CN101694795B - Preparation method of multi-pore canal nuclear shell type magnet gold compound nano-particle - Google Patents

Abstract

The invention discloses a method for preparing porous core-shell type magnetic gold composite nanoparticles. The characteristic steps are: first, in a closed environment of 160-200°C, hydrophilic magnetic nanomaterials and sugar solution are mixed and reacted to obtain a coating. Carbon spheres covered with magnetic cores; the carbon spheres coated with magnetic cores are then chemically modified with gold nanoparticles using a reflux method to obtain magnetic gold composite nanomaterials; and then the silicon source or titanium source is hydrolyzed on the carbon spheres. The surface of the magnetic gold composite nanomaterial is coated with a shell layer to form core-shell particles, and the surface of the core-shell particles is modified with polymer materials using a molar ratio of polymer materials and core-shell particles greater than 5:1; finally, inorganic alkali is used Liquid etching the core-shell magnetic gold composite nanoparticles of the modified polymer material to form core-shell magnetic gold composite nanoparticles with porous channels. The magnetic gold composite nanoparticles prepared by the present invention have the characteristics of uniform and controllable particle size, good dispersion, and the magnetic properties and optical properties are less affected by the surface inorganic shell layer.

Description

A kind of preparation method of porous core-shell type magnetic gold composite nanoparticle

technical field

The invention relates to a method for preparing nanoparticles, in particular to a method for preparing porous core-shell magnetic-gold composite nanoparticles. the

Background technique

The composite nanoparticles formed by composite assembly of magnetic particles and gold nanoparticles not only have the magnetron guidance and magnetic separation characteristics of magnetic nanomaterials, but also have the unique optical properties and catalytic properties of gold nanoparticles. Hot topics in research fields such as chemistry and catalysis. The performance and application effect of such composite functional nanoparticles are greatly affected by their structure. In order to ensure that the optical and catalytic properties of gold nanoparticles are not shielded by the surface coating layer, it is often reported in the literature that gold nanoparticles are directly combined with magnetic nanoparticles (or magnetic nanoparticles coated with inorganic or organic polymer materials). However, the magnetic-gold composite nanoparticles with this structure have the following problems in current applications: (1) The chemical stability of the magnetic nanoparticles is poor, and they are easily oxidized or agglomerated , if the magnetic particles are pre-coated by inorganic or organic polymer materials, the magnetic response sensitivity of the obtained magnetic gold composite nanoparticles is not enough; (2) the number of effective functional groups contained on the surface of the composite nanoparticles is relatively limited, which is not conducive to the regeneration of biomolecules. coupling. In response to the above problems, it was proposed that the magnetic nanoparticles should be wrapped with silica with good biocompatibility, and then the silica shell should be formed into a porous structure, and gold nanoparticles should be grafted or embedded in the porous structure. However, due to the limitation of the pore size of the silica shell on the surface of the magnetic nanoparticles, it is difficult to inlay gold nanoparticles and the yield is low. Therefore, in the case of improving the stability of magnetic-gold composite functional nanoparticles and avoiding agglomeration, how to ensure the magnetic and optical properties of composite particles has become the key to its application in biomedicine, catalysis and other fields. the

Contents of the invention

The object of the present invention is to provide a method for preparing porous core-shell magnetic gold composite nanoparticles. The porous core-shell type magnetic-gold composite nanoparticles prepared by the method is to embed magnetic particles and gold nanoparticles in the porous inorganic matrix material, so that the obtained porous core-shell type magnetic-gold composite nanoparticles have a particle size It is relatively uniform, can be adjusted between 80-500 nanometers, has good dispersion, can be placed for several months without agglomeration, and the magnetic and optical properties are less affected by the surface inorganic shell material. the

To achieve the above object, the technical scheme of the preparation method of the present invention is:

A method for preparing porous core-shell type magnetic gold composite nanoparticles is characterized in that it comprises the following steps: 1. Under the airtight environment of 160-200 ℃, the aqueous solution of hydrophilic magnetic nanoparticles and monosaccharide is mixed and reacted, And remove the homogeneous nucleated carbon spheres by magnetic separation to obtain carbon spheres containing magnetic nuclei;

II. The carbon spheres containing the magnetic core are chemically modified with gold nanoparticles by refluxing with chloroauric acid to obtain magnetic gold composite nanomaterials;

III. Cover the surface of the magnetic-gold composite nanomaterial with a silicon dioxide or titanium dioxide shell layer by hydrolyzing the silicon source or titanium source to form a core-shell composite nanomaterial, and feed the polymer material and the core-shell composite nanomaterial in moles The ratio is greater than 5:1, and the polymer material is modified on the surface of the core-shell particle;

IV. Etching the core-shell type magnetic-gold composite nanoparticles of the modified polymer material by using inorganic alkaline solution to form the core-shell type magnetic-gold composite nanoparticles with porous channels. the

Further, in the preparation method of the aforementioned porous core-shell type magnetic gold composite nanoparticles, the hydrophilic magnetic nanoparticles described in step I include γ-Fe ₂ O ₃ , Fe ₃ O ₄ iron-based nanomaterials and these iron The alloy of base nanomaterial, the aqueous solution of described monosaccharide comprises the aqueous solution containing glucose, threose or xylose; The silicon source used for hydrolysis in the step III is tetraethyl orthosilicate or propyl silicate, and the titanium source used is titanic acid Butyl ester or tetraisopropyl titanate; the macromolecular material described in step IV is one of polyethylene glycol, polyvinylpyrrolidone, and poloxamine F127 with a molecular weight greater than 8000, and the inorganic base used for etching is sodium hydroxide or potassium hydroxide.

Applying the preparation method of the present invention to prepare magnetic gold composite nanoparticles, compared with the preparation method reported in previous literature, its beneficial effect is reflected in:

(1) The presence of inorganic shell materials on the surface improves the chemical stability of the magnetic-gold composite nanoparticles and is not easy to agglomerate;

(2) The surface coating layer has a multi-channel structure, which avoids the serious decrease of the saturation magnetization of the composite functional nanoparticles relative to the magnetic nanoparticles, and is conducive to the navigation of the external magnetic field;

(3) The light permeability of the surface shell pores ensures that the optical properties of gold nanoparticles can be fully utilized;

(4) The porous channel matrix material is silicon dioxide or titanium dioxide, and its surface can be further endowed with active functional groups, such as amino, carboxyl, etc., by silane coupling agent, which is convenient for coupling other necessary small molecules or nanoparticles, which is conducive to its biological It is widely used in various fields such as medicine, catalysis, and separation. the

Description of drawings

Fig. 1 a is the transmission electron micrograph of the magnetic-gold composite nanoparticle of multi-channel core-shell type prepared by the present invention;

Fig. 1 b is the field emission scanning electron micrograph of the magnetic-gold composite nanoparticle of multi-channel core-shell type prepared by the present invention;

Fig. 2 is the XRD spectrum of the magnetic gold composite nanoparticles shown in Fig. 1a and Fig. 1b. the

Detailed ways

The invention provides a method for preparing porous core-shell magnetic gold composite nanoparticles, which mainly includes the following steps:

(1) Ultrasonic disperse the hydrophilic magnetic nanoparticles in the sugar solution, transfer to a reaction kettle, and react at 160-200° C. for 4-8 hours. After the reaction, the homogeneously nucleated carbon spheres were removed by magnetic separation, and the obtained carbon spheres coated with magnetic particles were washed three times with deionized water, and then dried in a vacuum oven at 60°C for 24 hours. the

(2) Take 100 mg of carbon spheres coated with magnetic cores, disperse them ultrasonically in secondary water at 0.5-20 mg/mL, and add dropwise 10-500 micrograms of chloroauric acid solution with a mass fraction of 1%-5% after reflux for 5 min. liter, continue to reflux for 20-120min, the color of the solution gradually changes from yellowish brown to red, and a magnetic composite nanomaterial with gold nanoparticles on the surface is obtained. the

(3) 4ml of aqueous dispersion of magnetic-gold composite nanoparticles with a concentration of 1mg/ml and 20ml of alcohol were ultrasonically mixed for 15min, then 0.5ml of concentrated ammonia was added dropwise and stirred for 15min, then slowly added 30-500 microliters of silicon source or titanium source for hydrolysis, and reacted for 24 hours at room temperature. After the reaction, centrifuge, wash with water and ethanol three times in turn, and then ultrasonically disperse in 20ml of water. the

(4) Add 3-6 g of polymer material to the aqueous dispersion of core-shell composite nanoparticles, stir and reflux for 4 hours, and the molar ratio of polymer material to core-shell particles is greater than 5:1. After cooling to room temperature, add 0.1g/ml inorganic alkaline solution to etch for 15-200min to obtain porous magnetic-gold composite nanoparticles. After centrifugation and washing, the product is dried in an oven at 60°C for 24h. the

in,

The magnetic particles described in step (1) can be iron-based materials such as ferric oxide and ferric oxide and alloys thereof, and the sugar solution can be an aqueous solution of monosaccharides such as glucose, threose, and xylose;

The alcohol described in step (3) can be ethanol or isopropanol, silicon source can be ethyl orthosilicate, propyl silicate, titanium source can be butyl titanate, tetraisopropyl titanate etc.;

The polymer material described in step (4) can be polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), poloxamine F127, etc. with a molecular weight greater than 8000, and the inorganic base can be sodium hydroxide, potassium hydroxide, etc. . the

According to the technical solution of the present invention, the magnetic-gold composite nanoparticles connected through the carbon layer can be embedded in the porous inorganic polymer shell. The thickness of the carbon layer on the surface of the magnetic nanoparticles is regulated by the concentration of the added monosaccharide and the hydrothermal time. In order to ensure the magnetic properties of the magnetic particles, the thickness of the carbon transition layer of the present invention is not more than 5nm, and the carbon spheres containing the magnetic particles The size of gold nanoparticles loaded on the surface can be adjusted by changing the amount of chloroauric acid, and the particle size of the whole core-shell type porous magnetic gold composite nanoparticles is determined by the concentration of silicon source or titanium source. The presence of surface polymer materials ensures the integrity of the shell skeleton during alkali etching, and the size of the shell pores increases with the extension of inorganic alkali etching time. the

The porous core-shell type magnetic gold composite nanoparticles prepared by the present invention have relatively uniform particle size and good dispersion, and the particle size can be adjusted between 80-500 nanometers, and can be placed for several months without agglomeration. The porous structure makes the magnetic properties of the magnetic particles and the optical properties of the gold particles less affected by the shell material. In addition, the porous matrix material is silicon dioxide or titanium dioxide, and its surface can be further endowed with active functional groups capable of coupling other necessary small molecules or nanoparticles, such as amino, carboxyl, etc. Applications. In addition, the porous structure on the surface indicates the potential value of the prepared magnetic-gold composite nanomaterials in high-efficiency catalysis. the

Fig. 1 a, Fig. 1 b are respectively the transmission electron micrograph and the field emission scanning electron micrograph of the magnetic-gold composite nanoparticle of porous core-shell type prepared by the technical scheme of the present invention, as can be seen from the TEM and SEM photographs of the sample , the prepared porous silicon dioxide-coated magnetic-gold composite nanoparticles have a particle size of 120nm, uniform particle size, and good monodispersity. As can be seen from the XRD pattern of the sample in Figure 2, the prepared porous silica-coated magnetic-gold composite nanoparticles have gold particles and magnetic ferric oxide nanoparticles with an inverse spinel structure as the core. the

The following is a detailed description of the technical solution of the present invention through specific examples, which are only typical application examples and do not constitute any limitation to the protection scope of the present invention. All technical solutions formed by equivalent replacement or equivalent transformation fall under the protection requirements of the present invention. within the range. the

Example 1:

Weigh 100mg of Fe ₃ O ₄ nanoparticles with an average particle size of 10nm and ultrasonically disperse them in 30ml of an aqueous solution containing 0.5g of glucose, transfer the dispersion into a reactor and react at 170°C for 4h. After the reaction, cool to room temperature, and remove the homogeneously nucleated carbon spheres by magnetic separation to obtain carbon spheres containing magnetic particles. The thickness of the carbon layer is about 1nm. Wash it three times with deionized water and place it in a vacuum drying oven. Dry at 60°C for 24h. Take 100 mg of carbon spheres containing magnetic cores in the resulting mixture, ultrasonically disperse them in 20 ml of water at a rate of 5 mg/mL, add 500 microliters of chloroauric acid solution with a mass fraction of 1% after reflux for 5 minutes, and continue to reflux for 20 minutes. The color of the solution changes from yellowish brown to is red, and the magnetic composite nanomaterial with gold nanoparticles loaded on the surface is obtained, and the average size of the gold particles is 20nm. After magnetic separation and washing with water, dry in a vacuum oven at 60°C for 24 hours.

Mix 4ml of the aqueous dispersion of magnetic-gold composite nanoparticles with a concentration of 1mg/ml and 20ml of isopropanol for 15min ultrasonically, add 0.5ml of concentrated ammonia water dropwise and stir for 15min, then slowly add 50 microliters of ethyl orthosilicate Reaction at room temperature for 24h. After the reaction, centrifuge, wash with water and ethanol three times in turn, then disperse in 20ml of water, add 3g of PEG with a molecular weight of 8000, stir evenly, heat up and reflux for 4h, then cool to room temperature, add 0.1g/ml of sodium hydroxide solution, and stir to react After 45 minutes, the magnetic-gold composite nanoparticles with an average particle size of 120nm and porous channels were obtained. The product was washed by centrifugation and then dried in an oven at 60°C for 24 hours. the

Example 2:

Weigh 100mg of Fe ₃ O ₄ nanoparticles with an average particle size of 10nm and ultrasonically disperse them in 30ml of an aqueous solution containing 0.5g of glucose, transfer the dispersion into a reactor and react at 170°C for 4h. After the reaction, cool to room temperature, and remove the homogeneous nucleated carbon spheres by magnetic separation to obtain carbon spheres containing magnetic particles. The thickness of the carbon layer is about 1nm. Wash it three times with deionized water and place it in a vacuum drying oven. Dry at 60°C for 24h. Take 100 mg of carbon spheres containing magnetic cores in the resulting mixture, ultrasonically disperse them in 20 ml of water at a rate of 5 mg/mL, add 300 microliters of chloroauric acid solution with a mass fraction of 1% after reflux for 5 minutes, and continue to reflux for 20 minutes. The color of the solution changes from yellowish brown to is red, and the magnetic composite nanomaterial with gold nanoparticles loaded on the surface is obtained, and the average size of the gold particles is 10nm. After magnetic separation and washing with water, dry in a vacuum oven at 60°C for 24 hours.

Mix 4ml of the aqueous dispersion of magnetic-gold composite nanoparticles with a concentration of 1mg/ml and 20ml of isopropanol for 15min ultrasonically, add 0.5ml of concentrated ammonia water dropwise and stir for 15min, then slowly add 200 microliters of ethyl orthosilicate , Reaction at room temperature for 24h. After the reaction, centrifuge, wash with water and ethanol three times in turn, then disperse in 20ml of water, add 3g of PEG with a molecular weight of 8000 and stir evenly, heat up and reflux for 4h, then cool to room temperature, add 0.1g/ml of sodium hydroxide solution, stir After reacting for 45 minutes, magnetic-gold composite nanoparticles with an average particle diameter of 200 nm and porous channels were obtained. The product was washed by centrifugation and then dried in an oven at 60° C. for 24 hours. the

Example 3:

Weigh 100mg of Fe ₃ O ₄ nanoparticles with an average particle size of 10nm and ultrasonically disperse them in 30ml of an aqueous solution containing 0.5g of glucose, transfer the dispersion into a reactor and react at 170°C for 4h. After the reaction, cool to room temperature, and remove the homogeneous nucleated carbon spheres by magnetic separation to obtain carbon spheres containing magnetic particles. The thickness of the carbon layer is about 1nm. Wash it three times with deionized water and place it in a vacuum drying oven. Dry at 60°C for 24h. Take 100 mg of carbon spheres containing magnetic cores in the resulting mixture, ultrasonically disperse them in 20 ml of water at a rate of 5 mg/mL, add 500 microliters of chloroauric acid solution with a mass fraction of 1% after reflux for 5 minutes, and continue to reflux for 20 minutes. The color of the solution changes from yellowish brown to is red, and the magnetic composite nanomaterial with gold nanoparticles loaded on the surface is obtained, and the average size of the gold particles is 20nm. After magnetic separation and washing with water, dry in a vacuum oven at 60°C for 24 hours.

Mix 4ml of the aqueous dispersion of magnetic-gold composite nanoparticles with a concentration of 1mg/ml and 20ml of isopropanol for 15min ultrasonically, add 0.5ml of concentrated ammonia water dropwise and stir for 15min, then slowly add 300 microliters of ethyl orthosilicate , Reaction at room temperature for 24h. After the reaction, centrifuge, wash with water and ethanol three times in turn, then disperse in 20ml of water, add 5g of PVP with a molecular weight of 10000 and stir evenly, heat up and reflux for 4h, then cool to room temperature, add 0.1g/ml of sodium hydroxide solution, stir After reacting for 60 minutes, magnetic-gold composite nanoparticles with an average particle diameter of 350 nm and porous channels were obtained. The product was washed by centrifugation and then dried in an oven at 60° C. for 24 hours. the

Claims (4)

1. a preparation method of porous core-shell type magnetic-gold composite nanoparticles, characterized in that it may further comprise the steps: 1. In a closed environment at 160-200°C, mix and react hydrophilic magnetic nanoparticles with an aqueous solution of monosaccharide, and remove homogeneous nucleated carbon spheres by magnetic separation to obtain carbon spheres containing magnetic nuclei; II. Chemically modifying the gold nanoparticles on the carbon spheres containing the magnetic core by refluxing with chloroauric acid to obtain a magnetic-gold composite nanomaterial; Ⅲ. Coat the surface of the magnetic-gold composite nanomaterial with a silicon dioxide or titanium dioxide shell layer by hydrolyzing the silicon source or titanium source to form a core-shell composite nanomaterial, and feed the polymer material and the core-shell composite nanomaterial The ratio is greater than 5:1, and the polymer material is modified on the surface of the core-shell particle; Ⅳ. Etching the core-shell type magnetic gold composite nanoparticles of the modified polymer material by using inorganic alkaline solution to form the core-shell type magnetic gold composite nanoparticles with porous channels. 2. The method for preparing porous core-shell magnetic gold composite nanoparticles according to claim 1, wherein the hydrophilic magnetic nanoparticles in step I include γ-Fe ₂ O ₃ , Fe ₃ O The iron-based nanomaterial of ₄ ; the aqueous solution of the monosaccharide includes an aqueous solution containing glucose, threose or xylose. 3. the preparation method of a kind of porous core-shell type magnetic gold composite nano-particle according to claim 1 is characterized in that: the silicon source used for hydrolysis in step III is ethyl orthosilicate or propyl silicate; The titanium source is butyl titanate or tetraisopropyl titanate. 4. The preparation method of a kind of porous core-shell type magnetic gold composite nanoparticle according to claim 1, characterized in that: the polymer material described in step IV is polyethylene glycol, polyvinylpyrrolidone with a molecular weight greater than 8000 , one of poloxamine F127, the inorganic base used for etching is sodium hydroxide or potassium hydroxide.

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