Gold-iron oxide composite nanoparticles and gold-iron oxide nanoprobes

Abstract

The present invention belongs to the field of materials science and technology and relates to gold-iron oxide composite nanoparticles and gold-iron oxide nanoprobes. The gold-iron oxide composite nanoparticles are formed by loading single gold atoms and / or gold clusters onto iron oxide nanoparticles. The gold atoms and / or gold clusters have extremely small particle sizes, which are beneficial for the SERS enhancement effect.

Description

Technical Field

[0001] The invention belongs to the technical field of material science and relates to gold-iron oxide composite nanoparticles and a gold-iron oxide nanoprobe. Background Art

[0002] Surface enhanced Raman scattering (SERS) is based on the localized plasmon resonance of precious metal or metal compound nanostructures, which significantly enhances the Raman signal by 10 6 -10 10 SERS spectroscopy has the advantages of good selectivity, high sensitivity, no photobleaching, anti-interference, rapidity and non-destructiveness. Surface-enhanced Raman scattering spectroscopy has shown great application potential in the field of optical detection, such as in vitro diagnostics and liquid biopsy. Currently, conventional SERS bioprobes are divided into precious metal probes and semiconductor bioprobes. The former has the advantage of high detection sensitivity, while the latter has functional advantages such as good signal stability and photoelectromagnetic response. Usually, in order to combine the advantages of both, precious metals and functional semiconductor materials are compounded through chemical synthesis. This method is relatively complex, and the obtained precious metal particles are large in size, which restricts the application and development of precious metals and semiconductor materials in the field of SERS. Summary of the Invention

[0003] The present invention aims to provide a gold-iron oxide composite nanoparticle and a gold-iron oxide nanoprobe to address the deficiencies in the prior art.

[0004] One object of the present invention is to provide a gold-iron oxide composite nanoparticle, which is formed by supporting gold single atoms and / or gold clusters on iron oxide nanoparticles.

[0005] Preferably, the particle size of the gold single atom is 0.2 to 0.3 nm, and more preferably, the particle size of the gold single atom is 0.288 to 0.3 nm.

[0006] Preferably, the particle size of the gold cluster is 0.3 nm < 3 nm, and more preferably, the particle size of the gold cluster is 0.5 to 2 nm. The gold cluster is formed by the aggregation of gold single atoms.

[0007] Preferably, the iron oxide nanoparticles are one or more of ferrous oxide nanoparticles, ferrous oxide nanoparticles, and ferrosoferric oxide nanoparticles.

[0008] Preferably, the particle size of the iron oxide nanoparticles is 1 to 1200 nm, more preferably 1 to 500 nm, more preferably 1 to 300 nm, and even more preferably 1 to 100 nm.

[0009] Preferably, the shape of the iron oxide nanoparticles is any one of dodecahedron, octahedron, hexahedron, tetrahedron, sphere, rod, wire, sheet, nanocage, and random.

[0010] Another object of the present invention is to provide a method for preparing gold-iron oxide composite nanoparticles, comprising the following steps:

[0011] Aqueous chloroauric acid solution is added to an aqueous dispersion of iron oxide nanoparticles, and after reaction, the mixture is washed and dried to obtain gold-iron oxide composite nanoparticles in which gold atoms and / or gold clusters are loaded on the iron oxide nanoparticles.

[0012] The concentration of the aqueous chloroauric acid solution can be selected from 0.01 to 100 mg / ml, and further selected from 0.1 to 10 mg / ml.

[0013] Preferably, the aqueous chloroauric acid solution is added dropwise to the aqueous dispersion of the iron oxide nanoparticles, with the volume of each drop being ≤0.08 ml.

[0014] Preferably, the iron oxide nanoparticles are dispersed in water and ultrasonically treated for 1 to 10 hours to obtain an aqueous dispersion of the iron oxide nanoparticles. In the aqueous dispersion of the iron oxide nanoparticles, the ratio of the mass (mg) of the iron oxide nanoparticles to the volume (ml) of water is 1:10 to 10:1.

[0015] Preferably, the reaction temperature is 30-80° C., and the reaction time is 5-50 h.

[0016] More preferably, the reaction temperature is 30 to 70° C., more preferably 35 to 60° C., and even more preferably 40 to 60° C. More preferably, the reaction time is 5 to 40 h, more preferably 5 to 30 h, and even more preferably 5 to 20 h.

[0017] Preferably, the mass ratio of the iron oxide nanoparticles to the chloroauric acid is [3-60]:1, where [3-60] means that the range of 3-60 includes both 3 and 60.

[0018] Preferably, when the mass ratio of the iron oxide nanoparticles to the chloroauric acid is [18-60]:1, [18-60] means that the range of 18-60 includes 18 and 60, and gold-iron oxide composite nanoparticles in which gold single atoms are supported on the iron oxide nanoparticles are obtained; optionally, the mass ratio of the iron oxide nanoparticles to the chloroauric acid is any one of 18:1, 19:1, 22:1, 25:1, 28:1, 40:1, 50:1, or a range between any two values;

[0019] When the mass ratio of the iron oxide nanoparticles to the chloroauric acid is (14-18):1, (14-18) means that 14 and 18 are not included in the range of 14-18, and gold-iron oxide composite nanoparticles in which gold atoms and gold clusters are loaded on the iron oxide nanoparticles are obtained; optionally, the mass ratio of the iron oxide nanoparticles to the chloroauric acid is any one of 15:1, 16:1, 17:1, or a range value between any two values;

[0020] When the mass ratio of iron oxide nanoparticles to chloroauric acid is [3-14]:1, more preferably [6-14]:1, gold-iron oxide composite nanoparticles in which gold clusters are loaded on iron oxide nanoparticles are obtained; optionally, the mass ratio of iron oxide nanoparticles to chloroauric acid is any one of 6:1, 8:1, 10:1, 12:1, 14:1 or a range value between any two values.

[0021] Another object of the present invention is to provide a gold-iron oxide nanoprobe, which comprises, from the inside out, the above-mentioned gold-iron oxide composite nanoparticles, a Raman / fluorescence signal molecule layer, a polymer layer and a target molecule layer.

[0022] Preferably, the Raman / fluorescent signal molecule is an organic substance having both fluorescence and Raman properties, that is, the Raman / fluorescent signal molecule is an organic substance having conjugated vibration in the Raman spectrum and can emit fluorescence under visible ultraviolet light, including but not limited to one or more of IR783, IR780, 3,3'-diethylthiotricarbocyanine iodide (DTTC), 4-mercaptoaniline, mercaptonaphthalene, p-fluorothiophenol, rhodamine, crystal violet, alizarin red, tetrazolium blue, mercaptopyridine, and Nile blue.

[0023] Preferably, the polymer has one or more functional groups capable of binding to Raman / fluorescent signal molecules, and the functional groups include one or more of thiol, amino, carboxyl, and hydroxyl groups; preferably, the molecular weight of the polymer is 1000 to 1000000 Daltons, preferably 5000 to 100000 Daltons; preferably, the polymer is selected from one or more of polypeptides, oligopeptides, proteins, polysaccharides, polyether compounds, and polyester compounds.

[0024] Preferably, the target molecule is an antibody or ligand that can specifically bind to a surface antigen or receptor of a cancer cell, and the cancer cell may be breast cancer, lung cancer, liver cancer, esophageal cancer, etc.; preferably, the target molecule is a polypeptide substance or a non-polypeptide substance, and polypeptide substances can be exemplified by monoclonal antibodies (such as EPCAM antibodies, CD44 antibodies), and non-polypeptide substances can be exemplified by folic acid and galactosamine.

[0025] Preferably, the mass ratio of the gold-iron oxide composite nanoparticles, Raman / fluorescent signal molecules, polymers, and target molecules is 5-100:5-30:1-50:1-20, and the mass ratio is more preferably 70-90:5-20:1-40:1-15.

[0026] The preparation method of the gold-iron oxide nanoprobe comprises the following steps:

[0027] S1, obtaining gold-iron oxide composite nanoparticles;

[0028] S2, attaching Raman / fluorescence signal molecules to the surface of gold-iron oxide composite nanoparticles to obtain nanoparticle II;

[0029] S3, coating the polymer on the surface of the Raman / fluorescence signal molecule to obtain nanoparticle III;

[0030] S4. Couple the target molecule to the polymer surface to obtain a gold-iron oxide nanoprobe.

[0031] Preferably, in step S2, the Raman / fluorescence signal molecule solution and the gold-iron oxide composite nanoparticle solution are mixed and stirred to obtain nanoparticles II.

[0032] The Raman / fluorescent signal molecule solution is formed by dissolving the Raman / fluorescent signal molecule in an organic solvent, and any organic solvent that can dissolve the Raman / fluorescent signal molecule can be used. The gold-iron oxide composite nanoparticle solution is formed by dispersing the gold-iron oxide composite nanoparticles in water.

[0033] Preferably, the concentration of the Raman / fluorescence signal molecule solution is 0.001 to 10,000,000 mmol; and the concentration of the gold-iron oxide composite nanoparticle solution is 0.0001 to 800,000 mg / mL.

[0034] Preferably, the concentration of the Raman / fluorescent signal molecule solution is any one of 0.01, 0.1, 1, 5, 10, 30, 50, 80, 100, 1000, and 100,000 mmol, or a range between any two of these values. The concentration of the gold-iron oxide composite nanoparticle solution is any one of 0.001, 0.01, 0.1, 1, 5, 10, 30, 50, 80, 800, and 8000 mg / mL, or a range between any two of these values.

[0035] Preferably, the volume ratio of the Raman / fluorescent signal molecule solution to the gold-iron oxide composite nanoparticle solution is 1:1000 to 10:1, more preferably 1:500 to 1:1, and even more preferably 1:500 to 1:100.

[0036] Preferably, the stirring time for obtaining the nanoparticles II is 0.1 to 10 h. Preferably, the stirring time is any one of 0.5, 1, 3, 5, and 8 h, or a range between any two of these values.

[0037] Preferably, in step S3, the nanoparticle II solution, ethanol, and ammonia water are mixed and stirred, and then the polymer solution is added to react to obtain nanoparticles III;

[0038] The nanoparticle II solution is formed by dispersing nanoparticles II in water. Preferably, the concentration of the nanoparticle II solution is 0.01 to 10 mg / ml. Preferably, the concentration of the nanoparticle II solution is any one of 0.01, 0.1, 0.3, 0.5, 1, 3, 5 mg / ml or a range between any two values.

[0039] The polymer solution is formed by dissolving the polymer in water. Preferably, the concentration of the polymer solution is 1 to 100 mg / ml. Optionally, the concentration of the polymer solution is any one of 1, 20, 30, 40, 50, 60, and 100 mg / ml, or a range between any two of these values.

[0040] Preferably, the volume ratio of the nanoparticle II solution, ethanol, ammonia water, and polymer solution is 5-55:2-16:0.3-1.5:0.4-10.

[0041] Preferably, the nanoparticle II solution, ethanol, and ammonia solution are stirred for 1 to 100 minutes. Optionally, the stirring time is any one of 1, 10, 20, 30, 50, 80, and 100 minutes, or a range between any two of these values.

[0042] Preferably, the reaction time for obtaining the nanoparticles III is 1 to 10 hours. Alternatively, the reaction time is any one of 1, 3, 5, 8, and 10 hours, or a range between any two of these values.

[0043] Preferably, in step S4, the solution containing the nanoparticles III, the buffer solution, and the antibody is mixed and stirred to obtain the gold-iron oxide nanoprobe.

[0044] Preferably, the buffer solution includes but is not limited to at least one of a Tris-HCl solution and an ammonia alkaline solution.

[0045] Preferably, the ratio of the mass of nanoparticle III in mg: the volume of buffer in ml: the mass of antibody in μg is 0.0005-1000: 0.001-10000: 0.0001-5000. More preferably, the ratio of the mass of nanoparticle III in mg: the volume of buffer in ml: the mass of antibody in μg is 0.05-100: 0.01-1000: 0.001-500. Even more preferably, the ratio of the mass of nanoparticle III in mg: the volume of buffer in ml: the mass of antibody in μg is 0.5-10: 0.1-100: 0.01-50.

[0046] Preferably, the solution containing nanoparticles III, buffer, and antibody is stirred for 0.01 to 720 hours at a temperature of 1 to 80° C. Preferably, the stirring time is any one of 1, 2, 10, 12, 15, 20, 30, 50, or 72 hours, or a range between any two of these values. Preferably, the stirring temperature is any one of 15, 20, 25, 30, 35, or 40° C., or a range between any two of these values.

[0047] Another object of the present invention is to provide the use of the gold-iron oxide nanoprobe in in vitro detection.

[0048] Preferably, the application includes the following steps: adding gold-iron oxide nanoprobes to the system to be tested, combining the gold-iron oxide nanoprobes with the target in the system to be tested, undergoing magnetic enrichment and separation, and then detecting by Raman spectroscopy and / or fluorescence spectroscopy to determine the concentration of the target in the system to be tested.

[0049] Another object of the present invention is to provide an in vitro detection device comprising the gold-iron oxide nanoprobe. The in vitro detection device may be a sensor, a detector, a spectral responder, or the like.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The preparation method of the gold-iron oxide composite nanoparticles provided by the present invention is simple, low-cost, and easy to promote on a large scale;

[0052] (2) The gold-iron oxide composite nanoparticles provided by the present invention are formed by loading gold single atoms and / or gold clusters on iron oxide nanoparticles. The particle size of the gold single atoms and / or gold clusters is extremely small, which is conducive to the SERS enhancement effect;

[0053] (3) The gold-iron oxide composite nanoparticles of the present invention can synergistically promote the surface enhanced Raman scattering effect, wherein the surface plasmon resonance effect of gold single atoms and / or gold clusters can promote the photoinduced charge transfer effect of the iron oxide nanoparticles, and the photoinduced charge transfer effect of the iron oxide nanoparticles can also promote the surface plasmon resonance effect of gold single atoms and / or gold clusters;

[0054] (4) The gold-iron oxide composite nanoparticles of the present invention have both high detection sensitivity and magnetic enrichment / separation properties. This is because gold single atoms and / or gold clusters have a high SERS enhancement factor as SERS substrates, and because the iron oxide nanoparticles have magnetic enrichment / separation properties, they can achieve efficient enrichment and rapid separation of tumor cells.

[0055] (5) After the gold-iron oxide composite nanoparticles of the present invention bind to cancer cells, they can be enriched and separated to detect cancer cells with high sensitivity at extremely low concentrations of the cancer cells to be detected;

[0056] (6) The gold-iron oxide nanoprobe of the present invention is coated with a polymer layer, which can effectively avoid interaction with non-cancerous cells and has a strong Raman signal. In addition, by modifying the nanomaterial with antibody proteins that specifically recognize different types of cancer (breast cancer, lung cancer, liver cancer, esophageal cancer, cervical cancer), it can universally detect tumor cells in peripheral blood samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a transmission electron micrograph of the single-atom gold-iron oxide composite nanoparticles of Example 1;

[0058] Figure 2 This is a transmission electron micrograph of the clustered gold-iron oxide composite nanoparticles of Example 4;

[0059] Figure 3 The SERS spectra of the single-atom gold-iron oxide composite nanoparticles of Example 1 and the gold nanoparticles composite ferroferric oxide of Comparative Example 1 to methylene blue molecules are shown;

[0060] Figure 4 The SERS spectra of the single-atom gold-iron oxide composite nanoparticles of Example 1 to crystal violet molecules at different concentrations are shown;

[0061] Figure 5 This is a graph showing the enrichment and capture of tumor cells by the nanoprobe in Example 5;

[0062] Figure 6 This is the SERS spectrum of the nanoprobe of Example 5 and clinical sample tumor cells. DETAILED DESCRIPTION

[0063] Below by specific embodiment and accompanying drawing, technical scheme of the present invention is further described explanation, it should be understood that specific embodiment described herein is only for helping to understand the present invention, is not used for specific limitation of the present invention.And accompanying drawing used herein, is only for better illustrating the disclosure of the present invention, does not have limiting effect on protection scope.If no special instructions, the raw materials adopted in the embodiment of the present invention are all raw materials commonly used in this area, and the method adopted in the embodiment is all conventional method in this area.

[0064] In the following examples, the ferroferric oxide nanospheres used were prepared by the following method:

[0065] 2 mmol of ammonium ferrous sulfate hexahydrate was added to 20 mL of ultrapure water to form a solution. 1 g of sodium hydroxide was added to a mixture of oleic acid (10 mL) and ethanol (10 mL) and stirred until completely dissolved. Then, 20 mL of the ammonium ferrous sulfate solution was added. After the mixture turned brownish-red, it was transferred to a 50 mL reactor and heated at 230°C for 8 h. After cooling, the reactor was removed, washed three times with ethanol by centrifugation, and dispersed in 20 mL of cyclohexane to produce the desired oil-soluble magnetic nanoparticles. Subsequently, 2 g of citric acid and 20 mL of the oil-soluble magnetic nanoparticles were added to a 30 mL mixture of chloroform / DMF (v / v: 1 / 1) and stirred for 12 h. The mixture was then washed three times with ethanol by centrifugation and dispersed in 20 mL of water to produce the desired water-soluble magnetic nanoparticles. The mixture was allowed to stand for 4 days, cooled naturally, and then washed by centrifugation. The sample was then washed three times with water and three times with ethanol. Finally, it was dried in a 70°C oven for 12 h to produce 4 nm Fe3O4 nanospheres.

[0066] Example 1

[0067] The single-atom gold-iron oxide composite nanoparticles of this embodiment were prepared by the following method:

[0068] 20 mg of ferroferric oxide nanospheres were dispersed in 90 mL of deionized water, and after ultrasonic treatment for 2 h, 0.5 mL of 1.0 mg / mL chloroauric acid aqueous solution was added dropwise, stirred at 55 ° C for 10 h, and then washed with ethanol and distilled water 5 times. Finally, it was dried in a vacuum oven at 45 ° C for 8 h to obtain single-atom gold-iron oxide composite nanoparticles with gold single atoms loaded on ferroferric oxide nanospheres. The transmission electron microscope image is shown in FIG. Figure 1 As shown in the figure, the circled area is the gold atom.

[0069] Example 2

[0070] The single-atom gold-iron oxide composite nanoparticles of this embodiment were prepared by the following method:

[0071] 20 mg of ferroferric oxide nanospheres were dispersed in 100 mL of deionized water and ultrasonically treated for 2 h. Then, 0.8 mL of 1.0 mg / mL chloroauric acid aqueous solution was added dropwise and stirred at 50 °C for 12 h. Then, the mixture was washed with ethanol and distilled water five times and finally dried in a vacuum oven at 45 °C for 8 h to obtain single-atom gold-iron oxide composite nanoparticles in which single gold atoms were loaded on ferroferric oxide nanospheres.

[0072] Example 3

[0073] The single-atom gold-iron oxide composite nanoparticles of this embodiment were prepared by the following method:

[0074] 20 mg of ferroferric oxide nanospheres were dispersed in 120 mL of deionized water and ultrasonically treated for 3 h. Then, 1.0 mL of 1.0 mg / mL chloroauric acid aqueous solution was added dropwise, stirred at 60 ° C for 12 h, and then washed with ethanol and distilled water 6 times. Finally, it was dried in a vacuum oven at 50 ° C for 8 h to obtain single-atom gold-iron oxide composite nanoparticles with gold single atoms loaded on ferroferric oxide nanospheres.

[0075] Example 4

[0076] The clustered gold-iron oxide composite nanoparticles of this embodiment were prepared by the following method:

[0077] 20 mg of ferroferric oxide nanospheres were dispersed in 90 mL of deionized water, and after ultrasonic treatment for 2 h, 2 mL of 1.0 mg / mL chloroauric acid aqueous solution was added dropwise, stirred at 55 ° C for 12 h, and then washed with ethanol and distilled water 5 times. Finally, it was dried in a vacuum oven at 50 ° C for 10 h to obtain clustered gold-iron oxide composite nanoparticles with gold clusters loaded on ferroferric oxide nanospheres. The transmission electron microscope image is shown as follows Figure 2 As shown, the average particle size of the gold clusters is 1 nm.

[0078] Comparative Example 1

[0079] The gold nanoparticle composite ferroferric oxide of Comparative Example 1 was prepared by the following method:

[0080] 20 mg of ferroferric oxide nanospheres were dispersed in 90 mL of deionized water and ultrasonically treated for 2 h. Then, 10 mL of 1.0 mg / mL chloroauric acid aqueous solution was added dropwise and stirred at 55 °C for 10 h. Then, the mixture was washed with ethanol and distilled water for 5 times and finally dried in a vacuum oven at 45 °C for 8 h to obtain gold nanoparticles composited with ferroferric oxide.

[0081] In order to compare the SERS detection imaging capabilities of the single-atom gold-iron oxide composite nanoparticles of Example 1 and the gold nanoparticles composite ferroferric oxide of Comparative Example 1, the single-atom gold-iron oxide composite nanoparticles of Example 1 were used as SERS substrates under the action of an excitation wavelength of 532 nm, and the concentration of 1×10 -5mol / L methylene blue molecules are subjected to SERS spectroscopy detection to generate a SERS spectrum graph, such as Figure 3 As shown, it can be seen that the gold-iron oxide composite nanoparticles loaded with gold single atoms have better SERS enhancement effect than the gold nanoparticles composite iron oxide.

[0082] The gold-iron oxide composite nanoparticles of Example 1 were used as SERS substrates and SERS spectra of crystal violet molecules at different concentrations were detected under an excitation wavelength of 633 nm. The results are as follows: Figure 4 As shown in Figure 2, the detection limit of gold-iron oxide composite nanoparticles for crystal violet molecules is 10 -10 M, with excellent SERS detection sensitivity.

[0083] Example 5

[0084] Preparation of gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA-folic acid antibody nanoprobes

[0085] (1) Preparation of gold-iron oxide composite nanoparticles-mercaptobenzoic acid nanoparticles

[0086] Add 150 μl of a 1 mmol / L 4-mercaptobenzoic acid ethanol solution to 15 ml of the gold-iron oxide composite nanoparticle solution of Example 1 (solvent: water, concentration: 0.21 mg / ml), stir with a polytetrafluoroethylene rod for 2 h, thoroughly rinse with deionized water, and finally disperse in 18 ml of deionized water to obtain a gold-iron oxide composite nanoparticle-mercaptobenzoic acid nanoparticle solution.

[0087] (3) Preparation of gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA nanoparticles

[0088] 18 ml of gold-iron oxide composite nanoparticles-mercaptobenzoic acid nanoparticle solution (solvent: water, concentration: 0.19 mg / ml), 8 ml of CH3CH2OH and 600 μl of NH3·H2O were mixed and stirred with a polytetrafluoroethylene rod for 20 min. Then, 2 ml of rBSA solution (40 mg / ml) was slowly added. After 5 hours, the mixture was thoroughly washed with deionized water and dispersed in 8 ml of deionized water to prepare a gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA nanoparticle solution.

[0089] (4) Preparation of gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA-folic acid antibody nanoparticles

[0090] Take 4 ml of gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA nanoparticle solution, use magnet adsorption to obtain gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA nanoparticles, pour out the supernatant, then add 4 ml of Tris-HCl solution (10 mM, pH = 8.5), then add 40 μg of folic acid antibody, stir at room temperature for 12 hours, wash 3 times with PBS to obtain gold-iron oxide composite nanoparticles-mercaptobenzoic acid-rBSA-folic acid antibody nanoprobe.

[0091] The nanoprobe of Example 5 was co-incubated with circulating tumor cells and combined with the magnetic enrichment module of the circulating tumor cell detection device. The enrichment effect was as follows: Figure 5 As shown, tumor cells have excellent binding properties with the nanoprobe. After magnetic enrichment, the tumor cells are enriched, and there are no tumor cells in the filtered waste liquid, indicating that the nanoprobe has excellent enrichment and capture capabilities for tumor cells.

[0092] The nanoprobe of Example 5 was co-incubated with clinical sample tumor cells (breast cancer, lung cancer, liver cancer, esophageal cancer, cervical cancer, colon cancer), and SERS spectroscopy was performed after magnetic enrichment and separation. The SERS spectrum is shown in the figure below. Figure 6 As shown, it can be seen that the nanoprobe has excellent versatility in tumor cell detection.

[0093] The various aspects, embodiments, and features of the present invention should be considered in all respects as illustrative and not limiting, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0094] In the preparation method of the present invention, the order of the steps is not limited to the order listed. Persons skilled in the art will appreciate that variations in the order of the steps are within the scope of the present invention without inventive effort. Furthermore, two or more steps or actions may be performed simultaneously.

[0095] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit its implementation. Persons skilled in the art may make various modifications, additions, or substitute similar methods for the described specific embodiments. It is not necessary and impossible to provide comprehensive examples of all implementations here. However, obvious variations or modifications arising from the essential spirit of the present invention remain within the scope of protection of the present invention, and interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A gold-iron oxide nanoprobe, characterized in that From the inside to the outside, it includes: gold-iron oxide composite nanoparticles, Raman / fluorescence signal molecules, polymers and target molecule layers; The gold-iron oxide composite nanoparticles are formed by loading gold single atoms on iron oxide nanoparticles, and include the following steps: adding a chloroauric acid aqueous solution dropwise into an aqueous dispersion of the iron oxide nanoparticles, wherein the mass ratio of the iron oxide nanoparticles to the chloroauric acid is [18-60]:1, the reaction temperature is 50-80°C, the reaction time is 5-50 hours, washing, and drying to obtain the gold-iron oxide composite nanoparticles in which the gold single atoms are loaded on the iron oxide nanoparticles.

2. A gold-iron oxide nanoprobe according to claim 1, characterized in that, The iron oxide nanoparticles are one or more of ferrous oxide nanoparticles, ferrous oxide nanoparticles, and ferrosoferric oxide nanoparticles; The particle size of iron oxide nanoparticles is 1~500nm.

3. A gold-iron oxide nanoprobe according to claim 1, characterized in that, The particle size of iron oxide nanoparticles is 1~100nm.

4. A gold-iron oxide nanoprobe according to claim 1, characterized in that, The Raman / fluorescent signal molecule is an organic substance that has conjugated vibration in the Raman spectrum and can emit fluorescence under visible ultraviolet light.

5. A gold-iron oxide nanoprobe according to claim 1 or 4, characterized in that, The Raman / fluorescence signal molecule is one or more of IR783, IR780, 3,3'-diethylthiotricarbocyanine iodide, 4-mercaptoaniline, mercaptonaphthalene, p-fluorothiophenol, rhodamine, crystal violet, alizarin red, tetrazolium blue, mercaptopyridine, and Nile blue.

6. The gold-iron oxide nanoprobe according to claim 1, characterized in that: The polymer has one or more functional groups capable of combining with Raman / fluorescent signal molecules, and the functional groups include one or more of thiol, amino, carboxyl, and hydroxyl groups.

7. A gold-iron oxide nanoprobe according to claim 1 or 6, characterized in that: The polymer is selected from one or more of polypeptides, oligopeptides, proteins, polysaccharides, polyether compounds, and polyester compounds.

8. The gold-iron oxide nanoprobe according to claim 1, characterized in that: The target molecule is an antibody or ligand that can specifically bind to an antigen or receptor on the surface of a cancer cell.

9. Use of the gold-iron oxide nanoprobe according to claim 1 in in vitro detection.

10. An in vitro detection device, characterized in that: The invention comprises the gold-iron oxide nanoprobe according to claim 1.

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