CN103310935A - Silicon dioxide nano magnetic microsphere and preparation method thereof - Google Patents

Abstract

The invention discloses a silica nano-magnetic microsphere, which has a particle diameter of 50-600nm, an inner core of magnetic nanoparticles with a particle diameter of 10-500nm, a middle layer of dense silicon dioxide with a thickness of 1-10nm, and an outer layer of The layer is mesoporous silicon dioxide, the specific surface area of the nano magnetic microsphere is 10-500m ² /g, and the average pore diameter is 2-50nm. It adopts the method of dispersing magnetic nanoparticles in a solvent, adding a dense silica precursor and stirring the reaction, so that the outer surface of the magnetic nanoparticles is covered with a layer of dense silica; then adding the mesoporous silica precursor and stirring the reaction ; Separation and mesoporization to obtain silica nano-magnetic microspheres with mesoporous structure. The silica nano-magnetic microspheres of the present invention have the functions of large specific surface area, adjustable pore size and the ability to load molecules of different sizes, and have a wide range of applications in cell separation, immobilized enzymes, protein separation, immunodetection, and immunodiagnosis of water pollutants. the use of.

Description

Silica nano-magnetic microspheres and preparation method thereof

technical field

The invention belongs to the technical field of inorganic nanoparticles, and in particular relates to a silicon dioxide nano-magnetic microsphere and a preparation method thereof.

Background technique

Magnetic nanoparticles can be magnetized under the action of an external magnetic field, and have been widely studied in the biological field, such as magnetic resonance imaging, drug delivery, biosensors, bioseparation, and thermomagnetic diagnosis and treatment, etc.; separated out. The method is sensitive, simple and efficient. Therefore, magnetic mesoporous materials with both magnetism and high specific surface area are considered to be a kind of macromolecule loading materials with great application potential. It has good application prospects in sewage treatment, separation and enrichment of biomolecules, heterogeneous catalyst carrier and other fields. However, bare magnetic nanoparticles such as _Fe3O4 are unstable, and the structure is easily destroyed under acidic and higher _temperature . Therefore, in general, magnetic composite materials have a magnetic core and a non-magnetic surface coating, including polymers, carbon, and silicon dioxide, which can provide high adsorption specific surface area and chemical stability. In comparison, SiO ₂ is considered to be an ideal coating material due to its stable performance and its surface is easily functionalized by some functional groups such as amino, mercapto, carboxyl, etc. Some scholars have proved that if a layer of inert material such as SiO ₂ can be coated on the surface of magnetic nanoparticles, in aqueous solution, the aggregation of magnetic nanoparticles can be prevented and their chemical stability can be improved.

Currently, CN200910219335 patent discloses a silica magnetic composite microsphere, which contains a core of magnetic iron oxide and a dense and non-porous silica shell. An important function of the inert, dense, non-porous silica shell is to coat the highly chemically active iron oxide, making it safe to use under different conditions. However, due to the dense and non-porous silica structure, the specific surface area of silica magnetic composite microspheres is small, and the number of loaded molecules is limited, which greatly reduces its application efficiency. One solution is to wrap a porous silica structure around the dense, nonporous silica layer. Chinese patents ZL200710055604 and ZL200810050222.9 disclose a method for preparing magnetic microspheres with porous nano-core-shell structure. The inventors used cetyltrimethylammonium bromide as a template to prepare a material with a porous silica shell. But on the one hand cetyltrimethylammonium bromide is very expensive, its usage is directly proportional to the pore structure, and the preparation cost is too high; None exceed 3.8nm, and the practical applicability is not strong. Therefore, the synthesis of silica nano-magnetic microspheres with high specific surface area, large pore volume and uniform pore size at a low cost has become an urgent problem to be solved.

Contents of the invention

The present invention aims to provide a low-cost preparation technology for preparing porous silica nano-magnetic microspheres, aiming at the main technical problems of the magnetic composite microspheres in the prior art, such as small specific surface area, small pore size and uneven distribution.

The nano-magnetic microsphere of the present invention has a particle diameter of 50-600nm, its inner core is a monodisperse magnetic nano-particle with a particle diameter between 10-500nm, the middle layer is dense silicon dioxide with a thickness of 1-10nm, and the outer layer is It is mesoporous silicon dioxide, wherein, the specific surface area of the nano magnetic microsphere is 10-500m ² /g, and the average pore diameter of the mesoporous silicon dioxide is 2-50nm. The pore size of the outer layer of silica can be controlled according to the size of the macromolecule to be loaded. The nano-magnetic microspheres of the present invention have a monodisperse structure, so that the dense silicon dioxide in the middle layer can be tightly coated on the surface of the magnetic nanoparticles, thereby ensuring that the magnetic nano-magnetic microspheres per unit mass are stronger, and their specific surface area is larger, which can provide more reactive groups.

A preferred embodiment of the present invention is that the present invention specifically provides a nano-magnetic microsphere with a small pore size and a large specific surface area. The specific surface area is 120-280m ² /g, preferably 130-180m ² /g. The average pore diameter of silicon is 2-8 nm, preferably 4.2-6 nm. Another preferred embodiment is that the present ^invention specifically provides a nano-magnetic microsphere with a large pore size and ^a small specific surface area. The average pore diameter is 10-50 nm, preferably 15-25 nm.

Preferably, the nano-magnetic microspheres have a particle size of 50-100 nm, preferably 50-90 nm, and the inner cores are magnetic nanoparticles with a monodisperse structure with a particle size of 50-200 nm, preferably 30-80 nm, The middle layer is dense silicon dioxide with a thickness of 5-10 nm, and the outer layer is mesoporous silicon dioxide with a thickness of 3-20 nm, preferably 3-8 nm.

The magnetic nanoparticles are preferably ferrite, such as Fe ₃ O ₄ , γ-Fe ₂ O ₃ or CoFe ₂ O ₄ .

Another object of the present invention is to provide a method for preparing the silica nano-magnetic microspheres of the present invention, which comprises the steps of:

Step 1) Disperse magnetic nanoparticles with a particle size of 10-500nm in a solvent so that the concentration is 0.1-10mg/mL, add a dense silica precursor and stir the reaction, so that the outer surface of the magnetic nanoparticles is coated with a layer of dense silica;

Step 2) Add the mesoporous silica precursor to the magnetic nanoparticles coated with dense silica on the outer surface obtained in step 1), and stir the reaction; separate and mesoporize to obtain the silica with mesoporous structure Silicon nanomagnetic microspheres.

Preferably, in step 1), after dispersing the magnetic nanoparticles in the solvent, ultrasonically disperse them for 0.5-3 hours, stir, and then use dilute hydrochloric acid, dilute sulfuric acid, acetic acid, etc. to adjust the pH to 2-5 or use ammonia water, hydrogen Sodium oxide, potassium hydroxide, etc. adjust the pH to 9-14, add a dense silica precursor such as tetraethyl orthosilicate (TEOS), and stir for 3 to 12 hours, so that the dense silica precursor such as orthosilicate Ethyl ester (TEOS) is hydrolyzed in acidic or alkaline environment to coat the surface of magnetic nanoparticles. The mass ratio of magnetic nanoparticles: ethyl orthosilicate is 0.05-1, preferably 0.08-0.5. With such an amount, the thickness of the dense silicon dioxide layer can be controlled at 1-10 nm.

The outer surface of the magnetic nanoparticles coated with dense silicon dioxide obtained in step 1) is first separated, for example, by a magnetic separation method, and washed several times with a solvent such as ethanol and water, and then dispersed in a solvent and stirred to make it The concentration is 0.1-10 mg/mL. In step 2), adjust the pH of the magnetic nanoparticles coated with dense silica on the outer surface obtained in step 1) to 2-5 or 9-14, for example, step 1) can be used Adjust the pH method, then add the mesoporous silica precursor dropwise and stir for 3 to 24 hours. The mesoporous silica precursor includes 1 volume part of multi-carbon organosilane such as dodecyl trimethoxy silane, hexadecyltrimethoxysilane, octadecyltrichlorosilane, triphenylsilane, etc. and 0 to 4 parts by volume of ethyl orthosilicate, the precursor of the mesoporous silica: magnetic nano The mass ratio of the particles is 2 to 12:1; the thickness of the mesoporous silica layer can be controlled by controlling the amount of long-chain alkyl silane in this way, and the mesoporous pore diameter can be controlled by using different multi-carbon organic chain silanes, such as those above C10 The multi-carbon organosilane is preferably C12 and above multi-carbon organosilane.

In step 2), after separation, wash with water-alcohol solvent for several times, then dry, and finally perform mesoporization; said mesoporization refers to burning in air to remove alkyl groups.

The solvent in step 1) and step 2) is a mixed solvent of water and alcohol with a volume ratio of 0.05-0.5. The alcohol is a lower alcohol miscible with water, such as methanol, ethanol, ethylene glycol and/or glycerol, and the separation can be any method that can separate the magnetic particles from the liquid, for example, magnetic separation method.

The method of the present invention further includes step 3) regulating the pore diameter of the mesoporous silica in the silica nano-magnetic microspheres with a mesoporous structure obtained in step 2). The control described in step 3) refers to adding the silica nano-magnetic microspheres with mesoporous structure obtained in step 2) to a buffer solution with a pH value of 2 to 12 such as sodium tetraborate, potassium hydrogen phthalate, Tris , barbiturate buffer, ammonium phosphate buffer, etc. for reflux reaction for 3 to 24 hours to regulate the pore size of the outer layer of mesoporous silica. Then, separation, washing and drying are carried out to obtain silicon dioxide nanometer magnetic microspheres with changed pore diameters.

The silica nano-magnetic microspheres prepared by the method of the present invention have a monodisperse structure, the specific surface area is as high as 10-500m ² /g, and the pore diameter is between 2-50nm, which can accommodate and adsorb molecules of various sizes , including water pollution such as organic matter, azoic acid, microcystin and heavy metals. In addition, due to the large pore size and high specific surface area of the expanded silica nano-magnetic microspheres, it also has great application potential in the separation and enrichment of biological macromolecules such as IgG antibodies. It can replace the traditional separation column method, and use the suspension of silica nano-magnetic microspheres to improve the binding efficiency of protein A and IgG on the surface of mesoporous silica, making the separation process simple and fast.

The advantages of the present invention are:

1) The silica nano-magnetic microspheres with a mesoporous structure of the present invention have a multilayer core-shell structure, and the inner core is a monodisperse magnetic nanoparticle, and the monodispersity can make the dense silica in the middle layer tightly coated on the magnetic nanoparticle. Particle surface, so as to ensure stronger magnetism per unit mass of nano-magnetic microspheres. The outer layer is mesoporous silica, which has a large specific surface area and a high loading capacity for macromolecules;

2) The method for preparing silica nano-magnetic microspheres of the present invention can conveniently control the specific surface area and pore diameter of nano-magnetic microspheres through the type and amount of long-chain alkylsilane precursors, and the specific surface area is as high as 10-500m ² / g, the pore size ranges from 2 to 10 nm, and can be adjusted according to the molecular size to be loaded. The pore size can be adjusted to 2 to 50 nm, and the operation method is simple and environmentally friendly.

Description of drawings

Fig. 1 is the structural representation of silica nano-magnetic microsphere of the present invention;

Fig. 2 is the transmission electron microscope TEM figure of silicon dioxide nano magnetic microsphere of the present invention;

Fig. 3 is the _{N of} silica nano-magnetic microsphere of the present invention Adsorption curve figure, wherein, C ₁₆ TMS is hexadecyltrimethoxysilane;

Fig. 4 is a pore size distribution diagram of the silica nano-magnetic microspheres of the present invention, wherein C ₁₆ TMS is hexadecyltrimethoxysilane.

Detailed ways

As shown in FIG. 1 , it is a schematic structural diagram of a silica nanomagnetic microsphere 10 of the present invention, which has a multi-layer core-shell structure and a particle size of 50-600 nm. The inner core 11 is a monodisperse magnetic nanoparticle with a particle size of 10-500 nm, which can be ferrite, such as Fe ₃ O ₄ , γ-Fe ₂ O ₃ or CoFe ₂ O ₄ . A dense silicon dioxide layer 14 is covered on the outer surface of the inner core 12 with a thickness of 1-10 nm. The outer surface of the dense silica layer 12 is covered with a layer of mesoporous silica layer 16. The mesoporous silica layer 16 has numerous irregularly shaped mesopores (not shown), with an average pore diameter of 2-2. 50nm. It provides the silica nano-magnetic microsphere 10 with a high specific surface area, such as 10-500m ² /g, and achieves the effect that the pore diameter can be adjusted according to the size of the adsorbed molecules.

Example 1

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 11 with 6 mL of ammonia water, then add 6 mL of TEOS (tetraethyl orthosilicate), stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse in 170 mL of ethanol and 30 mL of water again, add 8 mL of ammonia water, and add dropwise Mesoporous silica precursor (mixture of hexadecyltrimethoxysilane and ethyl orthosilicate at a volume ratio of 1:4), was added to 6 mL, and stirred for 12 h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 171.9 m ² /g and an average pore diameter of 3.3 nm when tested with a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 2

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 11 with 6 mL of ammonia water, then add 6 mL of TEOS, stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse again in 170 mL of ethanol and 30 mL of water, add 8 mL of ammonia water, and add the silica precursor hexadecane drop by drop A total of 6 mL of a mixture of trimethoxysilane and ethyl orthosilicate (volume ratio 1:1) was stirred for 16 h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 274.3 m ² /g and an average pore diameter of 3.3 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 3

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 11 with 6 mL of ammonia water, then add 6 mL of TEOS, stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse in 170 mL of ethanol and 30 mL of water again, add 8 mL of ammonia water, and add the silica precursor hexadecane drop by drop Trimethoxysilane 6mL, stirred for 16h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 168.3 m ² /g and an average pore diameter of 4.2 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 4

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 10 with 4 mL of ammonia water, then add 4 mL of TEOS, stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse again in 200 mL of ethanol and 50 mL of water, add 6 mL of ammonia water, and add octadecane, a precursor of silica, drop by drop A total of 5 mL of a mixture of trimethoxysilane and ethyl orthosilicate (volume ratio 4:1) was stirred for 24 h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 146.3 m ² /g and an average pore diameter of 4.5 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 5

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 10 with 4 mL of ammonia water, then add 4 mL of TEOS, stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse in 200 mL of ethanol and 50 mL of water, add 6 mL of ammonia water, and add octadecane, a precursor of silica, drop by drop A total of 6 mL of a mixture of trimethoxysilane and ethyl orthosilicate (volume ratio 2:1) was stirred for 24 h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 173.5 m2/g and an average pore diameter of 4.6 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 6

0.5 g of Fe ₃ O ₄ nanospheres prepared by hydrothermal synthesis were ultrasonically separated in 250 mL of 0.1 M HCl for 10 min, magnetically separated, washed three times with deionized water, and then uniformly dispersed in a mixed solvent of 400 mL of ethanol and 100 mL of water. Adjust the pH to 10 with 4 mL of ammonia water, then add 4 mL of TEOS, stir at room temperature for 6 hours, magnetically separate, wash repeatedly with ethanol and water, disperse again in 200 mL of ethanol and 50 mL of water, add 6 mL of ammonia water, and add octadecane, a precursor of silica, drop by drop Trimethoxysilane 5mL, stirred for 24h. Magnetic separation, washing with deionized water and ethanol several times, and vacuum drying at 60°C. Burn the obtained powder at 550° C. to remove the alkyl group, and obtain silica nano-magnetic microspheres with mesoporous structure. The obtained silica nano-magnetic microspheres have a specific surface of 131.8 m ² /g and an average pore diameter of 5.9 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 7

2 g of silica nano-magnetic microspheres with a mesoporous structure synthesized in Example 2 were dispersed in 50 mL of sodium carbonate-sodium bicarbonate, with a pH value of about 10.5, heated under reflux at 80°C and stirred for 20 h, magnetically separated, and deionized Washed several times with water and dried under vacuum at 60°C. The obtained silica nano-magnetic microspheres have a specific surface of 63.2m2/g and an average pore diameter of 17.3nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 8

Synthesize 5 g of silica nano-magnetic microspheres with a mesoporous structure as in Example 3, disperse them in 100 mL of acetic acid/ammonium acetate buffer solution, the pH value is about 3.7, heat and reflux at 100 ° C for 24 h, magnetically separate, and wash with deionized water Several times, vacuum drying at 60°C. The obtained silica nano-magnetic microspheres have a specific surface of 43.4m2/g and an average pore diameter of 21.8nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 9

Synthesize 5 g of silica nano-magnetic microspheres with a mesoporous structure as in Example 3, disperse them in 100 mL of Tris buffer solution, the pH value is about 8.0, heat and reflux at 100 ° C for 16 h, magnetically separate, wash several times with deionized water, 60 ℃ vacuum drying. The obtained silica nano-magnetic microspheres have a specific surface of 55.4 m ² /g and an average pore diameter of 23.6 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 10

Synthesize 5 g of silica nano-magnetic microspheres with a mesoporous structure in the same manner as in Example 4, disperse them in 100 mL of potassium hydrogen phthalate buffer solution with pH=4, heat and reflux at 100°C for 24 hours, magnetically separate, and wash with deionized water for several Once, vacuum-dried at 60°C. The obtained silica nano-magnetic microspheres have a specific surface of 61.4 m ² /g and an average pore diameter of 20.1 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example 11

Synthesize 5 g of silica nano-magnetic microspheres with a mesoporous structure in the same manner as in Example 5, disperse them in 100 mL of potassium hydrogen phthalate buffer solution with pH=4, heat and reflux at 100° C. and stir for 16 h, magnetically separate, and wash with deionized water for several Once, vacuum-dried at 60°C. The obtained silica nano-magnetic microspheres have a specific surface of 55.9 m ² /g and an average pore diameter of 22.3 nm when tested on a micrometrics ASAP2020 specific surface meter at a temperature of 77K.

Example of performance test

The silica nano-magnetic microspheres obtained in Example 1 were observed under a microscope or a TEM mirror. As shown in Figure 2, the nano-magnetic microspheres were in a spherical monodisperse structure, and each nano-magnetic microsphere had a dense inner core, and was coated with a A dense silica layer, the outer layer is a mesoporous silica layer. The size of the nano magnetic microsphere is between 50-100 nanometers, the dense silicon dioxide layer is about 5-10 nm, and the mesoporous silicon dioxide layer is about 3-8 nm.

The silicon dioxide nano-magnetic microspheres obtained in Examples 1-3 were subjected to _N2 adsorption test and pore size distribution test according to conventional methods, and were combined with _Fe3O4 nanospheres prepared by hydrothermal synthesis _method , that is, magnetic nanoparticles and coated Dense SiO ₂ magnetic nanoparticles were compared, as shown in Figures 3 and 4, respectively. As shown in the figure, the specific surface area of Fe ₃ O ₄ nanospheres, that is, magnetic nanoparticles and magnetic nanoparticles coated only with a dense silica layer is very small, both less than 20m ² /g. After coating with a mesoporous silica layer The specific surface increases obviously, reaching more than 100m ² /g. When the volume ratio of ethyl orthosilicate/hexadecyltrimethoxysilane is 1:1, the specific surface area reaches 274m ² /g. Figure 4 shows that the pore diameter of the nano-magnetic microspheres coated with the mesoporous silica layer before the pore expansion is about 4.2nm.

Claims (10)

1. silica nanometer magnetic microsphere, it is characterized in that: the particle diameter of described nano-magnetic microsphere is 50～600nm, its kernel is the magnetic nano-particle of the single dispersed structure of particle diameter between 10～500nm, the middle level is that thickness is at the compact silicon dioxide of 1～10nm, skin is mesoporous silicon oxide, wherein, the specific area of described nano-magnetic microsphere is 10～500m ²/ g, the average pore size of mesoporous silicon oxide is 2～50nm.

2. silica nanometer magnetic microsphere as claimed in claim 1, it is characterized in that: the specific area of described nano-magnetic microsphere is 30～90m ²/ g, preferred 40～70m ²/ g, the average pore size of mesoporous silicon oxide is 10～50nm, preferred 15～25nm; Perhaps, the specific area of described nano-magnetic microsphere is 120～280m ²/ g, preferred 130～180m ²/ g, the average pore size of mesoporous silicon oxide is 2～8nm, preferred 4.2～6nm.

3. silica nanometer magnetic microsphere as claimed in claim 1, it is characterized in that: the particle diameter of described nano-magnetic microsphere is 50～100nm, preferred 50～90nm, its kernel is the magnetic nano-particle of the single dispersed structure of particle diameter between 30～80nm, the middle level be thickness at the compact silicon dioxide of 5～10nm, skin is that thickness is at the mesoporous silicon oxide of the preferred 3～8nm of 3～20nm.

4. method for preparing silica nanometer magnetic microsphere claimed in claim 1, it comprises the steps:

Step 1) be that the magnetic nano-particle of 10～500nm is scattered in the solvent with particle diameter, making it concentration is 0.1～10mg/mL, adds compact silicon dioxide presoma and stirring reaction, makes the outer surface of magnetic nano-particle coat one deck compact silicon dioxide;

Step 2) adding the meso-porous titanium dioxide silicon precursor in step 1) outer surface that obtains is coated with in the magnetic nano-particle of compact silicon dioxide, and stirring reaction; Separate and mesoporousization, obtain having the silica nanometer magnetic microsphere of meso-hole structure.

5. method as claimed in claim 4, it is characterized in that in step 1) in, magnetic nano-particle is scattered in ultrasonic dispersion 0.5～3h behind the solvent, stir, regulate pH to 2～5 or 9～14, add compact silicon dioxide presoma and stirring reaction 3～12h, described compact silicon dioxide presoma is tetraethoxysilane, magnetic nano-particle: the mass ratio of tetraethoxysilane is 0.05～1, is preferably 0.08～0.5.

6. method as claimed in claim 4, it is characterized in that: in step 2) in, regulating step 1) outer surface that obtains is coated with the pH to 2 of the magnetic nano-particle of compact silicon dioxide～5 or 9～14, dropwise add again meso-porous titanium dioxide silicon precursor and stirring reaction 3～24h, many carbon organic chain silane that described meso-porous titanium dioxide silicon precursor comprises 1 parts by volume is dodecyltrimethoxysilane for example, the cetyl trimethoxy silane, octadecyl trichlorosilane alkane, the tetraethoxysilane of tri-phenyl-silane etc. and 0～4 parts by volume, described meso-porous titanium dioxide silicon precursor: the mass ratio of magnetic nano-particle is 2～12:1; Described mesoporousization refers to that calcination is to remove alkyl in air.

7. method as claimed in claim 6, it is characterized in that: in step 2) in, with step 1) outer surface that the obtains magnetic nano-particle that is coated with compact silicon dioxide separates first and washs, be scattered in again in the solvent, making it concentration is 0.1～10mg/mL, stir, then regulating step 1) outer surface that obtains is coated with the pH to 2 of the magnetic nano-particle of compact silicon dioxide～5 or 9～14; Step 1) and step 2) in solvent be that volume ratio is 0.05～0.5 water and pure mixed solvent.

8. method as claimed in claim 7, it is characterized in that: described alcohol is methyl alcohol, ethanol, ethylene glycol and/or glycerol, the described magnetism separate method that is separated into.

9. method as claimed in claim 4 is characterized in that also further comprising step 3) regulation and control step 2) aperture of the silica nanometer magnetic microsphere intermediary hole silicon dioxide with meso-hole structure of gained.

10. method as claimed in claim 9, it is characterized in that step 3) described regulation and control refer to step 2) the silica nanometer magnetic microsphere with meso-hole structure of gained is to carry out back flow reaction 3～24h in 2～12 cushioning liquid such as sodium tetraborate, Potassium Hydrogen Phthalate, Tris, barbitol buffer solution, ammonium phosphate buffer solution etc. in the pH value, to regulate and control the aperture of outer mesoporous silicon oxide.

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