Preparation method for functionalized NANO magnetic beads

Abstract

The present invention relates to a preparation method for functionalized nano magnetic beads. The preparation method comprises: mixing an iron salt with an alkali to obtain a magnetic core; subjecting glucan to a functionalization reaction, so as to obtain functionalized glucan; and mixing the magnetic core with the functionalized glucan, and then subjecting the mixture to an ultrasonic treatment and sorting, so as to obtain the functionalized nano magnetic bead. By means of the method of the present invention, nanoparticles having a particle size on a nanoscale can be obtained, and the surface of the particles is coated with polysaccharide molecules having a functional group. By means of the hydrophilicity of the polysaccharide molecules, the nanoparticles can be stably dispersed in an aqueous solution.

Description

A method for preparing functionalized nanomagnetic beads Technical Field

[0001] The present invention belongs to the technical field of immunomagnetic beads and relates to a preparation method of functionalized nanomagnetic beads and products thereof. Background Art

[0002] Magnetic beads are a new multifunctional material developed in recent years and widely used in the biomedical field. They typically consist of a magnetic core surrounded by a coating (such as a precious metal, polymer, inorganic oxide, or polysaccharide). Because the core is responsive to an external magnetic field, it rapidly aggregates in the presence of a magnetic field, allowing for rapid and complete separation within a dispersed solution. Upon removal of the magnetic field, they quickly disperse again. Generally, functionalized nanoparticles for use in the biological, medical, and food industries must meet several requirements: ① small and uniform particle size; ② good suspension stability; ③ high magnetic responsiveness; and ④ good biocompatibility.

[0003] Due to different reaction mechanisms, magnetic nanoparticles are generally prepared using methods such as coprecipitation, microemulsion, precursor thermal decomposition, hydrothermal, and sol-gel. Unmodified Fe₃O₄ magnetic cores easily aggregate in solution, are unstable, and are easily oxidized. Therefore, in practical applications, the cores must be surface-coated and modified to ensure chemical stability and biocompatibility. Furthermore, depending on the intended use, the beads must maintain good suspension in the dispersion solvent. Common surface modification methods include surface passivation, polymer coating, precious metal coating, and silica coating. Coating-modified magnetic particles can form a core-shell structure. SiO₂ is an ideal coating material due to its non-toxicity, excellent chemical stability, optical transparency, biocompatibility, and strong resistance to decomposition. Therefore, silica coating using a silanization agent is a commonly used coating method. Among reports on SiO₂ coating of magnetic nanoparticles, the sol-gel method is currently the most widely used and successful method. However, the Fe3O4@SiO2 composite particles obtained in many studies are not ideal, and the magnetic core agglomeration is serious, which affects further applications. The magnetic beads currently available on the market often have a contradiction between suspension stability and high magnetic responsiveness. In order to achieve high magnetic responsiveness, magnetic beads with large particle size are usually selected. However, large particle size leads to poor suspension stability and low adsorption capacity for target products. While increasing its adsorption capacity by adding a polymer coating layer will increase the content of non-magnetic substances, it will inevitably lead to a decrease in magnetic content, that is, a decrease in magnetic responsiveness.

[0004] Furthermore, the particle size distribution of magnetic beads produced by existing methods is relatively broad. Furthermore, the existing methods for producing magnetic beads of varying sizes are closely tied to time, primarily by controlling the time the beads are exposed to the magnetic field and the time they are eluted. This makes it difficult to reproducibly produce beads of a specific size, even under strictly controlled experimental conditions. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing functionalized nanomagnetic beads and a product thereof.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, a method for preparing functionalized nanomagnetic beads comprises:

[0008] (1) Mixing iron salt and alkali to obtain a magnetic core; performing a functionalization reaction on dextran to obtain functionalized dextran;

[0009] (2) Mix the magnetic core and the functionalized dextran, sonicate, and separate to obtain the product.

[0010] The magnetic core prepared by the above preparation method has a particle size of micrometer level, and the present invention creatively finds that functionalizing the dextran in advance and then mixing it with the magnetic core can improve the stability of the magnetic beads.

[0011] Preferably, the iron salt includes divalent iron salt and trivalent iron salt.

[0012] Preferably, the molar mass ratio of the divalent iron salt to the trivalent iron salt is (1-3):(1-2).

[0013] The specific point values ​​in (1-3) can be selected as 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc. The specific point values ​​in (1-2) can be selected as 1, 1.2, 1.4, 1.6, 1.8, 2, etc. Other specific point values ​​within the above numerical range can be selected, so they will not be listed here one by one.

[0014] Preferably, the mass ratio of the iron salt to the base is (1-2):(1-3).

[0015] The specific point values ​​in (1-3) can be selected as 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc. The specific point values ​​in (1-2) can be selected as 1, 1.2, 1.4, 1.6, 1.8, 2, etc. Other specific point values ​​within the above numerical range can be selected, so they will not be listed here one by one.

[0016] Preferably, the iron salt is mixed with the base in an oxygen-free environment.

[0017] Preferably, the mixing temperature is 60-90° C. and the mixing time is 0.5-2 h.

[0018] The temperature can be selected from 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, etc., and the time can be selected from 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, etc. Other specific point values ​​within the above numerical range can be selected, and they will not be repeated here.

[0019] Preferably, the iron salt and the alkali are mixed and then subjected to magnetic adsorption and washing.

[0020] Preferably, the functionalized dextran includes carboxylated dextran or amino dextran.

[0021] Preferably, the carboxylated dextran is prepared by the following method: mixing a dextran aqueous solution with sodium borohydride and sodium hydroxide, then mixing with a sodium chloroacetate solution and sodium hydroxide, dialyzing, and freeze-drying.

[0022] Preferably, the mass ratio of dextran, sodium hydroxide and sodium chloroacetate is (1-10):(0.1-1):(5-20):(0.5-5).

[0023] Among them, the specific point values ​​in (1-10) can be selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., the specific point values ​​in (0.1-1) can be selected from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc., the specific point values ​​in (5-20) can be selected from 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 7, 18, 19, 20, etc., the specific point values ​​in (0.5-5) can be selected from 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., and other specific point values ​​within the above numerical range can be selected, so they will not be listed here one by one.

[0024] Preferably, the amino-dextran is prepared by the following method: mixing dextran with dimethyl sulfoxide, then sequentially mixing with sodium cyanoborohydride and hexamethylenediamine, dialyzing, and freeze-drying.

[0025] Preferably, the mass ratio of dextran, dimethyl sulfoxide, sodium cyanoborohydride and hexamethylenediamine is (1-5):(40-100):(0.5-2):(0.05-0.5).

[0026] Among them, the specific point values ​​in (1-5) can be selected as 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., the specific point values ​​in (40-100) can be selected as 40, 50, 60, 70, 80, 90, 100, etc., the specific point values ​​in (0.5-2) can be selected as 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc., the specific point values ​​in (0.05-0.5) can be selected as 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc., and other specific point values ​​within the above numerical range can be selected, so they will not be listed here one by one.

[0027] Preferably, the mass ratio of the magnetic core to the functionalized dextran is (1-10):(1-100).

[0028] Among them, the specific point values ​​in (1-10) can be selected as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., and the specific point values ​​in (1-100) can be selected as 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, etc. Other specific point values ​​within the above numerical range can be selected, so they will not be listed here one by one.

[0029] Preferably, the power of the ultrasound is 200-2000W, and the time is 10s-60min.

[0030] The power can be selected from 200 W, 300 W, 400 W, 500 W, 600 W, 700 W, 800 W, 900 W, 1000 W, 1200 W, 1400 W, 1600 W, 1800 W, 2000 W, etc., and the time can be selected from 10 s, 20 s, 30 s, 40 s, 50 s, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc. Other specific point values ​​within the above numerical range can be selected, and they will not be described one by one here.

[0031] Preferably, the sorting step includes sorting in magnetic fields from weak to strong in sequence.

[0032] Preferably, the step of sorting comprises sequentially sorting in a magnetic field with a magnetic field strength of 4000-9000 gs.

[0033] The magnetic field strength can be selected as 4000gs, 5000gs, 6000gs, 7000gs, 8000gs, 9000gs, etc. Other specific point values ​​within the above numerical range can be selected, and they will not be described here one by one.

[0034] In a second aspect, the present invention provides magnetic beads prepared according to the method for preparing functionalized nanomagnetic beads described in the first aspect.

[0035] The magnetic beads can be used for labeling, tracing or separation of target products.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The method described herein can produce nanoparticles with nanometer-scale particle sizes, the surface of which is coated with polysaccharide molecules bearing functional groups. The hydrophilicity of the polysaccharide molecules allows the nanoparticles to be stably dispersed in aqueous solutions. The present inventors have discovered that pre-functionalizing the dextran before mixing it with the magnetic core can improve the stability of the magnetic beads. The method of the present invention can accurately and repeatedly prepare multiple nanomagnetic beads of a specific size in a single step, with high reproducibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a graph showing the particle size distribution of magnetic cores.

[0039] FIG2 is a comparison diagram of infrared spectra of carboxydextran and dextran.

[0040] FIG3 is a comparison chart of infrared spectra of aminodextran and dextran.

[0041] FIG4 is a graph showing the particle size distribution of the magnetic beads prepared in Example 1.

[0042] FIG5 is a graph showing the potential distribution of the magnetic beads prepared in Example 1.

[0043] FIG6 is a graph showing the potential distribution of the magnetic beads prepared in Example 1.

[0044] Figures 7a, 7b, and 7c are graphs showing the particle size distribution of the magnetic beads prepared in Example 2.

[0045] FIG8 is a comparison diagram of the magnetic beads prepared in Example 1 and Comparative Example 1 after mixing and standing for half an hour.

[0046] FIG9 is a comparison of magnetic beads prepared in Example 1 and Comparative Example 1, mixed and placed close to the same side of a magnet and left stationary for 2 minutes.

[0047] FIG10 is a comparison diagram of the magnetic beads prepared in Example 1 and Comparative Example 1, after being mixed and placed close to both sides of the same magnet and left to stand for 2 minutes. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] Preparation Example 1

[0050] This preparation example provides a magnetic core, which is prepared by the following method:

[0051] (1) Weigh 90.1 g of FeCl₃·6H₂O using an analytical balance and place it in a 500 mL beaker. Pour 500 mL of ultrapure water into the beaker and stir to dissolve.

[0052] (2) After dissolution, pour into a flask and stir (speed 300 rpm). Connect the flask to a vacuum pump and nitrogen gas line respectively.

[0053] (3) Turn on the vacuum pump switch, exhaust the air in the reaction system and stop the vacuum pump; then introduce nitrogen into the reaction system.

[0054] (4) Repeat step (3) twice.

[0055] (5) Finally, keep the reaction system connected to nitrogen.

[0056] (6) Weigh 40.5 g of FeCl2·4H2O into a 500 mL beaker and dissolve it in 450 mL of ultrapure water.

[0057] (7) Pour the dissolved FeCl2·4H2O liquid into the flask in step (2), and then perform step (3) three times.

[0058] (8) Keep the reaction system connected to nitrogen; install a constant pressure funnel on the flask, and add 320 mL of concentrated ammonia water into the funnel.

[0059] (9) Rotate the valve of the constant pressure funnel to allow the ammonia solution to drip into the three-necked flask.

[0060] (10) After the ammonia solution is added, install the condensing device on the flask and start the condensation.

[0061] (11) Turn on the thermostatic bath and set the temperature to 90°C for one hour. Turn off the heat and transfer all the sample in the three-necked flask that has cooled to room temperature to the beaker.

[0062] (12) Use a magnet to magnetically adsorb the liquid in the beaker. After all the magnetic cores are adsorbed, carefully pour out the supernatant. Remove the beaker from the magnet and add ultrapure water and stir evenly.

[0063] (13) Repeat step (12) until the pH of the supernatant reaches 7.

[0064] (14) The cleaned magnetic cores in step (13) are transferred to a wide-mouth bottle for storage to obtain micron magnetic cores.

[0065] Preparation Example 2

[0066] This preparation example provides a carboxylated glucan, which is prepared by the following method:

[0067] (1) Dissolve 10 g of dextran (average molecular weight 40k) in 40 mL of water and stir for 1 hour;

[0068] (2) Add sodium borohydride solution (0.3 g dissolved in 1.6 mL) and sodium hydroxide solution (1 g dissolved in 1.5 mL water), stir for 15 minutes, then add sodium chloroacetate solution (4.5 g dissolved in 40 mL water) and sodium hydroxide solution (4 g dissolved in 10 mL water);

[0069] (3) Heat to 90°C and maintain for 1 hour;

[0070] (4) Cool and neutralize with 1M hydrochloric acid to pH = 7;

[0071] (5) Place the sample in a 40K dialysis bag and dialyze it in phosphate buffer for 24 hours to remove salt and small molecular weight impurities;

[0072] (6) Freeze-dry the sample using a vacuum dryer.

[0073] Preparation Example 3

[0074] This preparation example provides an amino-glucan, which is prepared by the following method:

[0075] (1) Add 40 g of dimethyl sulfoxide to 2 g of dextran (average molecular weight 40k) and stir for 1 hour;

[0076] (2) 1 g of sodium cyanoborohydride was added to the solution of step (1) and stirred at room temperature for 24 hours;

[0077] (3) 0.3 g of hexamethylenediamine (HMDA) was added to the above reaction system and stirred at room temperature for 24 hours;

[0078] (4) Place the modified dextran in a 40K dialysis bag and dialyze it in phosphate buffer for 24 hours to remove salt and small molecular weight impurities;

[0079] (5) Freeze-dry the sample using a vacuum dryer.

[0080] Example 1

[0081] This embodiment provides a functionalized nanomagnetic bead, which is prepared by the following method:

[0082] (1) Disperse 1.0 g of the magnetic core described in Preparation Example 1 in 500 mL of phosphate buffer;

[0083] (2) Place the magnetic core dispersion in an ultrasonic crusher (500W), turn on the ultrasonic wave, and process for 20 minutes; the system temperature must be kept below 60 degrees during the ultrasonic process;

[0084] (3) Slowly add 500 mL of phosphate buffer containing 1 g of the carboxylated dextran described in Preparation Example 2 to the magnetic core dispersion;

[0085] (4) Continue ultrasonication for 30 minutes; the system temperature must be kept below 60 degrees during the ultrasonication process;

[0086] (5) Stop ultrasound, take out the sample, put it into a centrifuge, set it to 2000g, and centrifuge for 10 minutes;

[0087] (6) After centrifugation, carefully collect the supernatant and perform magnetic cleaning on the supernatant using a Miltenyi separator and separation column;

[0088] (7) Use phosphate buffer to collect the dextran magnetic beads in the separation column.

[0089] Example 2

[0090] This embodiment provides a functionalized nanomagnetic bead, which is prepared by the following method:

[0091] (1) Disperse 1.0 g of the magnetic core described in Preparation Example 1 in 500 mL of phosphate buffer;

[0092] (2) Place the magnetic core dispersion in an ultrasonic crusher (500W), turn on the ultrasonic wave, and process for 20 minutes; the system temperature must be kept below 60 degrees during the ultrasonic process;

[0093] (3) Slowly add 500 mL of phosphate buffer containing 1 g of the carboxylated dextran described in Preparation Example 2 to the magnetic core dispersion;

[0094] (4) Continue ultrasonication for 30 minutes; the system temperature must be kept below 60 degrees during the ultrasonication process;

[0095] (5) Stop ultrasound, take out the sample, put it into a centrifuge, set it to 2000g, and centrifuge for 10 minutes;

[0096] (6) After centrifugation, carefully collect the supernatant and perform magnetic cleaning on the supernatant by passing it through multiple Miltenyi separators and separation columns with different magnetic field strengths. Specifically, the carefully collected supernatant is sequentially passed through separation columns in separators with magnetic field strengths of increasing strength from weak to strong. Preferably, the supernatant is sequentially passed through three separation columns in separators with magnetic field strengths of 4000 gs, 6000 gs, and 9000 gs, respectively.

[0097] (7) Using phosphate buffer solution, the dextran magnetic beads in the above-mentioned multiple separation columns are collected separately, thereby preparing dextran magnetic beads with different median particle sizes at one time.

[0098] The particle size distribution of the magnetic beads prepared by Example 2 is shown in Figures 7a to 7c. Figure 7a shows the particle size distribution of the magnetic beads obtained by elution after being placed in a sorting column with a magnetic field strength of 4000gs. The particle size distribution of the magnetic beads shown in Figure 7a is in the range of 60-200nm, and the median particle size is about 90nm. Figure 7b shows the particle size distribution of the magnetic beads obtained by elution after being placed in a sorting column with a magnetic field strength of 6000gs. The particle size distribution of the magnetic beads shown in Figure 7b is in the range of 40-100nm, and the median particle size is about 60nm. Figure 7c shows the particle size distribution of the magnetic beads obtained by elution after being placed in a sorting column with a magnetic field strength of 9000gs. The particle size distribution of the magnetic beads shown in Figure 7c is in the range of 15-50nm, and the median particle size is about 20nm.

[0099] The method of this embodiment allows the simultaneous production of nanomagnetic beads with varying median particle sizes, resulting in a smaller, more uniform, and stable particle size distribution. The method of this embodiment allows the precise production of nanomagnetic beads of a specific size, and does not rely on strict control of sorting and elution times, requiring minimal operator intervention and exhibiting high reproducibility.

[0100] Example 3

[0101] This embodiment provides a functionalized nanomagnetic bead, which is prepared by the following method:

[0102] (1) Disperse 1.0 g of the magnetic core described in Preparation Example 1 in 500 mL of phosphate buffer;

[0103] (2) Place the magnetic core dispersion in an ultrasonic crusher (500W), turn on the ultrasonic wave, and process for 10 minutes; the system temperature must be kept below 60 degrees during the ultrasonic process;

[0104] (3) Slowly add 500 mL of phosphate buffer containing 2 g of the amino-dextran described in Preparation Example 3 to the magnetic core dispersion;

[0105] (4) Continue ultrasonication for 30 minutes; the system temperature must be kept below 60 degrees during the ultrasonication process;

[0106] (5) Stop ultrasound, remove the sample, and place it in a centrifuge at 2000g for 10 minutes;

[0107] (6) After centrifugation, carefully collect the supernatant and perform magnetic cleaning on the supernatant using a Miltenyi separator and separation column;

[0108] (7) Use phosphate buffer to collect the dextran magnetic beads in the separation column.

[0109] Comparative Example 1

[0110] This comparative example provides a functionalized nanomagnetic bead, which is prepared by the following preparation method:

[0111] (1) Use an analytical balance to weigh 9.02 g of FeCl3·6H2O and 30 g of dextran (average molecular weight 40K) into a 500 mL beaker. Pour 500 mL of ultrapure water into the beaker and stir to dissolve.

[0112] (2) After dissolution, pour into a three-necked flask (1 L) and stir (speed 300 rpm). Connect the flask to a vacuum pump and nitrogen gas line respectively.

[0113] (3) Turn on the vacuum pump switch, exhaust the air in the reaction system and stop the vacuum pump; then introduce nitrogen into the reaction system.

[0114] (4) Repeat step (3) twice.

[0115] (5) Finally, keep the reaction system connected to nitrogen.

[0116] (6) Weigh 4.03 g of FeCl2·4H2O and dissolve it in 450 mL of ultrapure water in a 500 mL beaker.

[0117] (7) Pour the dissolved FeCl2·4H2O liquid into the flask in step (2), and then perform step (3) three times.

[0118] (8) Keep the reaction system connected to nitrogen; install a constant pressure funnel on the flask, and add 320 mL of concentrated ammonia water into the funnel.

[0119] (9) Rotate the valve of the constant pressure funnel to allow the ammonia solution to drip into the three-necked flask.

[0120] (10) After the ammonia solution is added, install the condensation device on the flask and start condensation.

[0121] (11) Turn on the thermostatic bath and set the temperature to 90°C for one hour. Turn off the heat and pour the liquid in the three-necked flask, which has cooled to room temperature, into the beaker.

[0122] (12) Place the sample in a centrifuge, set to 2000g, and process for 10 minutes.

[0123] (13) After centrifugation, carefully collect the supernatant and perform magnetic cleaning on the supernatant using a Miltenyi separator and separation column.

[0124] (14) Use phosphate buffer to collect the dextran magnetic beads in the separation column.

[0125] (15) Sodium borohydride solution (0.3 g dissolved in 1.6 mL) and sodium hydroxide solution (1 g dissolved in 1.5 mL water) were added, stirred for 15 minutes, and then sodium chloroacetate solution (4.5 g sodium chloroacetate dissolved in 40 mL water) and sodium hydroxide solution (4 g sodium hydroxide dissolved in 10 mL water) were added.

[0126] (16) Heat to 90°C and maintain for 1 hour.

[0127] (17) Cool and neutralize with 1 M hydrochloric acid to pH = 7.

[0128] (18) Place the sample in a dialysis bag with a molecular weight of 40K and dialyze it in phosphate buffer for 24 hours to remove salt and small molecular weight impurities.

[0129] Test Example 1

[0130] Particle size analysis

[0131] The magnetic core prepared in Preparation Example 1 was subjected to particle size analysis. The results are shown in FIG1 . The particle size of the prepared magnetic core is in the micron level, and the particle size distribution is relatively wide, with the main particle size distribution being between 2 μm and 60 μm.

[0132] The infrared spectra of the carboxylated dextran prepared in Preparation Example 2 were compared with those of dextran. The results are shown in Figure 2. In the spectrum of the carboxylated dextran, the absorption peak intensity of OH at around 3000 is enhanced due to the influence of the C=O double bond. A strong C=O absorption peak appears between 1700 and 1600.

[0133] The infrared spectra of the aminodextran prepared in Preparation Example 3 were compared with those of dextran. As shown in Figure 3, the aminodextran showed a strong absorption peak of NH between 3400 and 3300, and an absorption peak of NH also appeared between 1700 and 1590. A strong absorption peak of CN appeared between 1100 and 1000.

[0134] The functionalized nanomagnetic beads prepared in Example 1 were subjected to particle size analysis. The results are shown in FIG4 . After ultrasound treatment, the particle size of the magnetic cores was reduced from micrometer level to nanometer level, and the distribution thereof was mostly concentrated between 30-100 nm.

[0135] The functionalized nanomagnetic beads prepared in Example 1 were subjected to zeta potential detection. The results are shown in FIG5 . The surface potential of the carboxyl magnetic beads was -20 to -30 mV, indicating that after ultrasound, the magnetic core was coated with carboxyl dextran and stably dispersed in water, and the surface had abundant carboxyl groups.

[0136] The functionalized nanomagnetic beads prepared in Example 2 were subjected to zeta potential detection. The results are shown in FIG6 . The surface potential was +20 to +30 mV, indicating that the magnetic cores were coated with aminodextran in the solution after ultrasonic dispersion, and the surface exhibited a positive potential due to the presence of amino groups.

[0137] Test Example 2

[0138] Stability analysis

[0139] Equal amounts of the dextran magnetic bead suspensions of Example 1 and Comparative Example 1 were mixed and allowed to stand in the same environment for 300 min. The results are shown in FIG8 . As can be seen from FIG8 , the magnetic bead suspension prepared by the method of the present invention did not settle, but the magnetic bead suspension prepared by the method of Comparative Example 1 did significantly settle.

[0140] Equal amounts of the dextran magnetic bead suspensions of Example 1 and Comparative Example 1 were mixed and placed symmetrically on both sides of the same surface of a magnet (5000GS) for 2 minutes. The results are shown in FIG9 . As can be seen from FIG9 , the magnetic bead suspension prepared by the method of the present invention remained stable, but the magnetic bead suspension prepared by the method of Comparative Example 1 was significantly adsorbed by the magnet.

[0141] Equal amounts of the dextran magnetic bead suspensions of Example 1 and Comparative Example 1 were mixed and placed close to each other on both sides of the same magnet (5000GS) for 2 minutes. The results are shown in FIG10 . As can be seen from FIG10 , the magnetic bead suspension prepared by the method of the present invention remained stable, but the magnetic bead suspension prepared by the method of Comparative Example 1 was significantly adsorbed by the magnet.

[0142] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the preparation method of functionalized nanomagnetic beads and the product thereof, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary ingredients, selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

[0143] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0144] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing functionalized nanomagnetic beads, characterized in that: The preparation method comprises: (1) Mixing iron salt and alkali to obtain magnetic cores with a particle size of micrometer level; performing functionalization reaction on dextran to obtain functionalized dextran; (2) Mixing the magnetic core with the functionalized dextran, ultrasonicating, and sorting to obtain the product; The mass ratio of the magnetic core to the functionalized dextran is 1:(1-2).

2. The method for preparing functionalized nanomagnetic beads according to claim 1, wherein The iron salts include divalent iron salts and trivalent iron salts; Preferably, the molar mass ratio of the divalent iron salt to the trivalent iron salt is (1-3):(1-2).

3. The method for preparing functionalized nanomagnetic beads according to claim 1 or 2, wherein: The mass ratio of the iron salt to the alkali is (1-2):(1-3); Preferably, the iron salt is mixed with the base in an oxygen-free environment.

4. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 3, characterized in that: The mixing temperature is 60-90° C. and the mixing time is 0.5-2 h.

5. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 4, characterized in that: The iron salt is mixed with the alkali and also includes magnetic adsorption and washing.

6. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 5, characterized in that: The functionalized glucan includes carboxylated glucan or amino glucan; Preferably, the carboxylated dextran is prepared by the following method: mixing a dextran aqueous solution with sodium borohydride and sodium hydroxide, then mixing with a sodium chloroacetate solution and sodium hydroxide, dialyzing, and freeze-drying to obtain the dextran; Preferably, the mass ratio of the dextran, sodium borohydride, sodium hydroxide and sodium chloroacetate is (1-10):(0.1-1):(5-20):(0.5-5).

7. The method for preparing functionalized nanomagnetic beads according to claim 6, characterized in that: The amino dextran is prepared by the following method: mixing dextran with dimethyl sulfoxide, then mixing with sodium cyanoborohydride and hexamethylenediamine in sequence, dialyzing, and freeze-drying to obtain the product; Preferably, the mass ratio of dextran, dimethyl sulfoxide, sodium cyanoborohydride and hexamethylenediamine is (1-5):(40-100):(0.5-2):(0.05-0.5).

8. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 7, characterized in that: The mass ratio of magnetic core to functionalized dextran is (1-10):(1-100).

9. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 8, characterized in that: The power of the ultrasound is 200-2000W, and the time is 10s-60min.

10. The method for preparing functionalized nanomagnetic beads according to any one of claims 1 to 9, characterized in that: The step of sorting includes sorting in magnetic fields from weak to strong in sequence; Preferably, the step of sorting comprises sequentially sorting in a magnetic field with a magnetic field strength of 4000-9000 gs.

Images