Iron-doped carbon quantum dot, preparation method thereof and application of iron-doped carbon quantum dot in magneto-optical dual-mode imaging

Abstract

The invention discloses an iron-doped carbon quantum dot, a preparation method thereof and application of the iron-doped carbon quantum dot in magneto-optical dual-mode imaging. The method comprises the following steps: dissolving trisodium citrate in ethylene glycol, adding FeCl3, stirring until the FeCl3 is completely dissolved, adding ethylenediamine, carrying out hydrothermal reaction under heating, and carrying out rotary evaporation on the obtained product to obtain the iron-doped carbon quantum dot. The iron-doped carbon quantum dots prepared in the invention successfully realize fluorescence imaging, and can be used for magnetic resonance imaging of mice; the fluorescence imaging of the fluorescent probe is proved to be effective on various biological samples, including cells, organoids and zebra fishes; in the magnetic resonance imaging process of mice, the iron-doped carbon quantum dots are accumulated in chest and lung areas and gradually metabolized as time goes on, which indicates that the iron-doped carbon quantum dots have potential targeting ability and open up a new way for detecting chest and lung diseases. Therefore, the excellent multi-mode imaging capability of the iron-doped carbon quantum dots is expected to bring a new scheme for the application in many fields.

Description

Technical Field

[0001] The invention relates to the fields of biology and nanomaterials, and in particular to an iron-doped carbon quantum dot, a preparation method thereof and application thereof in magneto-optical dual-mode imaging. Background Art

[0002] Molecular imaging techniques have become an indispensable tool in modern biological research, enabling researchers to visualize and study the distribution, structure, and function of biomolecules in cells, tissues, and organisms. These techniques provide opportunities for in-depth understanding of biological processes and disease mechanisms. Molecular imaging covers a variety of modalities, including mass spectrometry imaging, optical coherence imaging, radioisotope imaging, magnetic resonance imaging (MRI), conventional fluorescence imaging, and two-photon imaging. However, each molecular imaging technique has its own unique advantages and inherent limitations, making it difficult to obtain accurate and reliable information in specific research areas or physiological structures. For example, traditional fluorescence imaging based on the principle of fluorescent molecular labeling has high sensitivity, multicolor imaging capabilities, and real-time imaging capabilities. However, it is limited by depth imaging limitations, photodamage risks, and background autofluorescence. On the other hand, two-photon imaging is an advanced microscopy technique that overcomes some of the limitations of traditional fluorescence imaging by using two photons simultaneously to excite fluorescent markers within the sample. It enables high-resolution imaging in deep tissues, reduces the risk of photodamage, and provides higher spatial resolution. Two-photon imaging requires highly specialized equipment and expertise, is relatively expensive, and relies on specific fluorescent labels. MRI is a non-invasive imaging technology that uses the principle of nuclear magnetic resonance to generate high-resolution images. It has the advantages of radiation-free imaging, deep imaging capabilities, and multi-parameter information. Compared with microscopy technology, MRI scans are usually longer, more expensive, and have lower spatial resolution. In order to overcome these inherent limitations, there is an urgent need for a multimodal imaging technology that can effectively combine the advantages of different technologies to provide more powerful molecular imaging capabilities. For example, combining conventional fluorescence imaging and magnetic resonance imaging can achieve high-sensitivity, radiation-free deep imaging of various biological samples, greatly expanding imaging capabilities and application scenarios.

[0003] Initially, carbon quantum dots (CDs) were studied as emerging carbon materials, and their preparation methods were relatively simple, usually involving heat treatment or microwave irradiation of carbon sources such as sucrose or glucose. However, due to their excellent fluorescence properties, the material soon attracted widespread attention and became a research hotspot in the field of biological imaging and labeling. In the field of fluorescence imaging, CDs have become highly regarded optical probes due to their unique properties. Their biocompatibility and low toxicity make them ideal for labeling biological samples. At the same time, CDs also have potential in the field of magnetic resonance imaging (MRI). By utilizing magnetically functionalized CDs, they can be used as MRI contrast agents, enhancing the prospects of MRI in biomedical research and clinical diagnosis. Advances in this field mean that CDs can provide high-contrast images for MRI, thereby better visualizing tissue structures and biological processes. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an iron-doped carbon quantum dot, a preparation method thereof and its application in magneto-optical dual-mode imaging in view of the deficiencies in the above-mentioned prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: in the first aspect of the present invention, a method for preparing iron-doped carbon quantum dots is provided, characterized in that it comprises the following steps:

[0006] Dissolve trisodium citrate in ethylene glycol, add FeCl3, stir until completely dissolved, add ethylenediamine, carry out hydrothermal reaction under heating, and rotary evaporate the obtained product to obtain iron-doped carbon quantum dots.

[0007] Preferably, the temperature of the hydrothermal reaction is 180-220°C.

[0008] Preferably, the hydrothermal reaction time is 4-16 hours.

[0009] Preferably, the method for preparing iron-doped carbon quantum dots comprises the following steps: dissolving 1-4 g of trisodium citrate in 15-60 mL of ethylene glycol, adding 0.5-2 g of FeCl3, stirring until completely dissolved, adding 1-4 mL of ethylenediamine, transferring the resulting mixture to a reactor, reacting at 180-220° C. for 4-16 h, and rotary evaporating the obtained product to obtain iron-doped carbon quantum dots.

[0010] Preferably, the method for preparing iron-doped carbon quantum dots comprises the following steps: dissolving 2 g of trisodium citrate in 30 mL of ethylene glycol, adding 1 g of FeCl3, stirring until completely dissolved, adding 2 mL of ethylenediamine, transferring the resulting mixture to a reactor, reacting at 200 ° C for 8 h, filtering the obtained product to remove solid precipitated impurities, and then rotary evaporating to obtain iron-doped carbon quantum dots.

[0011] The second aspect of the present invention provides an iron-doped carbon quantum dot, which is prepared by the method as described above.

[0012] A third aspect of the present invention provides a use of the iron-doped carbon quantum dots as described above in fluorescence imaging.

[0013] A fourth aspect of the present invention provides a use of the iron-doped carbon quantum dots as described above in magnetic resonance imaging.

[0014] A fifth aspect of the present invention provides a use of the iron-doped carbon quantum dots as described above in the preparation of MRI contrast agents.

[0015] In a sixth aspect, the present invention provides an MRI contrast agent prepared from the iron-doped carbon quantum dots as described above.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides an iron-doped carbon quantum dot, a preparation method thereof and its application in magneto-optical dual-mode imaging. The Fe-doped carbon quantum dots (TPFe-CDs) prepared in the present invention successfully achieve fluorescence imaging and can be used for magnetic resonance imaging of mice; its fluorescence imaging has been proven to be effective for various biological samples, including cells, organoids and zebrafish; during the magnetic resonance imaging of mice, the iron-doped carbon quantum dots accumulate in the thoracic and lung regions and gradually metabolize over time, indicating that it has potential targeting capabilities, opening up a new way to detect thoracic and lung diseases. Therefore, the excellent multi-mode imaging capabilities of the TPFe-CDs provided by the present invention are expected to bring new solutions to applications in many fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a transmission electron microscope (TEM) photo of iron-doped carbon quantum dots;

[0019] Figure 2 is the X-ray diffraction pattern of iron-doped carbon quantum dots;

[0020] Figure 3 is the UV absorption spectrum of iron-doped carbon quantum dots;

[0021] Figure 4 This is the fluorescence spectrum of iron-doped carbon quantum dots;

[0022] Figure 5 This is the infrared spectrum of iron-doped carbon quantum dots;

[0023] Figure 6 Single-photon fluorescence imaging results of iron-doped carbon quantum dots in HeLa, zebrafish and organoids;

[0024] Figure 7 These are the MRI imaging results of iron-doped carbon quantum dots in mice. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0027] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0028] Example 1

[0029] An iron-doped carbon quantum dot, the preparation method of which comprises the following steps: dissolving 2g of trisodium citrate in 30mL of ethylene glycol, adding 1g of FeCl3, stirring until completely dissolved, adding 2mL of ethylenediamine, transferring the obtained mixture to a reactor, reacting at 200°C for 8h, filtering the obtained product to remove solid precipitate impurities, and then rotary evaporating to obtain iron-doped carbon quantum dots. Deionized water is added for dilution, and finally a fixed concentration of carbon quantum dot solution is prepared for subsequent experiments.

[0030] Performance Characterization and Testing

[0031] Reference Figure 1 , is a transmission electron microscope (TEM) photo of iron-doped carbon quantum dots, Figure 2 is the X-ray diffraction pattern of iron-doped carbon quantum dots. Figure 1 It can be seen from the figure that the carbon quantum dots are spherical. Figure 2 It can be seen that the X-ray diffraction 2θ angle of carbon quantum dots is 22°, which is consistent with TEM.

[0032] Reference Figure 3 , is the ultraviolet absorption spectrum of iron-doped carbon quantum dots. It can be seen from the figure that carbon quantum dots have the largest absorption band at 350nm, which corresponds to the characteristic peak of the n-π* transition of the base.

[0033] Reference Figure 4 , is the fluorescence spectrum of iron-doped carbon quantum dots. The fluorescence emission peak of carbon quantum dots is located at 500nm, and the corresponding excitation peak is located at 460nm.

[0034] Reference Figure 5, is the infrared spectrum of iron-doped carbon quantum dots. Analysis of the transmission peak intensity shows that the surface of carbon quantum dots is rich in groups, located at 3435cm -1 The characteristic absorption bands on the left and right correspond to CH stretching vibration, 2924cm -1 Corresponding to CH stretching vibration, 1637cm -1 and 1386cm -1 Corresponding to COO- in sodium citrate, at the same time, 1058cm -1 The absorption peak at corresponds to the stretching vibration of C-OH, which may come from the ethylene glycol in the reaction system. These results show that the iron-containing carbon nanodot material was successfully synthesized, and the surface is rich in various functional groups, laying a solid foundation for further material applications.

[0035] Reference Figure 6 , are the single-photon fluorescence imaging results of iron-doped carbon quantum dots in HeLa, zebrafish and organoids. It can be seen that iron-doped carbon quantum dots have good imaging effects in a variety of biological samples.

[0036] Figure 6 In A, Embryo and Larvae represent zebrafish embryos and larvae, respectively. Figure 6 In B, af are the tomographic scanning results at different depths during three-dimensional imaging of organoids. The penetration depth is marked in the upper right corner. g is the three-dimensional superimposed stereogram of af, showing the results of three-dimensional imaging of organoids using iron-doped carbon quantum dots.

[0037] The imaging method was as follows: iron-doped carbon quantum dots were co-incubated with HeLa cells, zebrafish embryos and zebrafish larvae for 1 h, and confocal images were taken after washing. Zebrafish embryos and larvae were provided by Nanjing Biotechnology Co., Ltd., Nanjing. Zebrafish were cultured at 28.5°C. All experiments were performed in accordance with the regulations of the institutional ethics committee and animal welfare guidelines. The co-incubation culture time of iron-doped carbon quantum dots and organoids was 12 h. After washing, the penetration depth was set on the confocal instrument and imaging results at different depths were taken. The overlay was processed using Image j software.

[0038] Reference Figure 7, are the MRI imaging results of iron-doped carbon quantum dots in mice. It can be seen that carbon quantum dots detected obvious magnetic resonance signals in the chest and lung areas, but there was no obvious distribution in the gastrointestinal area and tail area. In this experiment, the software was used to quantitatively analyze the ROIs selected from the three groups of magnetic resonance images. The results showed that there was no obvious fluctuation in the brightness of the gastrointestinal and tail areas, while the brightness of the chest and lung areas first increased and then decreased, reaching a peak at 45 minutes. These results show that carbon quantum dots have the ability to perform magnetic resonance imaging in animals and show potential targeting, providing new possibilities for the identification of chest and lung diseases; indicating that the iron-doped carbon quantum dots have the potential to be used as MRI contrast agents or for the preparation of MRI contrast agents.

[0039] In this experiment, the MRI imaging method is:

[0040] The prepared iron-doped carbon quantum dots were injected into mice through the tail vein and placed in an MRI device. MRI images of different parts were taken at 0, 10, 30, 45, 60, and 90 minutes. The signal intensity was processed using Image j software and plotted into a bar graph. The experimental equipment was a MesoMR23-060H-I medium-sized nuclear magnetic resonance imaging analyzer, produced by Suzhou Xinmai Medium-sized Nuclear Magnetic Resonance Imaging Analysis Instrument Co., Ltd. The resonant frequency was 21MHz, the magnet strength was 0.5T, the coil diameter was 60mm, and the magnet temperature was 32°C. Healthy 4-week-old female BALB / c mice were used in the experiment. All animal experiments were approved by the Medical Ethics Committee.

[0041] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing iron-doped carbon quantum dots, characterized in that: The following steps are involved: Dissolve trisodium citrate in ethylene glycol, add FeCl3, stir until completely dissolved, add ethylenediamine, carry out hydrothermal reaction under heating, and rotary evaporate the obtained product to obtain iron-doped carbon quantum dots.

2. The method for preparing iron-doped carbon quantum dots according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 180-220°C.

3. The method for preparing iron-doped carbon quantum dots according to claim 2, characterized in that: The hydrothermal reaction time is 4-16h.

4. The method for preparing iron-doped carbon quantum dots according to claim 3, characterized in that: The following steps are involved: Dissolve 1-4 g of trisodium citrate in 15-60 mL of ethylene glycol, add 0.5-2 g of FeCl3, stir until completely dissolved, add 1-4 mL of ethylenediamine, transfer the resulting mixture to a reactor, react at 180-220° C. for 4-16 hours, and rotary evaporate the resulting product to obtain iron-doped carbon quantum dots.

5. The method for preparing iron-doped carbon quantum dots according to claim 4, characterized in that: The method comprises the following steps: dissolving 2 g of trisodium citrate in 30 mL of ethylene glycol, adding 1 g of FeCl3, stirring until completely dissolved, adding 2 mL of ethylenediamine, transferring the obtained mixture to a reactor, reacting at 200° C. for 8 h, filtering the obtained product to remove solid precipitated impurities, and then rotary evaporating to obtain iron-doped carbon quantum dots.

6. Iron-doped carbon quantum dots prepared by the method according to any one of claims 1 to 5.

7. Use of the iron-doped carbon quantum dots as claimed in any one of claims 1 to 5 in fluorescence imaging.

8. Use of the iron-doped carbon quantum dots as claimed in any one of claims 1 to 5 in magnetic resonance imaging.

9. Use of the iron-doped carbon quantum dots as claimed in any one of claims 1 to 5 in the preparation of MRI contrast agents.

10. An MRI contrast agent, characterized in that: The carbon quantum dots are prepared from the iron-doped carbon quantum dots described in any one of claims 1 to 5.

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