A cucurbituril fluorescent probe, a preparation method and application thereof, and a qualitative and quantitative detection method for melamine

Abstract

The application provides a cucurbituril fluorescent probe and a preparation method and application thereof, and a qualitative and quantitative detection method of melamine, and belongs to the field of substance detection. The application provides a cucurbituril fluorescent probe, which comprises cucurbit[8]uril (CB[8]) and rhodamine, and the rhodamine is included in the cavity of the cucurbit[8]uril. The application contains the rhodamine in the cavity of CB[8] through host-guest non-covalent interaction, and aims at detecting melamine; the probe has high sensitivity, simple operation and the characteristics of rapid detection.

Description

Technical Field

[0001] This invention relates to the field of material detection technology, and in particular to a cucurbitacin fluorescent probe, its preparation method and application, and a qualitative and quantitative detection method for melamine. Background Technology

[0002] Melamine is an organic base primarily used in the synthesis of melamine-formaldehyde resin, which is used in the manufacture of chemicals, industrial products, and medical materials. Due to its nitrogen content, adding melamine to dairy products can produce incorrectly high readings when measuring protein content using traditional standard methods such as the Kjeldahl method or the Duma method. Ingestion of melamine exceeding safe limits can cause kidney failure and even death in infants. High-performance liquid chromatography (HPLC) is one of the most widely used methods for melamine detection, being simpler and faster than gas chromatography-mass spectrometry (GC-MS), making it suitable for quantifying high levels of melamine in food. However, it remains time-consuming. Therefore, developing simple, rapid, and sensitive molecular probes for the detection of melamine in food is highly valuable. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a cucurbitacin fluorescent probe, its preparation method and application, and a qualitative and quantitative detection method for melamine. The cucurbitacin fluorescent probe provided by this invention can achieve rapid and sensitive detection of melamine.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] The present invention provides a cucurbitacin fluorescent probe comprising cucurbita[8]urea and rhodamine, wherein the rhodamine is encapsulated in the cavity of the cucurbita[8]urea.

[0006] Preferably, the rhodamine includes rhodamine 110, rhodamine B, or rhodamine 123.

[0007] Preferably, the molar ratio of cucurbita[8]urea to rhodamine is 1:0.5 to 3.

[0008] Preferably, the molar ratio of cucurbita[8]urea to rhodamine is 1:1 to 2.

[0009] This invention also provides a method for preparing the cucurbita fluorescent probe described in the above technical solution, comprising the following steps:

[0010] The cucurbita[8]urea, rhodamine and water were mixed and subjected to inclusion reaction, followed by drying to obtain the cucurbita fluorescent probe.

[0011] Preferably, the inclusion reaction is carried out in a light-protected and protective atmosphere, and the inclusion reaction takes 24 to 72 hours and is carried out at a temperature of 30 to 90°C.

[0012] The present invention also provides the application of the cucurbitacin fluorescent probe described in the above technical solution or the cucurbitacin fluorescent probe prepared by the preparation method described in the above technical solution in the detection of melamine.

[0013] This invention also provides a qualitative detection method for melamine, comprising the following steps:

[0014] The cucurbita fluorescent probe described in the above technical solution or the cucurbita fluorescent probe prepared by the preparation method described in the above technical solution is mixed with water to obtain a probe aqueous solution;

[0015] When the probe aqueous solution is mixed with the test solution, if fluorescence quenching occurs, the test solution contains melamine; if no fluorescence quenching occurs, the test solution does not contain melamine.

[0016] This invention also provides a method for the quantitative detection of melamine, comprising the following steps:

[0017] The cucurbita fluorescent probe described in the above technical solution or the cucurbita fluorescent probe prepared by the preparation method described in the above technical solution is mixed with water to obtain a probe aqueous solution;

[0018] The probe aqueous solution was mixed with the melamine solution to be tested, and the fluorescence emission spectrum was measured to obtain the probe fluorescence intensity.

[0019] The content of melamine in the melamine solution to be tested is calculated according to a predetermined standard equation.

[0020] Preferably, the excitation wavelength for the fluorescence emission spectroscopy measurement is 440 nm.

[0021] The present invention provides a cucurbitacin fluorescent probe comprising cucurbitacin (CB[8]) and rhodamine, wherein the rhodamine is contained within the cavity of the cucurbitacin.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention uses non-covalent interaction between host and guest to contain rhodamine in the cavity of CB[8], aiming to detect melamine. Melamine is detected by competing rhodamine out of the cucurbita cavity and by the change in fluorescence intensity during this process. This probe has high sensitivity, simple operation and rapid detection characteristics.

[0024] The present invention also provides a quantitative detection method for melamine, which can monitor the concentration of melamine in real time. Attached Figure Description

[0025] Figure 1 This is the standard equation in Example 1. Detailed Implementation

[0026] The present invention provides a cucurbitacin fluorescent probe comprising cucurbitacin[8]urea (CAS: 259886-51-6) and rhodamine, wherein the rhodamine is encapsulated in the cavity of the cucurbitacin[8]urea.

[0027] In this invention, the rhodamine includes rhodamine 110 (CAS: 13558-31-1), rhodamine B (CAS: 81-88-9), or rhodamine 123 (62669-70-9).

[0028] In this invention, the molar ratio of cucurbita[8]urea to rhodamine is preferably 1:0.5 to 3, and more preferably 1:1 to 2.

[0029] This invention also provides a method for preparing the cucurbita fluorescent probe described in the above technical solution, comprising the following steps:

[0030] The cucurbita[8]urea, rhodamine and water were mixed and subjected to inclusion reaction, followed by drying to obtain the cucurbita fluorescent probe.

[0031] In this invention, the inclusion reaction is preferably carried out in a light-protected and protective atmosphere, the inclusion reaction time is preferably 24 to 72 hours, and the temperature is preferably 30 to 90°C.

[0032] In this invention, the cucurbita[8]urea and rhodamine are preferably added to a reaction vessel, pure water is added to the reaction vessel, and the mixture is stirred at 30-90°C to completely dissolve the cucurbita and carry out the inclusion reaction.

[0033] After the inclusion reaction is completed, the present invention preferably performs filtration, and the resulting filtrate is dried to obtain the cucurbitacin fluorescent probe.

[0034] The present invention does not impose any special limitations on the specific operation of the filtering, and any method known to those skilled in the art can be used.

[0035] In this invention, the drying is preferably freeze-drying. This invention does not have any special limitations on the specific parameters of the freeze-drying, and any method known to those skilled in the art can be used.

[0036] The present invention also provides the application of the cucurbitacin fluorescent probe described in the above technical solution or the cucurbitacin fluorescent probe prepared by the preparation method described in the above technical solution in the detection of melamine.

[0037] This invention also provides a qualitative detection method for melamine, comprising the following steps:

[0038] The cucurbita fluorescent probe described in the above technical solution or the cucurbita fluorescent probe prepared by the preparation method described in the above technical solution is mixed with water to obtain a probe aqueous solution;

[0039] When the probe aqueous solution is mixed with the test solution, if fluorescence quenching occurs, the test solution contains melamine; if no fluorescence quenching occurs, the test solution does not contain melamine.

[0040] In this invention, the concentration of the probe aqueous solution is preferably 3 × 10⁻⁶. -5 M.

[0041] This invention also provides a method for the quantitative detection of melamine, comprising the following steps:

[0042] The cucurbita fluorescent probe described in the above technical solution or the cucurbita fluorescent probe prepared by the preparation method described in the above technical solution is mixed with water to obtain a probe aqueous solution;

[0043] The probe aqueous solution was mixed with the melamine solution to be tested, and the fluorescence emission spectrum was measured to obtain the probe fluorescence intensity.

[0044] The content of melamine in the melamine solution to be tested is calculated according to a predetermined standard equation.

[0045] In this invention, the concentration of the probe aqueous solution is preferably 3 × 10⁻⁶. -5 M.

[0046] In this invention, the melamine solution to be tested is preferably a dairy product.

[0047] In this invention, the excitation wavelength for the fluorescence emission spectroscopy measurement is preferably 440 nm.

[0048] In this invention, the standard equation preferably uses the concentration of melamine as the abscissa and the probe fluorescence intensity as the ordinate.

[0049] The present invention does not impose any special limitation on the method of obtaining the standard equation. Any method known to those skilled in the art can be used, such as: preparing melamine solutions of different concentrations, making up to volume with water, centrifuging and then extracting the supernatant for fluorescence measurement.

[0050] To further illustrate the present invention, the following detailed descriptions, in conjunction with examples, illustrate the cucurbitacin fluorescent probe, its preparation method, its application, and the qualitative and quantitative detection method for melamine provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] 1. Weigh cucurbita[8]urea and rhodamine B in a molar ratio of 1:0.5 and add them to the reaction vessel.

[0053] 2. Add pure water to the reaction vessel and stir at 90°C until it is completely dissolved and the inclusion reaction occurs for 36 hours.

[0054] 3. Filter the reaction solution to obtain the solid, and freeze-dry the filtrate to obtain the target fluorescent probe.

[0055] 4. Prepare a solution of 3×10⁻⁶ fluorescent probes with water. -5 M probe solution.

[0056] 5. Add the melamine solution to be tested to step 4, and then perform fluorescence emission spectroscopy at a fixed excitation wavelength of 440 nm. If the fluorescence is quenched before and after adding the melamine solution, it indicates that melamine is present.

[0057] Detection of melamine concentration:

[0058] Prepare a solution of 3×10⁻⁶ fluorescent probes with water. -5 The probe solution was prepared by adding melamine solutions with concentrations of 0.0015, 0.0148, 0.0698, 0.1670, 0.2582, 0.3750, 0.4290, and 0.5 mM. Fluorescence emission spectra were then measured at a fixed excitation wavelength of 440 nm, and the quenching curves of the probe fluorescence intensity were recorded as the concentration of melamine increased. A linear fit was then performed between the melamine concentration and the fluorescence intensity, showing a correlation coefficient R0. 2 =0.9936, the result is as follows Figure 1 As shown. Using the formula LOD = 3σ / κ (where σ is the standard deviation of the blank measurement and κ is the slope between the probe fluorescence intensity and the melamine concentration), the detection limit of the probe was calculated to be 1.36 × 10⁻⁶. -5 M.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Application of a cucurbituril fluorescent probe in detecting melamine, wherein the cucurbituril fluorescent probe comprises cucurbit [8] urea and rhodamine, and the rhodamine is included in the cavity of the cucurbit [8] urea; the rhodamine comprises rhodamine 110, rhodamine B or rhodamine 123.

2. Use according to claim 1, characterized in that, The molar ratio of the cucurbit [8] urea and the rhodamine is 1:0.5-3.

3. Use according to claim 2, characterized in that, The molar ratio of the cucurbit [8] urea and the rhodamine is 1:1-2.

4. Use according to claim 1, characterized in that, The preparation method of the cucurbituril fluorescent probe comprises the following steps: The cucurbit [8] urea, the rhodamine and water are mixed to carry out an inclusion reaction, and then dried to obtain the cucurbituril fluorescent probe.

5. Use according to claim 4, characterized in that, The inclusion reaction is carried out in a light-proof and protective atmosphere, the time of the inclusion reaction is 24-72 h, and the temperature is 30-90℃.

6. A method for quantitative detection of melamine, characterized by, The preparation method of the cucurbituril fluorescent probe comprises the following steps: The cucurbituril fluorescent probe is mixed with water to obtain a probe aqueous solution; The probe aqueous solution is mixed with a melamine solution to be detected, and then fluorescence emission spectrum determination is carried out to obtain the fluorescence intensity of the probe; The content of melamine in the melamine solution to be detected is calculated according to a predetermined standard equation. The cucurbituril fluorescent probe comprises cucurbit [8] urea and rhodamine, and the rhodamine is included in the cavity of the cucurbit [8] urea; the rhodamine comprises rhodamine 110, rhodamine B or rhodamine 123.

7. The quantitative detection method according to claim 6, characterized in that, The excitation wavelength of the fluorescence emission spectrum determination is 440 nm.

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