A Fe 3+ Specific detection carbon dots and preparation methods thereof

Abstract

The present invention discloses a method for treating Fe 3+ Carbon dots with specific detection and their preparation method, the carbon dots have the following properties: (1) when dissolved in ethanol, they have bright red fluorescence, with an emission peak at 675 nm and a full width at half maximum of 25 nm, and groups such as hydroxyl, carboxyl, carbon-oxygen single bond and carbon-oxygen double bond exist on the surface. (2) When the carbon dots are dissolved in ethanol, only Fe 3+ After the addition of other metal ions, the fluorescence of the carbon dots is quenched. However, when other metal ions are added, the carbon dots still retain their fluorescence emission. 3+ Carbon dots with specific fluorescent behavior can be used in multiple fields such as water detection and anti-counterfeiting.

Description

Technical Field

[0001] The present invention relates to the field of organic carbon material application and detection method, in particular to a method for detecting Fe 3+ Carbon dots for specific detection and preparation methods thereof. Background Art

[0002] Human production and life cannot be separated from the participation of metal elements, but excessive metal ions may cause serious harm. Iron (Fe) is an element necessary for organisms and the environment, and is crucial for the growth and development of organisms. For example, Fe can participate in the synthesis of plant chlorophyll and human hemoglobin. However, iron ions (Fe 3+ ) Both excess and deficiency can cause damage to the human body. Excessive intake can lead to cirrhosis, heart disease, cancer, Alzheimer's disease, etc., while deficiency can lead to iron deficiency anemia. Therefore, it is necessary to develop environmentally friendly and sensitive detection methods to detect Fe in the environment and food. 3+ It is crucial to conduct accurate testing.

[0003] Carbon dots, a new type of zero-dimensional nanomaterial, possess numerous advantages, including low toxicity, good biocompatibility, and excellent optical properties. These properties have led to their widespread application in fields such as metal ion detection. However, the current preparation of fluorescent carbon dots mostly relies on organic compounds. The use of these organic reactants and reagents often causes secondary pollution to the environment, significantly impacting the practical application of carbon dots in environmental detection. Furthermore, most currently prepared carbon dots are prepared using a hydrothermal method, which is time-consuming and energy-consuming. Consequently, these prepared carbon dots exhibit poor recognition during actual detection. Summary of the Invention

[0004] In order to solve the above problems, the present invention discloses a method for 3+ Carbon dots for specific detection and their preparation method, the present invention uses renewable, cheap, green leaf materials as raw materials to prepare Fe 3+ Carbon dots that perform specific detection can be used in multiple fields such as water detection and anti-counterfeiting.

[0005] The present invention discloses a method for 3+ Carbon dots for specific detection and their preparation method, the carbon dots have the following optical properties: (1) after dissolving in water or ethanol, they have red fluorescence, with an emission peak at 675nm and a full width at half maximum of 25nm, and groups such as hydroxyl groups, carboxyl groups, carbon-oxygen single bonds and carbon-oxygen double bonds on the surface. (2) When the carbon dots are dissolved in ethanol, only Fe 3+ When ions are added, the carbon dots will experience fluorescence quenching, while when other metal ions are added, the carbon dots will still retain the fluorescence phenomenon.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A Fe 3+ The carbon dots for specific detection have the following optical properties:

[0008] (1) The emission peak is located at 675 nm, with a full width at half maximum of 25 nm. There are groups such as hydroxyl groups, carboxyl groups, carbon-oxygen single bonds, and carbon-oxygen double bonds on the surface.

[0009] (2) The carbon dots dissolved in ethanol were only 3+ When the carbon dots are in solution, fluorescence quenching occurs.

[0010] A Fe 3+ The method for preparing carbon dots for specific detection comprises the following steps:

[0011] Step (1) preparing a mulberry leaf powder purified solution: adding ethanol to the ground mulberry leaf powder to obtain a mulberry leaf powder ethanol solution, placing the mulberry leaf powder ethanol solution in an ultrasonic machine, and after the ultrasonication is completed, placing the solution in a centrifuge. After the centrifugation is completed, the supernatant in the centrifuged solution is separated from the precipitate, and the supernatant is collected. The supernatant is filtered using a 0.22 micron filter to obtain a pure filtrate.

[0012] Step (2) Preparation of carbon dots: Disodium ethylenediaminetetraacetate was added to the liquid prepared in step (1), the resulting solution was poured into a flask and heated in a microwave oven. After the microwave reaction was completed, the product was dissolved in water to obtain a carbon dot capable of reacting with Fe. 3+ Carbon dots for specific detection.

[0013] Furthermore, in the mulberry leaf powder ethanol solution prepared in step (1), the amount of ethanol is 20 mL and the amount of mulberry leaf powder is 0.5 g.

[0014] Furthermore, in step (1), the ethanol solution of mulberry leaf powder is placed in an ultrasonic machine for ultrasonication, and the ultrasonication time is 10 minutes.

[0015] Furthermore, in step (1), the mulberry leaf powder ethanol solution is centrifuged in a centrifuge using a 6*50mL rotor at a rotor speed of 8000 r / min for 5 minutes. Furthermore, in step (2), disodium edetate is added to the mulberry leaf powder purified solution, and the mass of the added disodium edetate is 0.2 g.

[0016] In step (2), the flask was heated in a microwave for 5 min at a power of 800 W.

[0017] In step (2), the microwave-treated product was dissolved in ethanol, and 5 mL of ethanol was added to the flask.

[0018] A carbon dot Fe 3+The specific detection method is to dissolve the prepared carbon dot powder in ethanol to obtain a carbon dot solution, and use a PL spectrometer to measure the fluorescence intensity of the carbon dot solution. The test solution is added to the carbon dot solution, and the fluorescence intensity of the mixed solution is measured using a PL spectrometer and compared. If fluorescence quenching occurs, it means that the test solution contains Fe 3+ ion.

[0019] Furthermore, it will be possible to 3+ The carbon dots for specific detection are dissolved in 5 mL to 15 mL of ethanol, and the carbon dot solution, the test solution, and ethanol are mixed in a ratio of 1:5:45. If the test solution contains Fe 3+ ions, the fluorescence spectrum changes from an obvious Gaussian distribution curve to an approximately horizontal straight line, and its PL spectrum intensity tends to a constant value, which is basically the same as the spectrum intensity of the carbon dot solution in the non-excitation light band.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention synthesizes Fe based on green leaves. 3+ Carbon dots for specific detection: (1) preparing mulberry leaf powder purified solution; (2) using the prepared mulberry leaf powder and disodium ethylenediaminetetraacetic acid to prepare a carbon dot that can detect Fe 3+ (3) using carbon dots that can detect Fe 3+ Carbon dots for specific detection of Fe 3+ Perform specific testing.

[0022] 2. Using leaf materials as raw materials for carbon dot preparation is cheaper than common organic compound raw materials such as urea, ethylenediamine, citric acid, etc., thus reducing the cost of detection.

[0023] 3. Using leaf materials as raw materials has better biocompatibility and shows good resistance to Fe 3+ It has high selectivity and can be used in environmental governance, biomedicine and other fields, with broad application prospects.

[0024] 4. The present invention uses microwave method to prepare carbon dots, which is simpler and easier to achieve large-scale production compared with other synthesis methods such as hydrothermal method, pyrolysis method and ultrasonic method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 For example 1, Fe 3+ Fluorescence spectra of carbon dots for specific detection under excitation at different wavelengths;

[0026] Figure 2 For example 1, Fe 3+ Absorption spectra of carbon dots for specific detection;

[0027] Figure 3 For example 1, Fe 3+ Fourier transform infrared spectroscopy (FTIR) of carbon dots for specific detection;

[0028] Figure 4 For example 2, Fe 3+ The relative fluorescence intensity of carbon dots after adding different metal ions to ethanol solution for specific detection, the excitation light wavelength is 380nm. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0030] Example 1

[0031] (1) Preparation of ethanol solution of mulberry leaf powder: Take 0.5 g of mulberry leaf powder, dissolve it in 20 mL of ethanol, and ultrasonicate it in an ultrasonic machine for ten minutes to fully disperse the reactants in the ethanol.

[0032] (2) Preparation of mulberry leaf extract: Centrifuge the ultrasonicated mulberry leaf powder ethanol solution at 8000 r / min for 5 min. Pour off the supernatant and discard the precipitate. Filter the supernatant and collect the clear solution. Add 0.2 g of disodium ethylenediaminetetraacetic acid to the filtered solution.

[0033] (3) Ability to Fe 3+ Preparation of carbon dots for specific detection: The liquid prepared in step (2) was poured into a flask and placed in a microwave oven for 5 min at a microwave power of 800 W. After the microwave reaction, the product was dissolved in 5 mL of water and the fluorescence spectrum of the solution was characterized.

[0034] (4) Preparation of metal ion solution: Take a certain amount of the substance to be tested (including Cu 2+ ,Zn 2+ ,Pb 2+ ,Na + ,K + ,Fe 3+ ,Fe 2+ For substances with a relative molecular mass of M, weigh (2M / 10) mg and dissolve it in 20 mL of water to prepare a test solution with a concentration of 10 mmol / L.

[0035] (5) Use Fe 3+ Carbon dots for specific detection of ions (Fe 3+ ): Take the Fe 3+ To 100 μL of the carbon dot solution for specific detection, add ethanol to make the total volume of the mixed solution reach 4.5 mL, and then add 0.5 mL of the metal ion solution prepared in step (4). The fluorescence spectrum of the solution is characterized.

[0036] Figure 1 To be able to Fe 3+ PL spectra of carbon dots in ethanol solution under 365nm-425nm excitation for specific detection. The optimal excitation wavelength is 405nm, with an emission peak at 675nm and a full width at half maximum of 25nm.

[0037] Figure 2 To be able to Fe 3+ Fourier transform infrared spectra of carbon dots subjected to specific detection. Analysis of peaks within different wavelength ranges in the spectrum reveals the presence of hydroxyl groups, carboxyl groups, carbon-oxygen single bonds, and carbon-oxygen double bonds on the carbon dot surface.

[0038] Figure 3 To be able to Fe 3+ The absorption spectra of carbon dots were specifically detected, and it was found that the peak wavelengths of their absorption spectra were all greater than 320nm, indicating that the peaks in their absorption spectra originated from the π-π* transition of their surface state / molecular state rather than the carbon core.

[0039] Figure 4 To be able to Fe 3+ The relative fluorescence intensity of the carbon dots after adding different metal ions to the ethanol solution for specific detection, the excitation wavelength is 380nm. Figure 4 As shown, it is possible to 3+ The carbon dots for specific detection were dissolved in ethanol and then reacted with Fe 3+ There is a specific response.

[0040] Example 2

[0041] (1) Preparation of ethanol solution of mulberry leaf powder: Take 0.5 g of mulberry leaf powder, dissolve it in 20 mL of ethanol, and ultrasonicate it in an ultrasonic machine for ten minutes to fully disperse the reactants in the ethanol.

[0042] (2) Preparation of mulberry leaf extract: Centrifuge the ultrasonicated mulberry leaf powder-ethanol solution at 8000 r / min for 5 min. Pour off the supernatant and discard the precipitate. Filter the supernatant and collect the clear solution. Add 0.2 g of disodium ethylenediaminetetraacetic acid to the filtered solution.

[0043] (3) Ability to Fe3+ Preparation of carbon dots for specific detection: The liquid prepared in step (2) was poured into a flask and placed in a microwave oven for 5 min at a microwave power of 800 W. After the microwave reaction, the product was dissolved in 5 mL of ethanol and the PL spectrum of the solution was characterized.

[0044] (4) Metal ions and Fe 3+ Preparation of mixed solution: Take a certain amount of metal salt (including Cu 2+ ,Zn 2+ ,Pb 2+ ,Na + ,K + ,Fe 2+ etc.), prepare a metal ion solution with a concentration of 10mmol / L. Add Fe 3+ solution to obtain the test solution.

[0045] (5) Use Fe 3+ Carbon dots for specific detection of ions (Fe 3+ ): Take the Fe 3+ 100uL of carbon dot solution for specific detection was added with ethanol to make the total volume of the mixed solution reach 4.5mL, and then the metal ions prepared in step (4) and Fe 3+ Prepare 0.5 mL of the mixed solution and characterize the solution by fluorescence spectrum.

[0046] The fluorescence of the solution was found to be quenched in the spectrum, indicating that the carbon dots were 3+ The specific detection is not affected by other metal ions.

[0047] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A kind of Fe 3+ The carbon dots for specific detection are characterized by: After preparation, it is in the form of green powder and turns light green at room temperature after being dissolved in ethanol. The ethanol solution of carbon dots emits red fluorescence under ultraviolet irradiation, with an emission peak at 675nm and a full width at half maximum of 25nm. The fluorescence originates from the π-π* transition of the surface state / molecular state electrons of carbon dots. There are hydroxyl groups, carboxyl groups, carbon-oxygen single bonds and carbon-oxygen double bonds on the surface of carbon dots. Only when Fe 3+ When the carbon dots are in solution, fluorescence quenching occurs.

2. A Fe 3+ A method for preparing carbon dots for specific detection, characterized in that: The following steps are involved: Step (1) preparing a mulberry leaf powder purified solution: adding ethanol to the ground mulberry leaf powder, placing the mixed solution in an ultrasonic machine for ultrasonication; after the ultrasonication is completed, placing the solution in a centrifuge for centrifugation; after the centrifugation is completed, separating the supernatant from the precipitate, and taking the supernatant; and filtering the supernatant using a 0.22 micron filter to collect the filtered clarified solution; Step (2) Preparation of carbon dots: Add disodium ethylenediaminetetraacetic acid powder to the liquid prepared in step (1), pour the resulting solution into a flask and heat it in a microwave oven; after the microwave reaction is completed, dissolve the product in ethanol to obtain a carbon dot capable of reacting with Fe. 3+ Carbon dots for specific detection.

3. a kind of Fe according to claim 2 3+ A method for preparing carbon dots for specific detection, characterized in that: The ratio of leaf powder to ethanol in step (1) is 0.5 g:20 ml, the ultrasonic time is 10 min to 30 min, and the centrifugal speed is 7000 r / min to 10000 r / min.

4. a kind of Fe according to claim 2 3+ A method for preparing carbon dots for specific detection, characterized in that: In the step (2), the mass ratio of the mulberry leaf powder purified liquid to the disodium ethylenediaminetetraacetic acid powder is 5:2; the microwave heating time is 2 min to 6 min, and the microwave power is 400 W to 800 W.

5. A carbon dot to Fe 3+ A method for performing specific detection, characterized in that: Dissolving the carbon dot powder prepared by the preparation method according to claim 2 in ethanol; Obtain a carbon dot solution, and use a PL spectrometer to measure the fluorescence intensity of the carbon dot solution; add the test solution to the carbon dot solution, and use a PL spectrometer to measure the fluorescence intensity of the mixed solution and compare them; if fluorescence quenching occurs, it means that the test solution contains Fe 3+ ion.

6. A carbon dot to Fe according to claim 5 3+ A method for performing specific detection, characterized in that: will be able to Fe 3+ The carbon dots for specific detection are dissolved in 5 mL to 15 mL of ethanol, and the carbon dot solution, the test solution, and ethanol are mixed in a ratio of 1:5:

45. If the test solution contains Fe 3+ ions, the fluorescence spectrum changes from an obvious Gaussian distribution curve to an approximately horizontal straight line, and its PL spectrum intensity tends to a constant value, which is basically the same as the spectrum intensity of the carbon dot solution in the non-excitation light band.

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