Application of fluorescent carbon dots for mycophenolic acid detection

Abstract

This invention discloses the application of fluorescent carbon dots for mycophenolic acid detection, relating to the field of drug content detection technology. The carbon dot preparation method includes the following steps: adding β-cyclodextrin and L-phenylalanine to deionized water, ultrasonically mixing, and performing a hydrothermal reaction to obtain a reaction solution; cooling to room temperature, and then sequentially filtering, dialyzing, and freeze-drying to obtain fluorescent carbon dots for mycophenolic acid detection. This invention uses water as the reaction solvent and employs a one-step hydrothermal method to synthesize fluorescent carbon dots, which have been successfully applied to the sensing and determination of mycophenolic acid with good results. It offers advantages such as convenient construction, high sensitivity, good specificity, and ease of use. This invention solves the problems of complex operation, high cost, and low accuracy in existing methods for mycophenolic acid content detection.

Description

Technical Field

[0001] This invention relates to the field of drug content detection technology, and specifically to the application of a fluorescent carbon dot for mycophenolic acid detection. Background Technology

[0002] Mycophenolate amino acid (MPA) is a highly potent and selective inhibitor of hypoxanthine mononucleotide dehydrogenase, widely used in solid organ transplantation and the treatment of immune-inflammatory diseases. Mycophenolate has a narrow therapeutic window, with a trough concentration range of 1-4 μg / mL and a peak concentration range of 10-55 μg / mL. The area under the concentration-time curve estimated by limiting sampling is 30-60 mg·h·L. -1 The pharmacokinetics of MPA (metastatic arteriovenous agonists) varies considerably among individuals. Its concentration is related to efficacy and adverse reactions, and is significantly affected by concomitant medication. Therefore, monitoring MPA concentration is of great importance, and MPA detection has been recognized as a valuable adjunct in clinical treatment. Currently, the main methods for determining MPA blood concentration include chromatographic analysis (HPLC and LC-MS / MS) and enzyme-amplified immunoassay (EMIT). A key issue in monitoring plasma concentrations of immunosuppressive drugs is the analytical specificity of the method. Chromatographic analysis can be used for specific analysis of MPA due to its high instrument precision and lack of cross-reactivity with metabolites. However, the expensive equipment and time-consuming sample pretreatment make it difficult to meet the time-sensitive reporting requirements of large-scale clinical blood drug concentration monitoring. Therefore, it is inconvenient for routine drug monitoring. LC-MS / MS may suffer from ion inhibition, leading to a decrease in MPA blood concentration. Compared with chromatographic analysis, EMIT has advantages such as high detection efficiency and simple operation, and is used as a routine monitoring method. However, the high cost of the reagent kit increases the economic burden on patients. Therefore, there is an urgent clinical need to establish a rapid, accurate, and low-cost MPA detection method to guide patients in rational drug use. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide an application of fluorescent carbon dots for mycophenolic acid detection, thereby resolving the issues of complex operation, high cost, and low accuracy in existing methods for detecting mycophenolic acid content.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: providing an application of fluorescent carbon dots for mycophenolic acid detection.

[0005] This invention also provides a method for detecting mycophenolic acid content, comprising the following steps:

[0006] S1: Mix the fluorescent carbon dots used for mycophenolic acid detection with water to prepare a carbon dot solution.

[0007] S2: Add mycophenolic acid standard solutions of different concentrations to the carbon dot solution prepared in step S1. Use 330nm as the excitation wavelength to measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the standard solution. Obtain the change in fluorescence intensity of the carbon dot solution at the maximum emission wavelength after the addition of the standard solution relative to the carbon dot solution before the addition of the standard solution.

[0008] S3: Based on the change in fluorescence intensity obtained in step S2 and the corresponding concentration of mycophenolic acid standard solution, plot a standard curve to obtain a linear equation;

[0009] S4: Add the mycophenolic acid solution to the carbon dot solution prepared in step S1. Using 330nm as the excitation wavelength, measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the mycophenolic acid solution. Obtain the change in fluorescence intensity of the carbon dot solution at the maximum emission wavelength after the addition of the mycophenolic acid solution relative to the carbon dot solution before the addition of the mycophenolic acid solution. Substitute this value into the linear equation to obtain the concentration of the mycophenolic acid solution.

[0010] Furthermore, in step S1, the fluorescent carbon dots used for mycophenolic acid detection are prepared by the following method:

[0011] (1) Add β-cyclodextrin and L-phenylalanine to deionized water, mix them evenly by ultrasonication, and perform hydrothermal reaction to obtain a reaction solution.

[0012] (2) Cool the reaction solution obtained in step (1) to room temperature, and then filter, dialyze and freeze dry in sequence to obtain fluorescent carbon dots for mycophenolic acid detection.

[0013] Furthermore, in step (1), the molar volume ratio of β-cyclodextrin, L-phenylalanine and deionized water is 0.5 mmol: 0.1-7 mmol: 10-25 mL.

[0014] Furthermore, in step (1), the molar volume ratio of β-cyclodextrin, L-phenylalanine and deionized water is 0.5 mmol: 0.25 mmol: 20 mL.

[0015] Furthermore, in step (1), the hydrothermal reaction is carried out at 140-240℃ for 2-10 hours.

[0016] Furthermore, in step (1), the hydrothermal reaction is carried out at 180°C for 6 hours.

[0017] Furthermore, in step (2), a 0.2-0.3μm microporous membrane is used for filtration.

[0018] Furthermore, in step (2), a 0.22μm microporous membrane is used for filtration.

[0019] Furthermore, in step (2), dialysis is performed for 12-48 hours using a dialysis bag with a molecular weight cutoff of 1000-5000 Da.

[0020] Furthermore, in step (2), dialysis is performed for 24 hours using a dialysis bag with a molecular weight cutoff of 1000 Da.

[0021] Furthermore, in step S1, the concentration of the carbon dot solution is 0.05-2 mg / mL.

[0022] Furthermore, in step S1, the concentration of the carbon dot solution is 1.5 mg / mL.

[0023] Furthermore, in step S2, the volume ratio of the carbon dot solution to the mycophenolic acid standard solution is 1:0.5-5.

[0024] Furthermore, in step S2, the volume ratio of the carbon dot solution to the mycophenolic acid standard solution is 1:1.

[0025] Furthermore, in step S2, the concentrations of the different mycophenolic acid standard solutions are 0 μg / mL, 5 μg / mL, 10 μg / mL, 20 μg / mL, 25 μg / mL, 30 μg / mL, 35 μg / mL, 40 μg / mL, 45 μg / mL, 55 μg / mL, and 60 μg / mL.

[0026] Furthermore, in step S3, the concentration of the mycophenolic acid standard solution is in the range of 0.06-10 μg / mL, and the linear equation is y = 869.27x - 2.3674, R0 2 =0.9993, where y is the change in fluorescence intensity, x is the concentration of the mycophenolic acid standard solution, and R 2 It is the linear fitting constant.

[0027] Furthermore, in step S3, the concentration of the mycophenolic acid standard solution is in the range of 10-36 μg / mL, and the linear equation is y = 631.25x + 2424.7, R0 2 =0.9964, y is the change in fluorescence intensity, x is the concentration of the mycophenolic acid standard solution, R 2 It is the linear fitting constant.

[0028] Furthermore, in step S4, the detection limit for mycophenolic acid in the mycophenolic acid solution to be tested is 0.013 μg / mL.

[0029] Furthermore, in step S2, the mycophenolic acid standard solution can also be mycophenolic acid standard plasma.

[0030] Furthermore, for mycophenolic acid standard plasma concentrations in the range of 0.06-3 μg / mL, the linear equation was y = 965.36x - 27.27, R0 2=0.9997, y is the change in fluorescence intensity, x is the concentration of mycophenolic acid in standard plasma, R 2 It is the linear fitting constant.

[0031] Furthermore, the linear equation for the concentration of mycophenolic acid in standard plasma was y = 846.53x + 327.41, R0 2 =0.9991, y is the change in fluorescence intensity, x is the concentration of mycophenolic acid in standard plasma, R 2 It is the linear fitting constant.

[0032] Furthermore, the detection limit for mycophenolic acid in plasma was 0.015 μg / mL.

[0033] The present invention has the following beneficial effects:

[0034] 1. This invention uses readily available β-cyclodextrin as a raw material, doped with amino small molecules, to prepare carbon quantum dots with high fluorescence performance and excellent water solubility. Water is used as the reaction solvent, and a one-step hydrothermal method is used for synthesis. The operation process is simple, green and environmentally friendly, economical and efficient, and has great social significance.

[0035] 2. This invention successfully applies carbon quantum dots to the sensing and determination of mycophenolic acid, achieving good results. It has advantages such as convenient construction, high sensitivity, good specificity, and ease of use. It can be applied to the determination of mycophenolic acid raw materials and their preparations, as well as drug concentration in clinical use. Attached Figure Description

[0036] Figure 1 This is a high-resolution transmission electron microscope image of the fluorescent carbon dots prepared in Example 1;

[0037] Figure 2 The infrared spectrum of the fluorescent carbon dots obtained in Example 1;

[0038] Figure 3 The image shows the ultraviolet spectrum of the fluorescent carbon dots obtained in Example 1.

[0039] Figure 4 The fluorescence spectrum of the fluorescent carbon dots obtained in Example 1 is shown below.

[0040] Figure 5 This is a photostogram of the photostability of the fluorescent carbon dots prepared in Example 1;

[0041] Figure 6 The working curve of the fluorescent carbon dots prepared in Example 1 in response to mycophenolic acid;

[0042] Figure 7 The graph shows the linear relationship between the fluorescence intensity change of the fluorescent carbon dots prepared in Example 1 and the concentration of mycophenolic acid (0.06-10 μg / mL).

[0043] Figure 8 The graph shows the linear relationship between the fluorescence intensity change of the fluorescent carbon dots prepared in Example 1 and the concentration of mycophenolic acid (10-36 μg / mL).

[0044] Figure 9 The graph shows the linear relationship between the fluorescence intensity change of the fluorescent carbon dots prepared in Example 2 and the concentration of mycophenolic acid (0.06-3 μg / mL).

[0045] Figure 10 The graph shows the linear relationship between the fluorescence intensity change of the fluorescent carbon dots prepared in Example 2 and the concentration of mycophenolic acid (3-27 μg / mL). Detailed Implementation

[0046] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0047] Example 1:

[0048] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0049] (1) Add 0.5 mmol of β-cyclodextrin and 0.25 mmol of L-phenylalanine to 20 mL of deionized water, mix thoroughly by ultrasonication, pour into a high-pressure reactor, and hydrothermally react at 180 °C for 6 h to obtain a reaction solution.

[0050] (2) Cool the reaction solution obtained in step (1) to room temperature, then filter it with a 0.22 μm microporous membrane, then dialyze it with a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h, and finally freeze dry it to obtain fluorescent carbon dots for mycophenolic acid detection.

[0051] A method for detecting mycophenolic acid content includes the following steps:

[0052] S1: Mix the fluorescent carbon dots used for mycophenolic acid detection with water to prepare a carbon dot solution with a concentration of 1.5 mg / mL.

[0053] S2: To 50 μL of the carbon dot solution prepared in step S1, add 50 μL of mycophenolic acid standard solution at different concentrations (0 μg / mL, 5 μg / mL, 10 μg / mL, 20 μg / mL, 25 μg / mL, 30 μg / mL, 35 μg / mL, 40 μg / mL, 45 μg / mL, 55 μg / mL, and 60 μg / mL). Using 330 nm as the excitation wavelength, measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the standard solution (see...). Figure 6 The fluorescence intensity change of the carbon dot solution at the maximum emission wavelength of 391 nm was obtained after the addition of the standard solution relative to the carbon dot solution before the addition of the standard solution.

[0054] S3: Based on the change in fluorescence intensity obtained in step S2 and the corresponding concentration of mycophenolic acid standard solution, plot a standard curve to obtain a linear equation;

[0055] The concentration of the mycophenolic acid standard solution was in the range of 0.06-10 μg / mL, and the linear equation was y = 869.27x - 2.3674, R0 2 =0.9993, y is the change in fluorescence intensity, x is the concentration of the mycophenolic acid standard solution, R 2 It is the linear fitting constant (see Figure 7 y = ΔF = F - F0, where F0 represents the fluorescence intensity without mycophenolic acid and F represents the fluorescence intensity with mycophenolic acid.

[0056] For mycophenolic acid standard solutions with concentrations ranging from 10 to 36 μg / mL, the linear equation is y = 631.25x + 2424.7, R0 2 =0.9964, y is the change in fluorescence intensity, x is the concentration of the mycophenolic acid standard solution, R 2 It is the linear fitting constant (see Figure 8 y = ΔF = F - F0, where F0 represents the fluorescence intensity without mycophenolic acid and F represents the fluorescence intensity with mycophenolic acid.

[0057] S4: Add 50 μL of the mycophenolic acid solution to 50 μL of the carbon dot solution prepared in step S1. Using 330 nm as the excitation wavelength, measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the mycophenolic acid solution. Obtain the change in fluorescence intensity of the carbon dot solution after the addition of the mycophenolic acid solution relative to the carbon dot solution before the addition of the mycophenolic acid solution at the maximum emission wavelength of 391 nm. Substitute the values ​​into the linear equation to obtain the concentration of the mycophenolic acid solution to be tested as 35.23 μg / mL.

[0058] The detection limit for mycophenolic acid is 0.013 μg / mL.

[0059] Example 2:

[0060] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0061] Same as Example 1.

[0062] A method for detecting mycophenolic acid content includes the following steps:

[0063] S1: Mix the fluorescent carbon dots used for mycophenolic acid detection with water to prepare a carbon dot solution with a concentration of 1.5 mg / mL.

[0064] S2: Add 50 μL of mycophenolic acid standard plasma at different concentrations (0 μg / mL, 5 μg / mL, 10 μg / mL, 20 μg / mL, 25 μg / mL, 30 μg / mL, 35 μg / mL, 40 μg / mL, 45 μg / mL, 55 μg / mL and 60 μg / mL) to 50 μL of the carbon dot solution prepared in step S1. Use 330 nm as the excitation wavelength to measure the fluorescence emission spectra of the carbon dot solution before and after the addition of standard plasma. The change in fluorescence intensity of the carbon dot solution after the addition of standard plasma relative to the carbon dot solution before the addition of standard plasma at the maximum emission wavelength of 391 nm is obtained.

[0065] S3: Based on the change in fluorescence intensity obtained in step S2 and the corresponding concentration of mycophenolic acid standard plasma, a standard curve is plotted to obtain a linear equation;

[0066] Among them, the concentration of mycophenolic acid in standard plasma was in the range of 0.06-3 μg / mL, and the linear equation was y = 965.36x - 27.27, R0 2 =0.9997, y is the change in fluorescence intensity, x is the concentration of mycophenolic acid in standard plasma, R 2 It is the linear fitting constant (see Figure 9 y = ΔF = F - F0, where F0 represents the fluorescence intensity without mycophenolic acid and F represents the fluorescence intensity with mycophenolic acid.

[0067] The concentration of mycophenolic acid in standard plasma ranged from 3 to 27 μg / mL, and the linear equation was y = 846.53x + 327.41, R0. 2 =0.9991, y is the change in fluorescence intensity, x is the concentration of mycophenolic acid in standard plasma, R 2 It is the linear fitting constant (see Figure 10 y = ΔF = F - F0, where F0 represents the fluorescence intensity without mycophenolic acid and F represents the fluorescence intensity with mycophenolic acid.

[0068] S4: Add 50 μL of mycophenolic acid plasma to 50 μL of the carbon dot solution prepared in step S1. Using 330 nm as the excitation wavelength, measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the mycophenolic acid plasma. Obtain the change in fluorescence intensity of the carbon dot solution after the addition of the mycophenolic acid plasma relative to the carbon dot solution before the addition of the mycophenolic acid plasma at the maximum emission wavelength of 391 nm. Substitute the values ​​into the linear equation to obtain the concentration of the mycophenolic acid solution to be tested as 26.77 μg / mL.

[0069] The detection limit for mycophenolic acid is 0.015 μg / mL.

[0070] Example 3:

[0071] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0072] (1) Add 0.5 mmol of β-cyclodextrin and 0.1 mmol of L-phenylalanine to 10 mL of deionized water, mix thoroughly by ultrasonication, pour into a high-pressure reactor, and hydrothermally react at 140 °C for 10 h to obtain a reaction solution.

[0073] (2) Cool the reaction solution obtained in step (1) to room temperature, then filter it with a 0.2 μm microporous membrane, then dialyze it with a dialysis bag with a molecular weight cutoff of 2000 Da for 48 h, and finally freeze dry it to obtain fluorescent carbon dots for mycophenolic acid detection.

[0074] Example 4:

[0075] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0076] (1) Add 0.5 mmol of β-cyclodextrin and 7 mmol of L-phenylalanine to 25 mL of deionized water, mix thoroughly by ultrasonication, pour into a high-pressure reactor, and hydrothermally react at 240 °C for 2 h to obtain a reaction solution.

[0077] (2) Cool the reaction solution obtained in step (1) to room temperature, then filter it with a 0.22 μm microporous membrane, then dialyze it with a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h, and finally freeze dry it to obtain fluorescent carbon dots for mycophenolic acid detection.

[0078] Examples 5-6:

[0079] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0080] In step (1), the hydrothermal reaction time is 2h and 10h respectively, and the rest is the same as in Example 1.

[0081] Example 7:

[0082] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0083] In step (1), 7 mmol of L-phenylalanine was used, and the hydrothermal reaction was carried out for 2 hours. The rest was the same as in Example 1.

[0084] Example 8:

[0085] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0086] In step (1), 0.125 mmol of L-phenylalanine was used, and the hydrothermal reaction was carried out for 6 hours. The rest was the same as in Example 1.

[0087] Example 9:

[0088] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0089] In step (1), the hydrothermal reaction was carried out at 140°C for 6 hours, and the rest was the same as in Example 1.

[0090] Example 10:

[0091] A fluorescent carbon dot for the detection of mycophenolic acids, the preparation method of which includes the following steps:

[0092] In step (1), the hydrothermal reaction was carried out at 240°C for 2 hours, and the rest was the same as in Example 1.

[0093] Test case

[0094] I. The fluorescent carbon dots prepared in Example 1 for mycophenolic acid detection were subjected to high-resolution transmission electron microscopy, infrared, and ultraviolet detection. The results are shown in [Figure 1]. Figure 1-3 .

[0095] Depend on Figure 1-3 It can be seen that the carbon dots are relatively regular spherical with uniform particle size distribution and an average particle size of about 9.4 nm. The infrared results show that the surface of the synthesized carbon dots contains hydroxyl, amino, carboxyl and other oxygen-containing functional groups, which endow the carbon dots with good water solubility and stability. The ultraviolet spectrum shows that the carbon dots have conjugated double bonds in their structure, including C=C and C=N bonds.

[0096] II. The fluorescent carbon dot solution for mycophenolic acid detection prepared in Example 1 was subjected to fluorescence spectroscopy. The results are shown in […]. Figure 4 .

[0097] Depend on Figure 4 It can be seen that the maximum excitation wavelength of this carbon dot is 330nm and the maximum emission wavelength is 391nm.

[0098] III. The fluorescent carbon dots for mycophenolic acid detection prepared in Example 1 were continuously irradiated with excitation light at 330 nm for 10 h, and their fluorescence signals are shown in [the figure]. Figure 5 .

[0099] Depend on Figure 5 This indicates that the carbon dots prepared by the present invention have strong anti-photobleaching effect and good photostability.

[0100] IV. The fluorescent carbon dots for mycophenolic acid detection prepared in Examples 1 and 5-10 were dissolved in water and their quantum yields were measured. The results are shown in Table 1.

[0101] Table 1 Quantumized Yields

[0102] project Quantized yield Example 1 9.96％ Example 5 6.15％ Example 6 4.43％ Example 7 5.56％ Example 8 3.18％ Example 9 6.47％ Example 10 1.16％

[0103] As shown in Table 1, the highest quantum yield of carbon dots (9.96%) was obtained when the ratio of β-cyclodextrin to L-phenylalanine was 2:1, the reaction temperature was 180℃, and the reaction time was 6h. This indicates that these conditions are the optimal conditions for carbon dot synthesis.

[0104] 5. Carbon dots were used to detect mycophenolic acid in actual samples. Each sample was measured three times. The results are shown in Table 2.

[0105] Table 2. Determination of MPA in human plasma

[0106]

[0107] As shown in Table 2, comparing the detection results with those obtained by EMIT, the relative errors were all within ±5%, which proves the reliability and accuracy of the method of the present invention and that it can be used to detect the concentration of mycophenolic acid in human plasma.

[0108] VI. Four concentrations of mycophenolic acid standard solutions were prepared using ethanol and plasma, with concentrations of 0.08 μg / mL, 0.8 μg / mL, 3 μg / mL and 8 μg / mL, respectively. Under optimal experimental conditions, each concentration was measured in triplicate, and the average recovery rate and RSD value were calculated. The results are shown in Table 3.

[0109] Table 3. Average recoveries and RSDs of anhydrous ethanol and plasma.

[0110]

[0111] Table 3 shows that the average recoveries in anhydrous ethanol ranged from 93.32% to 97.63%, with RSDs ranging from 0.11% to 5.64%. In plasma, the recoveries ranged from 97.81% to 100.64%, with RSDs ranging from 0.13% to 6.76%. This indicates that the MPA detection method has good accuracy and reproducibility.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application of fluorescent carbon dots for mycophenolic acid detection, characterized in that, The fluorescent carbon dots used for mycophenolic acid detection are prepared by the following method: (1) Add β-cyclodextrin and L-phenylalanine to deionized water, mix evenly by ultrasonication, and perform hydrothermal reaction to obtain a reaction solution; (2) Cool the reaction solution obtained in step (1) to room temperature, and then filter, dialyze and freeze dry in sequence to obtain fluorescent carbon dots for mycophenolic acid detection; In step (1), the molar volume ratio of β-cyclodextrin, L-phenylalanine and deionized water is 0.5 mmol: 0.1-7 mmol: 10-25 mL; In step (1), the hydrothermal reaction is carried out at 140-240℃ for 2-10 hours.

2. The application of the fluorescent carbon dots for mycophenolic acid detection according to claim 1, characterized in that, In step (2), a 0.2-0.3μm microporous membrane is used for filtration.

3. The application of the fluorescent carbon dots for mycophenolic acid detection according to claim 1, characterized in that, In step (2), dialysis is performed for 12-48 hours using a dialysis bag with a molecular weight cutoff of 1000-5000 Da.

4. A method for detecting mycophenolic acid content, characterized in that, Includes the following steps: S1: Mix the fluorescent carbon dots for mycophenolic acid detection as described in claim 1 with water to obtain a carbon dot solution; S2: Add mycophenolic acid standard solutions of different concentrations to the carbon dot solution prepared in step S1. Use 330nm as the excitation wavelength to measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the standard solution. Obtain the change in fluorescence intensity of the carbon dot solution at the maximum emission wavelength after the addition of the standard solution relative to the carbon dot solution before the addition of the standard solution. S3: Based on the change in fluorescence intensity obtained in step S2 and the corresponding concentration of mycophenolic acid standard solution, plot a standard curve to obtain a linear equation; S4: Add the mycophenolic acid solution to the carbon dot solution prepared in step S1. Using 330nm as the excitation wavelength, measure the fluorescence emission spectra of the carbon dot solution before and after the addition of the mycophenolic acid solution. Obtain the change in fluorescence intensity of the carbon dot solution at the maximum emission wavelength after the addition of the mycophenolic acid solution relative to the carbon dot solution before the addition of the mycophenolic acid solution. Substitute this value into the linear equation to obtain the concentration of the mycophenolic acid solution.

5. The method for detecting mycophenolic acid content according to claim 4, characterized in that, In step S1, the concentration of the carbon dot solution is 10-25 mg / mL.

6. The method for detecting mycophenolic acid content according to claim 4, characterized in that, In step S2, the volume ratio of carbon dot solution to mycophenolic acid standard solution is 1:0.5-5.

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