Binding a target substance

Abstract

Magnetic particles capable of binding a target substance, which comprise a magnetic material and a matrix material, wherein the magnetic material is remanent upon exposure to a magnetic field and the matrix material has a surface comprising functional groups which promote disaggregation of the particles in the presence of a liquid phase.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to magnetic particles capable of binding a target substance such as nucleic acid, a process for making such magnetic particles, and a process for isolating a target substance from a target substance-containing sample. BACKGROUND TO THE INVENTION

[0002] Procedures involving nucleic acids such as DNA and RNA continue to play a crucial role in biotechnology. Nucleic acid detection and manipulation including hybridisation, amplification, sequencing and other processes generally require nucleic acid to have been isolated from contaminating material. Where a nucleic acid-containing sample is a biological sample, contaminating material may include proteins, carbohydrates, lipids and polyphenols. Accordingly, a variety of approaches have hitherto been used in the isolation of DNA or RNA.

[0003] Early methods of isolating nucleic acid involved a series of extractions with organic solvents, involving ethanol precipitation and dialysi...

Examples

example 1

[0061] In this example, an aqueous dispersion of ferrimagnetic magnetite particles in sodium silicate solution (water glass) is mixed with an oil phase to form a water-in-oil emulsion with magnetite in the aqueous phase. Condensation polymerisation is performed in the presence of acid to produce the magnetic particles with an inorganic polymer.

[0062] Ferrimagnetic magnetite particles (size 200-300 nm) 20 g were dispersed in 40 g waterglass (NMD) using an ultraturax mixing device. After mixing for 1 min at 16000 rpm, the speed was reduced to 13000 rpm and 300 ml of an oilphase (for instance toluene or isopar) containing 3% of an emulsifier (for instance span 80, span 65) was added. The speed was increased to 1700 rpm for 1 min and the resulting water in oil emulsion (magnetite dispersed in the water phase) was stirred in a reactor for 10 min at 20° C. before 2M HNO3 (30 ml) was added. After stirring for 1 h and addition of methanol (30 ml), the suspension was stirred at 50° C. for 1...

example 2

[0063] In this example ferrimagnetic magnetite particles are dispersed in an organic monomer (EGDMA) and an oil in water emulsion is formed by mixing the particle suspension with an aqueous phase. The monomers are polymerised to produce the organic polymer magnetic particles.

[0064] Ferrimagnetic magnetite particles (size 200-300 nm) 6,6 g were dispersed in 20 g EGDMA. AIBN (0,45 g) was added to the dispersion and the organic phase containing magnetite was emulsified in water (150 ml) containing 0,5% polyvinylalcohol (Evanol) by use of an ultraturax (13000 rpm, 2 min). The resulting emulsion was stirred in an reactor for 20 h at 65° C. and the magnetic polymer beads were washed with methanol (5×150 ml) and dried at 80° C. for 6 h. Particle size 0,7 μm-6 μm. Relative susceptibility: 15×1 0−3 cgs.

example 3

[0065] In this Example ferrimagnetic magnetic particles are dispersed in an organic solvent with a monomer, which is then polymerised to form the particles.

[0066] Magnetite (1 g) is dispersed in an organic solvent such as THF, hexane or toluene (10 ml), where after an epoxiresin like bisphenol-A (10 ml) is added. Stirring is continued at 70° C. for 16 h and the magnetic particle are then washed 5 times with THF (25 ml each wash) by using a centrifuge. Finally the particles are dried in vacuum at 50° C. The particles have approximately 0.25 mmol / g epoxigroups.

FIELD OF THE INVENTION

[0001] The present invention relates to magnetic particles capable of binding a target substance such as nucleic acid, a process for making such magnetic particles, and a process for isolating a target substance from a target substance-containing sample. BACKGROUND TO THE INVENTION

[0002] Procedures involving nucleic acids such as DNA and RNA continue to play a crucial role in biotechnology. Nucleic acid detection and manipulation including hybridisation, amplification, sequencing and other processes generally require nucleic acid to have been isolated from contaminating material. Where a nucleic acid-containing sample is a biological sample, contaminating material may include proteins, carbohydrates, lipids and polyphenols. Accordingly, a variety of approaches have hitherto been used in the isolation of DNA or RNA.

[0003] Early methods of isolating nucleic acid involved a series of extractions with organic solvents, involving ethanol precipitation and dialysi...

Examples

example 1

[0061] In this example, an aqueous dispersion of ferrimagnetic magnetite particles in sodium silicate solution (water glass) is mixed with an oil phase to form a water-in-oil emulsion with magnetite in the aqueous phase. Condensation polymerisation is performed in the presence of acid to produce the magnetic particles with an inorganic polymer.

[0062] Ferrimagnetic magnetite particles (size 200-300 nm) 20 g were dispersed in 40 g waterglass (NMD) using an ultraturax mixing device. After mixing for 1 min at 16000 rpm, the speed was reduced to 13000 rpm and 300 ml of an oilphase (for instance toluene or isopar) containing 3% of an emulsifier (for instance span 80, span 65) was added. The speed was increased to 1700 rpm for 1 min and the resulting water in oil emulsion (magnetite dispersed in the water phase) was stirred in a reactor for 10 min at 20° C. before 2M HNO3 (30 ml) was added. After stirring for 1 h and addition of methanol (30 ml), the suspension was stirred at 50° C. for 1...

example 2

[0063] In this example ferrimagnetic magnetite particles are dispersed in an organic monomer (EGDMA) and an oil in water emulsion is formed by mixing the particle suspension with an aqueous phase. The monomers are polymerised to produce the organic polymer magnetic particles.

[0064] Ferrimagnetic magnetite particles (size 200-300 nm) 6,6 g were dispersed in 20 g EGDMA. AIBN (0,45 g) was added to the dispersion and the organic phase containing magnetite was emulsified in water (150 ml) containing 0,5% polyvinylalcohol (Evanol) by use of an ultraturax (13000 rpm, 2 min). The resulting emulsion was stirred in an reactor for 20 h at 65° C. and the magnetic polymer beads were washed with methanol (5×150 ml) and dried at 80° C. for 6 h. Particle size 0,7 μm-6 μm. Relative susceptibility: 15×1 0−3 cgs.

example 3

[0065] In this Example ferrimagnetic magnetic particles are dispersed in an organic solvent with a monomer, which is then polymerised to form the particles.

[0066] Magnetite (1 g) is dispersed in an organic solvent such as THF, hexane or toluene (10 ml), where after an epoxiresin like bisphenol-A (10 ml) is added. Stirring is continued at 70° C. for 16 h and the magnetic particle are then washed 5 times with THF (25 ml each wash) by using a centrifuge. Finally the particles are dried in vacuum at 50° C. The particles have approximately 0.25 mmol / g epoxigroups.