A nitrogen-doped tannic acid carbon dot nanomaterial, a preparation method and application thereof

Abstract

The present application relates to a kind of nitrogen-doped ellagic acid carbon dots (ET-CD) nanomaterials and its preparation method and application, preparation method as follows: (1) ellagic acid is mixed with L-tyrosine in aqueous solution uniformly, and white suspension is obtained;(2) the emulsion obtained in (1) is transferred to the hydrothermal reactor with polytetrafluoroethylene lining, and brown-black solution is prepared by hydrothermal method;(3) the supernatant of brown-black reaction liquid in (2) is centrifuged and dialyzed for 24-36h, and then the reaction liquid after dialysis is freeze-dried to obtain powder nitrogen-doped ellagic acid carbon dots nanomaterials.Compared with prior art, the present application studies and synthesizes a new type of nitrogen-doped ellagic acid carbon dots with photothermal properties and antioxidant activity, which can solve the damage caused by oxidative stress in the process of photothermal anticancer, and can protect normal cells while photothermal anticancer.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and molecular imaging technology, and in particular to a nitrogen-doped ellagic acid carbon dot nanomaterial, its preparation method, and its application. Background Technology

[0002] In recent years, heteroatom-doped carbon dots have become a hot topic in the field of nanomedicine due to their excellent optical properties, good chemical properties, and satisfactory biocompatibility. A series of carbon dots with excellent photochemical properties have been developed and applied to biological cancer treatment. However, cancer treatment still faces huge challenges in terms of anti-cancer efficiency and overcoming damage to normal cells. Therefore, there is an urgent need to develop nanomedicines and anti-cancer therapies with better and more complete functions.

[0003] Photothermal therapy (PTT) refers to a method in cancer treatment where a photothermal agent converts light energy into heat energy, thereby ablating tumor cells. However, the high photothermal temperatures during PTT can easily trigger an increase in reactive oxygen species (RONS) in the body, leading to oxidative stress-induced inflammation, damaging normal tissues, and thus inhibiting PTT to some extent. Summary of the Invention

[0004] The purpose of this invention is to address the problem of oxidative stress in cells caused by high photothermal temperatures during current photothermal anticancer treatments, which in turn induces inflammation. The invention provides a nitrogen-doped ellagic acid carbon dot (ET-CD) nanomaterial that integrates photothermal anticancer properties with protection of normal cells, along with its preparation method and applications.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] One aspect of the present invention provides a method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials, comprising the following steps:

[0007] S1: The precursor L-tyrosine and ellagic acid are mixed evenly, and a deionized aqueous solution containing alkaline solution is added. The mixture is ultrasonically vibrated to disperse the mixture evenly, resulting in a white emulsion. The white emulsion is then added to a hydrothermal reactor and placed in an oven for reaction.

[0008] S2: After the reaction is complete, the reactants in the reactor are centrifuged and filtered through a filter membrane to obtain a black reaction solution.

[0009] S3: The reaction solution described in step S2 is dialyzed to obtain the nitrogen-doped ellagic acid carbon dot nanomaterial solution.

[0010] S4: The nitrogen-doped ellagic acid carbon dot nanomaterial solution obtained in step S3 is freeze-dried to obtain a black powder of nitrogen-doped ellagic acid carbon dot nanomaterial.

[0011] Further, the ratio of L-tyrosine, ellagic acid and deionized water used in step S1 is 200-400 mg: 700-760 mg: 20-40 mL;

[0012] Furthermore, the preferred ratio of L-tyrosine, ellagic acid, and deionized water in step S1 is 300 mg: 730 mg: 30 mL.

[0013] Furthermore, the alkaline solution is sodium hydroxide, and the content of sodium hydroxide in the deionized aqueous solution is 0.03-0.07% w / v.

[0014] Furthermore, the alkaline solution in the deionized aqueous solution is preferably 0.05% w / v.

[0015] Furthermore, the reaction described in step S1 specifically involves a reaction temperature of 190-210℃ and a reaction time of 8-12 hours.

[0016] Furthermore, the preferred reaction temperature is 200°C, and the preferred reaction time is 10 hours.

[0017] Furthermore, the centrifugation described in step S2 specifically involves a centrifugation speed of 5000-8000 rpm and a centrifugation time of 5-8 min.

[0018] Furthermore, the filter membrane described in step S2 has a specification of 0.22 μm.

[0019] Furthermore, the dialysis described in step S3 specifically involves dialysis for 36-48 hours using a 3500 Da dialysis bag.

[0020] Furthermore, the freeze-drying process described in step S4 takes 24-48 hours.

[0021] The second aspect of this invention provides nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials prepared by the above method.

[0022] The third aspect of this invention provides an application of the nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials described above, using the nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials as a photosensitizer for photothermal therapy and a protective agent to alleviate cellular oxidative stress damage and inflammatory responses.

[0023] This material has good photothermal conversion efficiency. Nitrogen-doped ellagic acid carbon dots can convert light energy into heat energy under the mediation of near-infrared (NIR) laser for the thermal ablation of tumors. At the same time, nitrogen-doped ellagic acid carbon dots have excellent free radical scavenging activity, which can remove RONS, relieve intracellular oxidative stress, reduce photothermal inflammatory damage, thereby improving the efficiency of photothermal anticancer and protecting normal cell tissues.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials prepared in this invention have the advantages of good biocompatibility, ease of preparation, tunable physicochemical and optical properties, and low cost. The long-term biotoxicity of carbon dots (CDs) is low and acceptable, and their small size allows them to be rapidly metabolized and eliminated by the kidneys.

[0026] (2) Ellagic acid, the carbon precursor used in this invention, is a natural polyphenol organic compound that is widely found in various soft fruits and nuts. It has excellent antioxidant, anticancer, and antimutagenic properties. Research results show that ellagic acid has strong free radical scavenging and antioxidant capabilities, and can also inhibit lipid peroxidation and alleviate nitrite-induced nitration damage.

[0027] (3) In this invention, L-tyrosine is used as a nitrogen source for doping. Compared with non-nitrogen-doped carbon dots, nitrogen-doped carbon dots have better photoluminescence and higher photothermal conversion efficiency. Nitrogen-doped carbon dots have both excellent photothermal conversion function and good antioxidant activity, which provides a new solution for photothermal anticancer therapy. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials in Example 1 of the present invention;

[0029] Figure 2 This is a TEM image of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention;

[0030] Figure 3 This is a particle size distribution diagram of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of the present invention;

[0031] Figure 4 The image shows the XRD pattern of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention.

[0032] Figure 5 The image shows the Raman spectrum of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention.

[0033] Figure 6 The Fourier transform infrared spectrum of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention;

[0034] Figure 7 XPS image of nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention;

[0035] Figure 8 This is a high-resolution XPS image of the C1s peak in the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention.

[0036] Figure 9 The N1s peak image in high-resolution XPS of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 1 of this invention;

[0037] Figure 10 This is a temperature-time graph showing the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 2 of this invention at different concentrations.

[0038] Figure 11 This is a temperature-time graph of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 2 of the present invention under different powers;

[0039] Figure 12 This is a graph showing the heating / cooling curves of nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 2 of the present invention after 5 laser on / off cycles.

[0040] Figure 13 The graph shows the photothermal conversion efficiency and time constant of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 2 of this invention.

[0041] Figure 14 The diagram shows the ABTS radical scavenging activity of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 3 of this invention.

[0042] Figure 15 The diagram shows the DPPH radical scavenging activity of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 3 of this invention.

[0043] Figure 16 The diagram shows the hydroxyl radical scavenging activity of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 3 of this invention.

[0044] Figure 17 The diagram shows the superoxide anion scavenging activity of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared in Example 3 of this invention.

[0045] Figure 18 The images show a comparison of the photothermal heating of ET-CD, E-CD, and T-CD prepared in Examples 1, 1, and 2 of this invention. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The specific embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0047] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise described in detail in the following embodiments, it can be achieved using conventional experimental methods in the art.

[0048] This invention provides a nitrogen-doped ellagic acid carbon dot ET-CD nanomaterial that integrates photothermal anticancer and normal cell protection, as well as its preparation method and application.

[0049] Example 1

[0050] This embodiment provides a method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials that integrate photothermal anticancer properties and protection of normal cells. The method flow is as follows: Figure 1 As shown, the specific steps include:

[0051] S1: The precursor L-tyrosine and ellagic acid were mixed evenly, and a deionized aqueous solution containing sodium hydroxide (0.05% w / v) was added. The ratio of L-tyrosine, ellagic acid, and deionized water was 300 mg: 730 mg: 30 mL. The mixture was ultrasonically vibrated to disperse it evenly, resulting in a white emulsion. The white emulsion was added to a hydrothermal reactor with a tetrafluoroethylene liner, placed in an oven, and reacted at 200°C for 10 h using a hydrothermal method to obtain a nitrogen-doped ellagic acid carbon dot stock solution.

[0052] S2: After the reaction is complete, the reactants in the reactor are centrifuged at 5500 rpm for 6 hours and filtered through a 0.22 μm filter membrane to obtain a black reaction solution.

[0053] S3: The reaction solution described in step S2 is dialyzed using a 3500 Da dialysis bag for 42 hours to obtain the nitrogen-doped ellagic acid carbon dot nanomaterial solution.

[0054] S4: The nitrogen-doped ellagic acid carbon dot nanomaterial solution obtained in step S3 was placed in a -4℃ freezer and then freeze-dried for 36 hours to obtain black powdered nitrogen-doped ellagic acid carbon dot nanomaterial.

[0055] Ellagic acid and L-tyrosine used in this invention were both purchased from Shanghai Titan Technology Co., Ltd.

[0056] Figure 2 The image shows a TEM image of the nitrogen-doped ellagic acid carbon dot nanomaterials prepared. Figure 3 The corresponding particle size distribution is shown in the figure. It can be seen from the figure that the prepared nitrogen-doped ellagic acid carbon dots are uniformly dispersed and have a uniform particle size of approximately 2-3 nm. Furthermore... Figure 2 The inset is a high-resolution transmission electron microscope (HRTEM) image with a lattice spacing of 0.21 nm.

[0057] Figure 4 The X-ray diffraction (XRD) pattern of the nitrogen-doped ellagic acid carbon dot nanomaterials shows a broad peak centered at 2θ = 22.2°, which is distributed onto the (002) plane of the ET-CD graphitized carbon core. Figure 5The Raman spectra of the ET-CD are shown, with values ​​at 1250 cm⁻¹. -1 and 1600cm -1 The area shows a typical D band (sp). 3 Hybridization) and G-band (sp) 2 Hybridization). Disordered D band and crystalline G band (I D / I G The intensity ratio of 1.058 indicates that ET-CD has a highly ordered carbon nucleus.

[0058] Figure 6 The Fourier transform infrared (FTIR) spectra of the nitrogen-doped ellagic acid carbon dots prepared show the chemical composition of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials, with the 3200-2800 cm⁻¹ region being the most abundant. -1 This corresponds to the vibration of the OH component, 2960-2850 cm. -1 Corresponding to CH vibration, 1750-1680 cm -1 There is a C=O vibrational absorption peak, 1400-1200 cm⁻¹. -1 The amide band is a coupling absorption band of NH and CN, 750-600 cm⁻¹ -1 There is a broad absorption corresponding to the NH2 rocking vibration.

[0059] Figure 7 The X-ray photoelectron spectroscopy (XPS) spectrum of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials shows the presence of C, N, and O elements. Specifically, the high-resolution C1s XPS spectrum ( Figure 8 The results show that the peaks at 284 eV, 286 eV, 287 eV, and 288 eV contribute to CC or C=C, CN, C=O, and CO, respectively. High-resolution N1s XPS spectra ( Figure 9 The results show that the two peaks at 400 eV and 402 eV belong to amino nitrogen and graphitic nitrogen, respectively.

[0060] Example 2

[0061] The photothermal properties of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials were investigated, and the specific results are as follows:

[0062] An infrared thermal camera was used to monitor the photothermal effect of ET-CD suspension under NIR laser irradiation. For example... Figure 10 As shown, at 808nm (1W / cm) 2 Under laser irradiation (5 min), the temperature of the ET-CD solution gradually increased with increasing ET-CD concentration. Figure 11 This indicates that as the laser power density increases, the temperature of the ET-CD solution also gradually increases. Figure 12The heating / cooling curves for five laser-on / off photothermal cycles show that ET-CD has good photothermal stability under NIR laser irradiation. Figure 13 The graph shows the photothermal conversion efficiency and time constant of the ET-CD nanomaterial. According to formula (1-1), the photothermal conversion efficiency of ET-CD is calculated to be 36.8%.

[0063]

[0064] Example 3

[0065] The antioxidant activity of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials at the solution level was investigated, and the specific results are as follows:

[0066] Using ABTS as an indicator, the general antioxidant properties of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials against ROS were determined. Figure 14 As shown, ET-CD has strong scavenging activity against free radicals, with 120 μg / mL ET-CD achieving a scavenging rate of 84% for ABTS.

[0067] Using representative DPPH as an indicator, the general scavenging activity of the prepared nitrogen-doped ellagic acid carbon dot nanomaterials for reactive nitrogen (RNS) was evaluated, such as... Figure 15 As shown, ET-CD can effectively and continuously eliminate DPPH, with 120 μg / mL ET-CD achieving a 77% clearance rate for ABTS.

[0068] In addition, such as Figure 16 and Figure 17 As shown, the prepared nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials exhibit certain scavenging activities against hydroxyl radicals and superoxide anions. In summary, the prepared nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials inherit the antioxidant activity of the precursor ellagic acid and possess excellent antioxidant properties.

[0069] Comparative Example 1

[0070] Except for the absence of tyrosine (nitrogen source), the remaining operating steps are the same as in Example 1.

[0071] Comparative Example 2

[0072] Except for the absence of ellagic acid (carbon precursor), the other operating steps are the same as in Example 1.

[0073] pass Figure 18It can be seen that, under the same laser irradiation conditions, the ellagic acid carbon dots (E-CD) or tyrosine carbon dots (T-CD) prepared using only ellagic acid or only L-tyrosine as raw materials do not show significant temperature increases with changes in irradiation time. Their photothermal conversion ability is significantly weaker than that of nitrogen-doped ellagic acid carbon dots (ET-CD). This is because after high-temperature carbonization, the nitrogen-doped ellagic acid carbon dots have highly ordered carbon cores, and their graphite-N doping can reduce the HOMO-LUMO gap and the corresponding transition energy, thus enabling ET-CD to have significant absorption in the near-infrared region. This further illustrates the advantage of the prepared nitrogen-doped ellagic acid carbon dots having higher photothermal conversion efficiency.

[0074] The preparation method of this invention is simple, and the nitrogen-doped ellagic acid carbon dot ET-CD nanomaterials prepared are a novel nanotherapeutic material that integrates photothermal anticancer and normal tissue protection. As a photothermal conversion mediator for photothermal anticancer and a protectant for normal healthy cells and tissues, it protects normal tissues from a series of oxidative stress damages caused by photothermal during the process of photothermal anticancer therapy (PTT).

[0075] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials, characterized in that, Includes the following steps: S1: The precursor L-tyrosine and ellagic acid are mixed evenly, and then a deionized aqueous solution containing alkaline solution is added and evenly dispersed to obtain a white emulsion; the white emulsion is added to a hydrothermal reactor for reaction; S2: After the reaction is complete, the reactants in the reactor are centrifuged and filtered through a filter membrane to obtain a black reaction solution; S3: The reaction solution described in step S2 is dialyzed to obtain the nitrogen-doped ellagic acid carbon dot nanomaterial solution. S4: The nitrogen-doped ellagic acid carbon dot nanomaterial solution obtained in step S3 is freeze-dried to obtain a black powder of nitrogen-doped ellagic acid carbon dot nanomaterial. The ratio of L-tyrosine, ellagic acid, and deionized water used in step S1 is 200-400 mg: 700-760 mg: 20-40 mL; the alkaline solution is sodium hydroxide, and the content of sodium hydroxide in the deionized aqueous solution is 0.03-0.07% w / v. The reaction described in step S1 is specifically carried out at a reaction temperature of 190-210 ℃ and a reaction time of 8-12 h.

2. The method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials according to claim 1, characterized in that, The ratio of L-tyrosine, ellagic acid, and deionized water is 300 mg: 730 mg: 30 mL.

3. The method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials according to claim 1, characterized in that, The centrifugation described in step S2 specifically involves a centrifugation speed of 5000-8000 rpm and a centrifugation time of 5-8 min.

4. The method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials according to claim 1, characterized in that, The filter membrane described in step S2 has a diameter of 0.22 μm.

5. The method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials according to claim 1, characterized in that, The dialysis described in step S3 specifically involves using a 3500 Da dialysis bag for 36-48 hours.

6. The method for preparing nitrogen-doped ellagic acid carbon dot nanomaterials according to claim 1, characterized in that, The freeze-drying process in step S4 takes 24-48 hours.

7. A nitrogen-doped ellagic acid carbon dot nanomaterial prepared by the method described in any one of claims 1-6.

8. An application of the nitrogen-doped ellagic acid carbon dot nanomaterial as described in claim 7, characterized in that, Nitrogen-doped ellagic acid carbon dot nanomaterials were used to prepare photosensitizers for photothermal therapy.

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