Surface modified gold magnetic nanoparticles and preparation method and application thereof

Abstract

The present invention discloses a surface-modified gold magnetic nanoparticle and a preparation method and application thereof. The preparation method of the surface-modified gold magnetic nanoparticle comprises the following steps: S1, preparation of Fe3O4 magnetic core; S2, preparation of functionalized Fe3O4 magnetic core; S3, preparation of Fe3O4@Au nanoparticle; wherein, in step S1, the preparation of Fe3O4 magnetic core comprises mixing a first mixed solution containing an iron precursor and a reducing agent with an alkaline reagent to obtain a second mixed solution, heating in a one-step reaction, and cooling to obtain the second mixed solution. The preparation method of the present invention is simple and easy to implement, and the obtained surface-modified gold magnetic nanoparticles have uniform particle size, excellent monodispersity and stability, and when further used for capturing proteins, the capture effect can be significantly improved.

Description

Technical Field

[0001] The invention relates to surface-modified gold magnetic nanoparticles and a preparation method and application thereof. Background Art

[0002] With the development of synthesis technology, magnetic nanoparticles have gradually attracted attention due to their superior physical and chemical properties. Among them, gold nanoparticles have excellent electrical and optical properties and good biocompatibility. They can easily and stably bind to biological macromolecules (such as proteins, nucleic acids, and peptides) and are widely used in molecular recognition and biomarkers.

[0003] Traditional detection and diagnostic reagents, gold nanoparticles (GNPs), have the advantages of surface plasmon resonance (SPR) and easy surface modification (Au-S). However, since traditional gold nanoparticles are not magnetic, it is impossible to use a magnetic suction device to quickly separate the nanoparticles from the solution. Therefore, it is still necessary to use filtration, centrifugation and other methods to separate the gold nanoparticles from the solution, which is a cumbersome process.

[0004] At present, the methods for preparing Fe3O4 magnetic nanoparticles mainly include precipitation method, mechanical ball milling method, thermal decomposition method, electrochemical deposition method, microemulsion method, hydrothermal method and sol-gel method, on this basis, mixing with colloidal gold solution to achieve gold layer coating, during which the surface of Fe3O4 is modified after the nuclear magnetic properties are obtained, or the surface is modified after the gold layer is coated; overall, the steps are complicated, the cost is high, and it is difficult to ensure the particle size uniformity, dispersibility and stability of the obtained surface-modified gold magnetic nanoparticles.

[0005] In the prior art, methods for capturing plasma proteins in protein research and clinical diagnosis generally use affinity purification, molecular adsorption, immunoaffinity, etc. Affinity purification uses the specific interaction between a specific ligand and the target protein to capture the target protein. Molecular adsorption uses the pore size of molecular materials to selectively adsorb the target protein. Immunoaffinity uses the specific binding of antibodies to the target protein to capture the target protein. Overall, these methods capture a small number of proteins, are costly, and are complex to operate.

[0006] Therefore, how to obtain surface-modified gold magnetic nanoparticles with good particle size uniformity, dispersibility and stability while simplifying the preparation process so as to improve the effect when further used for capturing proteins is an urgent problem to be solved in this field. Summary of the invention

[0007] The present invention provides a surface-modified gold magnetic nanoparticle and a preparation method and application thereof to solve the defects of the existing preparation of gold magnetic nanoparticles, such as difficulty in ensuring uniform particle size, good dispersibility and stability. The preparation method constructed by the present invention is simple and easy to implement, and the obtained surface-modified gold magnetic nanoparticles have uniform particle size, excellent monodispersity and stability, and can also significantly improve the capture effect when further used for capturing proteins.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of the present invention provides a method for preparing surface-modified gold magnetic nanoparticles, which comprises the following steps: S1, preparation of Fe3O4 magnetic cores; S2, preparation of functionalized Fe3O4 magnetic cores; S3, preparation of Fe3O4@Au nanoparticles; wherein,

[0010] In step S1, the preparation of the Fe3O4 magnetic core includes mixing a first mixed solution containing an iron precursor and a reducing agent with an alkaline reagent to obtain a second mixed solution, heating in a one-step reaction, and cooling to obtain the second mixed solution.

[0011] In step S1, the temperature of the one-step reaction can be 190-220°C, preferably 200°C.

[0012] In step S1, the one-step reaction time may be 6-72 hours, preferably 10 hours.

[0013] In step S1, the iron precursor may be conventional in the art, preferably including one or more of ferrous chloride, ferric acetylacetonate, ferric chloride and ferric oxide, more preferably ferric chloride, such as ferric chloride hexahydrate.

[0014] In step S1, the reducing agent may be conventional in the art, such as trisodium citrate.

[0015] In some embodiments, in step S1, the molar ratio of the iron precursor to the reducing agent is (1.4-15.3):1, preferably (2.4-3.3):1, for example 3.1:1.

[0016] In step S1, the alkaline reagent can be conventional in the art, generally sodium acetate and / or sodium hydroxide, such as sodium acetate.

[0017] In some embodiments, in step S1, the molar ratio of the iron precursor to the alkaline reagent is (0.06-0.24):1, preferably (0.13-0.18):1, for example 0.16:1.

[0018] In step S1, the first mixed solution may further include ethylene glycol; the preparation of the first mixed solution preferably includes dissolving the iron precursor and the reducing agent in ethylene glycol.

[0019] In some embodiments, in step S1, the mixing is stirring mixing; the time of the stirring mixing is preferably 30-180 min, more preferably 90 min; the rotation speed of the stirring mixing is preferably 200-800 rpm, more preferably 300 rpm.

[0020] In step S2, the preparation of the functionalized Fe3O4 magnetic core may include stirring and mixing a functionalizing agent and a solution containing the Fe3O4 magnetic core.

[0021] The functionalizing agent may be an amination agent, preferably aminopropyltriethoxysilane (APTES).

[0022] In some embodiments, the usage ratio of the functionalizing agent to the Fe3O4 magnetic core is (0.5-2) μL:(0.5-2) mg, for example, 1 μL:1 mg.

[0023] The stirring and mixing can be performed using a stirring paddle.

[0024] The stirring speed of the stirring and mixing may be 100-500 rpm, for example 200 rpm.

[0025] The stirring time of the stirring and mixing may be 4-8 hours, for example 6 hours.

[0026] In step S3, the preparation of the Fe3O4@Au nanoparticles may include mixing a gold precursor, a reducing agent and the functionalized Fe3O4 magnetic cores, and then ultrasonicating the mixture.

[0027] The gold precursor may be conventional in the art, preferably including one or more of gold chloride, chloroauric acid, sodium gold thiosulfate and gold acetate, more preferably chloroauric acid, such as chloroauric acid tetrahydrate.

[0028] The reducing agent may be conventional in the art, such as trisodium citrate.

[0029] In some embodiments, in step S3, the molar ratio of the gold precursor to the reducing agent is (0.3-1.8):1, preferably 0.8:1.

[0030] The ultrasonic treatment time may be 15-60 min, preferably 30 min.

[0031] The frequency of the ultrasound may be 35-45 kHz, preferably 40 kHz.

[0032] The temperature of the ultrasound can be 25-60°C, preferably 50°C.

[0033] In steps S1, S2 and S3, a cleaning step may be included after the preparation is completed.

[0034] Wherein, the cleaning may be magnetic cleaning.

[0035] Wherein, the cleaning can be performed by using ethanol and / or deionized water alternately.

[0036] The cleaning may be performed 5-10 times, for example 10 times.

[0037] In some embodiments, after step S3, a step of modifying the peptide compound is further included, and the step preferably includes mixing a solution containing Fe3O4@Au nanoparticles and a solution containing the peptide compound, and reacting them to obtain the product.

[0038] Wherein, the peptide compound may include a polypeptide, and the polypeptide may be a thiol-modified polypeptide.

[0039] Wherein, the mass ratio of the peptide compound to the Fe3O4@Au nanoparticles may be (45-55):(1-5), for example, 50:3.

[0040] The reaction temperature may be 20-30°C, preferably 25°C.

[0041] The reaction time may be 3-24 hours, preferably 17 hours.

[0042] In some preferred embodiments, the "solution containing a peptide compound" further comprises TCEP (tris-(2-carboxyethyl)phosphine) and an alkaline agent.

[0043] The preparation of the "solution containing peptide compounds" may include dissolving the peptide compounds by ultrasonication, mixing with TCEP, allowing to stand, and adjusting the pH to 7 with an alkaline agent such as sodium hydroxide.

[0044] In some embodiments, after step S3, a step of modifying the non-peptide compound is also included, and the "step of modifying the non-peptide compound" preferably includes mixing a solution containing Fe3O4@Au nanoparticles and a solution containing the non-peptide compound, and reacting to obtain the mixture.

[0045] Among them, the non-peptide compound may include one or more of aromatic acid compounds, organic amine compounds and thiol compounds; the aromatic acid compound preferably includes pyromellitic acid and / or dimethylaminobenzoic acid; the organic amine compound preferably includes hexamethylenediamine; the thiol compound preferably includes one or more of 3-mercapto-1-propanol (3-Mercapto-1-propanol), 2-mercaptonicotinic acid (2-Mercaptonicotinic acid) and 3-mercaptopropionic acid (3-Mercaptopropionic acid).

[0046] Wherein, the mass ratio of the non-peptide compound to the Fe3O4@Au nanoparticles may be (3-5):(4-6), for example, 4:5.

[0047] Wherein, the reaction temperature may be 20-30°C.

[0048] The reaction time may be 8-17 hours, for example 12 hours.

[0049] The second aspect of the present invention provides a surface-modified gold magnetic nanoparticle, which comprises a Fe3O4 magnetic core and a gold layer, and is prepared by the preparation method of the surface-modified gold magnetic nanoparticle as described above.

[0050] In the present invention, the particle size of the Fe3O4 magnetic core can be 10nm-1μm, preferably 210nm.

[0051] In the present invention, the thickness of the gold layer may be 5-15 nm, preferably 10 nm.

[0052] The third aspect of the present invention provides a use of surface-modified gold magnetic nanoparticles in capturing proteins or preparing protein capturing reagents.

[0053] In the present invention, the protein can be a protein in human plasma, animal plasma, human serum, or animal serum.

[0054] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0055] The reagents and raw materials used in the present invention are commercially available.

[0056] The positive and progressive effects of the present invention are:

[0057] The present invention constructs a preparation method of surface-modified gold magnetic nanoparticles based on a specific solvent thermal method. Compared with the existing methods, the advantages are as follows:

[0058] The surface-modified gold magnetic nanoparticles prepared by the present invention have uniform particle size and a wide range, good dispersibility, high stability, can bind to compounds of different molecular sizes, and thus capture more proteins, and have a wide range of applications; the entire preparation method is simple and easy, has lower cost, is safer to operate, and the particle size is controllable during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is the DLS particle size analysis diagram of the Fe3O4 magnetic core, amino-treated Fe3O4 magnetic core and Fe3O4@Au nanoparticles in Example 1.

[0060] Figure 2 This is the Zeta potential analysis diagram of the Fe3O4 magnetic core, the aminated Fe3O4 magnetic core and the Fe3O4@Au nanoparticles in Example 1.

[0061] Figure 3 This is the UV-Vis image of the Fe3O4 magnetic core and Fe3O4@Au nanoparticles in Example 1.

[0062] Figure 4 This is a transmission electron microscope image of the Fe3O4 magnetic core in Example 1.

[0063] Figure 5 This is a transmission electron microscopy image of the Fe3O4@Au nanoparticles in Example 1.

[0064] Figure 6 This is the EDX surface scan image of Fe3O4@Au nanoparticles in Example 1.

[0065] Figure 7 This is the element distribution diagram of Fe3O4@Au nanoparticles in Example 1.

[0066] Figure 8 This is the UV-Vis image of the magnetic beads before and after polypeptide modification in Example 2.

[0067] Fig. 9 This is a statistical chart of protein types captured by polypeptide-modified magnetic beads in Example 2.

[0068] Fig.10 This is a statistical chart of protein types captured by magnetic beads modified with different non-peptide compounds in Example 3.

[0069] Fig.11 This is a statistical chart of protein types captured by magnetic beads modified with different non-peptide compounds in Example 4. DETAILED DESCRIPTION

[0070] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0071] Unless otherwise specified, the plasma used in the following examples is selected from human plasma, animal plasma, human serum, and animal serum.

[0072] Example 1 Preparation of Fe3O4@Au nanoparticles

[0073] (1) Preparation of Fe3O4 magnetic core:

[0074] Dissolve FeCl3·6H2O (0.65 g) and trisodium citrate (0.2 g) in 20 mL of ethylene glycol. Then add sodium acetate (1.2 g) under stirring and stir vigorously for 90 min. Pour into a 50 mL reactor, heat at 200 °C for 10 h, cool to room temperature, and clean by magnetic absorption 10 times with ethanol and deionized water respectively. Use deionized water to concentrate the Fe3O4 magnetic core to 2 mg / mL by magnetic absorption.

[0075] (2) Preparation of amination Fe3O4 magnetic core:

[0076] Take 200 μL of APTES and add it to the Fe3O4 magnetic core solution (50 mL, 2 mg / mL), use a stirring paddle, set the speed to 200 rpm and stir for 6 hours to amino-modify the Fe3O4 magnetic core. Then use deionized water and ethanol to alternately magnetically wash 10 times to wash away the unreacted APTES.

[0077] (3) Preparation of Fe3O4@Au nanoparticles:

[0078] Add 200 mL of deionized water to the washed amination Fe3O4 magnetic cores and add them to a round-bottom flask. Dissolve HAuCl4·4H2O (1 g) in 100 mL of deionized water. Dissolve 0.1 g of trisodium citrate in 10 mL of deionized water to prepare a 0.01 g / mL trisodium citrate solution. Take 10 mL of HAuCl4·4H2O aqueous solution and 10 mL of trisodium citrate solution and add them to the amination Fe3O4 magnetic core solution. Ultrasonicate the mixed solution at 40 kHz for 30 min.

[0079] The product was then washed alternately with deionized water and ethanol for 10 times, and concentrated by magnetic absorption with deionized water to a 2 mg / mL Fe3O4@Au nanoparticle solution.

[0080] (4) Result characterization:

[0081] The products obtained in steps (1)-(3) were characterized as follows:

[0082] DLS particle size characterization: Figure 1 As shown, the particle sizes of Fe3O4 magnetic core, aminated Fe3O4 magnetic core and Fe3O4@Au nanoparticles are 260nm, 272nm and 265nm respectively after DLS testing, and the dispersion PDI are 0.103, 0.098 and 0.105 respectively, indicating that the Fe3O4@Au nanoparticles of the present invention have uniform particle size and are well dispersed.

[0083] Zeta potential test: Figure 2 As shown, the Zeta potential of the Fe3O4 magnetic core, the aminated Fe3O4 magnetic core and the Fe3O4@Au nanoparticles changed from the initial -38.3 mV to +13.1 mV through aminated modification, and then to -36.2 mV through gold coating; among them, the potential changed from negative to positive, which shows that the Fe3O4 magnetic core was successfully aminated, and the potential changed from positive to negative again, which shows that the gold layer was successfully coated on the aminated Fe3O4 magnetic core.

[0084] Ultraviolet-visible spectroscopy (UV-Vis) test: Figure 3 As shown, the blank sample (deionized water) has no obvious absorption peak in the UV-visible absorption spectrum, and Fe3O4 has an absorption peak at 340nm, which is the characteristic absorption peak of Fe3O4 at 340nm. When gold is coated on the Fe3O4 magnetic core, the absorption peak moves to about 590nm, which further illustrates that gold is successfully coated on the Fe3O4 magnetic core.

[0085] Transmission electron microscopy test (morphology characterization): such as Figure 4-5 As shown, Figure 4 This is the morphology of Fe3O4 nanoparticles. Figure 5 The larger nanoparticles are Fe3O4 magnetic cores, and the nanoparticles attached to their surfaces are gold, which proves that Fe3O4@Au nanoparticles were successfully prepared.

[0086] Energy dispersive X-ray spectrometer test (EDX analysis): Figure 6-7 As shown, Figure 6 This is the EDX scan of Fe3O4@Au nanoparticles. It can be seen that gold is evenly distributed on the Fe3O4 surface. Figure 7 This is the distribution diagram of each element. It can be seen that the main elements of the magnetic core are Fe and O, and the surface is covered by Au.

[0087] Example 2 Preparation of peptide compounds combined with Fe3O4@Au nanoparticles (i.e., polypeptide-modified magnetic beads)

[0088] The Fe3O4@Au nanoparticles of Example 1 were used to bind the polypeptide according to the following steps:

[0089] (1) Peptide dissolution

[0090] 1 mg of peptide dry powder (purchased from GenScript Biotech Co., Ltd., with a peptide sequence of LRTLRGQGRYFGITDYDSNGC [SEQ ID NO: 1]) was dissolved in 10 mL of deionized water, mixed with an oscillating mixer for 20 seconds, and then sonicated for 5 minutes to fully dissolve the peptide to form a solution with a concentration of 0.1 mg / mL. 4 mL of the dissolved peptide solution was taken, 100 uL of 200 mM TCEP solution was added, and the solution was allowed to stand at room temperature for 2 hours.

[0091] After standing, 40 μL of 0.6 M NaOH solution was added to adjust the pH to 7.

[0092] (2) Incubation

[0093] Take Fe3O4@Au nanoparticles (1 mg / mL, 500 μL), deionized water (200 μL), and polypeptide (300 μL), add the corresponding amounts in sequence, and react at 25°C for 17 h to obtain polypeptide-modified magnetic beads.

[0094] (3) UV-visible spectrum test

[0095] like Figure 8 As shown, Fe3O4@Au nanoparticles and polypeptide-modified magnetic beads were subjected to UV-Vis tests respectively. It can be seen from the spectrum that the Fe3O4@Au nanoparticles before polypeptide modification have an obvious absorption peak at 400nm. After polypeptide modification, the absorption peak at 400nm increases significantly, indicating that the polypeptide is successfully modified.

[0096] (4) Plasma protein adsorption and mass spectrometry detection

[0097] The peptide-modified magnetic beads were magnetically eluted three times with deionized water to remove the unreacted peptides. They were then incubated with plasma, desalted, and eluted as follows:

[0098] Incubation: 100 μL (6 mg / mL) of peptide-modified magnetic beads were mixed with 100 μL (1:5 dilution) of human plasma, and incubated at room temperature for 1 h at a frequency of 1700 rpm; on a magnetic stand, 200 μL of 1×PBS was washed three times, and the supernatant was discarded; 50 μL of 8M urea (urea), 20mM DTT (dithiothreitol) in 1×PBS solution was added, 37°C, 1h, 1700 rpm; 20 μL of 0.2M IAA (indole-3-acetic acid) was added, room temperature, 0.5h, 1700 rpm; 130 μL of 0.0067 μg / μL trypsin (trypsin), 25mM ammonium bicarbonate solution was added, 37°C, 16h, 1700 rpm; 20 μL of 5% TFA (trifluoroacetic acid) was added.

[0099] Desalting: Activate the C18 in the desalting gun tip, 50% ACN (acetonitrile), 100 μL, blow twice; acidify the C18 in the desalting gun tip, 0.1% TFA, 100 μL, blow three times; use the activated and acidified C18 gun tip to absorb the incubated sample to be desalted, 200 μL, blow slowly ten times, and discard the waste liquid; absorb 0.1% TFA, 100 μL, blow three times, and discard the waste liquid.

[0100] Elution: Use 50uL of 20% ACN and 0.1% FA (folic acid) solution in the C18 gun tip that has been desalted as described above, and quickly pipette and aspirate five times at a speed of 120-150μL per 1s or 1-3s / time, and keep the solution in the gun tip; then add 50μL of 60% ACN and 0.1% FA solution, and quickly pipette and aspirate five times, and keep the solution in the gun tip; then add 50μL of 80% ACN and 0.1% FA solution, and quickly pipette and aspirate five times, and use the mixed solution for mass spectrometry detection.

[0101] The plasma treated with peptide-modified magnetic beads was subjected to mass spectrometry, and the plasma treated with conventional pretreatment (i.e., desalting and elution steps as above) was used as a control. The results were statistically shown as follows: Fig. 9 Among them, 449 proteins can be detected in plasma after peptide-modified magnetic beads treatment ( Fig. 9 A), while only 329 proteins were detected in conventional pre-treated plasma ( Fig. 9 B); that is, the number of protein types captured by the polypeptide-modified magnetic beads of the present invention is significantly increased compared with the number of protein types captured by conventional pre-treatment.

[0102] Example 3 Preparation of non-peptide compound-bound Fe3O4@Au nanoparticles (i.e., non-peptide compound-modified magnetic beads)

[0103] The Fe3O4@Au nanoparticles of Example 1 were used to bind non-peptide compounds according to the following steps:

[0104] (1) First, take 3 mL of Fe3O4@Au and place them in 4 different centrifuge tubes.

[0105] (2) Weigh 0.01 g each of pyromellitic acid, hexamethylenediamine, and dimethylaminobenzoic acid and dissolve them in 10 mL of deionized water.

[0106] (3) Take 100 μL of each of pyromellitic acid, hexamethylenediamine and dimethylaminobenzoic acid solution and add them to 3 mL of Fe3O4@Au solution and shake and mix for 12 hours (temperature 20-30°C).

[0107] (4) The product was washed five times by centrifugation with deionized water and ethanol, respectively, to obtain Fe3O4@Au modified with pyromellitic acid, hexamethylenediamine, and dimethylaminobenzoic acid, respectively.

[0108] (5) According to step (4) of Example 2, the non-polypeptide compound-modified magnetic beads in step (4) of this example are incubated with plasma, desalted, and eluted.

[0109] The plasma treated with non-peptide compound modified magnetic beads was subjected to mass spectrometry, and the plasma treated with conventional pre-treatment (i.e., the desalting and elution steps of Example 2) was used as a control. The results were statistically analyzed as follows: Fig.10 As shown. Among them, hexamethylenediamine, pyromellitic acid, and dimethylaminobenzoic acid modified magnetic beads can capture 449, 530, and 464 proteins respectively ( Fig.10 A, B, C), while only 320 proteins were detected in human plasma with conventional pretreatment.

[0110] Example 4 Preparation of non-peptide compound-bound Fe3O4@Au nanoparticles (i.e., non-peptide compound-modified magnetic beads)

[0111] The Fe3O4@Au nanoparticles of Example 1 were used to bind non-peptide compounds according to the following steps:

[0112] (1) First, take 3 mL of Fe3O4@Au and place them in 4 different centrifuge tubes.

[0113] (2) Weigh 0.01 g each of 3-mercapto-1-propanol, 2-mercaptonicotinic acid, and 3-mercaptopropionic acid and dissolve them in 10 mL of deionized water.

[0114] (3) Take 100 μL of 3-mercapto-1-propanol, 2-mercaptonicotinic acid, and 3-mercaptopropionic acid solutions respectively and add them to 3 mL of Fe3O4@Au solution and shake and mix for 12 hours (temperature 20-30°C).

[0115] (4) The product was washed five times by centrifugation with deionized water and ethanol, respectively, to obtain Fe3O4@Au modified with 3-mercapto-1-propanol, 2-mercaptonicotinic acid, and 3-mercaptopropionic acid, respectively.

[0116] (5) According to step (4) of Example 2, the non-peptide thiol compound-modified magnetic beads in step (4) of this example are incubated with plasma, desalted, and eluted.

[0117] The plasma treated with non-peptide compound modified magnetic beads was subjected to mass spectrometry, and human plasma treated with conventional pretreatment (i.e., the desalting and elution steps of Example 2) was used as a control. The results were statistically analyzed as follows: Fig.11As shown. Among them, 3-mercapto-1-propanol, 3-mercaptopropionic acid, and 2-mercaptonicotinic acid modified magnetic beads can capture 456, 474, and 492 proteins, respectively ( Fig.11 A, B, C), while only 320 proteins were detected in human plasma with conventional pretreatment.

[0118] Comparative Example 1

[0119] On the basis of Example 1, keeping other conditions unchanged, step 1 was changed to first heat the reaction at 170°C for 5h, and then react at 200°C for 5h after cooling to room temperature. The results were as follows:

[0120] After DLS testing, the particle sizes of Fe3O4 magnetic core, aminated Fe3O4 magnetic core, and Fe3O4@Au nanoparticles were 213nm, 320nm, and 350nm, respectively, and the dispersion PDI were 0.242, 0.214, and 0.301, respectively, which were higher than the PDI of Example 1, that is, the particle size uniformity was relatively poor; the Zeta potential of Fe3O4 magnetic core, aminated Fe3O4 magnetic core, and Fe3O4@Au nanoparticles was changed from -50.4mV to +35.1mV through aminated modification, and then to -20.8mV through gold coating. It can be seen that the absolute value of the Zeta potential after coating with the gold layer is smaller than that before coating, that is, the gold coating effect is poor and the stability is poor.

[0121] Comparative Example 2

[0122] On the basis of Example 1, keeping other conditions unchanged, changing the ultrasonic conditions to 60min, 45kHz, the results are as follows:

[0123] After DLS testing, the particle sizes of Fe3O4 magnetic core, aminated Fe3O4 magnetic core, and Fe3O4@Au nanoparticles were 260nm, 272nm, and 220nm, respectively, and the dispersions PDI were 0.103, 0.099, and 0.078, respectively; the Zeta potentials of Fe3O4 magnetic core, aminated Fe3O4 magnetic core, and Fe3O4@Au nanoparticles were changed from -38.2mV to +13.2mV through amination modification, and then to -25.6mV through gold coating. It can be seen that the absolute value of the Zeta potential after coating with the gold layer is smaller than that before coating, that is, the coating effect and stability are poor.

[0124] Comparative Example 3

[0125] On the basis of Example 1, keeping other conditions unchanged, the mass ratio of HAuCl4·4H2O and trisodium citrate was changed to 1.2:1, and the results were as follows:

[0126] The particle sizes of Fe3O4 magnetic core, aminated Fe3O4 magnetic core and Fe3O4@Au nanoparticles were 260nm, 272nm and 337nm respectively after DLS testing, and the dispersions PDI were 0.101, 0.097 and 0.241 respectively; the Zeta potentials of Fe3O4 magnetic core, aminated Fe3O4 magnetic core and Fe3O4@Au nanoparticles were changed from -38.1mV to +12.8mV through amination modification, and then to -10.8mV through gold coating. It can be seen that the absolute value of the Zeta potential after coating with gold layer is smaller than that before coating, that is, the coating effect and stability are poor.

Claims

1. A method for preparing surface-modified gold magnetic nanoparticles, characterized in that: The method comprises the following steps: S1, preparation of Fe3O4 magnetic core; S2, preparation of functionalized Fe3O4 magnetic core; S3, preparation of Fe3O4@Au nanoparticles; wherein, In step S1, the preparation of the Fe3O4 magnetic core includes mixing a first mixed solution containing an iron precursor, a reducing agent and ethylene glycol with an alkaline reagent to obtain a second mixed solution, heating the mixture in a one-step reaction, and cooling the mixture; The preparation method is a solvothermal method; The preparation of the first mixed solution comprises dissolving the iron precursor and the reducing agent in ethylene glycol to obtain; The iron precursor includes one or more of ferrous chloride, ferric acetylacetonate, ferric chloride and ferric oxide; The molar ratio of the iron precursor to the reducing agent is (2.4-3.3):1; The molar ratio of the iron precursor to the alkaline agent is (0.13-0.18):1; In step S2, the preparation of the functionalized Fe3O4 magnetic core comprises stirring and mixing a functionalizing agent and a solution containing the Fe3O4 magnetic core; The functionalizing agent is an amination agent; The usage ratio of the functionalizing agent and the Fe3O4 magnetic core is (0.5-2) μL: (0.5-2) mg; In step S3, the preparation of the Fe3O4@Au nanoparticles comprises mixing a gold precursor, a reducing agent and the functionalized Fe3O4 magnetic core, and then ultrasonicating the mixture; The gold precursor includes one or more of gold chloride, chloroauric acid, sodium gold thiosulfate and gold acetate; The molar ratio of the gold precursor to the reducing agent is (0.3-1.8):1; After step S3, a non-peptide compound modification step is also included, wherein the "non-peptide compound modification step" includes mixing a solution containing Fe3O4@Au nanoparticles and a solution containing a non-peptide compound, and reacting to obtain; The non-peptide compound is pyromellitic acid and / or 2-mercaptonicotinic acid; The mass ratio of the non-peptide compound to the Fe3O4@Au nanoparticles is (3-5):(4-6).

2. The preparation method according to claim 1, characterized in that In step S1, the temperature of the one-step reaction is 190-220°C; And / or, in step S1, the one-step reaction time is 6-72h; And / or, in step S1, the iron precursor is ferric chloride; And / or, in step S1, the reducing agent is trisodium citrate; And / or, in step S1, the alkaline reagent is sodium acetate and / or sodium hydroxide.

3. The preparation method according to claim 2, characterized in that: In step S1, the alkaline reagent is sodium acetate.

4. The preparation method according to claim 1, characterized in that: In step S2, the functionalizing agent is aminopropyltriethoxysilane.

5. The preparation method according to claim 1, characterized in that: In step S3, the gold precursor is chloroauric acid; And / or, the reducing agent is trisodium citrate; And / or, the ultrasonic time is 15-60min; And / or, the frequency of the ultrasound is 35-45kHz; And / or, the temperature of the ultrasound is 25-60°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In steps S1, S2 and S3, a cleaning step is included after the preparation is completed.

7. The preparation method according to claim 6, characterized in that: The cleaning is magnetic cleaning; And / or, the cleaning is performed by alternately using ethanol and / or deionized water; And / or, the cleaning is performed 5-10 times.

8. The preparation method according to claim 6, characterized in that: In the "non-peptide compound modification step", the reaction temperature is 20-30°C; And / or, the reaction time is 8-17h.

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