阅读说明：本技术 一种碳量子点荧光探针、试纸及其在桑色素检测中的应用 (Carbon quantum dot fluorescent probe, test paper and application of carbon quantum dot fluorescent probe and test paper in morin detection ) 是由 吴玉清 于旭 李洪伟 于 2019-10-21 设计创作，主要内容包括：一种碳量子点荧光探针、试纸及其在桑色素检测中的应用,属于荧光探针技术领域。是用二次蒸馏水配制8～15mM的聚乙烯亚胺溶液；随后,取1mL、8～15mM的聚乙烯亚胺溶液与9mL二次蒸馏水混合,并将它们转移到水热反应釜中,150～180℃下反应8～15h；反应结束后,将反应产物冷却到室温,随后转移到离心管中,得到碳量子点荧光探针溶液。进一步,取一张双圈定性滤纸放在玻璃片上,取碳量子点荧光探针溶液浸润滤纸,随后自然晾干,即得到碳量子点荧光试纸。本发明具有响应时间快、操作简单、灵敏度较高、不需要任何检测仪器的特点,对桑色素的相关代谢研究以及在食品样品中检测桑色素具有重要意义。(A carbon quantum dot fluorescent probe, test paper and application thereof in morin detection belong to the technical field of fluorescent probes. Preparing 8-15 mM polyethyleneimine solution by using secondary distilled water; then, mixing 1mL of 8-15 mM polyethyleneimine solution with 9mL of secondary distilled water, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-15 h at 150-180 ℃; after the reaction is finished, cooling the reaction product to room temperature, and then transferring the reaction product to a centrifugal tube to obtain the carbon quantum dot fluorescent probe solution. And further, placing a piece of double-circle qualitative filter paper on a glass sheet, soaking the filter paper in the carbon quantum dot fluorescent probe solution, and naturally airing to obtain the carbon quantum dot fluorescent test paper. The method has the characteristics of quick response time, simple operation, higher sensitivity and no need of any detection instrument, and has important significance for relevant metabolism research of morin and morin detection in food samples.)

1. A carbon quantum dot fluorescent probe is characterized in that: preparing 8-15 mM polyethyleneimine solution by using secondary distilled water; then, mixing 1mL of 8-15 mM polyethyleneimine solution with 9mL of secondary distilled water, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-15 h at 150-180 ℃; after the reaction is finished, cooling the reaction product to room temperature, and then transferring the reaction product to a centrifugal tube to obtain the carbon quantum dot fluorescent probe solution.

2. The carbon quantum dot fluorescent probe of claim 1, wherein: the particle size distribution of the carbon quantum dots is 2.0-7.0 nm, and the light-emitting range is 400-600 nm.

3. The carbon quantum dot fluorescent probe of claim 1, wherein: the molecular weight of the polyethyleneimine is 8000-12000.

4. Use of the carbon quantum dot fluorescent probe according to any one of claims 1 to 3 in morin detection.

5. A carbon quantum dot fluorescent test paper is characterized in that: placing a piece of double-circle qualitative filter paper on a glass sheet, soaking 5mL of the carbon quantum dot fluorescent probe solution prepared according to claim 1 into the filter paper, and naturally airing to obtain the carbon quantum dot fluorescent test paper.

6. The use of the carbon quantum dot fluorescence test paper of claim 5 in morin detection.

Technical Field

The invention belongs to the technical field of fluorescent probes, and particularly relates to a carbon quantum dot fluorescent probe, test paper and application thereof in morin detection.

Background

Morin is a natural polyphenol. It is widely present in leaves, fruits, stems and branches of Moraceae plants, and has therapeutic effect on various human diseases including diabetes, cancer, bacterial infection, hypertension, hypoglycemia, etc. In addition, morin can also reduce their side effects without interfering with the normal functioning of the drug. It has low toxicity and can be used for long-term administration. Therefore, the construction of the morin detection method is beneficial to monitoring the content of the morin in food and the metabolism condition in a human body, and plays a positive role in the application of the morin in the human body. The existing detection methods, namely liquid chromatography and gas chromatography, are long in time consumption and low in detection sensitivity.

The carbon quantum dot is a novel fluorescent carbon-based zero-dimensional material. Because of its characteristics of high stability, good conductivity, low toxicity, environmental friendliness, simple synthesis method and the like, it attracts the extensive attention of researchers. The most important properties of the fluorescent material are that the fluorescent material has excellent fluorescent performance and the light-emitting position is adjustable. Therefore, it can be applied to the fields of biomedicine, optoelectronics, catalysis, sensing and the like.

Disclosure of Invention

The invention aims to provide a carbon quantum dot fluorescent probe, test paper and application thereof in morin detection.

The carbon quantum dots are synthesized by using Polyethyleneimine (PEI), and the schematic diagram of the synthetic process is shown in FIG. 1. It is reported in the literature (chem. Commun.,2012,48,10889-10891) that carbon quantum dots have a graphene-structured core, and the black core in FIG. 1 represents the graphene-structured core. It also has a polymer chain toward the outside of the carbon core, and the gray chain structure in FIG. 1 represents the polymer chain. This polymer chain is the non-carbonized part of the reactants (i.e. the polymer).

The carbon quantum dots have the particle size distribution of 2.0-7.0 nm and the light-emitting range of 400-600 nm, and are products obtained by carbonizing Polyethyleneimine (PEI) in a hydrothermal reaction. The increase of the reaction time and the increase of the reaction temperature increase the average particle diameter of the carbon quantum dots and shorten the length of the outer polymer chain.

In the practical application process, the polyethyleneimine with the molecular weight of 8000-12000 is generally purchased to prepare the carbon quantum dots, and the prepared carbon quantum dots need to be refrigerated and stored in a dark place.

We used polyethyleneimine to synthesize carbon quantum dots, the specific procedure is slightly modified with reference to the synthesis method described in chem.commun.,2012,48,10889-10891 (see example 1 for details). Firstly, preparing 8-15 mM PEI solution by using secondary distilled water; then, mixing 1mL of 8-15 mM PEI solution with 9mL of redistilled water, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-15 h at 150-180 ℃; after the reaction is finished, cooling the reaction product to room temperature, transferring the reaction product into a centrifuge tube to obtain a carbon quantum dot fluorescent probe solution, and storing the carbon quantum dot fluorescent probe solution at 4 ℃ in a dark place; the particle size distribution of the carbon quantum dots is 2.0-7.0 nm, and the light-emitting range is 400-600 nm.

The mulberry pigment is detected by using the synthesized carbon quantum dot fluorescent probe solution. Taking the prepared carbon quantum dot fluorescent probe solution, and preparing a carbon quantum dot fluorescent probe solution with the concentration of 0.1mg/mL by using a HEPES solution with the pH of 7.4 and fetal bovine serum with the volume percentage of 1% as a buffer solution; adding morin with the final concentration range of 0-25 mu M into the solution, and forming double fluorescence emission peaks at 490nm and 550nm due to the interaction of morin and groups on the surface of the carbon dots, wherein the emission peak at the wavelength of 550nm is enhanced, and the fluorescence emission peak at the carbon quantum dot at the wavelength of 490nm is quenched; the detection of morin can be realized by drawing a standard curve by using the ratio of the fluorescence intensity at 550nm to the fluorescence intensity at 490nm as the ordinate (namely, a proportional fluorescent probe) and the morin concentration as the abscissa (see examples 3 and 4 for details).

Putting a double-circle qualitative filter paper (the model is 12.5CM (medium speed)) produced by whatman company on a glass sheet, soaking the filter paper by 5mL of prepared carbon quantum dot fluorescent probe solution, and naturally airing to obtain the carbon quantum dot test paper; different colors can be displayed under an ultraviolet lamp by dripping 10 mu L of morin solution with the concentration of 0-0.4 mu M into the carbon quantum dot test paper. The content of morin in the sample can be detected by comparing the fluorescence intensity with the color under an ultraviolet lamp (see examples 6 and 7 for details).

The carbon quantum dots prepared by using the polyethyleneimine have the characteristics of easiness in synthesis, high stability, high response sensitivity to morin and the like. The carbon quantum dots can be used as a proportional type (namely, the ratio of the fluorescence intensity at 550nm to the fluorescence intensity at 490nm is used as an ordinate) fluorescent probe of morin. And the carbon quantum dot test paper is prepared based on the carbon quantum dots, and the detection of morin can be realized. The two methods have the characteristics of quick response time, simple operation, higher sensitivity and no need of any detection instrument, and have important significance for relevant metabolism research of morin and morin detection in food samples.

Drawings

FIG. 1: a schematic diagram of a preparation process for preparing carbon quantum dots by using PEI;

preparing 8-15 mM PEI solution; then, mixing 1mL of 8-15 mM PEI solution with 9mL of redistilled water, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-15 h at 150-180 ℃ to obtain a carbon quantum dot (CDs) solution;

FIG. 2: a change curve of fluorescence intensity of a carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI with morin concentration (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10, 15, 20, 25. mu.M);

FIG. 3: the change curve of the ratio of fluorescence intensity at 550nm to 490nm of a carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI with the concentration of morin (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10, 15, 20, 25. mu.M);

FIG. 4: the ratio of fluorescence intensity at 550nm to 490nm of a carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI linearly changes with the morin concentration (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75. mu.M);

FIG. 5: the change curve of the fluorescence intensity of PEI-prepared carbon quantum dot fluorescent probe solution (0.1mg/mL) with the concentration of morin (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10, 15, 20, 25. mu.M) in 1% (volume percent) fetal calf serum;

FIG. 6: the change curve of the ratio of the fluorescence intensity at 550nm to 490nm of a carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI with the concentration of morin (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10, 15, 20, 25. mu.M) in 1% (volume percent) fetal calf serum;

FIG. 7: the ratio of the fluorescence intensity of the carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI at 550nm and 490nm in 1% (volume percent) of fetal calf serum and 1% (volume percent) of fetal calf serum linearly changes with the morin concentration (0, 0.1, 0.2, 0.3, 0.4. mu.M); (ii) a

FIG. 8: a bar graph of the ratio of fluorescence intensity at 550nm and 490nm after the action of carbon quantum dot fluorescent probe solution (0.1mg/mL) prepared by PEI, morin (10. mu.M), apigenin (10. mu.M), tea polyphenol (10. mu.M), quercetin (10. mu.M) and myricetin (10. mu.M).

FIG. 9: under the irradiation of an ultraviolet lamp, response pictures of the prepared carbon quantum dot test paper to different concentrations (2.0, 4.0, 6.0, 8.0, 10, 30, 50, 75 and 100 mu M) of morin are shown.

Detailed Description

All of the drugs used in the present invention can be purchased. Wherein, Polyethyleneimine (PEI) with molecular weight of 10000, 4-hydroxyethyl piperazine ethanesulfonic acid (HEPES), sodium hydroxide (NaOH) and morin are purchased from Shanghai Arlatin Biotechnology GmbH, fetal bovine serum is purchased from Gibco, Australia, secondary distilled water is purchased from Millipore ultrapure water system, and double-circle qualitative filter paper (model: 12.5CM (Medium speed)) is purchased from whatman.