Device for separating particles

 

(57) Abstract:

The invention relates to the separation of magnetic particles from the containing mixture and can be applied mainly in biotechnology, biochemistry and Biomedicine. The device comprises an elongated protective housing, in which the possibility of reciprocating movement is set magnetic rod. The ratio of the length of the magnetic core to its thickness is at least 2:1. The rod is introduced into the mixture, the magnetic particles are collected on the tip, then remove it and carry particles, for example, in another volume. The invention provides for the efficient collection of particles from a large volume to transfer them into a substantially small volume. 2 c. and 4 C.p. f-crystals, 6 ill.

The invention relates to the separation of magnetic particles from the containing mixture. The invention may have various applications, particularly in the fields of biotechnology, biochemistry and Biomedicine.

Magnetic microparticles are widely used for binding the biomaterial. One of the advantages of microparticles is a large surface area of the solid phase and the small diffusion length. The size of the microparticles is typically 0.05 - 10 μm, they can be manufactured from various materials and have found ways to separate magnetic particles provide the location of the vessel of the reactor in a magnetic field, so the particles are accumulated in the so-called tablet at the bottom of the vessel. After that, the liquid that is released from the particles, is decanted or sucked. However, removal of the fluid from the vessel must be very careful not to delete and particles.

In the international application WO-86/06493 proposed method, intended for use in immunological analysis, according to which the magnetic particles and the associated marked complex is separated from the liquid using a rod magnet and then selected for measurements. At the end of the rod are fixed magnet and a removable protective housing, on the outer surface of which particles are held. After separation of the particles and before the measurement, it is desirable to close the protective case is another case. After measuring both hulls are removed together with the particles are thrown out and replaced with new buildings for the next particle separation. According to the application, as the magnet can be an electromagnet so that the magnetic field can be removed when required.

In the international application WO-87/05536 a device for separating magnetic particles inside cats liquid containing particles, when the magnet is in the lower position, causing the particles accumulate at the end of the rod. When the magnet means in the upper position, allows the separation of particles from the terminal. This makes it possible to collect particles and transfer them from one fluid to another.

However, the described devices and methods for separating magnetic particles can be used effectively in cases where it is necessary to collect particles from a rather large volume and transfer to a significantly smaller size.

The invention is directed to solving tasks easy and efficient collection of magnetic particles contained within a fairly large vessel, with the possibility of further migration of particles in a container of very small volume.

For this task offers a new device for separating magnetic particles from a mixture, as well as a new method based on the use of this device. There are also preferred embodiments of the invention.

The device according to the present invention includes an elongated protective housing, in which is enclosed a mobile terminal containing a single bar magnet, oochitelya at least 3:1 and most preferably at least 12:1. And intensity, and gradient generated thus the magnetic field reaches the highest values near the end of the rod, so that when the magnet is in the lower position, the particles from the volume of the suspension collected directly at the tip of the housing. The particles can be discharged from the tip of the body to another volume, which can be many times smaller than the original.

Bar magnet preferably comprises a permanent magnet and a ferromagnetic rod, which is its continuation.

Preferably, bar magnet may have a sufficient length that the upper end of the dipole is always positioned above the surface of the partial compositions. If you want to collect particles of the powder layer, the height of which exceeds the length of the dipole, you must first collect particles from the top of the mixture at the end of the housing so that the upper end of the dipole is constantly located above the particles.

Since it is possible to provide the position of the upper end of the magnet over the mixture, it is possible to use a magnet with a higher efficiency relative to the volume of the composition and thereby to accelerate and facilitate the collection of particles.

The device according to sobradinho in the direction of the housing. This is especially advantageous when the particles are collected from the area of their concentration, which was previously created in some other way. An additional advantage is that there is an opportunity to provide significant force holding particles directly at the tip of the body, despite the force of adhesion of the liquid, which tends to tear the particles, especially when removing the protective housing from the liquid.

The extremity of the protective housing is preferably provided with a downward directed arrow. This minimizes the amount of liquid remaining in the tip casing. Typical shape of the tip is a cone. When migrating particles in very small vessels extremity preferably as a cone with a concave surface.

When the magnet is used ferromagnetic rod, magnet and magnetized rod together act as a long bar magnet. The rod reduces the gradient at the upper pole of the magnet, so that the upper pole does not collect particles. This way you can get the long bar magnet at low cost. However, even in the presence of a ferromagnetic rod is preferable to use relatively long magnet (the length of which is 1.5-10 times PR is raganot internal constant field.

The junction between the magnet and the rod is preferably performed so that in a short length of the rod and the magnet included in each other. The result eliminates the formation of strong gradients in the joint area, which could lead to the collection of particles.

The cross-section of a rod magnet can be, for example, round or rectangular. The round shape is the best from the point of view of manufacture and application. Indeed, in this case, the rotation of the magnet around its axis does not create any additional effects. In principle, to simplify the drive mechanisms of the rod can be made curved.

The shape of the protective housing on the rod depends on the specific application. As a rule, from the standpoint of manufacture and use, the most convenient round shape. To increase the strength of the case you can do the taper, which will also simplify the manufacture of the body by the method of injection molding. The casing is preferably made of polypropylene.

The invention is most advantageously used for particle sizes of 1-10 μm.

Further, as examples, will be described some preferred embodiments of the image is s;

in Fig. 2 - use of the device according to Fig. 1 for collecting particles from the suspension;

in Fig. 3 - use of the device according to Fig. 1 for dropping the collected particles in a very small vessel;

in Fig. 4 - use a different variant of execution of the device according to the invention for collecting particles from the wall of the tube;

in Fig. 5 - using the third option execution device according to the invention for collecting particles from a small amount of liquid; and

in Fig. 6 - use of the device according to Fig. 5 for flushing the collected particles in a very small vessel.

Separating the particles of the rod according to Fig. 1 includes an elongated protective housing 1 in which there is a channel 2. The lower ends of the housing 1 and channel 2 is made slightly tapering. So it's easier to keep on the top end of the housing 2 has a flange 3.

Channel 2 is freely magnetic rod 4. It consists of a vertical rod magnet 5 in the lower part thereof and located above him ferromagnetic rod 6, is designed as a continuation of a rod magnet. At the end of the rod has a handle 7.

The lower end of the housing is fitted with a tapered tip with tip 8 with a concave surface. The length of this is the CI distributed in suspension 9 inside the tubes. Separating the particles of the rod is inserted into the tube and moves it up and down. This allows you to collect particles on the cutting edge in the form of annular mass 10. While the magnet 5 is located in the lower part of the channel 2, the particles remain associated with the edge. When the particles to be reset, the magnet rises.

The tip 8 is particularly well suited for particle transport in very small vessels type cells 11 in the so-called HLA-Board (Board for research with human leukocyte antigen - see Fig. 3). The length of the edge in this case is slightly higher than the height of the cell. When the tip is introduced into the cell, the surface of the liquid due to the action of surface tension forces, rises on the surface of the tip. The edge of the moving surface of the liquid washes away particles from the tip in the liquid. Separation of particles from the edge can be enhanced by vzbaltyvaya movements of the rod. When the tip is removed from the cell, the liquid moves in the direction of the tip apex as a single film. Due to this, the liquid particles are completely separated from the edge.

For best separation of particles from liquids, it is desirable that they were concentrated in particular C is th providing particles allow sedimentation due to gravity, using centrifugation, or attracting the particles to the walls of the vessel by a magnetic field.

In Fig. 4 presents the set of particles at the wall of the tube to which they were initially attracted by the magnet with the formation of vertical strips 9. Holding the tip of the rod along the strip, you can force the particles to gather on the tip of the protective housing 1 with mass formation 10. In this case, the extremity of the protective housing 1 has the shape of a short cone with a relatively large angle at the vertex. This version is adapted for transport of the particles in the vessels when the end can be freely introduced into the liquid.

The ratio of the length of the magnet 5 and its diameter is about 10:1 and the ratio of the length of the rod to the length of the magnet is about 5:1. The stem is slightly thicker than the magnet, and the upper end of the magnet enters the lower end of the rod to a length about twice the diameter of the magnet.

In Fig. 5 and 6 presents the device containing the magnetic rod 4', consisting only of permanent magnet 5' covered by a suitable protective case, but not containing ferromagnetic rod. Veri device, for example, in automatic systems particle separation or analytical systems. The ratio of magnet length to its diameter is, for example, 7:1. The extremity of the case is made in the form of a cone with a relatively large angle at the vertex (the height of the cone is equal to about 1/3 of its diameter).

Fig. 5 illustrates the separation of particles from a relatively small volume of liquid in the vessel, the diameter of which is small relative to the diameter separation rod (diameter of the rod is approximately 70% of the internal diameter of the vessel). The bottom line 11 represents the free surface of the liquid, while the upper line 12 to the surface of the liquid, when it entered the device for separating particles. Magnetic particles are collected on the tip of the protective sheath with the formation of the mass 10, which can then be reintroduced in a relatively small volume of liquid (Fig. 6).

The device according to Fig. 5 and 6 is well adapted for use in vessels with a diameter of about 7 mm for micrometrology.

1. Device for separating magnetic particles from a mixture containing, characterized in that it includes an elongated protective housing (1; 1') with an upper end and a lower end, a cavity (2) to protect the; ') located in the cavity and elongated in the direction of the longitudinal axis of the cavity, while the ratio of the length of a rod magnet to its thickness selected at least 2:1, preferably at least 3:1.

2. The device under item 1, characterized in that the bar magnet (4) contains at its lower end a magnet (5), and at its upper end a ferromagnetic rod (6) attached to the upper end of the magnet.

3. The device under item 1 or 2, characterized in that the ratio of the length of a rod magnet (4) to its thickness is chosen not less 12:1.

4. The device under item 2 or 3, characterized in that the upper end of the magnet (5) and the lower end of the rod (6) into each other.

5. The method of separating magnetic particles from a mixture containing, characterized in that the mixture entering the device for separating particles containing elongated protective housing (1, 1') with an upper end and a lower end, a cavity (2) in a protective housing, passing from its upper end toward its lower end, a movable bar magnet (4; 4') located in the cavity and elongated in the direction of the longitudinal axis of the cavity, while the ratio of the length of a rod magnet to its thickness is chosen not less 2:1, preferably not less 3:1.

6. The method according to newago magnet remains above the surface of the mixture.

 

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