Polymer fluorescent carbon dot with PBAT as carbon source, preparation method of polymer fluorescent carbon dot and application of polymer fluorescent carbon dot in detection of iron ions

Abstract

The invention relates to the technical field of carbon quantum dots, in particular to a high-molecular fluorescent carbon dot with PBAT as a carbon source, a preparation method of the high-molecular fluorescent carbon dot and application of the high-molecular fluorescent carbon dot to detection of iron ions. The preparation method comprises the following steps: oxidizing a copolymer (PBAT) of butylene adipate and butylene terephthalate with air, then carrying out hydrothermal treatment in an H2O2 aqueous solution to prepare CDs, putting PBAT into an open ceramic crucible, and carrying out air oxidation to form a dark brown oxidation product. Then, a product is transferred into a reaction kettle containing an H2O2 solution; after hydro-thermal treatment, CDs are brown and dispersed. And carrying out centrifugation, dialysis and freeze drying on the CDs dispersion liquid to finally obtain CDs powder. The carbon quantum dot prepared by the invention is synthesized by a hydrothermal method in one step, has stable fluorescence characteristics and is non-toxic. The efficient fluorescent carbon quantum dot can be used as a fluorescent probe for quantitative measurement of iron ions.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent carbon quantum dots, and in particular relates to a polymer fluorescent carbon dot using PBAT as a carbon source, a preparation method thereof, and an application thereof in detecting iron ions. Background Art

[0002] With the increasing prominence of environmental problems and the demand for new functional materials, the use of plastics to prepare carbon dots as an innovative approach is gradually attracting widespread attention. The present invention reduces the dependence on traditional carbon sources and provides a new sustainable resource for the preparation of carbon dots. Using plastics as raw materials solves the problem of plastic pollution to the environment, converting them into carbon dots, and realizing waste recycling, which is in line with the concept of sustainable development. The preparation process is relatively simple, highly operable, and does not require toxic reagents. Fe 3+ It is a form of iron in the human body, and its content level can reflect the health of the human body. Trace detection can help people understand their own iron intake, absorption and metabolism, and has guiding significance for a reasonable diet, iron supplementation, etc., and helps prevent iron deficiency or iron overload. 3+ Trace detection can assist in the diagnosis of liver disease, anemia, etc., and provide a basis for treatment. In the development of certain drugs, it is also necessary to understand the effect of drugs on human iron metabolism. Trace detection of trivalent iron can provide data support for the safety and efficacy evaluation of drugs, and help researchers better understand the mechanism of action and potential side effects of drugs. In this study, a copolymer of butylene adipate and butylene terephthalate (PBAT) was used as a carbon source, and a hydrothermal method was used to synthesize blue-green fluorescent carbon dots. 3+ Shows excellent selectivity and sensitivity.

[0003] Fluorescent carbon quantum dots are a very promising nanomaterial with good biocompatibility, high water solubility and low toxicity, and are widely used in the field of trace detection. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention uses a hydrothermal method to prepare high-purity carbon quantum dots with high fluorescence properties in one step, and verifies that they can be widely used as a fluorescence probe for detecting iron ions.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A polymer fluorescent carbon dot using PBAT as a carbon source, the preparation method comprising the following steps:

[0006] Step 1: Place PBAT in an open ceramic crucible and heat it to form a dark brown oxidation product for later use;

[0007] Step 2: Transfer the product obtained in step 1 to a reaction kettle containing H2O2 solution;

[0008] Step 3: placing the above reaction kettle in an oven for hydrothermal treatment to obtain a dark brown dispersion;

[0009] Step 4: Centrifuge the above dispersion and take the supernatant;

[0010] Step 5: The obtained solution is placed in a dialysis bag and dialyzed in ultrapure water to remove impurities to obtain a light yellow solution;

[0011] Step 6: The obtained solution is placed in a freeze dryer and freeze-dried to obtain high molecular fluorescent carbon dots with PBAT as the carbon source.

[0012] In the above-mentioned polymer fluorescent carbon dots using PBAT as a carbon source, in step 1, the heating is performed at 330° C. in air for 2 hours.

[0013] For the above-mentioned polymer fluorescent carbon dots using PBAT as the carbon source, in step 2, the mass fraction of the H2O2 solution is 4wt%, and the product obtained in step 1: H2O2 solution = 1g: 60mL.

[0014] For the above-mentioned polymer fluorescent carbon dots using PBAT as a carbon source, in step 3, the hydrothermal treatment is a hydrothermal treatment at 180° C. for 6 hours.

[0015] For the polymer fluorescent carbon dots using PBAT as a carbon source, in step 4, the centrifugation is performed at 10,000 rpm for 30 min.

[0016] For the above-mentioned high molecular fluorescent carbon dots using PBAT as a carbon source, in step 5, the specification of the dialysis bag is 500Da, and the amount of ultrapure water used is 3L.

[0017] For the polymer fluorescent carbon dots using PBAT as a carbon source, in step 6, the freeze-drying temperature is -45°C and the time is 24h.

[0018] The above-mentioned polymer fluorescent carbon dots using PBAT as a carbon source are used as fluorescent probes in detecting iron ions.

[0019] The above application includes the following steps:

[0020] Step 1: 0.2 ml of the solution containing different concentrations of iron ions (0-67.64 μM) was measured, 0.6 ml of water was added, and then 0.2 ml of 0.1 mg / mL of the above fluorescent probe was added thereto, and after mixing evenly, the mixture was reacted for 10 minutes;

[0021] Step 2: Place the mixed solution obtained in step 1 into a fluorescence spectrometer, select 330 nm as the excitation light wavelength, set the spectral range to 330-600 nm, and after obtaining a complete fluorescence spectrum, read the fluorescence intensity value I at 451 nm;

[0022] Step 3: Measure 0.8 ml of ultrapure water and add it to 0.2 ml of 0.1 mg / mL of the above fluorescent probe, mix well, and react for 10 minutes;

[0023] Step 4: Place the mixed solution obtained in step 3 into a fluorescence spectrometer, select 330 nm as the excitation wavelength, set the spectral range to 330-600 nm, and after obtaining the complete fluorescence spectrum, read the fluorescence intensity value I0 at 451 nm.

[0024] Step 5: Calculate the value of (I-I0) / I0 and plot (I-I0) / I0 and Fe 3+ The standard curve can be used to calculate the Fe content in the test solution. 3+ concentration.

[0025] Get Fe 3+ The linear equation of concentration and fluorescence intensity of carbon dots is y = 0.01252x-0.16511, R 2 =0.995.

[0026] Follow the method from step 1 to step 5 to obtain a sample containing Fe at an unknown concentration. 3+ The fluorescence intensity values ​​I and I0 were obtained, and Fe 3+ concentration.

[0027] Furthermore, in the above application, the Fe 3+ The method for drawing the standard curve is as follows: take 200 μL of Fe 3+ To the standard solution, 200 μL of the above fluorescent carbon dot solution with a concentration of 0.1 mg / mL and 600 μL of water were added, and after mixing evenly, the mixture was reacted for 1 min to obtain a gradient concentration of Fe 3+ Fluorescent carbon dot mixed solution, respectively put the mixed solution into the fluorescence spectrometer, select 330nm as the excitation light wavelength, set the spectral range to 330nm-600nm, after obtaining the complete fluorescence spectrum, read the fluorescence intensity value I at 451nm, and use Fe 3+ The concentration of Fe is plotted as the horizontal axis and the value of (I-I0) / I0 is plotted as the vertical axis. 3+ The standard curve of

[0028] The carbon quantum dots have an optimal excitation wavelength of 330 nm, an optimal emission wavelength of 451 nm, and exhibit blue-green fluorescence under a 365 nm ultraviolet lamp.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] The fluorescent carbon quantum dots prepared by the hydrothermal method in one step have high purity, stable fluorescence properties and are non-toxic. Detection experiments show that the prepared carbon quantum dots can be used as a fluorescence probe to quantitatively detect iron ions, and are expected to become a fluorescent probe for detecting iron ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the synthesis of fluorescent carbon dots prepared in the present invention.

[0032] Figure 2 This is a transmission electron microscope image of the carbon quantum dots prepared by the present invention;

[0033] Figure 3 The best excitation spectrum, best emission spectrum and ultraviolet spectrum of the carbon quantum dots prepared by the present invention;

[0034] Figure 4 The fluorescence spectra of the carbon quantum dots prepared in the present invention at different excitation wavelengths;

[0035] Figure 5 This is a graph of the time stability fluorescence intensity of the carbon quantum dots prepared by the present invention;

[0036] Figure 6 This is a graph showing the fluorescence intensity changes of the carbon quantum dots prepared in the present invention under different ions;

[0037] Figure 7 Different concentrations of Fe are added to the carbon quantum dots prepared by the present invention. 3+ Fluorescence intensity change diagram after solution;

[0038] Figure 8 The fluorescent carbon dots prepared in the present invention are used as probes Fe 3+ Standard curve diagram of

[0039] Fig. 9 The carbon quantum dots prepared by the present invention are 3+ Linear relationship graph for solution concentration range of 32.89-47.09 μM / L.

[0040] Specific implementation method

[0041] The present invention is further described below by way of specific examples. The present invention is not limited to the embodiments, and slight variations are possible without departing from the scope described.

[0042] Example 1 A method for preparing polymer fluorescent carbon dots using PBAT as a carbon source

[0043] The steps include:

[0044] Step 1: Weigh 5 g of PBAT, put it into an open ceramic crucible, and heat it at 330 ° C in air for 2 hours to form a dark brown oxidation product for use;

[0045] Step 2: Weigh 0.5 g of the product obtained in step 1 and transfer it to a reactor containing 30 mL of 4 wt% H2O2 solution; the reactor capacity is 75 ml;

[0046] Step 3: Place the above reaction kettle in an oven and perform hydrothermal treatment at 180°C for 6 hours to obtain a dark brown dispersion;

[0047] Step 4: Centrifuge the above dispersion at 10000 rpm for 30 min and take the supernatant;

[0048] Step 5: The obtained solution was placed in a dialysis bag of 500Da and poured into 3L ultrapure water for dialyzing to remove impurities to obtain a light yellow solution.

[0049] Step 6: placing the obtained solution in a freeze dryer and freeze drying to obtain high molecular fluorescent carbon dots with PBAT as the carbon source.

[0050] Example 2 Characterization of polymer fluorescent carbon dots using PBAT as carbon source

[0051] The specific characterization results are as follows:

[0052] (1) Transmission electron microscopy: The polymer fluorescent carbon dots prepared in Example 1 using PBAT as the carbon source were characterized by transmission electron microscopy, and it was found that the size of the dots was about 4 nm (e.g. Figure 2 shown).

[0053] (2) The optimal excitation wavelength and emission wavelength of the polymer fluorescent carbon dot solution with PBAT as the carbon source are 330 nm and 451 nm, respectively (e.g. Figure 3 ), and it exhibits blue-green fluorescence under 365nm ultraviolet light; the ultraviolet absorption spectrum has an absorption peak near 238nm, which may be derived from the π-π* transition of the polyaromatic chromophore. The study of its fluorescence spectrum at different excitation wavelengths (330-380nm) found that (such as Figure 4 As shown in the figure, it exhibits excitation-independent fluorescence emission properties, which is related to the uniform size distribution and surface defects of the polymer fluorescent carbon dots synthesized with PBAT as the carbon source.

[0054] (4) The study on the fluorescence stability of polymer fluorescent carbon dots with PBAT as the carbon source shows that the fluorescence intensity of carbon quantum dots was tested under different metal ions, different 330nm UV light irradiation time and different salt ion strength. Figure 6As shown, the polymer fluorescent carbon dots with PBAT as the carbon source only have a quenching effect on iron ions in different metal ion aqueous solutions, and other metal ions have almost no effect on the fluorescence intensity of the polymer fluorescent carbon dots with PBAT as the carbon source. This shows that the polymer fluorescent carbon dots with PBAT as the carbon source can be used as a fluorescent probe for detecting iron ions.

[0055] Under different UV light irradiation times, the fluorescence intensity of carbon quantum dots remained almost unchanged, indicating that the carbon quantum dots have good resistance to photobleaching. Figure 5 shown).

[0056] Example 3: Detection of iron ions using PBAT as a carbon source and high molecular weight fluorescent carbon dots as a fluorescent probe

[0057] The specific detection method includes the following steps:

[0058] Step 1: Take 0.2 ml of the solution containing different concentrations of iron ions (0-67.64 μM) and add 0.6 ml of water to it, add 0.2 ml of 0.1 mg / mL carbon quantum dot solution fluorescent probe, mix well, and react for 10 minutes;

[0059] Step 2: Place the mixed solution obtained in step 1 into a fluorescence spectrometer, select 330 nm as the excitation light wavelength, set the spectral range to 330-600 nm, and after obtaining a complete fluorescence spectrum, read the fluorescence intensity value I at 451 nm;

[0060] Step 3: Measure 0.8 ml of ultrapure water and add it to 0.2 ml of the 0.1 mg / mL carbon dot solution fluorescent probe, mix well, and react for 10 minutes;

[0061] Step 4: Place the mixed solution obtained in step 3 into a fluorescence spectrometer, select 330 nm as the excitation wavelength, set the spectral range to 330-600 nm, and after obtaining a complete fluorescence spectrum, read the fluorescence intensity value I0 at 451 nm. Comparison of I and I0 proves that the fluorescent probe can be effectively quenched by iron ions.

[0062] Step 5: Calculate the value of (I-I0) / I0 and plot (I-I0) / I0 and Fe 3+ The standard curve can be used to calculate the Fe content in the test solution. 3+ concentration.

[0063] Fluorescence intensity of polymer fluorescent carbon dots with PBAT as carbon source and Fe 3+ The relationship between concentration (such as Figure 7 When the carbon quantum dot solution is added with Fe 3+ Solution Fe 3+The higher the concentration, the lower the fluorescence intensity. Take 200 μL of Fe with a concentration of 0-67.64 μmol / L respectively. 3+ To the standard solution, 200 μL of the above fluorescent carbon dot solution with a concentration of 0.1 mg / mL and 600 μL of water were added, and after mixing evenly, the mixture was reacted for 1 min to obtain a gradient concentration of Fe 3+ Fluorescent carbon dot mixed solution, respectively put the mixed solution into the fluorescence spectrometer, select 330nm as the excitation light wavelength, set the spectral range to 330nm-600nm, after obtaining the complete fluorescence spectrum, read the fluorescence intensity value I at 451nm, and use Fe 3+ The concentration of Fe is plotted as the horizontal axis and the value of (I-I0) / I0 is plotted as the vertical axis. 3+ The standard curve ( Figure 8 and Fig. 9 ). 3+ There is a good linear relationship between the fluorescence intensity of carbon dots (such as Fig. 9 As shown), y = 0.01252x-0.16511, R 2 =0.995, which can quantitatively detect trivalent iron ions.

[0064] In summary, the polymer fluorescent carbon dots prepared by the hydrothermal method using PBAT as the carbon source have high purity and stable fluorescent properties and are non-toxic. Detection experiments show that the prepared carbon quantum dots can be used as fluorescent probes for quantitative detection of iron ions.

Claims

1. A polymer fluorescent carbon dot with PBAT as a carbon source, characterized in that: The preparation method comprises the following steps: Step 1: Place PBAT in an open ceramic crucible and heat it to form a dark brown oxidation product for later use; Step 2: Transfer the product obtained in step 1 to a reaction kettle containing H2O2 solution; Step 3: placing the above reaction kettle in an oven for hydrothermal treatment to obtain a dark brown dispersion; Step 4: Centrifuge the above dispersion and take the supernatant; Step 5: The obtained solution is placed in a dialysis bag and dialyzed in ultrapure water to remove impurities to obtain a light yellow solution; Step 6: The obtained solution is placed in a freeze dryer and freeze-dried to obtain high molecular fluorescent carbon dots with PBAT as the carbon source.

2. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1, characterized in that: In step 1, the heating is performed at 330° C. in air for 2 hours.

3. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1, characterized in that: In step 2, the mass fraction of the H2O2 solution is 4wt%, and the product obtained in step 1: H2O2 solution = 1g: 60mL.

4. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1, characterized in that: In step 3, the hydrothermal treatment is performed at 180° C. for 6 hours.

5. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1 are characterized in that: In step 4, the centrifugation is performed at 10,000 rpm for 30 min.

6. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1, characterized in that: In step 5, the specification of the dialysis bag is 500Da, and the amount of ultrapure water used is 3L.

7. The polymer fluorescent carbon dots using PBAT as a carbon source according to claim 1, characterized in that: In step 6, the freeze-drying temperature is -45°C and the time is 24 hours.

8. Use of the polymer fluorescent carbon dots with PBAT as the carbon source as claimed in any one of claims 1 to 7 as a fluorescent probe in detecting iron ions.

9. The use according to claim 8, characterized in that: The steps include: Step 1: 0.2 ml of a solution containing different concentrations of iron ions (0-67.64 μM) is measured, 0.6 ml of water is added, and then 0.2 ml of 0.1 mg / mL fluorescent probe according to any one of claims 1 to 7 is added thereto, and after mixing evenly, the mixture is reacted for 10 minutes; Step 2: Place the mixed solution obtained in step 1 into a fluorescence spectrometer, select 330 nm as the excitation light wavelength, set the spectral range to 330-600 nm, and after obtaining a complete fluorescence spectrum, read the fluorescence intensity value I at 451 nm; Step 3: Measure 0.8 ml of ultrapure water and add it to 0.2 ml of 0.1 mg / mL of the fluorescent probe according to any one of claims 1 to 7, and after mixing evenly, react for 10 minutes; Step 4: Place the mixed solution obtained in step 3 into a fluorescence spectrometer, select 330 nm as the excitation wavelength, set the spectral range to 330-600 nm, and after obtaining a complete fluorescence spectrum, read the fluorescence intensity value I0 at 451 nm. Step 5: Calculate the value of (I-I0) / I0 and plot (I-I0) / I0 and Fe 3+ The standard curve can be used to calculate the Fe content in the solution to be tested. 3+ concentration.

10. The use according to claim 9, characterized in that: The Fe 3+ The method for drawing the standard curve is as follows: take 200 μL of Fe 3+ To the standard solution, 200 μL of the above fluorescent carbon dot solution with a concentration of 0.1 mg / mL and 600 μL of water were added respectively, and after mixing evenly, the mixture was reacted for 1 min to obtain a gradient concentration of Fe 3+ Fluorescent carbon dot mixed solution, respectively put the mixed solution into the fluorescence spectrometer, select 330nm as the excitation light wavelength, set the spectral range to 330nm-600nm, after obtaining the complete fluorescence spectrum, read the fluorescence intensity value I at 451nm, and use Fe 3+ The concentration of Fe is plotted as the horizontal axis and the value of (I-I0) / I0 is plotted as the vertical axis. 3+ The standard curve of

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