Carbon dots for specific detection of Fe < 3 + > and preparation method thereof

Abstract

The invention discloses a carbon dot with specific detection on Fe < 3 + > and a preparation method thereof. The carbon dot has the following properties: (1) the carbon dot has bright red fluorescence when dissolved in ethanol, the emission peak is 675 nm, the full width at half maximum is 25 nm, and groups such as hydroxyl, carboxyl, carbon-oxygen single bond and carbon-oxygen double bond exist on the surface; and (2) when the carbon dots are dissolved in ethanol, fluorescence of the carbon dots is quenched after only Fe < 3 + > is added, and fluorescence emission of the carbon dots is still retained after other metal ions are added. According to the invention, the carbon dot with specific fluorescence behavior on Fe < 3 + > is prepared by taking a renewable, cheap and green leaf material as a raw material, and the carbon dot can be used in multiple fields such as water body 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 essential 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] As a new type of zero-dimensional nanomaterials, carbon dots have many advantages such as low toxicity, good biocompatibility and excellent optical properties. These characteristics make carbon dots widely used in fields such as metal ion detection. However, the preparation of fluorescent carbon dots currently relies on organic compounds. The use of such organic reactants and organic reagents often causes secondary pollution to the environment, greatly affecting the practical application of carbon dots in environmental detection. In addition, most of the carbon dots currently prepared are prepared by hydrothermal method, which takes a long time and wastes energy. The prepared carbon dots have poor recognition in actual detection. Summary of the invention

[0004] In order to solve the above problems, the present invention discloses a method for Fe 3+ Carbon dots for specific detection and preparation method thereof, 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 invention discloses a method capable of treating Fe 3+ Carbon dots for specific detection and preparation method thereof, the carbon dots have the following optical properties: (1) after being dissolved in water or ethanol, they have red fluorescence, the emission peak is located at 675nm, the half-maximum full width is 25nm, and there are 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 undergo 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 kind of Fe 3+ The carbon dots for specific detection have the following optical properties:

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

[0009] (2) The carbon dots were dissolved in ethanol and only after the addition of Fe 3+ When in solution, the carbon dots will undergo fluorescence quenching.

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

[0011] Step (1) preparing 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, placing the solution in a centrifuge after ultrasonication, separating the supernatant from the precipitate in the centrifuged solution after centrifugation, and taking the supernatant. Filtering the supernatant with a 0.22 micron filter to obtain a pure filtrate.

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

[0013] Furthermore, in the mulberry leaf powder ethanol solution prepared in step (1), the ethanol is 20 mL and the 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 for 10 minutes.

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

[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 microwaved product was dissolved in ethanol, and 5 mL of ethanol was added to the flask.

[0018] A carbon dot for 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. Add the test solution to the carbon dot solution, 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.

[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 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 the preparation of carbon dots is cheaper than common organic compound raw materials such as urea, ethylenediamine, citric acid, etc., which reduces 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, and has 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 than synthesis methods such as hydrothermal method, pyrolysis method and ultrasonic method. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0028] Figure 4 For example, in Example 2, Fe 3+ 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 is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific 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 allow the reactants to be fully dispersed in the ethanol.

[0032] (2) Preparation of mulberry leaf purified liquid: The ultrasonic mulberry leaf powder ethanol solution was centrifuged at 8000 r / min for 5 min. The supernatant in the solution after centrifugation was poured out and the precipitate was discarded. The supernatant was filtered and the clear solution was collected. 0.2 g of disodium ethylenediaminetetraacetate was added to the filtered liquid.

[0033] (3) Ability to Fe 3+ Preparation of carbon dots for specific detection: Pour the liquid prepared in step (2) into a flask and place it in a microwave oven for 5 min at a microwave power of 800 W. After the microwave reaction is completed, the product is dissolved in 5 mL of water and the fluorescence spectrum of the solution is 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 a method that can 3+ Carbon dots for specific detection of ions (Fe 3+ ): Take the Fe 3+ 100uL of the carbon dot solution for specific detection was added with ethanol to make the total volume of the mixed solution reach 4.5mL, and then 0.5mL of the metal ion solution prepared in step (4) was added to characterize the fluorescence spectrum of the solution.

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

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

[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* transitions of their surface states / molecular states 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, Fe 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 allow the reactants to be fully dispersed in the ethanol.

[0042] (2) Preparation of mulberry leaf purified solution: The ultrasonic mulberry leaf powder-ethanol solution was centrifuged at 8000 r / min for 5 min. The supernatant in the solution after centrifugation was poured out and the precipitate was discarded. The supernatant was filtered and the clear solution was collected. 0.2 g of disodium ethylenediaminetetraacetate was added to the filtered liquid.

[0043] (3) Ability to Fe3+ Preparation of carbon dots for specific detection: Pour the liquid prepared in step (2) into a flask and place it 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 10mmol / L Fe 3+ solution to obtain the test solution.

[0045] (5) Use a method that can 3+ Carbon dots for specific detection of ions (Fe 3+ ): Take the Fe 3+ 100uL of the 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+ 0.5 mL of the mixed solution was added and the fluorescence spectrum of the solution was characterized.

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

[0047] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes 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 after dissolving in ethanol, it turns light green at room temperature. The ethanol solution of carbon dots emits red fluorescence under ultraviolet irradiation, with an emission peak at 675nm and a half-maximum width 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 is added, the red fluorescence is generated. 3+ When in solution, the carbon dots will undergo fluorescence quenching.

2. A kind of 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, and collecting the clarified solution after filtration; Step (2) Preparation of carbon dots: Add disodium diaminetetraacetate 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 (g) to ethanol (mL) taken in step (1) is 1:30, the ultrasonic time is 10 min to 30 min, and the centrifugal speed is 7000 r / min to 10000 r / min.

4. according to claim 2 can Fe 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 for Fe 3+ A method for performing specific detection, characterized in that: The prepared carbon dot powder was dissolved in ethanol; A carbon dot solution is obtained, and the fluorescence intensity of the carbon dot solution is measured using a PL spectrometer; a 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 solution to be tested 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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