Cubic gold-iron nano preparation, preparation method and application of cubic gold-iron nano preparation in tumor multi-mode imaging

Abstract

The invention provides a cubic gold-iron nano preparation, a preparation method and application of the cubic gold-iron nano preparation in tumor multi-mode imaging, and belongs to the technical field of biomedical nano materials. The particle size of the nano preparation is 30-300 nm, the nano preparation comprises gold, iron and oxygen elements, the content of the gold element is 1-10%, and the content of the iron element is 0.3-10%. The nano preparation is a carrier and is loaded with at least one functional molecule selected from lipophilic fluorescent molecules and small molecular chemotherapeutic drugs. And the lipophilic fluorescent molecule is DID. Based on a multi-modal imaging strategy of a gold-iron nano platform, high spatial resolution of CT, soft tissue contrast advantages of MRI and high sensitivity of photo-thermal and fluorescence imaging can be integrated, and precise visualization of a tumor microenvironment is realized.

Description

Technical Field

[0001] This invention relates to the field of biomedical nanomaterials technology, specifically to cubic gold-iron nanoparticles, their preparation methods, and their application in tumor multimodal imaging. Background Technology

[0002] Tumor imaging plays a crucial role in early diagnosis, efficacy evaluation, and personalized treatment. Current clinical imaging techniques include computed tomography (CT), magnetic resonance imaging (MRI), and optical and nuclear medicine imaging. However, each imaging modality has limitations: CT, despite its high spatial resolution, has limited soft tissue contrast capabilities; MRI, while offering excellent soft tissue contrast, suffers from long scan times and insufficient sensitivity; optical and fluorescence imaging offer high sensitivity, but their tissue penetration depth is limited. Therefore, current technologies struggle to simultaneously acquire structural, functional, and molecular information about tumors, resulting in limited imaging sensitivity and diagnostic accuracy, failing to meet the clinical demand for high-precision, multimodal imaging.

[0003] Nanocontrast agents, due to their tunable physicochemical properties and multifunctional integration capabilities, have become an important approach to achieving multimodal imaging. Gold nanoparticles, with their high atomic number and surface plasmon resonance characteristics, can enhance CT and photothermal imaging signals; iron oxide nanoparticles, exhibiting superparamagnetism, can be used for T1 / T2 MRI contrast. However, existing metal nanocontrast agents are mostly for single-mode or dual-mode imaging, suffering from problems such as uneven signal intensity, poor structural stability, and unclear biological metabolic pathways, making it difficult to achieve highly sensitive, multimodal, and traceable tumor imaging diagnosis.

[0004] Against this technological backdrop, there is an urgent need to develop a nanocontrast agent that is structurally stable, easy to prepare, and has multimodal imaging capabilities, in order to solve the problems of low sensitivity, uneven signal, and poor tissue targeting of existing single or dual-modal contrast agents, and to provide a new solution for precise tumor diagnosis and image-guided therapy. Summary of the Invention

[0005] The purpose of this invention is to provide a gold-iron nanoparticle formulation that integrates gold and iron, two functional components, into a single nanostructure, achieving integrated CT / MRI / photothermal / fluorescence multimodal imaging. This formulation not only possesses high X-ray attenuation capability, magnetic response characteristics, and optical absorption performance, but also maintains good dispersibility and biocompatibility. It can passively accumulate in tumor tissue through the EPR effect, significantly improving imaging sensitivity and diagnostic accuracy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The cubic gold-iron nanoparticles have a particle size of 30-300nm and contain gold, iron and oxygen elements, with the gold content being 1-10% and the iron content being 0.3-10%.

[0007] Preferably, the nano-formulation is a carrier loaded with at least one functional molecule selected from lipophilic fluorescent molecules and small molecule chemotherapeutic drugs.

[0008] Preferably, the lipophilic fluorescent molecule is DID (1,1'-octadecyl-3,3,3',3'-tetramethylindole dicarboxyanine perchlorate).

[0009] Preferably, the small molecule chemotherapy drug is a chemical drug used for tumor treatment.

[0010] To achieve the objective of this invention, the following technical solution is adopted: a method for preparing cubic gold-iron nanoparticles, comprising the following steps: (a) preparing thiol-functionalized gold nanoparticles; (b) forming an iron layer on the surface of the thiol-functionalized gold nanoparticles by an iron deposition reaction, thereby obtaining the gold-iron nanoparticles.

[0011] Preferably, the preparation of the thiol-functionalized gold nanoparticles in step (a) includes: mixing hexadecyltrimethylammonium bromide (CTAB), chloroauric acid (HAuCl4), sodium citrate and polyvinylpyrrolidone (PVP) in an aqueous solution, reacting them in an autoclave at 100-120°C for 10-14 hours to obtain gold nanoparticles; and then reacting the gold nanoparticles with thioglycolic acid to perform thiol functionalization.

[0012] Preferably, in step (a), the concentration of the mother liquor of CTAB is 200-300 mM, the concentration of the mother liquor of HAuCl4 is 8-12 mM, the concentration of the mother liquor of sodium citrate is 40-60 mM, and the concentration of the mother liquor of PVP is 8-12 mg / mL; in step (b), the iron deposition reaction includes reacting functionalized gold nanoparticles with ferric chloride (FeCl3·6H2O) and trimesic acid (H3BTC) in an ethanol solution at 60-80°C for 20-40 minutes.

[0013] Another technical solution of the present invention is: the application of cubic gold-iron nanoparticles in tumor multimodal imaging, wherein the application involves realizing at least one imaging mode among computed tomography (CT), magnetic resonance imaging (MRI), photothermal imaging (PTI), and fluorescence imaging through the nanoparticles.

[0014] Preferably, the multimodal imaging includes a combination of CT imaging, MRI imaging, photothermal imaging, and fluorescence imaging, used for tumor localization, lesion identification, or treatment monitoring.

[0015] Preferably, the application includes administering the nanoformulation to tumor model animals via tail vein injection at a dose of 50-150 μg for in vivo imaging.

[0016] Compared with the prior art, the present invention achieves the following technical effects: This invention effectively overcomes the inherent limitations of existing single-modality tumor imaging in clinical practice. By constructing a cubic gold-iron nanoparticle formulation, multiple functions such as computed tomography (CT), magnetic resonance imaging (MRI), photothermal imaging (PTI), and fluorescence imaging are successfully integrated on a single nanoplatform, achieving synergy and complementarity of multimodal imaging.

[0017] Its technological advantages are specifically reflected in the following aspects: Leveraging the high atomic number of gold, this formulation provides X-ray attenuation capabilities far exceeding those of clinical standard contrast agents (such as iohexol), thereby significantly improving the contrast and signal-to-noise ratio of CT imaging. Simultaneously, its iron oxide component endows the formulation with excellent magnetic response characteristics, enabling simultaneous modulation of T1 / T2 weighted magnetic resonance signals to obtain clearer soft tissue contrast images than clinical gadolinium agents. Furthermore, the surface plasmon resonance effect of the gold nanostructure gives it highly efficient near-infrared photothermal conversion capabilities, which can be used for photothermal imaging and therapy; further labeling of the surface with fluorescent molecules (such as DiD) achieves highly sensitive fluorescence tracking.

[0018] Ultimately, this multimodal integration strategy combines the high spatial resolution of CT, the superior soft tissue resolution of MRI, and the high sensitivity of optical imaging, thereby achieving a more comprehensive and precise visualization of the tumor microenvironment. This not only significantly improves the reliability and efficiency of image diagnosis, providing richer evidence for clinical decision-making, but also demonstrates enormous application potential in precision medicine and image-guided therapy, providing strong new technological support for the early diagnosis and personalized treatment of tumors. Attached Figure Description

[0019] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 The images show transmission electron microscopy (TEM) images of cubic gold-iron nanoparticles. (a) is the TEM image, and (b) shows the elemental mapping of the cubic gold-iron nanoparticles.

[0021] Figure 2 XPS spectra of cubic gold-iron nanoparticles. (a) C1S spectrum, (b) Au4f spectrum, (c) Fe2p spectrum, (d) AuFe full element spectrum.

[0022] Figure 3 This is a characterization diagram of the photothermal properties of a cubic gold-iron nanoparticle formulation.

[0023] Figure 4 In vivo fluorescence imaging of DID-labeled cubic gold-iron nanoparticles.

[0024] Figure 5 This is an in vivo CT imaging image of a cubic gold-iron nanoparticle formulation.

[0025] Figure 6 This is an in vivo photothermal imaging effect of a cubic gold-iron nanoparticle formulation.

[0026] Figure 7 The images show in vivo MRI results of cubic gold-iron nanoparticles. (a) shows the relative signal intensity changes of different concentrations of gadopentetate (Gd-DTPA) and cubic gold-iron nanoparticles (AuFe@mTOMV), (b) shows representative in vitro images of different concentrations of gadopentetate (Gd-DTPA) and cubic gold-iron nanoparticles (AuFe@mTOMV), and (c) shows the in vivo MRI results of gadopentetate (Gd-DTPA) and cubic gold-iron nanoparticles (AuFe@mTOMV) in mice. Detailed Implementation

[0027] The following are specific embodiments of the present invention, described in conjunction with the accompanying drawings, to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0029] Unless otherwise specified, the materials, practices, and experimental equipment involved in the embodiments of this invention are all commercially available products in the relevant chemical and biotechnology fields.

[0030] Example 1: Preparation of gold-iron nanoparticles Preparation method of thiol-functionalized cubic gold nanoparticles: First, three stock solutions were prepared: CTAB stock solution with a concentration of 250 mM, HAuCl4 stock solution with a concentration of 10 mM, sodium citrate stock solution with a concentration of 50 mM, and polyvinylpyrrolidone with a concentration of 10 mg / mL. Each stock solution was prepared using deionized water as the solvent, stirred at room temperature until completely dissolved, then brought to a final volume and stored in the dark for later use.

[0031] In a fume hood, approximately 24 mL of deionized water was added to a clean beaker. Under magnetic stirring, 1.8 mL of CTAB stock solution, 0.6 mL of HAuCl4 stock solution, 0.3 mL of sodium citrate stock solution, and 0.3 mL of polyvinylpyrrolidone stock solution were added sequentially. After each component was added, stirring was continued for 1–2 minutes to ensure thorough mixing. The volume was then adjusted to 30.0 mL with deionized water. The mixture was then transferred to a 50 mL PTFE-lined stainless steel autoclave, sealed, and reacted at 110 °C for 12 h. The autoclave was then allowed to cool naturally to room temperature. The resulting cubic gold nanoparticles were collected by centrifugation at 10,000 rpm for 5 minutes and washed twice with deionized water and ethanol, respectively. After freeze-drying, the gold nanoparticles were obtained. Finally, 10 mg of the gold nanoparticles were added to 10 mL of a 0.029 M thioglycolic acid solution prepared with ethanol and shaken at room temperature for 24 h. The product was collected by centrifugation (13,000 rpm) and washed several times with ethanol to obtain Au nanonuclei functionalized with thioglycolic acid.

[0032] To obtain cubic gold-iron nanoparticles, we prepared them via iron deposition on the surface of cubic gold nanoparticles. Specifically, 10 mg of functionalized Au nanoparticles were dispersed in 4 mL of ethanol FeCl3·6H2O solution (2 mM) and reacted for 15 min, followed by the addition of 4 mL of trimesic acid ethanol solution (H3BTC, 2 mM). The mixture was incubated at 70 °C for 30 min, depositing iron on the surface of the gold nanoparticles. Finally, the AuFe cubic gold-iron nanoparticle formulation was collected by centrifugation at 12,000 rpm.

[0033] Example 2 Characterization of cubic gold-iron nanoparticle formulations (e.g.) Figure 1-3 ) Morphological characterization of cubic gold-iron nanoparticles: 200 μL of a 0.1 mg / mL gold-iron nanoparticle solution was centrifuged at 10,000 rpm for 10 min, the supernatant was discarded, and the solution was resuspended in deionized water and ultrasonically dispersed. 5 μL of the dispersion was added dropwise onto a copper grid (Cu grid, 200 mesh) coated with a carbon film and allowed to stand for 2–3 min to allow the nanoparticles to naturally adsorb onto the membrane surface. Excess liquid was then gently blotted away with filter paper and allowed to air dry at room temperature. TEM analysis was performed using a transmission electron microscope (FEI Tecnai G2 F20) with an accelerating voltage of 200 kV. The obtained images clearly showed that the nanoparticles exhibited a highly regular cubic structure with uniform side lengths and distinct outlines, indicating good morphological consistency and crystallinity. Furthermore, the particles were independent of each other, with no obvious aggregation, indicating good dispersion stability of the prepared nanomaterials in solution. These morphological results fully validate the effectiveness of the synthesis strategy of this invention, laying a reliable foundation for its further medical applications.

[0034] XPS Characterization of Cubic Gold-Iron Nanoparticle Formulation: To further confirm the elemental composition and valence state of the prepared cubic gold-iron nanoparticle contrast agent, X-ray photoelectron spectroscopy (XPS) analysis was performed on the sample. The specific method is as follows: The gold-iron nanoparticle sample, after being washed three times with pure water and freeze-dried, was pressed onto a conductive adhesive and placed on the sample stage of an XPS instrument (Thermofisher ESCALAB 250) for testing. The above results collectively demonstrate that the cubic gold-iron nanoparticle formulation of this invention possesses a clear and stable elemental composition and valence state characteristic, providing crucial evidence for its application performance in medical contrast imaging and photothermal therapy.

[0035] Photothermal properties characterization of cubic gold-iron nanoparticles: Different concentrations of cubic gold-iron nanoparticle dispersions (0, 12.5, 25, 50, 75, 100, and 125 µg / mL) were prepared. -1 Each 1 mL sample was prepared using an 808 nm laser (China Haoliang Technology Co., Ltd.) at a wavelength of 1.0 W cm⁻¹. -2 Irradiation at a power density of 1.0 W / cm² was performed for 10 minutes. Temperature was recorded every 15 seconds, and temperature change curves were plotted. - At a power density of 2, the concentration was 50.0 μg / mL. - The solution temperature rose to 46.8 °C within 10 minutes, at a concentration of 125 μg / mL. - ¹ The temperature reached 58.3 °C, demonstrating concentration-dependent photothermal conversion behavior. These data indicate that the nanomaterials prepared in this invention can efficiently convert light energy into heat energy under near-infrared light irradiation, possessing potential advantages for photothermal therapy and photothermal imaging.

[0036] Example 3: Multimodal imaging of cubic gold-iron nanoparticles in vivo (e.g.) Figure 4-7 ) Construction of mouse mammary carcinoma in situ: To establish a 4T1 tumor mouse model, 2 × 10⁻⁶ tumors were generated. 6 4T1 cells in the logarithmic growth phase were injected into the inguinal fat pad of female mice. In vivo multimodal imaging was performed when the tumor volume reached approximately 500 mm³.

[0037] In vivo fluorescence imaging: To perform in situ tumor fluorescence imaging in mice, the obtained cubic gold-iron nanoparticles were labeled with DiD dye. An appropriate amount of the gold-iron nanoparticle dispersion (e.g., 1 mL, concentration approximately 1 mg / mL) was taken. -1 Add pre-prepared DiD ethanol stock solution (1 mg / mL) -1 This brings the final DiD concentration to 5–10 μg·mL. -1 The mixture was incubated with gentle stirring or rotation for 1–2 h in the dark. Free dye was then removed by centrifugation (10,000 rpm, 10 min), and the mixture was resuspended in PBS or deionized water. Subsequently, 100 μg of DiD-labeled cubic gold-iron nanoparticles were injected via tail vein. Biodistribution and fluorescence signals in tumor tissues and lymph nodes were monitored at predetermined time points using an IVIS Spectrum imaging system (Caliper Scientific, California, USA). [The text then abruptly shifts to a seemingly unrelated topic: "Combined with attached..."] Figure 4 The results show that the nano-formulation exhibits significant tumor-targeting accumulation and fluorescence signal enhancement effects in vivo, further demonstrating its excellent potential for high-sensitivity fluorescence imaging.

[0038] In vivo CT imaging: To investigate the in vivo CT imaging effects of the cubic gold-iron nanoparticle formulation, we administered 100 μg of the formulation via tail vein injection or an equivalent dose of iohexol (a commercially available CT contrast agent). In vivo CT imaging analysis was performed at predetermined time points using an ultra-high resolution CT system (Ultra3D, Beijing Longshi Instruments Co., Ltd.). (See attached...) Figure 5 The results showed that, compared with commercially available iohexol, cubic gold-iron nanoparticles could achieve more durable and contrasting CT signal enhancement in the tumor area, fully demonstrating their excellent in vivo CT imaging capabilities and diagnostic application potential.

[0039] In vivo photothermal imaging: To study the in vivo photothermal imaging effect of cubic gold-iron nanoparticles, we administered 100 μg of the cubic gold-iron nanoparticles via tail vein injection or 100 μL of physiological saline as a control. Twenty-four hours after injection, fixed time points were irradiated with an 808 nm near-infrared laser, and images were captured using a digital infrared thermal imaging camera. (See attached image.) Figure 6 The results showed that, compared with the control group, the tumor site in the cubic gold-iron nanoparticle treatment group rapidly heated up after laser irradiation and showed significant and sustained overheating signal enhancement, demonstrating excellent photothermal conversion and imaging performance, further proving the application potential of this nanoparticle in tumor photothermal therapy.

[0040] In vivo MRI: To investigate the in vivo CT imaging effect of cubic gold-iron nanoparticles, we administered 100 μg of the cubic gold-iron nanoparticles via tail vein injection or an equivalent dose of gadopentetate dimeglumine (GD-DTPA, a commercially available MRI contrast agent). Imaging analysis was performed at predetermined time points using a 5T MRI scanner (uMR Jupiter; United Imaging Healthcare). The cubic gold-iron nanoparticles produced more significant contrast enhancement at the tumor site, exhibiting superior tumor-targeting imaging capability and more durable signal retention compared to GD-DTPA, fully demonstrating its potential application value as a high-performance MRI contrast nanoplatform.

[0041] Those skilled in the art to which this application pertains may make various modifications or additions to the specific embodiments described, or adopt similar methods to replace them, without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A cubic gold-iron nanoparticle formulation, characterized in that, The particle size is 30-300nm, containing gold, iron and oxygen elements, with gold content of 1-10% and iron content of 0.3-10%.

2. The cubic gold-iron nanoparticle formulation as described in claim 1, characterized in that, The nano-formulation serves as a carrier, loading at least one functional molecule selected from lipophilic fluorescent molecules and small molecule chemotherapeutic drugs.

3. The cubic gold-iron nanoparticle formulation as described in claim 2, characterized in that, The lipophilic fluorescent molecule is 1,1'-octadecyl-3,3,3',3'-tetramethylindole dicarboxyanine perchlorate.

4. The cubic gold-iron nanoparticle formulation as described in claim 2, characterized in that, The small molecule chemotherapy drug is a chemical drug used for tumor treatment.

5. A method for preparing the cubic gold-iron nanoparticle formulation as described in claim 1, characterized in that, Includes the following steps: (a) Prepare thiol-functionalized gold nanoparticles; (b) Form an iron layer on the surface of the thiol-functionalized gold nanoparticles by iron deposition reaction to obtain gold-iron nanoparticle formulation.

6. The method as described in claim 5, characterized in that, The preparation of the thiol-functionalized gold nanoparticles in step (a) includes: mixing hexadecyltrimethylammonium bromide, chloroauric acid, sodium citrate and polyvinylpyrrolidone in an aqueous solution, reacting them in an autoclave at 100-120°C for 10-14 hours to obtain gold nanoparticles; and then reacting the gold nanoparticles with thioglycolic acid to perform thiol functionalization.

7. The method as described in claim 6, characterized in that, In step (a), the concentration of the mother liquor of hexadecyltrimethylammonium bromide is 200-300 mM, the concentration of the mother liquor of HAuCl4 is 8-12 mM, the concentration of the mother liquor of sodium citrate is 40-60 mM, and the concentration of the mother liquor of polyvinylpyrrolidone is 8-12 mg / mL; in step (b), the iron deposition reaction includes reacting functionalized gold nanoparticles with ferric chloride and trimesic acid in an ethanol solution at 60-80°C for 20-40 minutes.

8. The application of a cubic gold-iron nanoparticle formulation as described in claim 1 in tumor multimodal imaging, characterized in that, The application relates to achieving at least one of the following imaging modalities via the nanoformulation: computed tomography, magnetic resonance imaging, photothermal imaging, and fluorescence imaging.

9. The application as described in claim 8, characterized in that, The multimodal imaging includes a combination of CT imaging, MRI imaging, photothermal imaging, and fluorescence imaging, used for tumor localization, lesion identification, or treatment monitoring.

Images