Two, background technology
At present magnetic nanoparticle just is being widely used in biological field: from magnetic separation, medicament transport carrier, tumor thermotherapy to the magnetic resonance imaging MRI contrast-enhancing agent, when wherein being applied to the separation of biomacromolecules such as protein, DNA and enrichment, need improve the magnetic-particle surface when it.And in various embedded materials, silicon-dioxide be studied the earliest, the most a kind of material.Compare with other material, silicon-dioxide is little to the non-specific adsorption of biomolecules, and this coating can provide hydroxy functional group for the magnetic nanoparticle surface, has made things convenient for itself and silane coupling agent reaction.The latter's appearance not only helps the surface-functionalized of magnetic Nano composite granules, and helps nano particle stable existence in non-aqueous solvent.In addition, the magnetic-particle finishing silicon-dioxide, it is about 3 that also that it is surperficial equipotential point drops to pH, thereby has increased the stability (the pH scope of broad, higher ionic concn in) of particle in the aqueous solution.According to bibliographical information, often be used to form SiO at nano grain surface
2The method of shell has two kinds: first method is with famous
Process promptly forms silica shell by the hydrolysis of original position, precursor such as the tetraethoxy that polymerization can generate sol-gel at particle surface for the basis.This method with generating on the iron oxygen iron nano-particle with club shaped structure, is then used on the red iron-stone colloid of micron-scale by Matijevic and colleague thereof at first, is extended to again on other the ferric oxide nanometer particle afterwards.Second method is a microemulsion synthesis method, its utilization reaction micelle is limited to silica precursor around the required embedded nano particulate, then deposit layer of silicon dioxide at particle surface, disclose a kind of the utilization in the silicon dioxide embedded magnetic nanoparticle DNA isolation method such as CN 1421455A and just used this method by the hydrolysis silica precursor.But the disadvantage of this method is to need a large amount of tensio-active agents in the building-up process, and this brings certain difficulty for the particle purifying of back.In addition, the size distribution broad of gained composite particles, out-of-shape.
Therefore, method with the most use also is based at present
Process.But in experiment, if we find directly magnetic fluid to be added to contain TEOS, NH
3.H
2In the mixing solutions of the ethanol/water of O (4: 1), the carrying out along with reaction a large amount of flockss will occur soon, makes reaction to carry out.Infer reason may because the pH value in the ethanol/water mixed system than simple magnetic fluid more near the isopotential point of nano particle, thereby reduced intergranular repulsion, caused Fe
3O
4Be agglomerated into big particle.In addition, along with the hydrolysis and the polymerization of tetraethoxy, the ionic strength in the solution also strengthens gradually, has aggravated intergranular agglomeration further.1994, people such as Albert P.Philipse proposed: as passing through fresh H
2SiO
3Solution is at Fe
3O
4The surface deposits layer of silicon dioxide in advance, can effectively reduce
Process Fe
3O
4The agglomeration of nano particle.Even now is worked as Fe
3O
4When the add-on of nano particle delimits above one (0.17g/L), also can cause generating in the reaction process a large amount of flockss.Certainly, also have in order to improve above reunion situation adding fresh H
2SiO
3(or Na
2SiO
3) this process of solution carries out ultra-sonic dispersion, as super-paramagnetism nano/micron microballoon and the preparation method's (patent No.: CN1519866A) that proposes people such as Liu Xianzhou.But this method is only cured the symptoms, not the disease, and sees or a large amount of .Fe is arranged from microcosmic
3O
4Nanoparticle agglomerates together, and ultrasonic procedure is bigger to final product form influence.Therefore, more than utilize
Process prepares the method for silicon dioxide embedded magnetic nanoparticle, not only is faced with the preparation process complexity, but also has limited the preparation amount of product.
Three, summary of the invention
The present invention is directed in the silicon dioxide embedded magnetic nanoparticle method of above traditional preparation process existing deficiency and improve, avoid the deposited phenomenon that occurs occurring in the preparation process, product can be prepared in a large number.
The invention provides a kind of method of silicon dioxide embedded magnetic Nano composite granules: the reaction process that provides as Fig. 1, at first prepare magnetic nanoparticle with coprecipitation method, magnetic nanoparticle is after vinyl-acetic ester or methyl methacrylate polymerization embedding treatment, by hydroxylation handle magnetic Nano composite granules, pass through at last
Process is embedding silicon-dioxide on magnetic Nano composite granules.
For guaranteeing that magnetic nanoparticle exists
Do not reunite in the process or improve the add-on of magnetic-particle in the preparation process, the increase that just need overcome reaction process intermediate ion intensity is to influence that particle caused.And the stability of nano particle in solution depends primarily on aspect two: (1) intergranular electrical charge rejection; (2) intergranular sterically hindered.Therefore, can modify this technical scheme of macromolecular material (for particle surface provides sterically hindered) in advance by the magnetic-particle surface and solve above shortcoming.In addition, we find as silicon dioxide molecules successfully will be deposited on the magnetic nanoparticle surface of polymer embedding in advance, also must improve the above particle surface that obtains, make by the nano grain surface of embedding contain can be further with the functional group of silicic acid molecular reaction or have electric charge and utilize electrostatic interaction with the silicic acid molecular adsorption to its surface.By last surface analysis as can be seen: directly will expose in the conventional procedure or join in the mixing solutions of ethanol/water through the magnetic-particle of silicic acid molecular modification, carry out silicon dioxide embedded then.Different is with traditional preparation method, and our invention is carrying out in advance before the magnetic nanoparticle embedding silicon-dioxide macromolecule modified, then macromolecule surface is handled, and its core concept is for the magnetic-particle surface provides sterically hindered, prevents
Because of causing magnetic nanoparticle, the increase of ionic strength reunites in the process.
A kind of method for preparing silicon dioxide embedded magnetic Nano composite granules is characterized in that preparation process is: prepare magnetic nanoparticle with coprecipitation method earlier; Magnetic nanoparticle by vinyl-acetic ester or methyl methacrylate embedding after, through hydroxylation handle magnetic Nano composite granules; Embedding silicon-dioxide on magnetic Nano composite granules.Getting magnetic nanoparticle is dispersed in the methanol solution, being made into mass volume ratio concentration is the magnetic fluid suspension of 10g/L, the ratio that adds 0.1 gram trimethoxy propenyl silane with every gram magnetic nanoparticle adds trimethoxy propenyl silane MPS, liquid heat was refluxed 4 hours, treat liquid cooling centrifuging and taking precipitation to the room temperature, water, ethanol replace the washing and precipitating thing, and the throw out after cleaning is scattered in the ethanolic soln, get MPS-magnetic nanoparticle alcohol suspension; With the water preparation trimethylammonium hexadecyl brometo de amonio-n-butanol aqueous solution after the nitrogen degassing, wherein the mass volume ratio concentration of trimethylammonium hexadecyl brometo de amonio is 0.004g/mL, propyl carbinol accounts for solvent volume 2%, ultrasonic mixing, adding mass volume ratio concentration is the vinyl-acetic ester suspension of the MPS-magnetic nanoparticle of 0.04g/mL, the volume ratio of add-on and trimethylammonium hexadecyl brometo de amonio-butanol solution is 1: 10, ultrasonic mixing, with liquid heat to 65~80 ℃, the benzoyl peroxide that adds vinyl-acetic ester quality 2~10%, kept this temperature 8~10 hours, after reaction finishes, product is isolated from reaction solution and water and acetone wash products by externally-applied magnetic field; Above-mentioned product is dispersed in the ethanolic soln, be mixed with concentration and be 5~10% magnetic fluid suspension, adding ammoniacal liquor then makes the interior ammonia concn of system between 0.5~50%, the ultrasonic mixing post-heating of gained suspension was refluxed 2~6 hours, replenish ammoniacal liquor in the reflux course, keep ammonia concn, after reaction finishes, magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis is isolated from reaction solution, cleans with distilled water, removes residual ammoniacal liquor.
Getting magnetic nanoparticle is dispersed in the methanol solution, being made into mass volume ratio concentration is the magnetic fluid suspension of 10g/L, the ratio that adds 0.1 gram trimethoxy propenyl silane with every gram magnetic nanoparticle adds trimethoxy propenyl silane MPS, with suspension reflux 4 hours, centrifuging and taking precipitated after question response liquid was cooled to room temperature, water, ethanol replace the washing and precipitating thing, and solid sediment is scattered in the ethanolic soln, get MPS-magnetic nanoparticle alcohol suspension; With the water preparation Sodium dodecylbenzene sulfonate-cetyl alcohol solution after the nitrogen degassing, wherein the mass volume ratio concentration of Sodium dodecylbenzene sulfonate is 0.002g/mL, cetyl alcohol mass volume ratio concentration is 0.005g/mL, stirred solution makes cetyl alcohol dissolve fully, then adding mass volume ratio concentration is the methyl methacrylate suspension of the MPS-magnetic nanoparticle of 0.04g/mL, ultrasonic mixing, with liquid heat to 65~80 ℃, the benzoyl peroxide that adds methyl methacrylate quality 2~10%, kept this temperature 8~10 hours, after reaction finishes, magnetic nanoparticle is isolated water and acetone wash products by externally-applied magnetic field from solution; Above-mentioned product is dispersed in the ethanolic soln, be mixed with concentration and be 5~10% magnetic fluid suspension, adding ammoniacal liquor then makes the interior ammonia concn of system between 0.5~50%, the ultrasonic post-heating of gained suspension was refluxed 2~6 hours, replenish ammoniacal liquor in the reflux course to keep ammonia concn, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Getting magnetic nanoparticle is dispersed in the methanol solution, being made into mass volume ratio concentration is the magnetic fluid suspension of 10g/L, prepared magnetic fluid suspension is heated to 80 ℃, constant temperature left standstill 30 minutes dropwise add oleic acid and ammoniacal liquor under agitation condition after, the centrifuging and taking precipitation, water, ethanol replace the washing and precipitating thing, and the throw out after cleaning is scattered in the ethanolic soln, get oleic acid-magnetic nanoparticle alcohol suspension; With the water preparation trimethylammonium hexadecyl brometo de amonio-n-butanol aqueous solution after the nitrogen degassing, wherein the mass volume ratio concentration of trimethylammonium hexadecyl brometo de amonio is 0.004g/mL, propyl carbinol accounts for solvent volume 2%, ultrasonic mixing, adding mass volume ratio concentration is the vinyl-acetic ester suspension of oleic acid-magnetic nanoparticle of 0.04g/mL, the volume ratio of add-on and trimethylammonium hexadecyl brometo de amonio-butanol solution is 1: 10, ultrasonic mixing, reaction solution is heated to 65~80 ℃, the benzoyl peroxide that adds vinyl-acetic ester quality 2~10%, kept this temperature 8~10 hours, after reaction finishes, by externally-applied magnetic field magnetic nanoparticle is isolated from solution, water and acetone replace wash products 3 times; Above-mentioned product is dispersed in the ethanolic soln, be mixed with concentration and be 5~10% magnetic fluid suspension, adding ammoniacal liquor then makes the interior ammonia concn of system between 0.5~50%, the ultrasonic post-heating of gained suspension was refluxed 2~6 hours, replenish ammoniacal liquor in the reflux course to keep ammonia concn, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Getting magnetic nanoparticle is dispersed in the methanol solution, being made into concentration is the magnetic fluid suspension of 10g/L, prepared magnetic fluid suspension is heated to 80 ℃, constant temperature left standstill 30 minutes dropwise add oleic acid and ammoniacal liquor under agitation condition after, the centrifuging and taking precipitation, water, ethanol replace the washing and precipitating thing, and solid sediment is scattered in the ethanolic soln, get oleic acid-magnetic nanoparticle alcohol suspension; With the water preparation Sodium dodecylbenzene sulfonate-cetyl alcohol solution after the nitrogen degassing, wherein the mass volume ratio concentration of Sodium dodecylbenzene sulfonate is 0.002g/mL, cetyl alcohol mass volume ratio concentration is 0.005g/mL, stirred solution makes cetyl alcohol dissolve fully, then adding mass volume ratio concentration is the methyl methacrylate suspension of oleic acid-magnetic nanoparticle of 0.04g/mL, ultrasonic mixing, with liquid heat to 65~80 ℃, the benzoyl peroxide that adds methyl methacrylate quality 2~10%, keep this temperature after 8~10 hours, magnetic nanoparticle is isolated water and acetone wash products by externally-applied magnetic field from reaction solution; Above-mentioned product is dispersed in the ethanolic soln, be mixed with concentration and be 5~10% magnetic fluid suspension, adding ammoniacal liquor then makes the interior ammonia concn of system between 0.5~50%, the ultrasonic post-heating of gained suspension was refluxed 2~6 hours, replenish ammoniacal liquor in the reflux course to keep ammonia concn, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Magnetic nanoparticle is Fe
3O
4, Fe
2O
3Or Co Fe
2O
4Add benzoyl peroxide behind Heating temperature to 65~70 ℃.The benzoyl peroxide add-on is 3~8% of used vinyl-acetic ester of this step or a methyl methacrylate quality.Temperature maintenance is 9 hours behind the adding benzoyl peroxide.
Preparation technology of the present invention by the magnetic nanoparticle surface is modified, can improve the maximum adding quantity of magnetic nanoparticle in the reaction process, thereby improves
The preparation amount of silicon dioxide embedded magnetic Nano composite granules in the process, and gained composite particles narrow diameter distribution, outward appearance slyness reach the commercialization standard fully.
Five, embodiment
Embodiment 1: utilize traditional co-precipitation method to prepare Fe respectively
3O
4, Fe
2O
3, CoFe
2O
4Each 2.2g of nano particle after reaction finishes, utilize externally-applied magnetic field that the gained precipitation is separated from reaction medium, and water cleans 3 times.
Embodiment 2: with any fresh nanoparticulate dispersed of embodiment 1 preparation in the 220mL methanol solution, being made into concentration is the magnetic fluid suspension of 10g/L, the ratio that adds 0.1 gram with every gram magnetic nanoparticle adds trimethoxy propenyl silane (MPS), with vlil 4 hours, treat that solution is cooled to centrifuging and taking precipitation after the room temperature, water, ethanol replace three circulations of washing and precipitating thing, throw out are scattered in the ethanolic soln again, get MPS-magnetic nanoparticle ethanolic soln;
Embodiment 3: in the 220mL aqueous solution, being made into concentration is the magnetic fluid suspension of 10g/L with any fresh nanoparticulate dispersed of embodiment 1 preparation, by prior art nitrogen degassing method, by nitrogen gas stream with the suspension degassing 20 minutes.Then, prepared magnetic fluid suspension is heated to 80 ℃, and under 800 rev/mins stirring velocity condition, 3mL oleic acid is dropwise added, then add 1mL ammoniacal liquor, after adding gained suspension is kept half hour under this reaction conditions.At last, by the centrifugal precipitation of collecting, and water, ethanol replace three circulations of washing and precipitating thing respectively, and throw out is scattered in the ethanolic soln, get oleic acid-magnetic nanoparticle alcohol suspension.
Embodiment 4: at first take into account and add 100mL water in the four neck flasks of airway to being furnished with agitator, prolong, temperature, and by nitrogen gas stream with the aqueous solution degassing 20 minutes, remove air wherein.Then, to wherein adding 0.4g trimethylammonium hexadecyl brometo de amonio (CTAB) and 2mL propyl carbinol, and ultrasonic mixing, the ultrasound parameter during the mixing operation is set no specific requirement.Then, add 10mL to the flask the inside and be dissolved with 0.4gMPS-Fe
3O
4The vinyl-acetic ester suspension of nano particle mixes in order to make suspension, utilizes ultrasonic wave that ultrasonic 20 minutes suspension homogeneous phases until the inside of above suspension are distributed once more., suspension be heated to 65 ℃, and add 0.2g benzoyl peroxide (BOP) thereafter.At last, suspension was kept 8 hours under this temperature.Along with the carrying out of reaction, the color of liquid gradually becomes sorrel by original grey, and reaction is isolated target product by externally-applied magnetic field after finishing from liquid, and successively utilizes water and acetone that the gained solid is cleaned 3 times.
Embodiment 5: with embodiment 4, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-Fe
3O
4Nano particle, Heating temperature are 70 ℃, and benzoyl peroxide is 0.5g, keep Heating temperature 9 hours.
Embodiment 6: with embodiment 4, wherein MPS-Fe
3O
4Nano particle is changed to MPS-Fe
2O
3Nano particle, Heating temperature are 67 ℃, and benzoyl peroxide is 1g, keep Heating temperature 10 hours.
Embodiment 7: with embodiment 4, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-Fe
2O
3Nano particle, Heating temperature are 68 ℃, and benzoyl peroxide is 0.6g, keep Heating temperature 8 hours.
Embodiment 8: with embodiment 4, wherein MPS-Fe
3O
4Nano particle is changed to MPS-CoFe
2O
4Nano particle, Heating temperature are 69 ℃, and benzoyl peroxide is 0.3g, keep Heating temperature 9 hours.
Embodiment 9: with embodiment 4, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-CoFe
2O
4Nano particle, Heating temperature are 66 ℃, and benzoyl peroxide is 0.8g, keep Heating temperature 10 hours.
Embodiment 10: at first take into account and add 100mL water in the four neck flasks of airway to being furnished with agitator, prolong, temperature, and by nitrogen gas stream with water degasification 20 minutes, remove air wherein.Then, to wherein adding 0.2g Sodium dodecylbenzene sulfonate (SDS) and 0.5g cetyl alcohol (CA), and made cetyl alcohol dissolve fully in 30 minutes at 50 ℃ of following stirred solutions.Then, add 10mL to the inside and be dissolved with 0.4g MPS-Fe
3O
4The styrene suspension liquid of nano particle mixes in order to make suspension, utilizes ultrasonic wave that ultrasonic 20 minutes suspension homogeneous phases until the inside of above solution are distributed.With liquid heat to 80 ℃, and add 0.2g benzoyl peroxide (BOP) thereafter.At last, liquid was kept 8 hours under this temperature.Along with the carrying out of reaction, the color of solution gradually becomes sorrel by original grey black, and reaction is isolated target product by externally-applied magnetic field after finishing from solution, and successively utilizes water and acetone that the gained solid is cleaned 3 times.
Embodiment 11: with embodiment 10, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-Fe
3O
4Nano particle, adding benzoyl peroxide after being heated to 70 ℃ is 0.3g, keeps Heating temperature 9 hours.
Embodiment 12: with embodiment 10, wherein MPS-Fe
3O
4Nano particle is changed to MPS-Fe
2O
3Nano particle, adding benzoyl peroxide after being heated to 68 ℃ is 0.6g, keeps Heating temperature 10 hours.
Embodiment 13: with embodiment 10, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-Fe
2O
3Nano particle, adding benzoyl peroxide after being heated to 67 ℃ is 0.7g, keeps Heating temperature 8 hours.
Embodiment 14: with embodiment 10, wherein MPS-Fe
3O
4Nano particle is changed to MPS-CoFe
2O
4Nano particle, adding benzoyl peroxide after being heated to 66 ℃ is 0.8g, keeps Heating temperature 9 hours.
Embodiment 15: with embodiment 10, wherein MPS-Fe
3O
4Nano particle is changed to oleic acid-CoFe
2O
4Nano particle, adding benzoyl peroxide after being heated to 65 ℃ is 1g, keeps Heating temperature 10 hours.
Embodiment 16: arbitrary product among the embodiment 4~15 is dispersed in the ethanolic soln, be mixed with concentration and be 5% magnetic fluid suspension, add ammoniacal liquor then and make that ammonia concn is 0.5% in the system, the ultrasonic mixing post-heating of gained suspension was refluxed 2 hours, keep ammonia concn in the reflux course 0.5%, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Embodiment 17: arbitrary product among the embodiment 4~15 is dispersed in the ethanolic soln, be mixed with concentration and be 8% magnetic fluid suspension, add ammoniacal liquor then and make that ammonia concn is 25% in the system, the ultrasonic mixing post-heating of gained mixing solutions was refluxed 4 hours, keep ammonia concn in the reflux course 25%, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Embodiment 18: arbitrary product among the embodiment 4~15 is dispersed in the ethanolic soln, be mixed with concentration and be 10% magnetic fluid solution, add ammoniacal liquor then and make that ammonia concn is 50% in the system, the ultrasonic mixing post-heating of gained mixing solutions was refluxed 6 hours, keep ammonia concn in the reflux course 50%, after reaction finished, the magnetic nanoparticle after utilizing externally-applied magnetic field with hydrolysis was isolated from reaction solution, clean with distilled water, remove residual ammoniacal liquor.
Embodiment 19: Fig. 2 has provided gained PVAc/Fe
3O
4Particulate TEM photo, its particle diameter is between 50~200 nanometers.Fig. 3, Fig. 4 provide the thick SiO of different silica shells
2/ (PVAc/Fe
3O
4) particle TEM photo, Fig. 5 is SiO
2/ (PVAc/Fe
3O
4) particulate SEM photo, therefrom as can be seen at black PVAc/Fe
3O
4One deck light color material silicon-dioxide that distributed uniformly around the particle, the whole particle profile presents circle, has nucleocapsid structure preferably, above result shows fully, in the reaction process, the silicic acid molecule of generation by with PVAc/Fe
3O
4The hydroxyl reaction of particle surface has constituted with PVAc/Fe in solution
3O
4Particle is the reaction system of nucleus.Experimental result is found can improve greatly by the pre-embedding of the polymer that the magnetic-particle surface is carried out
The maximum adding quantity of magnetic-particle in the process, its 0.17g/L by the past traditional method is increased to 3g/L.