiment are shown in FIG. 18.

Fig. 9 and 11 show that: with the addition of acidic amino acids, the fluorescence of C-dots gradually decreased. Fig. 10 and 12 show that: within a certain range, the concentration of acidic amino acids is linearly related to the change of fluorescence of C-dots. Fig. 13, 15 and 17 show: with the addition of basic amino acids, the fluorescence of C-dots gradually increases. Fig. 14, 16 and 18 show that: within a certain range, the concentration of the basic amino acid is linearly related to the change of fluorescence of C-dots.

Claims

1. The amino acid type detection is carried out by the fluorescent probe for quantitatively detecting acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method, and the method is characterized in that: the method comprises the following specific steps:

(3) obtaining a linear equation of the contents of the acidic and basic amino acids and the fluorescence intensity of C-dots: respectively adding amino acid stock solutions with different volumes into a C-dots solution with the concentration of 0.0349 mg/mL, and recording the fluorescence intensity value of C-dots under 561 nm at an excitation wavelength of 410 nm; the amino acid concentration and the C-dots fluorescence intensity were linearly fitted by Origin software to obtain five linear equations: aspartic acid, (F)₀-F)/F₀ = 0.0080c_(Asp) + 0.0699，R²= 0.9989, linear range is 10.94-29.80 [ mu ] mol/L; glutamic acid, (F)₀- F)/F = 0.0057c_(Glu) + 0.0421，R²= 0.9970, linear range 11.94-47.11 [ mu ] mol/L; histidine, (F-F)₀)/F₀ = 0.0122c_(His) + 0.0155，R²= 0.9975, linear range is 6.47-28.81 μmol/L; arginine, (F-F)₀)/F₀ = 0.0169c_(Arg) + 0.0460，R²= 0.9982, linear range is 6.97-29.80 μmol/L; lysine, (F-F)₀)/F₀ = 0.0078c_(Lys) + 0.0465，R²= 0.9995, linear range is 7.96-81.54 [ mu ] mol/L; in the formula F₀F is the fluorescence intensity of C-dots before and after the amino acid is added;

the fluorescent probe for quantitatively detecting the acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method is characterized in that o-phenylenediamine and p-aminobenzoic acid are used as substrates to synthesize the carbon quantum dot C-dots by a hydrothermal method, and the C-dots solid powder is obtained by rotary evaporation, centrifugation and freeze drying, namely the fluorescent probe for quantitatively detecting the acidic or basic amino acid based on the carbon quantum dot fluorescence quenching or enhancing method;

the preparation method comprises the following steps: