Viscosity-responsive luminescent probe, preparation method and application thereof

Abstract

The application provides a viscosity-responsive luminescent probe, a preparation method and application. The luminescent probe has an ultra-sensitive viscosity response performance, and the viscosity response range thereof covers the viscosity change range of edible oil. After the luminescent probe is added into the edible oil, the fluorescence intensity has a high correlation with the content of the polar component in the edible oil. The change of the polar component of the edible oil is obtained by using the response of the luminescent probe to the viscosity change of the edible oil, so that the rapid and sensitive detection of the polarity of the frying oil is realized.

Description

Technical Field

[0001] This application belongs to the field of fluorescence detection, specifically relating to a viscosity-responsive luminescent probe, its preparation method, and its application. Background Technology

[0002] Frying in cooking oil is a common food processing method that quickly cooks food, improves its color and texture, and imparts a unique flavor. Essentially, frying is a dehydration process; when food is fried, the water and other substances in it are heated and transferred out into the surrounding oil. However, as frying time increases, the main component of cooking oil, triglycerides, undergoes oxidation, polymerization, cracking, and hydrolysis under high temperatures, producing components with higher polarity, such as compounds containing ketone, aldehyde, hydroxyl, hydrogen peroxide, and carboxyl groups, as well as free fatty acids, monoglycerides, and diglycerides. These substances not only affect the quality of fried food but can also harm human health, causing growth retardation, liver enlargement, and liver dysfunction in animals. Many regions set a legal limit of 25%-27% (by mass) of polar components in frying oil; oil exceeding this limit is mandatory for disposal and cannot be reused.

[0003] Currently, the traditional method for detecting polar components in frying oils is column chromatography. This method requires specialized personnel and equipment, and is time-consuming and labor-intensive, consuming large amounts of reagents and frying oil samples. Therefore, it cannot meet the requirements for real-time monitoring. In addition, high-performance gel size exclusion chromatography, near-infrared spectroscopy, and electrochemical analysis have also been developed for detecting polar components in edible oils. However, these methods also have drawbacks and are far from meeting the requirements for real-time online detection. Therefore, developing a simple, sensitive, and rapid method for detecting polar components in edible oils is of great significance.

[0004] Fluorescent probes, also known as fluorescent chemical sensors, are "molecular devices" that convert biological and chemical information into analytable fluorescent signals to qualitatively or quantitatively detect analytes by altering fluorescence signals. However, most polar-responsive fluorescent probes currently available operate on an "on-off" mechanism. These fluorescence-quenching probes are often affected by environmental factors, leading to easily distorted results that fail to meet expectations. While some fluorescence-on probes exist, they typically carry a charge, significantly reducing their lipid solubility and making them unsuitable for use in edible oil systems. Furthermore, the changes in polar components in edible oils at different frying times are minimal, making it difficult to select suitable and sensitive polar-responsive fluorescent probes. Summary of the Invention

[0005] This application proposes a viscosity-responsive luminescent probe, its preparation method, and its application. The luminescent probe provided in this application has ultrasensitive viscosity response performance, and its viscosity response range covers the viscosity change range of edible oil. After the luminescent probe is added to edible oil, its fluorescence intensity is highly correlated with the content of polar components in the edible oil. By utilizing the response of the luminescent probe to changes in the viscosity of edible oil, the changes in the polar components of edible oil can be obtained, thereby achieving rapid and sensitive detection of the polarity of frying oil.

[0006] According to the first aspect of this application, a viscosity-responsive luminescent probe is provided, wherein the luminescent probe is a fluorescent probe with the molecular formula C. 15 H 15 N3O3 has the following structural formula.

[0007] According to a second aspect of this application, a method for preparing a viscosity-responsive luminescent probe is provided, wherein the luminescent probe of claim 1 is prepared, and the reaction formula is as follows:

[0008]

[0009] In some embodiments, the following steps are included:

[0010] 1,4-Dimethylaminocinnamaldehyde and 2,4,6-pyrimidinetrione were added to N,N-dimethylformamide and piperidine in a set ratio; and the reaction was carried out at 140℃-150℃ for 3-4 hours. The reaction solution was then filtered to obtain the reaction solid.

[0011] The luminescent probe can be obtained by washing the reaction solid and then vacuum drying it.

[0012] In some embodiments, the molar ratio of the 2,4,6-pyrimidinetrione to the 1,4-dimethylaminocinnamaldehyde is 1:1-1.1.

[0013] In some embodiments, the volume ratio of piperidine to N,N-dimethylformamide is 1:15-20.

[0014] According to a third aspect of this application, the luminescent probe described in the above embodiments is used to detect the content of different polar components in edible oils.

[0015] In some embodiments, the detection method includes:

[0016] The luminescent probe was dissolved in 1,4-dioxane to prepare a stock solution with a concentration of 1 mM.

[0017] The reserve solution is added to the edible oil to be tested, and the content of polar components in the edible oil is determined by fluorescence intensity detection.

[0018] In some embodiments, the temperature for detecting the edible oil is room temperature; the detection concentration of the luminescent probe is 20 μM.

[0019] In some embodiments, during fluorescence intensity detection, the fluorescence intensity value at the point of increased fluorescence intensity is substituted into the linear fitting curve of fluorescence intensity and polarity content of edible oils with different polarity components, for the purpose of quantifying the content of polar components in the edible oil.

[0020] This application has the following beneficial effects:

[0021] (1) The synthesis and purification steps of the fluorescent probe proposed in this application are simple, easy to operate, and have good lipid solubility.

[0022] (2) The fluorescent probe provided in this application can achieve ultrasensitive response to viscosity and has the advantages of good photostability and high chemical stability.

[0023] (3) The probe of this application can realize the rapid detection of the viscosity of edible oil with different polar components, thereby indirectly determining the polar components of edible oil. The probe concentration is 20 μM, which has certain application value in the actual detection of polar components of frying oil. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1a A linear relationship between the polar components and viscosity values ​​of edible oils with different polarity components;

[0026] Figure 1b The linear relationship of the luminescent probe in methanol / glycerol mixtures with different ratios is shown in the graph.

[0027] Figure 2a The fluorescence emission spectra of the luminescent probe in methanol / glycerol mixtures with different ratios are shown.

[0028] Figure 2b The linear relationship of the luminescent probe in methanol / glycerol mixtures with different ratios is shown in the graph.

[0029] Figure 3a The fluorescence emission spectra of the luminescent probe in edible oils with different polarity components are shown.

[0030] Figure 3bThe graph shows the linear relationship between the viscosity of edible oils with different polar components and the 590 nm fluorescence emission peak.

[0031] Figure 3c The graph shows the linear relationship between the polar components of edible oils with different polar components and the 590 nm fluorescence emission peak.

[0032] Figure 4 The 1H NMR spectrum of the luminescent probe prepared in Example 1;

[0033] Figure 5 The carbon NMR spectrum of the luminescent probe prepared in Example 1;

[0034] Figure 6 The image shows a high-resolution mass spectrum of the luminescent probe prepared in Example 1. Detailed Implementation

[0035] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] According to the first aspect of this application, a viscosity-responsive luminescent probe is proposed. The luminescent probe is a fluorescent probe with the molecular formula C. 15 H 15 N3O3 has the following structural formula.

[0037] In this embodiment, the luminescent probe is a cysteine ​​fluorescent probe based on coumarin ketaldehyde.

[0038] According to the second aspect of this application, a method for preparing a viscosity-responsive luminescent probe is provided, and the reaction formula for preparation is shown below:

[0039]

[0040] The preparation of the luminescent probe includes the following steps:

[0041] A mixture of 2,4,6-pyrimidinetrione and 1,4-dimethylaminocinnamaldehyde in a molar ratio of 1:1-1.1 is used as the reaction raw material. N,N-dimethylformamide and piperidine are then added to the reaction raw material, wherein the volume ratio of N,N-dimethylformamide to piperidine is 15-20:1. Examples of understandable molar ratios of 2,4,6-pyrimidinetrione and 1,4-dimethylaminocinnamaldehyde include 1:1 and 1:1.1. Similarly, examples of volume ratios of N,N-dimethylformamide to piperidine of 15-20:1 include 15:1, 16:1, 17:1, 18:1, 19:1, and 20:1. The reaction was refluxed at 140℃-150℃ for 3-4 hours, and the reaction process was monitored by thin-layer chromatography until the reaction was complete. After the reaction was completed, the reaction solution was filtered to obtain a purplish-black reaction solid. The solid was washed three times with water to remove excess N,N-dimethylformamide, and then dried in a vacuum drying oven at 60℃ to obtain purplish-black crystals, which are the luminescent probe.

[0042] According to the third aspect of this application, the application of the luminescent probe in the detection of edible oils with different polarity components in the above embodiments is proposed, and the method is as follows:

[0043] A stock solution with a luminescent probe concentration of 1 mM was prepared by dissolving the luminescent probe in 1,4-dioxane.

[0044] The stock solution was added to edible oil at room temperature to obtain a sample oil with a detection concentration of 20 μM for the luminescent probe. The content of polar components in the sample oil was determined by fluorescence intensity detection. If it is necessary to quantify the polar components in the sample oil, the fluorescence intensity value at the point of increase in fluorescence intensity was substituted into the linear fitting curve of fluorescence intensity and polarity content of different polar components in edible oil during the fluorescence intensity detection process.

[0045] Example 1

[0046] Preparation of the luminescent probe: 1 mol of 1,4-dimethylaminocinnamaldehyde and 1 mol of 2,4,6-pyrimidinetrione were weighed into a dry round-bottom flask. 7.5 mL of N,N-dimethylformamide and 0.5 mL of piperidine were added. The mixture was refluxed at 140 °C, and the reaction was monitored by thin-layer chromatography until complete. After the reaction was complete, the reaction solution was filtered to obtain a purplish-black solid. The solid was washed three times with water to remove excess N,N-dimethylformamide from the reaction system, and then dried in a vacuum oven at 60 °C to obtain purplish-black crystals.

[0047] The obtained purplish-black crystals were subjected to nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry analysis, among which... Figure 4 This is the proton NMR spectrum of the luminescent probe prepared in this embodiment. 1H NMR(600MHz,DMSO-d6)δ8.22(dd,J=15.0,12.3Hz,1H),7.97(d,J=12.3Hz,1H),7 .62(d,J=15.0Hz,1H),7.54(d,J=8.7Hz,2H),6.79(d,J=9.1Hz,2H),3.05(s,6H). like Figure 5 This is the carbon NMR spectrum of the luminescent probe prepared in this embodiment. 13 CNMR (151MHz, DMSO) δ 164.09, 163.84, 156.49, 155.97, 153.33, 150.85, 131.51, 123.21, 119.56, 112.59, 110.92, 40.01. (For example...) Figure 6 This is a high-resolution mass spectrum of the luminescent probe prepared in this embodiment.

[0048] Different volumes of glycerol were mixed with methanol to prepare methanol / glycerol systems with volume fractions of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. A 10 μM luminescent probe was added to each methanol / glycerol system to prepare a test solution. All test solutions were placed in a 10.0 mm quartz fluorescence cuvette at room temperature, and fluorescence data were measured at an excitation wavelength of 570 nm. Fluorescence data were obtained from... Figure 3a It can be seen that the fluorescence intensity at 620 nm gradually increases with the increase of glycerol volume. A linear fit between the maximum fluorescence intensity and the viscosity parameters of methanol solutions containing different volumes of glycerol is shown in Figure 3(b), where R... 2 =0.9964, the linear equation is: Log I 620nm =0.4794×Log(η)+2.0801. The linear relationship between the polar components of edible oils with different polar components and the 590nm fluorescence emission peak is shown in Figure 3(c). It can be seen that the probe in this embodiment has a good response capability to the viscosity of the environmental system.

[0049] Example 2

[0050] As the heating time of edible oil increases, the oil molecules undergo many complex oxidation, hydrolysis, and polymerization reactions, generating substances with higher polarity than normal triglycerides. This increases the content of polar substances in the frying oil, and due to the formation of various polymers, its viscosity also shows a continuous upward trend. The viscosity values ​​of edible oils with different polar components were measured using an NDJ-8S viscometer to determine the relationship between the content of polar components and viscosity. Taking commercially available soybean oil as an example, as the frying time of soybean oil increases, its polar component content gradually increases. Figure 1aAs shown, the viscosity of soybean oil increases as the polar component content varies from 0% to 30%. Figure 1b As shown, there is a good positive correlation between the polar component content and viscosity value of frying oil, with a correlation coefficient of 0.9840 and a linear equation of Log(η)=0.8275×TPM+1.9541.

[0051] Example 3

[0052] The fluorescence emission spectra of a 10 μM luminescent probe in methanol / glycerol mixtures of different volume ratios are shown below. Figure 2a As shown, the excitation wavelength is 580 nm. With increasing glycerol content, the viscosity of the mixed solution continuously increases, and the fluorescence intensity of the probe continuously strengthens. The linear relationship between the viscosity of different proportions of methanol / glycerol mixtures and the 620 nm fluorescence emission peak is shown in the figure. Figure 2b As shown, therefore by Figures 2a-2b The results show a good linear relationship between the viscosity of frying oil and the content of its polar components. The linear relationship R between the viscosity of frying oil and the content of its polar components is shown. 2 =0.9964, the linear equation is Log(η) = 0.4794 × Log(I 620nm The result of 2.0801 demonstrates that the probe has a strong response capability to changes in environmental viscosity.

[0053] Example 4

[0054] The following method utilizes probes to detect the content of polar components in edible oils:

[0055] (1) Preparation of oil samples with different polar component contents: Commercially available Jinlongyu brand soybean oil was used to fry dough sticks. Samples were taken at different time periods, and the polar component content was tested according to the national standard method (GB 5009.202-2016). The polar component contents were obtained as 0% and 30%. The edible oils with 0% and 30% polar component contents were mixed in different proportions to obtain test oil samples with polar component contents of 0%, 5%, 10%, 15%, 20%, 25%, and 30%.

[0056] (2) Sample Detection: Test oil samples with polar component contents of 0%, 5%, 10%, 15%, 20%, 25%, and 30% were used. 2 mL of each sample was taken, and 1 mM 1,4-dioxane stock solution containing 40 μL of the luminescent probe was added and mixed thoroughly to achieve a detection concentration of 20 μM. The test solution was placed in a 10.0 mm quartz fluorescence cuvette at room temperature, and fluorescence data were measured at an excitation wavelength of 570 nm. The fluorescence intensity was measured. As shown in Figure 3(a), the fluorescence intensity of the luminescent probe at 590 nm gradually increased in edible oils with increasing viscosity, exhibiting a good relationship. The correlation coefficient R between fluorescence intensity and viscosity value was [value missing]. 2 =0.9893, the linear equation is: LogI 590nm =1.9419×Log(η)-1.2282, as shown in Figure 3(b); the correlation coefficient between fluorescence intensity and soybean oil polarity reaches 0.9976, and its linear equation is: I 590nm =2277.72×TPM+333.74, as shown in Figure 3(c).

Claims

1. The application of luminescent probe in detecting the content of different polar components in edible oil, characterized in that, The luminescent probe is a fluorescent probe, and its molecular formula is C 15 H 15 N3O3, and its structural formula is as follows, 。 2. Use according to claim 1, characterized in that, The luminescent probe is prepared according to the following reaction formula: 。 3. Use according to claim 1, characterized in that, The preparation of the luminescent probe includes the following steps: 1,4-Dimethylaminocinnamaldehyde and 2,4,6-pyrimidinetrione were added to N,N-dimethylformamide and piperidine in a set ratio; and the reaction was carried out at 140℃-150℃ for 3-4 hours. The reaction solution was then filtered to obtain the reaction solid. The luminescent probe can be obtained by washing the reaction solid and then vacuum drying it.

4. Use according to claim 3, characterized in that, The molar ratio of the 2,4,6-pyrimidinetrione to the 1,4-dimethylaminocinnamaldehyde is 1:1-1.

1.

5. Use according to claim 3, characterized in that, The volume ratio of piperidine to N,N-dimethylformamide is 1:15-20.

6. Use according to claim 1, characterized in that, The detection methods include: The luminescent probe was dissolved in 14-dioxane to prepare a stock solution with a concentration of 1 mM. The reserve solution is added to the edible oil to be tested, and the content of polar components in the edible oil is determined by fluorescence intensity detection.

7. The use according to claim 1, characterized in that, The temperature for detecting the edible oil is room temperature; the detection concentration of the luminescent probe is 20 μM.

8. The use according to claim 1, characterized in that, During fluorescence intensity detection, the fluorescence intensity value at the point of increased fluorescence intensity is substituted into the linear fitting curve of fluorescence intensity versus polarity content of edible oils with different polarity components, which is used to quantify the content of polar components in the edible oil.

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