A rare earth ion-doped gold nanocluster contrast agent for x-ray imaging and a preparation method thereof
Patent Information
- Application Number
- CN202510126642.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-27
- Publication Date
- 2026-10-23
- Estimated Expiration
- 2045-01-27
AI Technical Summary
现有的金基X射线成像造影剂主要以金纳米颗粒为主，其粒径超过10 nm，超过肾脏的清除阈值(5.5 nm左右)，容易在体内积聚产生毒性
(1) 本发明合成的稀土离子掺杂的金纳米团簇采用常温水相法合成，合成工艺简单、成本低易于工业化生产。
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Figure CN119868593B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of X-ray imaging, specifically to a rare-earth ion-doped gold nanocluster contrast agent for X-ray imaging and its preparation method. Background Technology
[0002] X-ray imaging, as a non-invasive imaging technique, is widely used in medical diagnostics. Due to the strong penetrating power of X-rays and the varying absorption rates of different tissues within the body, X-ray imaging has become an effective means of visualizing internal tissues. According to the principles of X-ray absorption, higher atomic numbers absorb X-rays more strongly, making bones easily detectable. However, some soft tissues are difficult to detect due to weak X-ray absorption, especially in the detection of gastrointestinal diseases. X-ray contrast agents are materials with strong X-ray absorption capabilities, enhancing the contrast of different tissues or structures in X-ray imaging, and possessing characteristics such as low toxicity and good biocompatibility. These contrast agents typically contain elements with high atomic numbers, such as iodine, barium, and gold. In biomedical research and medical diagnostics, enhancing the contrast of X-ray imaging allows for clearer observation of internal organs, blood vessels, and soft tissue structures. Currently, X-ray imaging contrast agents such as barium meals and iodine-based compounds have been developed. While these can improve the resolution and sensitivity of gastrointestinal X-ray imaging, they still have serious side effects. For example, barium meals are insoluble and may remain in the gastrointestinal tract after examination, making metabolism difficult. Furthermore, barium meals are not suitable for patients with gastrointestinal perforation, while iodine-based compounds may cause allergic reactions and nephrotoxicity. In recent years, with the development of nanomaterials, they have gradually become alternatives to traditional X-ray contrast agents. Therefore, developing a small-sized, low-toxicity, and biocompatible nanomaterial as an X-ray imaging contrast agent is of great significance.
[0003] Gold nanoclusters (AuNCs) are nanomaterials composed of several to tens of gold atoms. Their ultra-small size (2-3 nm), low toxicity, excellent biocompatibility, and unique physicochemical properties have attracted widespread research interest in the biomedical field. Furthermore, gold's high atomic number (Z=79) and K-boundary value (80.7 keV) endow gold nanoclusters with good X-ray imaging capabilities. Existing gold-based X-ray imaging contrast agents are mainly composed of gold nanoparticles with particle sizes exceeding 10 nm, surpassing the kidney's clearance threshold (around 5.5 nm), and easily accumulating in the body, leading to toxicity.
[0004] Based on this, this invention synthesizes gold nanoclusters with an ultra-small size (approximately 2 nm) using glutathione as a ligand, and further enhances their stability by doping with erbium ions. The synthesized rare-earth ion-doped gold nanoclusters exhibit good stability, biocompatibility, and X-ray imaging capability. Mice were orally administered 0.2 ml of the gold nanoclusters (50 mg / mL) via tube feeding. After gavage, the mice underwent X-ray irradiation, and the gastrointestinal tract contours of the mice at different time points were clearly recorded using an X-ray flat panel detector, enabling real-time monitoring of gastrointestinal motility. In summary, this invention develops a rare-earth ion-doped gold nanoclusters for gastric X-ray imaging contrast agents, enabling X-ray imaging of soft tissues such as the gastrointestinal tract. Compared with the existing commercial contrast agent iohexol, the gold nanoclusters synthesized in this invention show significantly enhanced X-ray absorption capacity, improving their sensitivity and resolution, providing a new approach for assessing gastrointestinal motility disorders and achieving early diagnosis of gastrointestinal diseases. Summary of the Invention
[0005] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a rare-earth ion-doped gold nanoclusters contrast agent for X-ray imaging and its preparation method. This invention provides gold nanoclusters protected by glutathione and doped with rare-earth ions, exhibiting strong X-ray contrast capabilities, good stability, and excellent biocompatibility.
[0006] The present invention is achieved through the following technical solution.
[0007] A rare-earth ion-doped gold nanocluster contrast agent for X-ray imaging: the molecular formula of the rare-earth ion-doped gold nanocluster contrast agent is Au. 24 Er1SR 18 , where SR represents the ligand glutathione; the particle size of the rare earth ion-doped gold nanoclusters is 2 nm.
[0008] Furthermore, the rare-earth ion-doped gold nanocluster contrast agent is based on gold nanoclusters Au 25 SR 18 It is doped with rare earth ions Er.
[0009] Furthermore, the gold nanoclusters Au 25 SR 18 It has a core-shell structure and is composed of Au 13 The core consists of six (-SR-Au-SR-Au-SR-) motifs; among which, thirteen Au atoms are linked by Au-Au bonds to form an Au structure with an icosahedral shape. 13At its core, the thiol group in the glutathione ligand SR forms an Au-S bond with an Au atom. Three S atoms and two Au atoms are arranged to form a (-SR-Au-SR-Au-SR-) motif structure. This six motif structure acts as a shell, connecting with the icosahedral Au atom through S-Au and Au-Au bonds. 13 Core components combined to form Au 25 SR 18 Core-shell structure.
[0010] Furthermore, the rare earth ion Er doping site is located on the motif structure.
[0011] A method for preparing rare-earth ion-doped gold nanoclusters as a contrast agent material for X-ray imaging includes the following steps: (1) Chloroauric acid solution and erbium nitrate solution were reacted with glutathione ligand in a solvent under stirring at room temperature; (2) Add sodium hydroxide solution to adjust the pH of the system to be alkaline; (3) Slowly add sodium borohydride solution and continue stirring the reaction; (4) After the reaction is complete, the product is purified by ultrafiltration centrifugation; (5) The purified sample is placed in a freeze dryer for freeze drying to obtain a solid sample, which is the rare earth ion doped gold nanocluster contrast agent.
[0012] Preferably, the solvent in step (1) is ultrapure water.
[0013] Preferably, in step (1), the molar ratio of chloroauric acid solution to erbium nitrate solution is 1:1, and the molar ratio of glutathione ligand solution to chloroauric acid solution is 1:4; in step (2), the molar ratio of sodium hydroxide solution to chloroauric acid solution is 50:1; and in step (3), the molar ratio of sodium borohydride solution to chloroauric acid solution is 5.68:1.
[0014] Preferably, in step (1), the amounts of chloroauric acid solution and erbium nitrate solution are 0.24 mL and 0.01 mL, respectively, and the amount of glutathione ligand solution is 2 mL; in step (2), the amount of sodium hydroxide solution is 0.3 mL; and in step (3), the amount of sodium borohydride solution is 0.1 mL.
[0015] Preferably, in step (1), chloroauric acid and rare earth ions are added to ultrapure water at room temperature first, followed by the addition of glutathione ligand, and the reaction time is 5 min; in step (2), sodium hydroxide is added to adjust the pH to strong alkalinity and the reaction time is continued for 2 min; in step (3), sodium borohydride is added as a reducing agent and the reaction time is continued for 12 h. The reaction temperature in all steps (1)-(4) above is room temperature 25℃, the stirring speed is 500 rpm, and all reactions are carried out in a light-protected environment.
[0016] Preferably, in step (4), the purification operation using ultrafiltration centrifugation at room temperature includes: first, removing the larger gold nanoparticles from the solution after the stirring reaction using a 50 kDa ultrafiltration centrifuge tube, with an ultrafiltration centrifugation time of 15 min and a rotation speed of 6000 rpm, repeating three times; then, removing the unreacted substrate from the solution after removing the large particles using a 3 kDa ultrafiltration centrifuge tube and concentrating it, with an ultrafiltration centrifugation time of 15 min and a rotation speed of 5500 rpm, using ultrapure water as the washing solvent, and then performing ultrafiltration concentration after washing.
[0017] Application: The application of the above-mentioned rare-earth ion-doped gold nanoclusters as a contrast agent material for gastric X-ray imaging includes the following steps: First, the prepared rare earth ion-doped gold nanoclusters were redispersed and diluted to an appropriate concentration with ultrapure water. Then, mice were treated with oral gavage. After gavage, the mice were exposed to X-rays, and the gastrointestinal images of the mice could be clearly recorded by an X-ray flat panel detector.
[0018] Preferably, the rare earth ion-doped gold nanoclusters are diluted to a concentration of 50 mg / mL, the X-ray power is 10 W (50 kV, 200 μA), the irradiation time is 10 s, and images are taken every 15 minutes.
[0019] This invention employs an aqueous phase synthesis method, using glutathione as a template. Chloroauric acid is dissolved in a strongly alkaline solution, and sodium borohydride is used as a reducing agent to reduce trivalent gold ions to zero valence. Simultaneously, rare earth ions are doped. Under suitable temperature, stirring speed, and purification conditions, rare earth ion-doped gold nanoclusters are synthesized. The synthesis process is simple and easy for industrial production. The gold nanoclusters synthesized by this method exhibit low toxicity, excellent stability, and good biocompatibility. Furthermore, due to the heavy atom effect of gold, the rare earth ion-doped gold nanoclusters prepared by this method can be used as contrast agents for gastric X-ray imaging, showing promising applications in the detection of gastrointestinal diseases.
[0020] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The rare earth ion-doped gold nanoclusters synthesized in this invention are synthesized by a room temperature aqueous phase method. The synthesis process is simple, low in cost, and easy to industrialize.
[0021] (2) The rare earth ion-doped gold nanoclusters synthesized in this invention have good biocompatibility, low toxicity and good stability.
[0022] (3) Due to the heavy atom effect, the rare earth ion-doped gold nanoclusters synthesized in this invention have strong X-ray imaging capabilities and can be used for gastric imaging. Attached Figure Description
[0023] Figure 1 Transmission electron microscope image (a) and particle size distribution diagram (b) of rare earth ion-doped gold nanoclusters. Figure 2 Emission spectrum (a) and absorption spectrum (b) of rare earth ion-doped gold nanoclusters; Figure 3 X-ray photoelectron spectroscopy of rare earth ion-doped gold nanoclusters; Figure 4 Fourier transform infrared spectrum of rare earth ion-doped gold nanoclusters; Figure 5 Stability testing of rare earth ion-doped gold nanoclusters; Figure 6 Cell Counting Kit-8 (CCK-8) is used to analyze the survival rate of 4T1 (mouse breast cancer cells) cells incubated with rare earth ion-doped gold nanoclusters. Figure 7 Comparison of X-ray absorption capacity between rare earth ion-doped gold nanoclusters and commercial contrast agent iohexol; Figure 8 Schematic diagram of an X-ray imaging of the stomach; Figure 9 An image of rare-earth ion-doped gold nanoclusters used as a contrast agent in gastric X-ray imaging.
[0024] Specific implementation examples A rare-earth ion-doped gold nanocluster material for gastric X-ray imaging: the gold nanoclusters have a core-shell structure and are composed of Au 13 The core is composed of six (-SR-Au-SR-Au-SR-) "staple" motifs (SR stands for the ligand glutathione). Specifically, thirteen Au atoms are linked by Au-Au bonds to form an icosahedral Au structure. 13At its core, the thiol group in the glutathione ligand forms an Au-S bond with an Au atom, where three S atoms and two Au atoms are arranged to form a (-SR-Au-SR-Au-SR-) "staple" motif. These six "staple" motifs act as a shell, connected to the icosahedral Au atom via S-Au and Au-Au bonds. 13 Core components combined to form Au 25 SR 18 The rare earth ion doping is located on the "staple" motif, and its precise structure is Au. 24 Er1SR 18 The single gold nanoparticle clusters are about 2 nm in size; the gold nanomaterials have strong X-ray attenuation capabilities.
[0025] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0026] Example 1 The preparation method of rare-earth ion-doped gold nanoclusters as a contrast agent for gastric X-ray imaging is as follows: Under light-protected conditions at room temperature, 0.24 mL of chloroauric acid aqueous solution (20 mM) and 0.01 mL of erbium nitrate aqueous solution (20 mM) were added to a glass bottle containing 2.35 mL of ultrapure water. The mixture was stirred at 500 rpm, followed by the addition of 2 mL of glutathione aqueous solution (5 mM) and stirring for 5 min. Then, 0.3 mL of sodium hydroxide solution (1 M) was added and stirring was continued for 2 min. Finally, 0.1 mL of sodium borohydride solution (4.3 mg / mL) was slowly added dropwise and stirring was continued for 12 h.
[0027] After the reaction, the solution was purified by ultrafiltration centrifugation at room temperature. The specific procedures included: first, removing larger gold nanoparticles from the reaction solution using a 50 kDa ultrafiltration centrifuge tube at 6000 rpm for 15 min, repeated three times; then, removing unreacted substrate and concentrating the solution using a 3 kDa ultrafiltration centrifuge tube at 5500 rpm for 15 min, washing with ultrapure water as the solvent, followed by ultrafiltration concentration. The purified and concentrated sample was then freeze-dried to obtain a solid sample, which is the rare-earth ion-doped gold nanocluster contrast agent Au. 24 Er1SR 18 .
[0028] Depend on Figure 1 The transmission electron microscope image of rare earth ion-doped gold nanoclusters (a) shows that their particle size is approximately 2 nm, with good dispersibility and uniform size distribution. (Particle size distribution diagram follows.) Figure 1 The synthesized gold nanoclusters shown in (b) have a particle size of 2 nm, consistent with the results of transmission electron microscopy. Figure 2 As shown in (a), the characteristic emission peak of the synthesized gold nanoclusters is around 1100 nm. Furthermore, the emission intensity is significantly enhanced after doping with rare earth ions, as shown in (a). Figure 2 As shown in (b), the absorption peaks of the synthesized gold nanoclusters are at 450 nm and 670 nm, which is attributed to their unique interband transitions, belonging to Au. 25 The characteristic absorption peaks were observed, and the positions of these peaks did not change after rare earth ion doping, indicating that the doping of rare earth ions did not alter the structure of the gold cluster. Figure 3 As shown, X-ray photoelectron spectroscopy analysis revealed that the gold atoms in the synthesized gold nanoclusters mainly existed in a zero-valent state, while some monovalent gold atoms were also present in an oxidized state. Figure 4 As shown, the Fourier transform infrared spectrum of the gold clusters reveals that at 1600 cm⁻¹... -1 and 1394 cm -1 It exhibits the characteristic vibrational peak of -COO- in the ligand glutathione, at 2556 cm⁻¹. -1 The absence of a characteristic -SH vibration peak at 1900 cm⁻¹ indicates that an Au-S bond (1900 cm⁻¹) has been formed between the gold atom and the thiol group on the ligand glutathione. -1 -2300cm -1 (This is due to miscellaneous peaks caused by instrument malfunction). For example... Figure 5 As shown, the stability of the gold clusters was tested, and their luminescence intensity remained almost unchanged after seven days. The luminescence intensities after seven days were 47216, 46935, 46373, 47746, 46098, 45035, and 45335, respectively (excitation source: 808 nm laser with power of 2W; fluorescence spectrometer slit width: 5nm), indicating that the synthesized gold clusters have good stability. Figure 6 As shown, cell experiments were performed using a standard cell counting kit (CCK-8). The results showed that after 24 hours of co-incubation with different concentrations of gold flocculants (0, 1, 10, 20, 40, 50, 60 mg / mL), the viability of 4T1 cells remained above 95%, indicating that the synthesized gold flocculants have good biocompatibility. Figure 7 As shown, at the same concentration, gold clusters exhibit better X-ray blocking ability than iohexol, indicating that the synthesized gold clusters have stronger X-ray absorption capacity, thus improving imaging sensitivity and resolution. These characterizations fully demonstrate the successful synthesis and excellent performance of rare-earth ion-doped gold nanoclusters.
[0029] Example 2 Rare-earth ion-doped gold nanoclusters were used to construct gastric X-ray imaging techniques. The synthesized and purified gold nanoclusters were dissolved in ultrapure water (concentration 50 mg / mL) to obtain a brown solution. Figure 8 As shown, the prepared rare-earth ion-doped gold nanoclusters were administered orally to normal mice. Specifically, mice were fed 0.2 ml of the gold nanoclusters (50 mg / mL) via oral gavage. After gavage, the mice were exposed to X-rays (10 W power), and the outline of the gastrointestinal tract was clearly recorded using an X-ray flat panel detector, enabling real-time monitoring of the gastrointestinal tract. Figure 9 As shown, (a) is an image of mice without being fed gold nanoclusters, where only the skeleton is visible, but soft tissues such as the gastrointestinal tract are not. (bf) are images of mice after gavage treatment, showing that the stomach is visible 5 minutes after gavage, and the entire outline of the gastrointestinal tract becomes clear over time, enabling real-time monitoring of the mouse's gastrointestinal tract. The above data demonstrate that the rare-earth ion-doped gold nanoclusters of this invention possess stable X-ray imaging capabilities and exhibit good biocompatibility and low toxicity, making them suitable for detecting gastrointestinal diseases.
[0030] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. The use of rare-earth ion-doped gold nanoclusters in the preparation of contrast agents for X-ray imaging, characterized in that, The molecular formula of the rare-earth ion-doped gold nanoclusters contrast agent is Au. 24 Er1SR 18 , where SR represents the ligand glutathione; the particle size of the rare earth ion-doped gold nanoclusters is 2 nm; The rare earth ion-doped gold nanoclusters contrast agent is based on gold nanoclusters Au 25 SR 18 Rare earth ion Er is doped in the middle. The gold nanoclusters Au 25 SR 18 It has a core-shell structure and is composed of Au 13 The core consists of six (-SR-Au-SR-Au-SR-) motifs; among which, thirteen Au atoms are linked by Au-Au bonds to form an Au structure with an icosahedral shape. 13 At its core, the thiol group in the glutathione ligand SR forms an Au-S bond with an Au atom. Three S atoms and two Au atoms are arranged to form a (-SR-Au-SR-Au-SR-) motif structure. This six motif structure acts as a shell, connecting with the icosahedral Au atom through S-Au and Au-Au bonds. 13 Core components combined to form Au 25 SR 18 Core-shell structure; rare earth ion Er doping is located on the motif structure; The method for preparing the rare-earth ion-doped gold nanoclusters contrast agent for X-ray imaging includes the following steps: (1) Chloroauric acid solution and erbium nitrate solution were reacted with glutathione ligand in water under stirring at room temperature; (2) Add sodium hydroxide solution to adjust the pH of the system to be alkaline; (3) Add sodium borohydride solution dropwise and continue stirring to react; (4) After the reaction is complete, the product is purified by ultrafiltration centrifugation; (5) The purified sample is placed in a freeze dryer for freeze drying to obtain a solid sample, which is the rare earth ion doped gold nanocluster contrast agent. In step (1), the molar ratio of chloroauric acid solution to erbium nitrate solution is 1:1, and the molar ratio of glutathione ligand solution to chloroauric acid solution is 1:4; in step (2), the molar ratio of sodium hydroxide solution to chloroauric acid solution is 50:1; in step (3), the molar ratio of sodium borohydride solution to chloroauric acid solution is 5.68:
1. In step (1), the reaction time is 5 min; in step (2), sodium hydroxide solution is added to adjust the pH to strong alkalinity and the reaction is stirred for another 2 min; in step (3), the reaction time is stirred for another 12 h. All reactions in steps (1)-(4) were carried out at room temperature (25°C), with a stirring speed of 500 rpm, and all reactions were conducted in a dark environment.
2. The use according to claim 1, characterized in that, In step (1), the amounts of chloroauric acid solution and erbium nitrate solution used are 0.24 mL and 0.01 mL, respectively, and the amount of glutathione solution used is 2 mL; in step (2), the amount of sodium hydroxide solution used is 0.3 mL; in step (3), the amount of sodium borohydride solution used is 0.1 mL.
3. The use according to claim 1, characterized in that, The purification operation in step (4) specifically includes: first, removing the larger gold nanoparticles from the solution after the reaction by using a 50 kDa ultrafiltration centrifuge tube. The ultrafiltration centrifugation time is 15 min and the rotation speed is 6000 rpm, and this is repeated three times. Then, removing the unreacted substrate from the solution after removing the large particles by using a 3 kDa ultrafiltration centrifuge tube and concentrating the solution. The ultrafiltration centrifugation time is 15 min and the rotation speed is 5500 rpm. The solvent added for washing is ultrapure water. After washing, ultrafiltration concentration is performed.