阅读说明：本技术 一种应用铜掺杂碳量子点检测甲硝唑含量的方法 (Method for detecting metronidazole content by using copper-doped carbon quantum dots ) 是由 杜金艳 范婷婷 漆双庆 杨影 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种应用铜掺杂碳量子点检测甲硝唑含量的方法,包括：分别测定各待测溶液和空白待测溶液的最大荧光强度；以待测溶液的最大荧光强度和空白待测溶液的最大荧光强度的比值为纵坐标,甲硝唑的浓度为横坐标,建立荧光发射光谱曲线方程；测定待检测甲硝唑的最大荧光强度,然后根据荧光发射光谱曲线方程计算得到甲硝唑的浓度；其中,铜掺杂碳量子点通过以下方法制备得到,所述制备方法包括：将EDC、乙酸铜和水混合,得到澄清透明的溶液,将所得溶液经水热反应,离心后收集产物,得到铜掺杂碳量子点。该铜掺杂碳量子点作为荧光探针应用于甲硝唑检测时,具备良好选择性和高灵敏度,且响应时间短、能够实时检测。(The invention discloses a method for detecting metronidazole content by using copper-doped carbon quantum dots, which comprises the following steps: respectively measuring the maximum fluorescence intensity of each solution to be measured and the blank solution to be measured; establishing a fluorescence emission spectrum curve equation by taking the ratio of the maximum fluorescence intensity of the solution to be detected to the maximum fluorescence intensity of the blank solution to be detected as a vertical coordinate and the concentration of metronidazole as a horizontal coordinate; measuring the maximum fluorescence intensity of the metronidazole to be detected, and then calculating according to a fluorescence emission spectrum curve equation to obtain the concentration of the metronidazole; the copper-doped carbon quantum dot is prepared by the following method, and the preparation method comprises the following steps: mixing EDC, copper acetate and water to obtain a clear and transparent solution, carrying out hydrothermal reaction on the obtained solution, centrifuging and collecting a product to obtain the copper-doped carbon quantum dot. When the copper-doped carbon quantum dot is used as a fluorescent probe and applied to metronidazole detection, the copper-doped carbon quantum dot has good selectivity and high sensitivity, is short in response time and can be used for real-time detection.)

1. A method for detecting metronidazole content by using copper-doped carbon quantum dots is characterized by comprising the following steps:

(1) respectively mixing metronidazole with different concentrations with a carbonate buffer solution and a purified copper-doped carbon quantum dot solution, and fixing the volume to obtain a solution to be detected;

(2) mixing the purified copper-doped carbon quantum dot solution with a carbonate buffer solution, and fixing the volume to obtain a blank solution to be measured;

(3) respectively measuring the maximum fluorescence intensity of each solution to be measured and the blank solution to be measured;

(4) establishing a fluorescence emission spectrum curve equation by taking the ratio of the maximum fluorescence intensity of the solution to be detected to the maximum fluorescence intensity of the blank solution to be detected as a vertical coordinate and the concentration of metronidazole as a horizontal coordinate;

(5) measuring the maximum fluorescence intensity of the metronidazole to be detected, and then calculating according to a fluorescence emission spectrum curve equation to obtain the concentration of the metronidazole;

the copper-doped carbon quantum dot is prepared by the following method, and the preparation method comprises the following steps: mixing EDC, copper acetate and water to obtain a clear and transparent solution, carrying out hydrothermal reaction on the obtained solution, centrifuging and collecting a product to obtain the copper-doped carbon quantum dot.

2. The method as claimed in claim 1, wherein ascorbic acid is further added into the solution before hydrothermal reaction in the preparation process of the copper-doped carbon quantum dot, wherein the molar ratio of ascorbic acid to copper acetate is 0-0.3: 1.

3. the method of claim 2, wherein during the preparation of the copper-doped carbon quantum dots, before the hydrothermal reaction is performed, in solution: the concentration of copper acetate is 0.06-0.08mol/L, the concentration of EDC is 0.04-0.07mol/L, and the concentration of ascorbic acid is 0-0.36 mol/L.

4. The method according to any one of claims 1 to 3, wherein during the preparation of the copper-doped carbon quantum dots, the conditions of the hydrothermal reaction comprise: the temperature is 200-220 ℃; and/or the time is 4-8 h.

5. The method of claim 4, wherein the preparation process of the copper-doped carbon quantum dots further comprises a step of dialyzing the obtained product with a dialysis bag.

6. The process according to claim 1, wherein the carbonate buffer solution has a concentration of 0.004-0.08mol/L and a pH of 8-11.

7. The method of claim 1, wherein the maximum fluorescence intensity measurement is performed in the wavelength range of 330-600 nm.

8. The method of claim 7, wherein the maximum fluorescence intensity is at a temperature of 298-308K.

9. The method according to claim 8, wherein each test solution is allowed to stand for 3 to 10min before the maximum fluorescence intensity is measured.

10. The method according to any one of claims 1 to 9, wherein the amount of the copper-doped carbon quantum dots is 1.5 to 3.0mg per 1L of the test solution or the blank test solution.

Technical Field

The invention relates to the field of nano material sensing research, in particular to a method for detecting metronidazole content by using copper-doped carbon quantum dots.

Background

Metronidazole (MNZ) is a derivative of nitroimidazole and is commonly used in the treatment of human diseases including parasitic infections, trichomoniasis, giardiasis and amebiasis. MNZ is also used as a veterinary drug for preventing and treating infections or promoting growth and increasing feed conversion efficiency. However, when the cumulative dose of MNZ exceeds the therapeutic threshold in humans, some toxic effects will be caused. Such as seizures, peripheral neuropathies and ataxia. Therefore, MNZ and several other nitroimidazoles have been banned from use in europe. Uncontrolled use of MNZ, or parts of feed accidentally contaminated with MNZ, may result in its residue being present in the edible tissue. Therefore, it is of great significance to accurately detect the MNZ content in drugs and biological samples.

Various quantitative analytical strategies are currently used for the detection of MNZ, including mainly High Performance Liquid Chromatography (HPLC), Gas Chromatography (GC), Thin Layer Chromatography (TLC), spectrophotometry and electrochemical sensors. Given the disadvantages of these methods, such as time consuming sample preparation and the complex instrumentation required, the need for better analytical methods remains a challenge. In addition to the above methods, fluorescence analysis methods are of great interest because of their relatively low cost, high sensitivity, simple operation, reliable method and low detection limit.

Disclosure of Invention

The invention aims to provide a copper-doped carbon quantum dot, and a preparation method and application thereof.

In order to achieve the above object, the present invention provides a method for preparing copper-doped carbon quantum dots, comprising: mixing 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC), copper acetate and water to obtain a clear and transparent solution, carrying out hydrothermal reaction on the obtained solution, centrifuging and collecting a product to obtain the copper-doped carbon quantum dot.

Preferably, before hydrothermal reaction, ascorbic acid is added into the solution, wherein the ratio of Ascorbic Acid (AA) to copper acetate is 0.05: 1.

the invention also provides the copper-doped carbon quantum dot which is prepared by the preparation method.

In addition, the invention also provides a method for detecting the content of metronidazole by using the copper-doped carbon quantum dots; the method comprises the following steps:

(1) respectively mixing metronidazole with different concentrations with a carbonate buffer solution and a purified copper-doped carbon quantum dot solution, and fixing the volume to obtain a solution to be detected;

(2) mixing the purified copper-doped carbon quantum dot solution with a carbonate buffer solution, and fixing the volume to obtain a blank solution to be measured;

(3) respectively measuring the maximum fluorescence intensity of each solution to be measured and the blank solution to be measured;

(4) establishing a fluorescence emission spectrum curve equation by taking the ratio of the maximum fluorescence intensity of the solution to be detected to the maximum fluorescence intensity of the blank solution to be detected as a vertical coordinate and the concentration of metronidazole as a horizontal coordinate;

(5) and (3) determining the maximum fluorescence intensity of the metronidazole to be detected, and then calculating according to a fluorescence emission spectrum curve equation to obtain the concentration of the metronidazole.

According to the technical scheme, in the reaction process of the preparation method of the copper-doped carbon quantum dot, EDC is used as a carbon source for synthesizing the copper-doped carbon quantum dot, and is used as a chelating agent of copper acetate, and ascorbic acid is used as a reducing agent. The copper-doped carbon quantum dot prepared by the method has high fluorescence quantum yield, good dispersibility, controllability, low production cost and good reproducibility, and a uniform morphology structure is formed by controlling the use amount and concentration of raw materials and the temperature and time of reaction; due to the internal filtering effect between the prepared copper-doped carbon quantum dots and metronidazole, the fluorescence of the copper-doped carbon quantum dots is effectively quenched. The detection method has the advantages that high-sensitivity and high-selectivity sensing of metronidazole is realized according to the linear dependence relationship between the change of the fluorescence intensity of the copper-doped carbon quantum dots and the concentration of the metronidazole, the detection method has good selectivity and high sensitivity, the response time is short, and real-time detection can be realized.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a Transmission Electron Micrograph (TEM) of the copper-doped carbon quantum dots prepared in example 1;

fig. 2 is a Fluorescence excitation dependence graph (Fluorescence) of the copper-doped carbon quantum dot prepared in example 1;

fig. 3 is a uv absorption graph (Absorbance) of the copper-doped carbon quantum dot prepared in example 1;

FIG. 4 is a graph comparing the quenching effect of copper-doped carbon quantum dots on metronidazole prepared in examples 1-3;

FIG. 5 is a fluorescence emission spectrum of metronidazole detection using the copper-doped carbon quantum dots prepared in example 1;

FIG. 6 is a linear graph of fluorescence intensity of metronidazole detected using the copper-doped carbon quantum dots prepared in example 1;

FIG. 7 is a graph showing the relationship between the fluorescence intensity of the carbon quantum dots prepared in comparative example 1 and the concentration of metronidazole;

FIG. 8 is a fluorescence emission spectrum of metronidazole for detection of carbon quantum dots prepared in comparative example 2;

FIG. 9 is a bar graph of the fluorescence response of different substances to copper-doped carbon quantum dots.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a preparation method of copper-doped carbon quantum dots, which is characterized by comprising the following steps: mixing 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC), copper acetate and water to obtain a clear and transparent solution, carrying out hydrothermal reaction on the obtained solution, centrifuging and collecting a product to obtain the copper-doped carbon quantum dot.

Preferably, before hydrothermal reaction, ascorbic acid is further added into the solution, wherein the molar ratio of copper acetate to Ascorbic Acid (AA) is 1: 0-0.3.

According to the technical scheme, in the reaction process, EDC is used as a carbon source for synthesizing the copper-doped carbon dots and is used as a chelating agent of copper acetate. AA (ascorbic acid) is used as a reducing agent in the process of synthesizing the copper-doped carbon quantum dots, and copper acetate is used as a metal dopant. The copper-doped carbon quantum dot prepared by the method has the advantages of high fluorescence quantum yield, good dispersibility, controllability, low production cost and good reproducibility.

In order to improve the yield, dispersibility and sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the invention, before the hydrothermal reaction is carried out, in solution: the concentration of copper acetate is 0.06-0.08mol/L, the concentration of EDC is 0.04-0.07mol/L, and the concentration of ascorbic acid is 0-0.36 mol/L.

In order to improve the yield, dispersibility and sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the present invention, the conditions of the hydrothermal reaction include: the temperature is 200-220 ℃.

In order to improve the yield, dispersibility and sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the present invention, the conditions of the hydrothermal reaction include: the time is 4-8 h.

In order to improve the yield, the dispersity and the sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the invention, the method further comprises the step of dialyzing the obtained product by using a dialysis bag.

The invention also provides a method for detecting the content of metronidazole by using the copper-doped carbon quantum dots; the method comprises the following steps:

(1) respectively mixing metronidazole with different concentrations with a carbonate buffer solution and a purified copper-doped carbon quantum dot solution, and fixing the volume to obtain a solution to be detected;

(2) mixing the purified copper-doped carbon quantum dot solution with a carbonate buffer solution, and fixing the volume to obtain a blank solution to be measured;

(3) respectively measuring the maximum fluorescence intensity of each solution to be measured and the blank solution to be measured;

(4) establishing a fluorescence emission spectrum curve equation by taking the ratio of the maximum fluorescence intensity of the solution to be detected to the maximum fluorescence intensity of the blank solution to be detected as a vertical coordinate and the concentration of metronidazole as a horizontal coordinate;

(5) and (3) determining the maximum fluorescence intensity of the metronidazole to be detected, and then calculating according to a fluorescence emission spectrum curve equation to obtain the concentration of the metronidazole.

According to the technical scheme, in the reaction process of the preparation method of the copper-doped carbon quantum dot, EDC is used as a carbon source for synthesizing the copper-doped carbon quantum dot, and is used as a chelating agent of copper acetate, and ascorbic acid is used as a reducing agent. The copper-doped carbon quantum dot prepared by the method has high fluorescence quantum yield, good dispersibility, controllability, low production cost and good reproducibility, and a uniform morphology structure is formed by controlling the use amount and concentration of raw materials and the temperature and time of reaction; due to the internal filtering effect between the prepared copper-doped carbon quantum dots and metronidazole, the fluorescence of the copper-doped carbon quantum dots is effectively quenched. The detection method has the advantages that high-sensitivity and high-selectivity sensing of metronidazole is realized according to the linear dependence relationship between the change of the fluorescence intensity of the copper-doped carbon quantum dots and the concentration of the metronidazole, the detection method has good selectivity and high sensitivity, the response time is short, and real-time detection can be realized.

In a preferred embodiment of the present invention, the carbonate buffer solution has a concentration of 0.004 to 0.08mol/L and a pH of 8 to 11 in order to further improve the detection sensitivity and detection effect.

In a preferred embodiment of the present invention, in order to further improve the detection sensitivity and detection effect, the maximum fluorescence intensity measurement is performed in the wavelength range of 330-600 nm; the maximum fluorescence intensity was performed under the temperature conditions of 298-308K.

In a preferred embodiment of the present invention, in order to further improve the detection sensitivity and detection effect,

in order to improve the yield, the dispersibility and the sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the invention, each solution to be detected needs to be kept still for 5-10min before the maximum fluorescence intensity is measured.

In order to improve the yield, the dispersibility and the sensitivity of the prepared copper-doped carbon quantum dots to metronidazole detection, in a preferred embodiment of the invention, the dosage of the copper-doped carbon quantum dots in each 1L of solution to be detected or blank solution to be detected is 1.5-3.0 mg.

The present invention will be described in detail below by way of examples.