Blue fluorescent carbon quantum dots and applications thereof
By preparing blue fluorescent carbon quantum dots as fluorescent probes, the problem of cumbersome and time-consuming detection of ethanol content in liquor in existing technologies has been solved, achieving rapid, accurate, and low-cost ethanol detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI UNIV
- Filing Date
- 2024-03-20
- Publication Date
- 2026-06-23
Smart Images
Figure CN118206108B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fluorescent probe detection technology, specifically relating to a blue fluorescent carbon quantum dot and its application, particularly for the rapid detection of ethanol content in baijiu (Chinese liquor). Background Technology
[0002] Carbon quantum dots, a novel zero-dimensional carbon-based nanomaterial with a size of less than 10 nm, have attracted increasing attention since their discovery in 2004 due to their simple preparation, abundant raw materials, tunable multicolor emission, high photostability, and easy surface functionalization. Furthermore, compared to traditional semiconductor quantum dots, organic fluorescent dyes, and other fluorescent materials, they possess advantages such as good biocompatibility and low toxicity, and have already found wide applications in biosensors, optoelectronic imaging, catalysis, drug delivery, and pollution degradation.
[0003] Chinese Baijiu, one of the world's eight major distilled spirits, is made from fermented starch or sugar raw materials, followed by distillation. Its long history, unique craftsmanship, mellow flavor, and lingering aftertaste have made it popular with consumers worldwide. Traditional Chinese Baijiu contains various components, such as alcohols, acids, esters, ethers, and heterocyclic compounds. Alcohol content, representing the volume percentage of ethanol in the liquor, is a crucial indicator of quality and a primary basis for consumer decision-making. To regulate the quality of Baijiu sold in the market, the ethanol content in qualified Baijiu must accurately match its labeled alcohol content.
[0004] Currently, according to my country's national standard GB5009.225-2016, standard methods for measuring the ethanol concentration in baijiu (Chinese liquor) are specified. These methods include: density bottle method, alcohol meter method, gas chromatography, and digital density meter method. Although these methods have high measurement accuracy (0.5% vol), the testing process is extremely cumbersome, the equipment cost is high, and the testing time is long. Therefore, there is an urgent need to develop a simple, inexpensive, sensitive, and efficient method for detecting the ethanol content in baijiu. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide a blue fluorescent carbon quantum dot and its application, specifically an application for rapid detection of ethanol content in baijiu (Chinese liquor). It has the advantages of being simple, having a fast response speed, short analysis time, low cost, environmentally friendly, and requiring no pretreatment, and can provide an accurate and reliable means for detecting ethanol content in baijiu.
[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0007] This invention discloses a blue fluorescent carbon quantum dot, which is prepared by reacting thiosulfate T as a raw material and ethanol as a solvent in a microwave reactor at a controlled temperature of 100-160°C. The excitation wavelength range of the blue fluorescent carbon quantum dot is 300-400 nm, and the emission wavelength range is 400-600 nm.
[0008] Further, the preparation method of the blue fluorescent carbon quantum dots is as follows: Weigh 1-10 mg of thioflavone T and dissolve it in 1-4 mL of ethanol. Sonicate the solution for 1-5 minutes to ensure complete dissolution. Then, transfer the solution to a microwave tube. Set the reaction conditions in the microwave reactor to 100-160°C and maintain the reaction for 2-4 hours. After the reaction is complete, cool to obtain a clear yellow liquid. Transfer the solution to a beaker, add 300-500 mL of water, and let it stand for 24-48 hours. A grayish-white precipitate will appear. Filter the precipitate, wash the filtered precipitate with water 3-5 times, and dry to obtain blue fluorescent carbon quantum dots.
[0009] This invention also discloses the application of the above-mentioned blue fluorescent carbon quantum dots in the rapid detection of ethanol content in baijiu (Chinese liquor), including the following steps:
[0010] (1) Prepare mixed solutions of ethanol and water with different ethanol contents, add the above-mentioned blue fluorescent carbon quantum dots respectively, measure the fluorescence intensity of the solution, and establish the relationship curve of "fluorescence emission peak intensity-ethanol content";
[0011] (2) Add the above blue fluorescent carbon quantum dot powder to the liquor sample to be tested, sonicate and mechanically vibrate it, then transfer it into a cuvette. Under the same instrument conditions as in step (1), measure the fluorescence intensity and substitute its value into the relationship curve obtained in step (1) to calculate the ethanol content in the liquor sample to be tested.
[0012] Furthermore, in the application, the detection concentration of blue fluorescent carbon quantum dots in steps (1) and (2) is 1-10 μg / mL;
[0013] Furthermore, in the application, the fluorescence intensity measured in steps (1) and (2) is the fluorescence intensity at 430 nm.
[0014] This invention also discloses a method for rapidly detecting the ethanol content in baijiu (Chinese liquor). The method uses the aforementioned blue fluorescent carbon quantum dots as fluorescent probes to rapidly detect the ethanol content in baijiu using a fluorescent probe method.
[0015] Furthermore, the steps of the method include the following:
[0016] (1) Prepare mixed solutions of ethanol and water with different ethanol contents, add the above-mentioned blue fluorescent carbon quantum dots respectively, measure the fluorescence intensity of the solution, and establish the relationship curve of "fluorescence emission peak intensity-ethanol content";
[0017] (2) Add the above blue fluorescent carbon quantum dot powder to the liquor sample to be tested, sonicate and mechanically vibrate it, then transfer it into a cuvette. Under the same instrument conditions as in step (1), measure the fluorescence intensity and substitute its value into the relationship curve obtained in step (1) to calculate the ethanol content in the liquor sample to be tested.
[0018] Furthermore, in the method, in steps (1) and (2), the detection concentration of blue fluorescent carbon quantum dots is 1-10 μg / mL;
[0019] Furthermore, in the method, in steps (1) and (2), the fluorescence intensity measured is the fluorescence intensity at 430 nm.
[0020] The invention's concept is as follows: Using thiosulfate T as a raw material and ethanol as a solvent, a one-step microwave method was used to synthesize nitrogen- and sulfur-doped blue fluorescent carbon quantum dots with a large conjugated structure. These carbon quantum dots are sparingly soluble in water but readily soluble in organic solvents, exhibiting a sensitive fluorescence response to ethanol in a mixed solution of ethanol and water. Experiments revealed that several common baijiu additives had no effect on the fluorescence intensity of these carbon quantum dots. Using them as a fluorescent probe, a common fluorometer can be used for rapid and efficient detection of ethanol content in baijiu.
[0021] The beneficial effects of this invention are as follows: This invention uses thiosulfate T as raw material and ethanol as solvent to react in a microwave reactor at a controlled temperature of 100-160℃ to prepare blue fluorescent carbon quantum dots, which are then used as probes to detect the ethanol content in baijiu. This method has the advantages of being simple, having a fast response speed, short analysis time, low cost, being environmentally friendly, and requiring no pretreatment. It can provide an accurate and reliable means for detecting the ethanol content in baijiu. Attached Figure Description
[0022] Figure 1 Optical photographs of blue fluorescent carbon quantum dots in different commercially available liquors under 365nm ultraviolet irradiation;
[0023] Figure 2 The curves showing the relationship between fluorescence emission peak intensity and ethanol content for blue fluorescent carbon quantum dots in mixed standard solutions of ethanol and water with different ethanol contents (0% to 100%).
[0024] Figure 3 The fluorescence spectra of blue fluorescent carbon quantum dots in different commercially available liquors. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the invention and should not be construed as limiting the scope of protection of the invention. All technologies implemented based on the above content of this invention are covered within the scope of protection intended by this invention. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by known methods.
[0026] This invention discloses a blue fluorescent carbon quantum dot, which is prepared by reacting thiosulfate T as a raw material and ethanol as a solvent in a microwave reactor at a controlled temperature of 100-160°C. The excitation wavelength range of the blue fluorescent carbon quantum dot is 300-400 nm, and the emission wavelength range is 400-600 nm.
[0027] In some embodiments, the preparation method of the blue fluorescent carbon quantum dots is as follows: Weigh 1-10 mg of thioflavone T and dissolve it in 1-4 mL of ethanol. Sonicate the solution for 1-5 minutes to ensure complete dissolution. Then transfer the solution to a microwave tube. Set the reaction conditions in the microwave reactor to 100-160°C and maintain the reaction for 2-4 hours. After the reaction is complete, cool to obtain a clear yellow liquid. Transfer the solution to a beaker, add 300-500 mL of water, and let it stand for 24-48 hours. A grayish-white precipitate will appear. Filter the precipitate, wash the filtered precipitate with water 3-5 times, and dry to obtain blue fluorescent carbon quantum dots.
[0028] This invention also discloses the application of the above-mentioned blue fluorescent carbon quantum dots in the rapid detection of ethanol content in baijiu (Chinese liquor), including the following steps:
[0029] (1) Prepare mixed solutions of ethanol and water with different ethanol contents, add the above-mentioned blue fluorescent carbon quantum dots respectively, measure the fluorescence intensity of the solution, and establish the relationship curve of "fluorescence emission peak intensity-ethanol content";
[0030] (2) Add the above blue fluorescent carbon quantum dot powder to the liquor sample to be tested, sonicate and mechanically vibrate it, then transfer it into a cuvette. Under the same instrument conditions as in step (1), measure the fluorescence intensity and substitute its value into the relationship curve obtained in step (1) to calculate the ethanol content in the liquor sample to be tested.
[0031] In some embodiments, in the application, the detection concentration of blue fluorescent carbon quantum dots in steps (1) and (2) is 1-10 μg / mL;
[0032] In some embodiments, in the application, the fluorescence intensity measured in steps (1) and (2) is the fluorescence intensity at 430 nm.
[0033] This invention also discloses a method for rapidly detecting the ethanol content in baijiu (Chinese liquor). The method uses the aforementioned blue fluorescent carbon quantum dots as fluorescent probes to rapidly detect the ethanol content in baijiu using a fluorescent probe method.
[0034] In some embodiments, the method includes the following steps:
[0035] (1) Prepare mixed solutions of ethanol and water with different ethanol contents, add the above-mentioned blue fluorescent carbon quantum dots respectively, measure the fluorescence intensity of the solution, and establish the relationship curve of "fluorescence emission peak intensity-ethanol content";
[0036] (2) Add the above blue fluorescent carbon quantum dot powder to the liquor sample to be tested, sonicate and mechanically vibrate it, then transfer it into a cuvette. Under the same instrument conditions as in step (1), measure the fluorescence intensity and substitute its value into the relationship curve obtained in step (1) to calculate the ethanol content in the liquor sample to be tested.
[0037] In some embodiments, in the method, in steps (1) and (2), the detection concentration of blue fluorescent carbon quantum dots is 1-10 μg / mL;
[0038] In some embodiments, in the method, the fluorescence intensity measured in steps (1) and (2) is the fluorescence intensity at 430 nm.
[0039] The following will provide further explanation with reference to specific embodiments.
[0040] Example 1
[0041] 1. Preparation of blue fluorescent carbon quantum dots
[0042] 10 mg of thioflavone T (ThT) was dissolved in 1 mL of ethanol and sonicated for 5 minutes to ensure complete dissolution. The solution was then transferred to a microwave tube, and the reaction was carried out at 160 °C for 2 hours in a microwave reactor. After the reaction was complete, a clear yellow liquid was obtained. The solution was then transferred to a beaker, and 500 mL of water was added. The solution became cloudy, and after standing for 24 hours, a grayish-white precipitate appeared. The precipitate was filtered, washed three times with plenty of water to remove free ThT, and then dried to obtain blue fluorescent carbon quantum dots.
[0043] The prepared blue fluorescent carbon quantum dots were subjected to performance testing. The results showed that the excitation wavelength range of the prepared blue fluorescent carbon quantum dots was 300–400 nm, and the emission wavelength range was 400–600 nm. They also exhibited solubility characteristics of being sparingly soluble in water but readily soluble in organic solvents. 10 μg of blue fluorescent carbon quantum dot powder was dissolved in 1.5 mL of commercially available baijiu (Chinese liquor) of different brands with different ethanol contents. Under 365 nm ultraviolet irradiation, as... Figure 1As shown, commercially available baijiu solutions containing carbon dots of different brands with different ethanol contents emitted blue fluorescence that was visible to the naked eye. This characteristic allows blue fluorescent carbon quantum dots to be used as fluorescent probes to detect the ethanol content in baijiu.
[0044] 2. Establish the relationship curve between fluorescence emission peak intensity and ethanol content.
[0045] Prepare 1.5 mL mixed standard solutions of ethanol and water with different ethanol contents (15%, 23%, 40%, 42%, 45%, 50%, 56%). Add 10 μg of the blue fluorescent carbon quantum dots prepared in Example 1 to each solution. Set the fluorescence spectrometer parameters (excitation wavelength 385 nm, emission wavelength range 390–550 nm) and measure the fluorescence emission spectrum of the standard solutions. Establish a "fluorescence emission peak intensity-ethanol content" relationship curve. The results are as follows: Figure 2 As shown. At an emission wavelength of 430 nm, the linear relationship between ethanol content (x) and carbon dot fluorescence intensity (y) is: y = -65.253x³ + 6905.3x² - 178643x + 1407540, R² = 0.99.
[0046] 3. Determine the ethanol content in alcohol.
[0047] 10 μg of the blue fluorescent carbon quantum dots prepared in Example 1 were added to 1.5 mL of commercially available baijiu solutions with different ethanol contents (15%, 23%, 40%, 42%, 45%, 50%, 56%). The fluorescence emission spectra of the solutions were measured using a fluorescence spectrometer with excitation wavelength of 385 nm and emission wavelength range of 390–550 nm. The results are as follows: Figure 3 As shown, by substituting the peak fluorescence intensity value at the emission wavelength of 430nm into the formula for the "fluorescence emission peak intensity - ethanol content" relationship curve obtained in step 2, the ethanol content corresponding to each brand of commercially available baijiu solution was simply calculated, and the results are shown in the table below:
[0048] Serial Number Labeled content value Determined content value 1 15％ 15.1％ 2 23％ 23.3％ 3 40％ 38.5％ 4 42％ 43.8％ 5 45％ 45.6％ 6 50％ 49.7％ 7 56％ 54.1％
[0049] The measured results corresponded well to the originally labeled alcohol content, indicating that the present invention has good accuracy in detecting ethanol content in liquor and has broad application potential in developing into a portable alcohol detection method.
[0050] 4. Method Validation
[0051] 4.1 Limit of Detection (LOD)
[0052] Three sets of 1.5 mL mixed standard solutions of ethanol and water with different ethanol contents (2%–60%, spaced two percentages apart) were prepared. 10 μg of blue fluorescent carbon quantum dots were added to each solution. The fluorescence emission spectrometer parameters were set (excitation wavelength 385 nm, emission wavelength range 390–550 nm), and the fluorescence emission spectra of the standard solutions were measured. After error bar analysis, a "fluorescence emission peak intensity-ethanol content" relationship curve was established. The detection line was calculated to be 0.2% based on the standard deviation of the response value and the slope of the standard curve.
[0053] 4.2 Recovery rate
[0054] Ten sets of 1.5 mL mixed standard solutions of ethanol and water (50% ethanol content) were prepared. 10 μg of blue fluorescent carbon quantum dots were added to each solution. The fluorescence emission spectrometer parameters were set (excitation wavelength 385 nm, emission wavelength range 390–550 nm). The fluorescence emission spectra of the standard solutions were measured. The content was calculated based on the calibration curve, and then the recovery rate was calculated. The recovery rate was in the range of 98.96%–104.59%.
[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., 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 blue fluorescent carbon quantum dots in the rapid detection of ethanol content in baijiu (Chinese liquor), characterized in that, The blue fluorescent carbon quantum dots are prepared by reacting thioflavone T as a raw material and ethanol as a solvent in a microwave reactor at a controlled temperature of 100-160 °C. The excitation wavelength range of the blue fluorescent carbon quantum dots is 300-400 nm, and the emission wavelength range is 400-600 nm. The application is to use the blue fluorescent carbon quantum dots as fluorescent probes to rapidly detect the ethanol content in baijiu using ordinary fluorophotometer analysis methods.
2. The application according to claim 1, characterized in that, The preparation method of the blue fluorescent carbon quantum dots is as follows: Weigh 1-10 mg of thioflavone T and dissolve it in 1-4 mL of ethanol. Sonicate the solution for 1-5 minutes to ensure complete dissolution. Then transfer the solution to a microwave tube. Set the reaction conditions in the microwave reactor to 100-160 °C and maintain the reaction for 2-4 hours. After the reaction is complete, cool to obtain a clear yellow liquid. Transfer the solution to a beaker and add 300-500 mL of water. After standing for 24-48 hours, a grayish-white precipitate appears. Filter the precipitate and wash it with water 3-5 times. After drying, the blue fluorescent carbon quantum dots are obtained.
3. The application according to claim 1, characterized in that, Includes the following steps: (1) Prepare mixed solutions of ethanol and water with different ethanol contents, add the blue fluorescent carbon quantum dots respectively, measure the fluorescence intensity of the solution, and establish the relationship curve of "fluorescence emission peak intensity-ethanol content"; (2) Add the blue fluorescent carbon quantum dot powder to the liquor sample to be tested, sonicate and mechanically vibrate it, then transfer it into a cuvette. Under the same instrument conditions as in step (1), measure the fluorescence intensity and substitute its value into the relationship curve obtained in step (1) to calculate the ethanol content in the liquor sample to be tested.
4. The application according to claim 3, characterized in that, In steps (1) and (2), the detection concentration of blue fluorescent carbon quantum dots is 1-10 μg / mL.
5. The application according to claim 4, characterized in that, In steps (1) and (2), the fluorescence intensity measured is the fluorescence intensity at 430 nm.