Preparation method and application of Gd / Ho bimetallic doped carbon dots

Abstract

The invention discloses a preparation method and application of Gd / Ho bimetallic doped carbon dots, and relates to the technical field of nanomaterials, the preparation method comprises the following steps: 1, carrying out ultrasonic treatment on urea, gallic acid, a Ho-containing compound and a Gd-containing compound in deionized water to obtain a mixed emulsion; step 2, adding the mixed emulsion obtained in the step 1 into a microwave oven, and carrying out closed high-temperature reaction to obtain a reaction solution; and step 3, treating the reaction liquid obtained in the step 2 with deionized water, centrifuging, taking supernate, dialyzing in water to obtain dialysate, and freeze-drying the dialysate to obtain the Ho / Gd doped carbon dots. According to the carbon dot synthesized by doping Gd and Ho, the carbon dot has a fluorescence / magnetic resonance / electronic computed tomography three-mode imaging function at the same time, and the three imaging modes have excellent imaging capability, so that the carbon dot is beneficial to the practical application of biological imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and more specifically to a preparation method of Gd / Ho bimetallic doped carbon dots and applications thereof. Background Art

[0002] Cancer (malignant tumor) is one of the major threats to human health. With the rapid development of science and technology, new tumor diagnosis and treatment methods continue to emerge. Emerging treatment methods such as photothermal therapy (PTT) are constantly being studied in depth and gradually entering clinical trials, providing a broader space and richer ideas for the development of tumor treatment. In addition, the diagnosis and treatment technology that combines tumor diagnosis and treatment has received widespread attention in tumor treatment. It can realize real-time monitoring of the treatment effect, and then adjust the dosage or treatment plan in time, so as to achieve individualized drug administration for patients and improve the treatment effect. Nanomedicine has attracted widespread attention in the field of tumor treatment due to its advantages such as versatility and multi-therapy combination, and medical imaging technology can realize the screening, monitoring and treatment response of tumors due to its advantages such as real-time and non-invasiveness. Therefore, a new type of integrated nanodiagnosis and treatment probe is developed for imaging-guided cancer combined treatment.

[0003] Medical imaging technology plays an indispensable role in the diagnosis, treatment and prognosis of cancer. Among them, magnetic resonance imaging (MRI) has attracted widespread attention due to its advantages such as high temporal and spatial resolution, no penetration depth limitation and no radiation damage. Among them, T1 is called longitudinal relaxation time, and T1-weighted imaging is mostly used to observe fat tissue or anatomical structure; T2 is called transverse relaxation time, and T2-weighted imaging is generally used to identify diseased tissue. Magnetic resonance contrast agents can further enhance MRI signals by reducing T1 or T2 of water protons. In a magnetic resonance examination, simultaneous acquisition of T1 and T2 weighted images can better display the structural information of local lesions and the observed site, and cross-validation can be used to obtain more accurate diagnostic results. Specifically, T1-T2 dual-modality MRI can be used for accurate imaging of early tumors, vascular systems, central nervous systems and other parts, avoiding the influence of MRI artifacts on diagnostic results under single mode. Therefore, constructing a multifunctional nano-diagnostic agent with ultra-high field T1-T2 dual-modality imaging capability is of great significance for the imaging visualization treatment of cancer.

[0004] Carbon quantum dots (CQDs) have been selected as the ideal framework for constructing nanoprobes due to their excellent optical properties, superior biocompatibility, and ease of doping and surface modification. CQDs are further doped to give nanoprobes a variety of medical imaging functions.

[0005] Therefore, it is necessary to propose a preparation method of Gd / Ho bimetallic doped carbon dots and its application to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to solve the problem of the influence of MRI artifacts on diagnosis results under single mode.

[0007] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0008] A method for preparing Gd / Ho bimetallic doped carbon dots comprises the following steps:

[0009] Step 1, urea, gallic acid, a compound containing Ho and a compound containing Gd are ultrasonically treated in deionized water to obtain a mixed emulsion;

[0010] Step 2, adding the mixed emulsion obtained in step 1 into a microwave oven, and reacting at high temperature to obtain a reaction liquid;

[0011] Step 3: Treat the reaction solution obtained in step 2 with deionized water, centrifuge, take the supernatant, dialyze in water to obtain a dialysate, and freeze-dry the dialysate to obtain Ho / Gd-doped carbon dots.

[0012] Furthermore, in the step 1, the doping ratio of urea to gallic acid is in the range of 20:5 to 10.

[0013] Furthermore, in step 1, the ratio of urea to the Gd-containing compound is in the range of 20:1.

[0014] Furthermore, in step 1, the ratio of urea to the Ho-containing compound is in the range of 20:1-2.

[0015] Furthermore, in the step 1, the volume of the deionized water in step 1 is 10 to 30 ml.

[0016] Furthermore, the microwave time in step 2 is 5 to 10 minutes.

[0017] Furthermore, the Gd-containing compounds include but are not limited to GdCl3·6H2O and Gd(NO3)3; the Ho-containing compounds include but are not limited to HoCl3·6H2O.

[0018] Furthermore, in step 2, the high temperature reaction temperature is 140 to 200° C., and the reaction time is 6 to 12 hours.

[0019] Furthermore, the reaction solution of step 2 is mixed evenly with deionized water, centrifuged at 8000 rpm for 5-10 minutes, the supernatant is added to a dialysis bag, dialyzed in pure water for 2-3 days, and the dialysate obtained after dialysis is freeze-dried to obtain Gd / Ho doped carbon dots.

[0020] An application of Gd / Ho bimetallic doped carbon dots, comprising Gd / Ho bimetallic doped carbon dots prepared by the above-mentioned preparation method of Gd / Ho bimetallic doped carbon dots, wherein the Gd / Ho bimetallic doped carbon dots are used to prepare bionic nano-diagnostic and therapeutic preparations for performing magnetic resonance T1 / T2 dual-mode imaging of tumor sites.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention, by doping Gd and Ho to synthesize carbon dots, enables the carbon dots to have the functions of fluorescence / magnetic resonance / computer tomography three-modality imaging, and enables the three imaging modalities to have excellent imaging capabilities, making it beneficial to the practical application of biological imaging.

[0023] 2. The present invention improves the optical properties of carbon quantum dots through the above-mentioned improvements, so that its emission peak reaches the green light region, and the ability of fluorescence imaging is improved. At the same time, the incorporation of Gd and Ho makes the carbon dots have relatively good magnetic resonance / CT imaging functions. In addition, since the selected compounds are all commonly used contrast agents or their precursors in clinical practice, and the compounds are chelated in carbon quantum dots, the biological toxicity of the contrast agent is extremely low. In addition, the present invention synthesizes carbon dots by a simple one-step microwave method, which is easy to operate and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagrams of fluorescence effects of three embodiments of the present invention;

[0025] Figure 2 The MRI T1 effect diagrams and mapping diagrams of the three embodiments of the present invention are, from top to bottom, embodiment 1, embodiment 2, and embodiment 3;

[0026] Figure 3 The MRI T2 effect diagrams and mapping diagrams of the three embodiments of the present invention are, from top to bottom, embodiment 1, embodiment 2, and embodiment 3;

[0027] Figure 4 The CT renderings of three embodiments of the present invention are, from top to bottom, Embodiment 1, Embodiment 2, and Embodiment 3. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1-4 , a method for preparing Gd / Ho bimetallic doped carbon dots comprises the following steps.

[0030] Step 1: Weigh 1.0 g urea, 0.5 g gallic acid, 0.025 g HoCl3·6H2O and 0.05 g GdCl3·6H2O respectively, dissolve them in 10 mL deionized water (H2O), and disperse them by ultrasonic for 5 minutes to obtain a white mixed emulsion;

[0031] Urea in the raw material is rich in amino groups, which act as a passivating agent in the reaction process. Its functions are: 1. Surface passivation can increase the fluorescence quantum yield of carbon quantum dots; 2. The presence of amino groups helps to improve the water solubility of carbon quantum dots;

[0032] Step 2, adding the white mixed emulsion obtained in step 1 into a microwave, heating and reacting at 180° C. for 5 minutes to obtain a reaction solution;

[0033] The one-step microwave synthesis method first chelates Gd and Ho in the carbon dot structure through a simple method, giving the carbon dots the imaging function of magnetic resonance / CT. Among them, Gd can interact with water protons in the external environment, thereby increasing the longitudinal relaxation rate (R1) of water protons, and its chelate is often used to enhance magnetic resonance longitudinal (T1) imaging; Ho, as a rare earth metal, has a high magnetic moment and non-zero electron spin. These properties make Ho have strong magnetism, which can enhance the local magnetic field, thereby enhancing the transverse relaxation rate (R2) of protons, thereby improving image contrast. And because of its high atomic coefficient, Ho can absorb X-rays, thereby enhancing CT imaging, and its compounds are also often used as CT contrast agents in clinical practice. Selecting compounds of these two elements as raw materials can give carbon dots a better magnetic resonance / CT imaging enhancement effect and ensure its biocompatibility;

[0034] In the process of using urea to prepare carbon dots at high temperature, urea provides the carbon dots with abundant functional groups, which can absorb light energy and emit light, forming specific fluorescence characteristics. This improves its ability of deep tissue fluorescence imaging, which is more conducive to its application in the field of living biological imaging;

[0035] Step 3: Take out the reaction solution obtained in step 2, add 10 mL of deionized water, shake and mix evenly to obtain a black-brown solution; centrifuge the black-brown solution at 8000 rpm for 10 minutes, take the supernatant, add it into a dialysis bag (molecular cutoff is 1000), dialyze in pure water for 2 days, and freeze-dry the solution obtained after dialysis to obtain the product Ho / Gd@CDs, which is stored in a desiccator.

[0036] Example 2

[0037] Step 1, 1.0 g urea, 0.25 g gallic acid, 0.05 g HoCl3·6H2O and 0.05 g GdCl3·6H2O were weighed and dissolved in 10 mL deionized water (H2O), and ultrasonically dispersed for 5 minutes to obtain a white mixed emulsion;

[0038] Step 2, adding the white mixed emulsion obtained in step 1 into a microwave, heating and reacting at 180° C. for 5 minutes to obtain a reaction solution;

[0039] Step 3: Take out the above reaction solution, add 10 mL of deionized water, shake and mix evenly to obtain a black-brown solution; centrifuge the black-brown solution at 8000 rpm for 10 minutes, take the supernatant, add it into a dialysis bag (molecular cutoff is 1000), dialyze in pure water for 2 days, and freeze-dry the solution obtained after dialysis to obtain the product Ho / Gd@CDs, which is stored in a desiccator.

[0040] Example 3

[0041] Step 1, 1.0 g urea, 0.5 g gallic acid, 0.1 g HoCl3·6H2O and 0.05 g GdCl3·6H2O were weighed and dissolved in 10 mL deionized water (H2O), and ultrasonically dispersed for 5 minutes to obtain a white mixed emulsion;

[0042] Step 2, adding the white mixed emulsion obtained in step 1 into a microwave, heating and reacting at 180° C. for 5 minutes to obtain a reaction solution;

[0043] Step 3: Take out the above reaction solution, add 10 mL of deionized water, shake and mix evenly to obtain a black-brown solution; centrifuge the above black-brown solution at 8000 rpm for 10 minutes, take the supernatant, add it into a dialysis bag (molecular cutoff is 1000), dialyze in pure water for 2 days, and freeze-dry the solution obtained after dialysis to obtain the product Ho / Gd@CDs, which is stored in a desiccator.

[0044] During the heating reaction, the raw materials are dehydrated and carbonized to form carbon dots, and Gd and Ho are chelated in the carbon quantum dot structure, which respectively endow the contrast agent with the functions of fluorescence, magnetic resonance, and electronic computer tomography triple-modality imaging enhancement. Due to the carbonization and condensation reaction of urea at high temperature, carbon-rich nanoparticles are formed. These particles will self-assemble into carbon dots with fluorescent properties during the formation process. The contrast agent has better fluorescence / magnetic resonance / CT triple-modality imaging capabilities, which improves its application potential in the field of biological imaging.

[0045] From the experimental results, Figure 1 The fluorescence effects of the three embodiments are shown. It can be seen that the fluorescence effect of the second embodiment is stronger.

[0046] Figure 2The MRI T1 effect diagram and mapping diagram of the three embodiments show that they all have good T1 imaging capabilities;

[0047] Figure 3 The T2 effect diagrams and mapping diagrams of MRI of the three embodiments show that the T2 imaging capability of embodiment 3 is stronger;

[0048] Figure 4 From the CT renderings of the three embodiments, it can be seen that all of them have good CT imaging capabilities.

[0049] From the above results, it can be seen that the MRI and CT imaging effects of Examples 2 and 3 are both good, but since the fluorescence effect of Example 2 is the best, Example 2 is the best choice.

[0050] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A method for preparing Gd / Ho bimetallic doped carbon dots, characterized in that: The following steps are involved: Step 1, urea, gallic acid, a compound containing Ho and a compound containing Gd are ultrasonically treated in deionized water to obtain a mixed emulsion; Step 2, adding the mixed emulsion obtained in step 1 into a microwave oven, and reacting at high temperature to obtain a reaction liquid; Step 3: Treat the reaction solution obtained in step 2 with deionized water, centrifuge, take the supernatant, dialyze in water to obtain a dialysate, and freeze-dry the dialysate to obtain Ho / Gd-doped carbon dots.

2. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: The doping ratio of urea to gallic acid in step 1 is in the range of 20:5-10.

3. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: In the step 1, the ratio of urea to the Gd-containing compound is 20:

1.

4. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: In step 1, the ratio of urea to the Ho-containing compound is in the range of 20:1-2.

5. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: The volume of the deionized water in step 1 is 10 to 30 ml.

6. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: The microwave time in step 2 is 5 to 10 minutes.

7. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: The Gd-containing compounds include but are not limited to GdCl3·6H2O and Gd(NO3)3; the Ho-containing compounds include but are not limited to HoCl3·6H2O.

8. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: In step 2, the high temperature reaction temperature is 140-200° C., and the reaction time is 6-12 hours.

9. The method for preparing Gd / Ho bimetallic doped carbon dots according to claim 1, characterized in that: The reaction solution of step 2 was mixed evenly with deionized water, centrifuged at 8000 rpm for 5-10 minutes, and the supernatant was added to a dialysis bag, dialyzed in pure water for 2-3 days, and the dialyzate obtained after dialysis was freeze-dried to obtain Gd / Ho doped carbon dots.

10. An application of Gd / Ho bimetallic doped carbon dots, comprising the Gd / Ho bimetallic doped carbon dots prepared by the method for preparing Gd / Ho bimetallic doped carbon dots according to any one of claims 1 to 9, characterized in that: The Gd / Ho bimetallic doped carbon dots are used to prepare bionic nano-diagnostic and therapeutic preparations and perform magnetic resonance T1 / T2 dual-mode imaging of tumor sites.

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