JPH07235407A - Magnetic particle - Google Patents

Abstract

PURPOSE:To provide particles which can be efficiently and selectively separated from a sample after it is mixed or reacted with the sample. CONSTITUTION:The magnetic particle comprises a ferromagnetic material 3 having silica gel 1 on a surface and covered in a center with an anticorrosion coating 2. Sol is formed by ice-cooling 3N aqueous solution of alkaline sodium silicate (water glass), adding ice-cooled 3N hydrochloric acid thereto while agitating it to prepare its pH to about 1. After it is left to stand for one night, its filtrate is heated to 60 deg.C, thereby gelatinizing it. In this case, ferromagnetic particles covered with anticorrosion coating such as gold-plating, etc., are mixed, cut to a suitable size in a shape containing the ferromagnetic particles, washed, slightly dried, further washed with flowing water when it becomes elastic gel to remove soluble salt, and then dried at 110 deg.C to obtain glassy gel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hygroscopic particles containing ferromagnet or immobilized enzyme particles.

[0002]

2. Description of the Related Art As a conventional hygroscopic material, quicklime, silica gel and the like are well known. When using these to take the moisture of a target sample, considering recovery,
Generally, these hygroscopic agents have been isolated and used in bags with good air permeability such as filter paper and cellophane.

To make an immobilized enzyme or the like adsorb an enzyme to a particle, bind it ionicly or covalently, or confine the enzyme in a polymer gel network structure, it is necessary to collect and reuse the water-soluble enzyme. In the past, many methods have been invented as means for binding microparticles and analytes. For example, Tokuhyo Hira 3-504276, Bayer Yeah and Will Check M: Method In
Biochemistry Analysis, 26, pp. 1-45
(1980) (Bayer, EA & Wilche.
k, M. : Meth. in Biochem. Ana
l. , 26, pp. 1-45 (1980)), U.S. Pat. No. 4,654,267.

In order to quantify, analyze, and fractionate a specific sample, it is necessary to separate the target sample from other substances by some method, but the conventional centrifugation method, column separation method, electric method, etc. Methods such as electrophoresis require only a long time for separation, and there is also the possibility of denaturation or the like due to extreme changes in environmental conditions. Therefore, there has been a conventional idea of adding a ferromagnetic material to specific fine particles in order to separate the fine particles (for example, JP-A-60-32955).
"Ion-exchange resin bed", JP-A-60-244251 "Magnetically reactive particles and method for producing the same"), in these techniques, the ferromagnetic substance itself self-associates and exists in a dispersed state when reacting. There was no way to disperse when I wanted to.

In recent years, a method using superparamagnetic magnetic beads has been developed as a method for overcoming this disadvantage, and magnetic beads are used as a solid phase for immobilizing a sample, and proteins, cells, DNA are used.
Is used for the separation and analysis of
501956, Tokuyo Hyodai 4-501957, Tokuyo Hyodai 4-5
01958, Tokuyohei 4-501959).

These superparamagnetic magnetic beads are obtained by forming magnetic particles such as iron oxide into ferromagnetic fine particles having a size smaller than the size of magnetic domains required to maintain permanent magnetism and dispersing them in the beads. It has the property of exhibiting ferromagnetism only when an external magnetic field is applied. Utilizing this superparamagnetic property, the superparamagnetic magnetic beads are used to prevent the beads from aggregating in the solution during the reaction despite containing the magnetic substance. Only magnetic beads are aggregated specifically.

[0007]

The conventional hygroscopic agent, immobilized enzyme, and catalyst cannot be selectively removed when mixed in a sample. In addition, in the case of conventional particles containing a ferromagnetic substance, it is necessary to disperse them in order to effectively carry out reactions etc., but due to the properties of the ferromagnetic substance, the particles themselves self-assemble due to the magnetic field. It had a fatal drawback that it could not be dispersed.

To compensate for this drawback, particles using a superparamagnetic material instead of a ferromagnetic material have been developed, but the superparamagnetic material must be dispersed particles smaller than the magnetic domain structure in order to obtain its properties. , The external force exerted on the particles by the external magnetic field is infinitesimally smaller than that of the ferromagnetic material, and the external magnetic field must be sufficiently large to support its own weight. In addition, when agglomeration of fine particles is performed using only superparamagnetic properties, it is impossible to selectively respond to an external magnetic field, and all superparamagnetic particles are aggregated with respect to the external magnetic field. There was a problem.

Further, if the particle size of the particles is made sufficiently small due to the nature of the superparamagnetic particles, there is a problem that the force due to the magnetic field weakens and the particles cannot be collected. Further, since superparamagnetic particles have the property of self-associating only in the presence of an external magnetic field, it was necessary to always act on the external magnetic field in order to move them between the containers while they were associated.

Further, since the particles contain a ferromagnetic material or a superparamagnetic material, there is a problem that they react with the water contained in the reaction solution and other fine particles to cause corrosion.

An object of the present invention is to provide particles which can be efficiently and selectively separated from a sample after being mixed with or reacted with the sample.

[0012]

[Means for Solving the Problems] In order to selectively aggregate particles containing a conventional ferromagnetic material or to obtain particles having a selective self-assembly ability having a stronger magnetic force than a conventional superparamagnetic material, As the magnetic substance included in the above, a ferromagnetic substance having a Curie point temperature at which the melting point of the particles or the function of the particles is not destroyed may be used. Further, in order to selectively self-assemble a plurality of different types of particles one by one, a plurality of magnetic particles each having a different Curie point temperature are combined, and a magnetic field is selectively changed by combining a temperature change and a magnetic field. The beads may be aggregated or diffused. Regarding the magnetic particles, for the magnetic particles that are desired to self-associate, it suffices if the particles include a ferromagnetic material larger than the magnetic domain necessary to maintain permanent magnetism in the magnetic particles, and the external magnetic field works. For magnetic particles that do not want to self-associate except at times, the particles may contain a ferromagnetic material smaller than the magnetic domain necessary to maintain permanent magnetism. In order to prevent the ferromagnetic material or superparamagnetic material contained in the particles from being corroded, the surface of these ferromagnetic material or superparamagnetic material may be subjected to surface corrosion treatment such as gold plating.

[0013]

[Function] Ferromagnetic material has a T
At temperatures lower than c, it becomes a ferromagnetic material and has spontaneous magnetization,
At a temperature higher than c, the paramagnetic material does not have spontaneous magnetization. Therefore, for a particle containing a ferromagnetic material having Tc at a temperature low enough not to impair the function of the particle, the particle is first heated to a temperature higher than Tc to destroy the magnetic domain structure and demagnetize.
The demagnetized particles do not have spontaneous magnetization and remain dispersed even at a temperature lower than the solution temperature Tc until an external magnetic field is applied. When an external magnetic field is temporarily applied to the particles when the magnetic fields in the magnetic domains are aligned and start to associate with each other, the particles become spontaneously magnetized and self-associate. After that, the particles remain stable as aggregates regardless of the presence or absence of a magnetic field.

Particles containing a superparamagnetic material have ferromagnetic particles smaller than the magnetic domains required to maintain permanent magnetism dispersed therein and are arranged in the particles. Therefore, only when an external magnetic field is working. The particles associate. Therefore, the same method as the conventional method may be used. In this way, the magnetic particles aggregate only when their Curie point temperature is higher than the environmental temperature of the solution or the like and an external magnetic field is applied.

Curie point temperatures T1, which are different from each other,
Different types of particles including a ferromagnetic material or a superferromagnetic material having T2, T3, ... (T1>T2>T3> ...), all kinds of particles have spontaneous magnetization when the environmental temperature is higher than T1. It does not have and diffuses in the reaction solution. Next, the environmental temperature is sequentially lowered to T1, T2, T3, ... By applying an external magnetic field each time, magnetic particles having a Curie point temperature higher than the environmental temperature can be captured and separated one by one. it can.

[0016]

EXAMPLE FIG. 1 (a) is a sectional view showing the structure of a particle containing a ferromagnetic material. The particles have a ferromagnetic material 3 having silica gel 1 on the surface and a corrosion resistant coating 2 at the center. In the manufacturing method, a 3N aqueous solution of alkaline sodium silicate (water glass) is ice-cooled, and ice-cooled 3N hydrochloric acid is added to this while stirring to adjust the pH to about 1 to form a sol. After standing overnight, the filtered solution is heated to 60 ° C. to gel. At this time, the ferromagnetic particles coated with a corrosion-resistant coating such as gold plating are mixed, cut into an appropriate size containing the ferromagnetic material, washed with water, and dried a little to become an elastic gel. After thoroughly washing to remove soluble salts, it is dried at 110 ° C. to obtain a glassy gel.

Here, as a ferromagnetic material for carrying out the present invention, for example, the materials shown in Table 1 below can be used.

[0018]

[Table 1]

FIGS. 1 (b) to 1 (d) show a flow chart of an embodiment using magnetic particles produced by the above procedure.

In (b), the magnetic particles shown in (a) above are placed in the container 4 in contact with the heat source 5, and the heat given from the heat source 5 causes the magnetic particles to curly the ferromagnetic material therein. The magnetic particles are demagnetized by heating to the point temperature Tc or higher. Next, in (c), the demagnetized magnetic particles and the sample are mixed. Further, in (d), magnetic particles are selectively removed from the sample. At this time, the temperature of the magnetic particles is kept lower than Tc, and the electromagnet 7 is turned on to attract the magnetic particles to the electromagnet. The magnetic particles taken out can be returned to the step (b) again to heat the moisture-absorbed magnetic particles to simultaneously dry and demagnetize the particles so that the magnetic particles can be reused.

For this magnetic particle, silica gel was used in the present embodiment, but a ferromagnetic material was wrapped with a polymer such as polystyrene, and the surface was modified by the method as shown in US Pat. No. 4,654,267 to obtain an enzyme or the like. May be fixed, or the surface of the ferromagnetic material may be coated with platinum to be used as a catalyst, or the surface of the ferromagnetic material may be coated with an ion exchange resin.

Further, in this embodiment, the ferromagnetic material is contained in the particles having the function, but the ferromagnetic material may be adhered to the surface of the particle having the function. Further, when it is desired to selectively capture a plurality of types of fine particles, a ferromagnetic material having different Curie point temperatures (T1, (>) T2, T3, ...) Is used and the temperature is sequentially increased from T> T1 to T1. When>T> T2, the particles having the Curie point temperature T1 become a ferromagnetic material and are selectively captured by the external magnetic field, and then T2>T>
When the temperature reaches T3, the particles having the Curie point temperature T2 become a ferromagnetic body and are selectively captured by the external magnetic field, and similarly, the particles having the Curie point temperature T3 or lower can be captured.

In the above examples, the ferromagnetic particles were used, but it is also possible to replace them entirely with superparamagnetic particles and use them in the same manner.

[0024]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has an effect that particles having a function can be efficiently and selectively mixed with or reacted with a sample and then separated. .

[Brief description of drawings]

FIG. 1A is a schematic view showing a cross section of particles containing a ferromagnetic material, and FIGS. 1B to 1D are flow charts showing a procedure of an embodiment of the present invention.

[Explanation of symbols]

1 ... Silica gel, 2 ... Corrosion resistant coating, 3 ... Ferromagnetic material, 4 ...
Container, 5 ... Heat source, 6 ... Sample, 7 ... Electromagnet.

Claims (7)

[Claims] 1. A particle containing a ferromagnetic material, which contains a ferromagnetic material having a Curie point temperature lower than a melting point of the particle. 2. The fine particles according to claim 1, wherein the ferromagnetic material has a superparamagnetic structure. 3. The fine particles according to claim 1, which have a hygroscopic material. 4. The fine particles according to claim 3, wherein silica gel is used as the hygroscopic material. 5. The fine particles according to claim 1, wherein the surface of the magnetic material or the superparamagnetic material is subjected to anticorrosion treatment. 6. The fine particles according to claim 1 or 2, wherein the fine particles have an immobilized enzyme. 7. The fine particles according to claim 1 or 2, wherein the fine particles have a catalyst.