Apparatus for separating fine particles using magnetophoresis, and method for separating fine particles using same

Abstract

The present invention relates to an apparatus for separating fine particles using magnetophoresis, and to a method for separating fine particles using same, and particularly, to an apparatus for separating fine particles using magnetophoresis, which includes a fine, patterned magnetic structure capable of quickly and efficiently separating even particles that are weakly magnetized and coupled to fine particles, and to a method for separating fine particles using same.

Claims

1. An apparatus for separating fine particles using magnetophoresis comprising: an upper substrate; a lower substrate comprising a fine structure of a magnetic material; a microfluidic channel, which is formed between the upper substrate and the lower substrate, and where a sample comprising fine particles passes in a sample flow direction, the sample comprising magnetic fine particles; and an external magnetic field source generating a magnetic field around the fine structure of the magnetic material; the microfluidic channel is divided into a microfluidic channel domain for injection, a microfluidic channel domain for separation, and a microfluidic channel domain for discharge; wherein the fine structure of the magnetic material is plurality of linear structures, and is patterned and contained in the lower substrate by molding, wherein the sample flow direction has an angle ? and each linear structure has angles of inclination relative to the sample flow direction, ?.sub.1, ?.sub.2, ?.sub.3 . . . ?.sub.n, in order respectively, in the direction from the microfluidic channel domain for injection to the microfluidic channel domain for discharge, the angles of inclination relative to the sample flow direction, ?.sub.1, ?.sub.2, ?.sub.3 . . . ?.sub.n, satisfying the following relation expression:
?.sub.1??.sub.2??.sub.3? . . . ?.sub.n(3?n); wherein the point (P) where the angle of inclination is changed from ?.sub.n-1 to ?.sub.n is located in a horizontally extended part of the microfluidic channel domain for discharge, wherein the angle ?.sub.n is 90?, wherein the fine structure of the magnetic material is patterned to make both sides of the microfluidic channel have symmetry based on the center line of the microfluidic channel domain for separation.

2. The apparatus for separating fine particles using magnetophoresis according to claim 1, wherein the microfluidic channel is divided into: the microfluidic channel domain for injection comprising a sample inlet and a buffer inlet, where the sample comprising fine particles and a buffer are injected; the microfluidic channel domain for separation, where the sample comprising fine particles is separated by magnetophoresis while passing through into a separated sample comprising magnetic fine particles and the rest of the separated sample; and the microfluidic channel domain for discharge comprising a plurality of outlets, where the separated sample comprising magnetic fine particles and the rest of the separated sample are separately discharged.

3. The apparatus for separating fine particles using magnetophoresis according to claim 2, wherein the microfluidic channel domain for discharge comprises an outlet for the separated sample comprising magnetic fine particles, and an outlet for the rest of the separated sample.

4. The apparatus for separating fine particles using magnetophoresis according to claim 2, wherein the microfluidic channel domain for injection comprises the buffer inlet, and the sample inlet, which is a plurality of sample inlets symmetrically formed on both sides of the buffer inlet.

5. The apparatus for separating fine particles using magnetophoresis according to claim 2, wherein the microfluidic channel domain for injection comprises the sample inlet, and the buffer inlet, which is a plurality of buffer inlets symmetrically formed on both sides of the sample inlet.

6. The apparatus for separating fine particles using magnetophoresis according to claim 1, wherein the fine structure of the magnetic material comprises a nickel-iron alloy or a nickel-iron-cobalt alloy.

7. The apparatus for separating fine particles using magnetophoresis according to claim 6, wherein the fine structure of the magnetic material is any one of permalloy (Fe 50%, Ni 50%), moly permalloy (Ni 81%, Fe 17%, Mo 2%) or superalloy (Co 52%, Fe 26%, Ni 22%).

8. The apparatus for separating fine particles using magnetophoresis according to claim 1, wherein in the apparatus for separating fine particles using magnetophoresis, the angles of inclination relative to the sample flow direction, ?.sub.1, ?.sub.2, ?.sub.3 . . . ?.sub.n of each linear structure of the plurality of linear structures, the thickness of the fine structure of the magnetic material, gap between adjacent linear structures of the plurality of linear structures of the fine structure of the magnetic material, the number of linear structures of the plurality of linear structures to be installed, the size of the external magnetic field source and the fluid flow rate in the microfluidic channel are changed according to the sample comprising fine particles to be separated.

9. The apparatus for separating fine particles using magnetophoresis according to claim 1, wherein the upper substrate comprises a patterned fine structure of a magnetic material, patterned in the same shape as the fine structure of the magnetic material of the lower substrate.

10. A method for separating fine particles using magnetophoresis and using the apparatus of claim 1 for separating fine particles using magnetophoresis comprising: a first step of injecting the sample comprising fine particles, the sample comprising magnetic fine particles into a sample inlet of the microfluidic channel domain for injection; a second step of injecting a buffer into a buffer inlet of the microfluidic channel domain of infection; a third step of separating the sample comprising magnetic fine particles from the rest of the sample comprising fine particles, wherein an external magnetic field source is generated, thereby a magnetic force is generated around the fine structure of the magnetic material, and the sample comprising magnetic fine particles is separated from the rest of the sample comprising fine particles by the magnetic force generated around the fine structure of the magnetic material while the rest of the sample comprising fine particles is passing through the microfluidic channel domain for separation; and a fourth step of collecting separately, the rest of the sample comprising fine particles and the sample comprising fine magnetic particles separated in the third step at the microfluidic channel domain for discharge.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The above and other objects and features of the present invention will become apparent from the following description of the invention taken in conjunction with the following accompanying drawings, which respectively show:

(2) FIG. 1: a schematic diagram of the existing magnetophoresis apparatus;

(3) FIG. 2 and FIG. 3 are a cross-sectional view and a plane view of the apparatus for separating fine particles using magnetophoresis according to one embodiment of the present invention;

(4) FIG. 4 is a drawing showing a process for manufacturing the fine structures of a magnetic material to be contained in the lower glass substrate by molding;

(5) FIG. 5 and FIG. 6 are drawings showing the direction of the magnetic field and the magnetic force applied to the fine particles in the microfluidic channel when external magnetic field is applied to the apparatus for separating fine particles using magnetophoresis of the present invention;

(6) FIG. 7 is a mimetic diagram of the apparatus for separating fine particles using magnetophoresis of the present invention when the angle of inclination of the fine structure of a magnetic material is changed according to one embodiment of the present invention;

(7) FIG. 8 and FIG. 9 are mimetic drawings showing the apparatus for separating fine particles using magnetophoresis according to another embodiment of the present invention;

(8) FIG. 10 is a mimetic drawing showing the apparatus for separating fine particles using magnetophoresis, which also contains the fine structure of a magnetic material in the upper substrate, according to another embodiment of the present invention;

(9) FIG. 11 is a mimetic drawing showing the apparatus for separating fine particles using magnetophoresis, which also contains the fine structure of a magnetic material in the upper substrate, according to another embodiment of the present invention;

(10) FIG. 12 is a drawing showing the apparatus for separating fine particles using magnetophoresis manufactured according to one embodiment of the present invention;

(11) FIG. 13 is a drawing mimetically showing a process for separating the RNA combined with the magnetic particles by using the apparatus for separating the fine particles combined with the magnetic particles using magnetophoresis manufactured according to one embodiment of the present invention;

(12) FIG. 14 is images showing that the RNA combined with the magnetic particles flow along the channel when an external magnetic field was applied or not applied to the apparatus for separating the fine particles combined with the magnetic particles using magnetophoresis manufactured according to one embodiment of the present invention;

(13) FIG. 15 is a drawing showing the results of the efficiency separating the RNA combined with the magnetic particles and the purity of the RNA according to change the sample flow rate when separating the RNA combined with the magnetic particles by using the apparatus for separating the fine particles combined with the magnetic particles using magnetophoresis manufactured according to one embodiment of the present invention;

(14) FIG. 16 is a drawing showing the result of RT-PCR for detecting human ? actin (219 bp) from the RNA extract according to one embodiment of the present invention;

(15) FIG. 17 is an image of the apparatus for separating fine particles using magnetophoresis manufactured according to another embodiment of the present invention, and an image showing that the circulating tumor cells combined with the magnetic particles flow along the channel of the separation apparatus when separating the circulating tumor cells by using the separating apparatus;

(16) FIG. 18 is a drawing showing the result of measuring the separation efficiency of the circulating tumor cells combined with the magnetic particles when changing the flow rate of the sample;

(17) FIG. 19 is a drawing showing the result of measuring the number of the circulating tumor cells separated by using the apparatus for separating fine particles according to one embodiment of the present invention while changing the number of the circulating tumor cells spiked in the sample;

(18) FIG. 20 is a drawing showing the result of performing RT-PCR to the circulating tumor cells separated by using the apparatus for separating fine particles according to one embodiment of the present invention; and

(19) FIG. 21 is a drawing showing the result of separating the circulating tumor cells from patients of breast cancer and lung cancer by using the apparatus for separating fine particles according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(20) Hereinafter, the present invention will be described in further detail with reference to examples. These examples are illustrative purposes only and are not to be construed to limit the scope of the present invention.

Preparation of Apparatus for Separating Fine Particles Combined with Magnetic Particles by Magnetophoresis

(21) In order to form a microfluidic channel, a Ti/Cu/Cr seed layer was deposited on a bottom glass substrate of 0.7 mm thick (Borofloat?, Howard Glass Co., Worchester, Mass.), a pattern was formed by photoresist, and then a ferromagnetic nickel wire of 30 ?m thick was formed through a plating process.

(22) In this Example, two ferromagnetic nickel wires were contained in the lower glass substrate of a microfluidic channel for separation part, and one wire of them was contained with an angle of inclination to the direction of sample flow of 5.7?, and the other wire was patterned, wherein the angle of inclination was 7.1? at first followed by being changed to 11.3? at the end of the microfluidic channel for separation, and then changed again to 90?.

(23) In order to reduce the phenomenon that cells are attached to the surface of the microfluidic channel, the ferromagnetic nickel wire was constructed to be separated 100 ?m from the channel surface of a microfluidic channel part for separation. A lower substrate comprising the ferromagnetic nickel wire as a magnetic structure was manufactured by removing the photoresist, coating an epoxy adhesive followed by leveling the surface.

(24) Then, SU-8 was formed on an upper glass substrate as a microfluidic channel pattern, an upper glass substrate was manufactured by making a sample inlet by using Nitrile rubber O-rings (size 001-1/2, McMaster-Carr, IL, USA), and the manufactured lower glass substrate and a UV adhesive (1187-M, DYMAX Co., Torrington, Conn.) were joined together so as to finally complete an apparatus for separating fine particles using magnetic flux as shown in FIG. 12.

RNA Separation

RNA Separation From Blood

(25) As magnetic particles, 2.8 ?m diameter magnetic beads (Dynabeads Oligo (dT)25) were used. Human blood 50 ?l was collected from a finger, and RNA lysis buffer 175 ?l A was mixed with the magnetic particles to manufacture a sample comprising RNA combined with the magnetic particles. The sample prepared above was injected into the sample inlet of the apparatus for separating fine particles manufactured in Example 1.

(26) A process for separating RNA in the fine particle separating apparatus comprising a plurality of fine structures of a magnetic material, when the angle of inclination to the fluidic flow was changed at the same point with the same angle, was mimetically illustrated in FIG. 13.

(27) Images of white blood cell-dissolved blood and the magnetic particles flowing along the channel when an external magnetic field was applied or not applied to the particle separating apparatus manufactured in Preparation Example 1 were illustrated in FIG. 14A and FIG. 14B, respectively. When the external magnetic field was applied, it could be confirmed that the blood and the RNA combined with the magnetic particles are apparently separated and collected.

Measuring Separation Efficiency According to Sample Flow Rate

(28) The procedure of Example 1 was repeated, and efficiency for separating the RNA combined with the magnetic particles and purity of the separated RNA when sample flow rate was changed to 10, 15, 20 and 25 ml/h, respectively, were measured, and the results were shown in FIG. 15a and FIG. 15b.

(29) As shown in FIG. 15a and FIG. 15b, according to increase of the sample flow rate, the efficiency for separation was decreased. Accordingly, it could be found that: the efficiency for separation can be controlled by changing the sample flow rate according to the fine particles to be separated; and in the case of the blood, it is preferred that the sample flow rate may be 15 to 20 ml/h in terms of the efficiency and the speed for separation in order to separate RNA.

Performing RT-PCR Using Separated RNA

(30) Whether the RNA extract according to the present invention can be used for performing RT-PCR or not was checked by performing RT-PCR for detecting a human ? actin (219 bp) using the RNA separated in Example 1.

(31) After performing the RT-PCR, the result of the gel electrophoresis shown in FIG. 16 was obtained, and accordingly, it can be found that the RNA separated according to the RNA extraction method of the present invention can be used for the RT-PCR.

Manufacturing Apparatus for Separating Fine Particles Combined with Magnetic Particles Using Magnetophoresis

(32) In this Example, two ferromagnetic wires were formed to be contained in the lower glass substrate of the microfluidic channel for separation part. The procedure of Preparation Example 1 was repeated to manufacture the apparatus for separating the fine particles combined with the magnetic particles by magnetophoresis except that: the width of the wire was 50 ?m, the both of the two wires were contained with the angle of inclination of 5.7? to the direction of the sample flow, and it is patterned to have the angle of inclination of 90? near the outlet. The fine structure of a magnetic material in the manufactured separation apparatus and the state of separating the CTC using the same were illustrated in FIG. 17.

Separation of Circulating Tumor Cells (CTC)

Example 2-1

(33) Blood sample was collected from a breast cancer patient and a lung cancer patient, and the circulating tumor cells in the sample were combined with magnetic nanoparticles by mixing with the magnetic nanoparticles labeled with anti-EpCAM antibody against an epithelial cell adhesion molecule. As the magnetic particles, magnetic nanobeads (STEMCELL Technologies), which has the diameter of several tens nm and is coated with the anti-EpCAM antibody.

(34) The blood sample comprising the circulating tumor cells combined with the magnetic particles as prepared above was injected into the apparatus for separating fine particles manufactured in Preparation Example 2. An enlarged image, showing that the circulating tumor cells combined with the magnetic particles flow along the channel of the apparatus for separating fine particles manufactured in Preparation Example 2 when applying the external magnetic field source to the fine structure of a magnetic consisting of the ferromagnetic nickel wire, was illustrated in FIG. 17. As shown in FIG. 17, it could be confirmed that the circulating tumor cells combined with the magnetic particles were separated while moving to the lateral direction when the external magnetic field was applied.

Measuring Separation Efficiency According to Sample Flow Rate

(35) The procedure of Example 2-1 was repeated, and the separation efficiency of the circulating tumor cells combined with the magnetic particles, and the purity of the separated circulating tumor cells were measured when changing the sample flow rate to 2, 3, 4 and 5 ml/h, respectively, and the result was shown in FIG. 18.

(36) As shown in FIG. 18, the separation efficiency of circulating tumor cells combined with the magnetic particles was 78.7%, and it could be found that the separation efficiency for the circulating tumor cells was not changed by the flow rate in the flow rate range of 2 to 5 ml/h.

Measuring Separation Efficiency According to Content of Circulating Tumor Cells in Sample

(37) The procedure of Example 2-1 was repeated, and the number of the circulating tumor cells separated by the apparatus for separating fine particles manufactured in Preparation Example 2 while changing the number of the circulating tumor cells spiked in the sample to 10, 10.sup.2, 10.sup.3 and 10.sup.4, and the result was shown in FIG. 19. As shown in FIG. 19, it could be found that the number of the spiked circulating tumor cells and the number of the separated circulating tumor cells are reciprocally proportional, and the separation efficiency of the circulating tumor cells was very high of 79%.

Performing RT-PCR According to Amount of Spike of Circulating Tumor Cells in Sample

(38) To each sample containing the number of the spiked circulating tumor cells of 10, 10.sup.2 and 10.sup.3, respectively, RT-PCR was performed to detect the circulating tumor cells separated in Example 2-3, and the result was shown in FIG. 20.

(39) As the result of RT-PCR shown in FIG. 20, it could be confirmed that the cells were separated by PCR even when the number of the spiked circulating tumor cells is very small of 10.

Separation of CTC Cells from Cancer Patient

(40) The circulating tumor cells were separated from samples of three breast cancer patients and one lung cancer patient by the apparatus separating fine particles manufactured in Preparation Example 2, and the result was shown in FIG. 21. It could be confirmed that the circulating tumor cells were completely separated in FIG. 21.

INDUSTRIAL APPLICABILITY

(41) The apparatus for separating the fine particles using magnetophoresis of the present invention has effects of: improving the magnetic force applied to the magnetic particles by comprising the fine structure of a magnetic material on the lower glass substrate by a molding process; and improving the efficiency for separating the fine particles combined with the magnetic particles and reducing the separation time by controlling the moving direction of the magnetic particles by patterning the fine structure of a magnetic material to have a certain angle of inclination of the direction of sample flow.

(42) While the invention has been described with respect to the above specific embodiments, it should be recognized that various modifications and changes may be made and also fall within the scope of the invention as defined by the claims that follow.