Method for producing magnetic polymer particles

Abstract

To provide a production method capable of producing magnetic polymer particles having a more uniform shape and reduced variation in particle size, even with a polymer different from that of the conventional technology.SOLUTION: There is provided a method for producing magnetic polymer particles which comprises: an emulsification step of preparing an emulsion by emulsifying a dispersion obtained by dispersing magnetic particles and a polymer in an organic solvent and an aqueous solvent containing water and a hydrophilic organic solvent; and a formation step of forming magnetic polymer particles by removing at least a part of the organic solvent contained in the dispersion from the emulsion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for producing magnetic polymer particles.

Background Art

[0002] Magnetic polymer particles are widely used in the field of life sciences such as the recovery or detection of DNA or viruses, or in the field of clinical tests using chemiluminescence immunoassay, and research and development of magnetic polymer particles themselves is actively carried out.

[0003] For example, Non-Patent Document 1 discloses a method for producing magnetic polystyrene particles by an emulsion evaporation method. Further, Non-Patent Document 2 discloses a method for producing magnetic poly(lactide-co-glycolide) (PLGA) particles by an emulsion evaporation method.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technique described in Non-Patent Document 1 has problems that anisotropic particles inconvenient in practical use, such as rugby ball-shaped particles, are likely to be formed, and the particle size variation of the obtained particles is large. Further, the technique described in Non-Patent Document 2 is a technique targeting a specific biodegradable polymer, and a method for producing magnetic polymer particles applicable to other polymers has not been studied.

[0006] One aspect of the present invention aims to provide a manufacturing method capable of manufacturing magnetic polymer particles having a more uniform shape and a smaller variation in particle diameter even with polymers different from those of the prior art.

Means for Solving the Problems

[0007] In order to solve the above problems, a method for manufacturing magnetic polymer particles according to one aspect of the present invention includes an emulsifying step of emulsifying a dispersion liquid in which magnetic particles and a polymer are dispersed in an organic solvent and an aqueous solvent containing water and a hydrophilic organic solvent to prepare an emulsion liquid, and a forming step of removing at least a part of the organic solvent contained in the dispersion liquid from the emulsion liquid to form magnetic polymer particles.

Effects of the Invention

[0008] According to one aspect of the present invention, a manufacturing method capable of manufacturing magnetic polymer particles having a more uniform shape and a smaller variation in particle diameter even with polymers different from those of the prior art is provided.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 9

Embodiments for Carrying Out the Invention

[0010] 〔Method for Producing Magnetic Polymer Particles〕 As a result of intensive studies by the present inventors, in the production of magnetic polymer particles containing a polymer as a matrix, by carrying out the emulsion evaporation method using an aqueous solvent containing water and a hydrophilic organic solvent as the continuous phase solvent, magnetic polymer particles having a more uniform shape and a reduced variation in particle size than in the prior art can be obtained, and the present invention has been completed.

[0011] That is, the method for producing magnetic polymer particles according to one aspect of the present invention includes an emulsifying step of emulsifying a dispersion in which magnetic particles and a polymer are dispersed in an organic solvent and an aqueous solvent containing water and a hydrophilic organic solvent to prepare an emulsion, and a forming step of removing at least a part of the organic solvent contained in the dispersion from the emulsion to form magnetic polymer particles. Hereinafter, the method for producing magnetic polymer particles according to one aspect of the present invention may be abbreviated as "this production method".

[0012] In this specification, "magnetic polymer particles" refers to particles in which magnetic particles are encapsulated in polymer particles.

[0013] 〔Dispersion Step〕 This production method may further include a dispersion step of dispersing magnetic particles and a polymer in an organic solvent to prepare a dispersion before the emulsifying step. The type and amount of each component such as magnetic particles used in the dispersion step can be appropriately selected according to the type and concentration of each component in the dispersion liquid described later for the emulsifying step. The polymer is preferably used in the form of a fluid in order to be uniformly dissolved in the organic solvent.

[0014] As a method of dispersing, for example, a method of adding magnetic particles and a polymer to an organic solvent in any order or simultaneously to the organic solvent and stirring may be mentioned. In order to disperse the magnetic particles more uniformly, a shear mixing device that generates a high shear force may be used, or the magnetic particles may be ultrasonically treated in advance before mixing. Further, other components such as a surfactant may be appropriately added to the organic solvent.

[0015] 〔Emulsification step〕 This production method includes an emulsification step. The emulsification step is a step of emulsifying a dispersion liquid in which magnetic particles and a polymer are dispersed in an organic solvent and an aqueous solvent to prepare an emulsion. According to the emulsification step, an emulsion containing a dispersed phase composed of the dispersion liquid and a continuous phase composed of the aqueous solvent is formed.

[0016] (Dispersion liquid) The dispersion liquid is a solution in which magnetic particles and a polymer are dispersed in an organic solvent, and forms a dispersed phase in the emulsion prepared in the emulsification step. In the dispersion liquid, the polymer is typically dissolved in the organic solvent as one mode of dispersion.

[0017] (Magnetic particles) The magnetic particles contained in the dispersion liquid may be any of ferromagnetic, paramagnetic or superparamagnetic magnetic particles. In terms of excellent magnetic collection property and redispersibility, the magnetic particles are preferably superparamagnetic. Examples of the magnetic particles include particles composed of metals such as ferrite, iron oxide, iron, manganese oxide, manganese, nickel oxide, nickel, cobalt oxide, cobalt, or alloys. In terms of excellent sensitivity to a magnetic field, low cost, and low toxicity, the magnetic particles are preferably iron oxide particles.

[0018] The magnetic particles are preferably magnetic particles coated with a long-chain fatty acid in view of their high dispersibility in each of the organic solvent and the polymer. In the present specification, the long-chain fatty acid refers to a saturated fatty acid or an unsaturated fatty acid having 6 or more carbon atoms contained in the whole fatty acid. Examples of the long-chain fatty acid include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, linolenic acid, linoleic acid, oleic acid, 5-phenylvaleric acid, and the like.

[0019] In view of high dispersibility in the polymer, the number average particle diameter of the magnetic particles is preferably 0.1 nm or more, more preferably 1 nm or more. Also, in view of high dispersibility in the polymer, the number average particle diameter of the magnetic particles is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 20 nm or less.

[0020] The content of the magnetic particles in the dispersion is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more with respect to 100% by mass of the dispersion. The higher the content of the magnetic particles within this range, the higher the magnetic particle content, and magnetic polymer particles showing strong magnetism can be obtained. Also, the content of the magnetic particles in the dispersion is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less with respect to 100% by mass of the dispersion. The lower the content of the magnetic particles within this range, the lower the solution viscosity, and a uniform emulsion can be formed.

[0021] In this production method, commercially available products may be used as the magnetic particles. Examples of commercially available products of magnetic particles coated with a long-chain fatty acid include the magnetic nanoparticles for biomedical use EMG1400 manufactured by Ferrotec Corporation.

[0022] (Polymer) The polymer contained in the dispersion is not particularly limited as long as it is a polymer that dissolves in an organic solvent and is substantially insoluble in water. Examples of the polymer include, but are not limited to, polymers containing structural units derived from hydrophobic aromatic compounds. Magnetic polymer particles containing a polymer containing structural units derived from hydrophobic aromatic compounds are not decomposed by enzymes or the like as compared with biodegradable polymers such as PLGA, and thus have been put to practical use in the field of clinical diagnosis. On the other hand, in the prior art, it has been difficult to produce magnetic polymer particles having a uniform shape and little variation in particle size. According to one aspect of the present invention, it is possible to produce magnetic polymer particles that are less susceptible to decomposition by enzymes or the like with a more uniform shape and less variation.

[0023] The hydrophobic aromatic compound is preferably at least one selected from the group consisting of styrene, vinylnaphthalene, divinylbenzene, vinyltoluene, vinylnaphthalene, vinylanthracene, vinylpyridine, thiophene, and derivatives thereof. These hydrophobic aromatic compounds are preferable because they are relatively inexpensive and have biocompatibility. These hydrophobic aromatic compounds may be used alone or in combination of two or more. Among these, styrene-based compounds which are styrene or styrene derivatives are more preferable in terms of easy production of spherical particles, and styrene is even more preferable. In other words, it is more preferable that the polymer contains polystyrene.

[0024] Examples of the styrene derivative include alkylstyrenes such as methylstyrene, ethylstyrene, propylstyrene, t-butylstyrene, cyclohexylstyrene, dodecylstyrene, and dimethylstyrene; halogenated styrenes such as monochlorostyrene, dichlorostyrene, monobromostyrene, and dibromostyrene; alkoxystyrenes such as methoxystyrene, ethoxystyrene, propoxystyrene, and butoxystyrene; carboxystyrene such as carboxystyrene; aminostyrenes such as 4-aminostyrene, dimethylaminostyrene, and diethylaminostyrene; hydroxystyrene; or isomers thereof.

[0025] The structural unit derived from the hydrophobic aromatic compound may have a functional group for surface-modifying the produced magnetic polymer particles. Examples of the functional group include a carboxy group, an amino group, a sulfo group, an epoxy group, and the like.

[0026] The polymer may be a crosslinked polymer or an uncrosslinked polymer. For example, depending on the type of the organic solvent contained in the dispersion liquid and the hydrophilic organic solvent contained in the aqueous solvent, either a crosslinked polymer or an uncrosslinked polymer may be selected.

[0027] The polymer may contain a structural unit derived from a monomer other than the hydrophobic aromatic compound. Examples of the other monomer include polymerizable unsaturated carboxylic acids such as itaconic acid, maleic acid, and fumaric acid; polymerizable unsaturated sulfonic acids such as sodium styrenesulfonate or salts thereof; polymerizable carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, and tribromophenyl methacrylate; unsaturated carboxylic acid amides such as methacrylonitrile, methacrylamide, N-methylolmethacrylamide, methylenebismethacrylamide, butadiene, isoprene, vinyl acetate, vinyl pyridine, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, and vinyl bromide; polymerizable unsaturated nitriles; vinyl halides; conjugated dienes; and the like.

[0028] The content of the structural unit derived from the hydrophobic aromatic compound in the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on 100% by mass of the polymer, in terms of obtaining high-strength magnetic polymer particles. Further, the content of the structural unit derived from the hydrophobic aromatic compound in the polymer may be 100% by mass.

[0029] The weight-average molecular weight of the polymer is preferably 1000 or more, more preferably 5000 or more, and still more preferably 10000 or more. Also, the weight-average molecular weight of the polymer is preferably 1000000 or less, more preferably 800000 or less, and still more preferably 600000 or less.

[0030] The content of the polymer in the dispersion is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% by mass or more, based on 100% by mass of the dispersion. The higher the content of the polymer within this range, the larger the particle diameter produced. Also, the content of the polymer in the dispersion is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less, based on 100% by mass of the dispersion. The lower the content of the polymer within this range, the lower the solution viscosity and the more uniform the emulsion can be formed.

[0031] As the polymer, a commercially available polymer may be used, or a polymer obtained by a known polymerization method may be used. The polymer is typically used in the form of a fluid in order to be uniformly dispersed or dissolved in an organic solvent.

[0032] (organic solvent) The organic solvent contained in the dispersion is not limited as long as the magnetic particles are dispersed and the polymer is dissolved therein. The organic solvent is preferably a hydrophobic organic solvent in terms of its high affinity with the polymer and high dispersibility of the magnetic particles.

[0033] Examples of hydrophobic organic solvents include halogenated hydrocarbon solvents such as chloroform, dichloromethane, and chlorobenzene; aromatic hydrocarbon solvents such as toluene; aliphatic hydrocarbon solvents such as cyclohexane; esters such as ethyl acetate; ethers such as tetrahydrofuran; ketones such as cyclohexanone; and the like. These hydrophobic organic solvents may be used alone or in combination of two or more. In terms of higher dispersibility of magnetic particles, the organic solvent is preferably at least one selected from the group consisting of halogenated hydrocarbon solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents, more preferably at least one selected from the group consisting of halogenated hydrocarbon solvents, and even more preferably chloroform.

[0034] The boiling point of the organic solvent contained in the dispersion is preferably 25°C or higher, more preferably 50°C or higher. The higher the boiling point within this range, the easier it is to form an emulsion. Also, the boiling point of the organic solvent contained in the dispersion is preferably 150°C or lower, more preferably 100°C or lower. The lower the boiling point within this range, the faster the production rate of polymer particles in the formation process.

[0035] The content of the organic solvent in the dispersion is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more based on 100% by mass of the dispersion. The higher the content of the organic solvent within this range, the more polymer can be dispersed. Also, the content of the organic solvent in the dispersion is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99.3% by mass or less based on 100% by mass of the dispersion. The lower the content of the organic solvent within this range, the smaller the particle size of the magnetic polymer particles obtained.

[0036] (Other components of the dispersion) In addition to magnetic particles, polymers, and organic solvents, the dispersion may further contain other components. Examples of other components include surfactants, bioactive substances, and the like. Among these, it is preferable that the dispersion further contains a surfactant. By using a dispersion containing a surfactant, the variation in particle size in the resulting magnetic polymer particles is reduced.

[0037] Examples of surfactants include anionic surfactants, nonionic surfactants, and the like. Examples of surfactants include fatty acids such as stearic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, linolenic acid, linoleic acid, oleic acid, 5-phenylvaleric acid, or salts thereof; amphiphilic polymers such as polyvinyl alcohol and polyvinyl pyrrolidone; and the like.

[0038] The content of the surfactant in the dispersion is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and still more preferably 0.005% by mass or more, based on 100% by mass of the dispersion. The higher the content of the surfactant within this range, the more the dispersion stability of the produced magnetic polymer particles in the aqueous solution can be expected to improve. Also, the content of the surfactant in the dispersion is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less, based on 100% by mass of the dispersion. The lower the content of the surfactant within this range, the more the aggregation of the produced magnetic polymer particles can be reduced.

[0039] (Aqueous solvent) The aqueous solvent is a solution containing water and a hydrophilic organic solvent, and forms a continuous phase in the emulsion prepared in the emulsification step.

[0040] By using an aqueous solvent containing water and a hydrophilic organic solvent, the variation in particle size in the resulting magnetic polymer particles is reduced, and the magnetic particle content in the magnetic polymer particles is improved.

[0041] Examples of hydrophilic organic solvents include alcohols, ethers, ketones, nitriles, etc. Examples of alcohols include methanol, ethanol, propanol, isopropyl alcohol, tert-butyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol, ethylene glycol, propylene glycol, etc. Examples of ethers include dimethoxyethane, diethylene glycol, etc. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, etc. Examples of nitriles include acetonitrile, acrylonitrile, etc. The hydrophilic organic solvent may be used alone or in combination of two or more.

[0042] Among them, the hydrophilic organic solvent is preferably an alcohol having 1 to 6 carbon atoms, more preferably an alcohol having 1 to 4 carbon atoms, and even more preferably methanol. By using such an alcohol, the particle size of the obtained magnetic polymer particles becomes more uniform, and the magnetic particle content in the magnetic polymer particles is improved.

[0043] The concentration of the hydrophilic organic solvent in the aqueous solvent is preferably 1% by volume or more, more preferably 4% by volume or more, based on 100% by volume of the aqueous solvent. The higher the concentration of the hydrophilic organic solvent within this range, the more the polymer in the hydrophobic organic solvent can be aggregated. Also, the concentration of the hydrophilic organic solvent in the aqueous solvent is preferably 20% by volume or less, more preferably 15% by volume or less, even more preferably 10% by volume or less, based on 100% by volume of the aqueous solvent. The lower the concentration of the hydrophilic organic solvent within this range, the higher the stability of the formed emulsion.

[0044] (SP value of each component) The SP value of the polymer contained in the dispersion (also called solubility parameter or Hildebrand parameter. Unit: (cal / cm 3 ) 1 / 2 ) δ P is preferably 8.0 or more, more preferably 8.5 or more. Also, the SP value δ of the polymerP is preferably 10.0 or less, more preferably 9.5 or less. The SP value δ of the polymer P When it is within such a range, in the emulsion, the polymer contained in the dispersed phase is less likely to leak into the continuous phase constituted by the aqueous solvent, so that the particle diameter of the obtained magnetic polymer particles is more controlled.

[0045] The SP value δ of the organic solvent contained in the dispersion O is preferably 8.0 or more, more preferably 8.5 or more. Also, the SP value δ of the organic solvent O is preferably 10.0 or less, more preferably 9.5 or less. The SP value δ of the organic solvent O When it is within such a range, during the preparation of the dispersion, the polymer easily dissolves in the organic solvent, and after the formation of the emulsion, the organic solvent is easily removed from the emulsion by evaporation or the formation of a precipitation layer. Examples of the organic solvent that can be used in this production method and their SP values δ O are shown in Table 1 below.

[0046] The SP value δ of the hydrophilic organic solvent contained in the aqueous solvent HO is preferably 10 or more, more preferably 14 or more. Also, the SP value δ of the hydrophilic organic solvent HO is preferably 20 or less, more preferably 15 or less. The SP value δ of the organic solvent HO When it is within such a range, the particle diameter of the obtained magnetic polymer particles becomes more uniform and the magnetic particle content in the magnetic polymer particles is improved. Examples of the hydrophilic organic solvent that can be used in this production method and their SP values δ HO are shown in Table 1 below.

[0047]

Table 1

[0048] The SP value δ of the organic solvent contained in the dispersion O and the difference δ between the SP value δ of the polymer P δ O -δ Pis preferably within the range of ±1.0, more preferably within the range of ±0.5. The difference δ of the SP values O -δ P When it is within such a range, the polymer is easily dissolved in the organic solvent when preparing the dispersion liquid.

[0049] The SP value δ of the organic solvent contained in the dispersion liquid O and the SP value δ with the hydrophilic organic solvent contained in the aqueous solvent HO The difference is preferably within the range of ±10, more preferably within the range of ±6. Also, among the components contained in the dispersion liquid and the aqueous solvent, the SP value δ of water W , the SP value δ of the polymer P , the SP value δ of the organic solvent O , and the SP value δ of the hydrophilic organic solvent HO are preferably in the magnitude relationship of δ W ≧δ HO ≧δ O ≧δ P . When the difference in SP values is within such a range and the SP values are in such a magnitude relationship, the hydrophilic organic solvent has not only high water solubility but also a certain degree of affinity for the organic solvent in the dispersion liquid and a lower affinity for the polymer. Therefore, a small amount of the hydrophilic organic solvent dissolves in the dispersed phase in the emulsion, and the polymer with a low affinity for the hydrophilic organic solvent aggregates in the dispersed phase by globule transfer. Due to the aggregation, the particle size of the obtained magnetic polymer particles becomes uniform, and since the magnetic particles in the dispersed phase are encapsulated in the polymer during aggregation, the magnetic particle content in the magnetic polymer particles is improved.

[0050] In this specification, the SP value can be calculated according to the description of the solubility parameter δ in the Chemical Handbook of the Chemical Society of Japan, Applied Edition (published in 1973), and Polymer Handbook (4th Edition, edited by Johannnes Brandrup and E.H. Immergut, published in 1998).

[0051] (Usage amounts of the dispersion liquid and the aqueous solvent) In the emulsification step, the ratio of the usage amounts of the dispersion liquid and the aqueous solvent can be appropriately selected within the range where the dispersion liquid forms the dispersed phase in the emulsion. The ratio of the usage amounts may be selected, for example, according to the desired average particle diameter of the magnetic polymer particles.

[0052] The usage amount of the dispersion liquid with respect to 1 mL of the aqueous solvent is preferably 0.01 mL or more, more preferably 0.05 mL or more, and even more preferably 0.1 mL or more. The larger the usage amount of the dispersion liquid within this range, the more uniformly the polymer can be dispersed. Also, the usage amount of the dispersion liquid with respect to 1 mL of the aqueous solvent is preferably 1 mL or less, more preferably 0.5 mL or less, and even more preferably 0.25 mL or less. The smaller the usage amount of the dispersion liquid within this range, the easier it is to form the emulsion.

[0053] (Operation of the emulsification step) The emulsification step can be carried out using a known method for emulsifying the above-described dispersion liquid and aqueous solvent. Examples of the emulsifying method include a method of mixing the dispersion liquid and the aqueous solvent and stirring using an ultrasonic irradiation device, a mixer, or a stirrer.

[0054] (Irradiation step) Among the methods for emulsifying, it is preferable to use an ultrasonic irradiation device because a dispersed phase having a uniform particle diameter can be obtained. In other words, the emulsification step preferably includes an irradiation step of irradiating the mixture of the dispersion liquid and the aqueous solvent with ultrasonic waves.

[0055] In the irradiation step, the irradiation time of the ultrasonic waves is preferably 1 second or more, more preferably 300 seconds or more. The longer the irradiation time within this range, the more stable the emulsion can be formed. Also, the irradiation time of the ultrasonic waves is preferably 1800 seconds or less, more preferably 1000 seconds or less. The shorter the irradiation time within this range, the more the local heating in the solution due to ultrasonic irradiation is reduced, and the formation of anisotropic particles is decreased.

[0056] In the irradiation step, the intensity of the ultrasonic waves is preferably 100 mW / cm2 or more, more preferably 1000 mW / cm 2 or more. The higher the intensity within this range, the shorter the irradiation time required to form the emulsion. Also, the intensity of the ultrasonic waves is preferably 100000 mW / cm 2 or less, more preferably 50000 mW / cm 2 or less. The lower the intensity within this range, the less local heating in the solution and the fewer anisotropic particles formed.

[0057] (Cooling step) The emulsification step preferably includes a cooling step of cooling the mixture of the dispersion and the aqueous solvent. According to the cooling step, the temperature rise of the mixture due to the operation of emulsifying the mixture, such as ultrasonic treatment, can be alleviated, and thereby the formation of the emulsion can be suitably controlled. The cooling step can be carried out using a known method, for example, by placing the container of the mixture in an ice bath.

[0058] The cooling step may be carried out after the operation of emulsifying the mixture or simultaneously with the operation. For example, in the emulsification step, the above-described irradiation step and cooling step may be carried out simultaneously.

[0059] In the cooling step, the mixture is preferably cooled to 10°C or lower, more preferably 5°C or lower. The lower the cooling temperature within this range, the less local heating in the solution and the fewer anisotropic particles formed. Also, in the cooling step, the lower limit of the temperature of the mixture is, for example, 0°C or higher.

[0060] 〔Formation step〕 This manufacturing method includes a formation step after the emulsification step. The formation step is a step of removing at least a part of the organic solvent contained in the dispersion from the emulsion to form magnetic polymer particles. According to the formation step, the organic solvent constituting the dispersed phase is removed from the emulsion, so that the remaining part of the dispersed phase, particularly the magnetic particles and the polymer, aggregate to form magnetic polymer particles. At this time, since the removal of the organic solvent and the aggregation of the polymer proceed with a suitable balance, magnetic polymer particles having a uniform shape can be obtained.

[0061] (Operation of the forming process) The forming process can be carried out, for example, by allowing the emulsion to stand still. By allowing it to stand still, at least a part of the organic solvent of the dispersion liquid constituting the dispersed phase moves into the continuous phase over time. The moved organic solvent is removed from the emulsion by evaporating and further moving into the gas phase, or by precipitating to form a precipitate layer separated from the emulsion, or by both of these. Here, which of evaporation and precipitation occurs is determined according to the temperature of the emulsion and the type of the organic solvent.

[0062] The temperature of the emulsion is not particularly limited. For example, it is preferably 0 °C or higher, more preferably 10 °C or higher, and even more preferably 20 °C or higher. The higher the temperature within this range, the higher the rate at which the organic solvent is removed, and magnetic polymer particles are formed in a shorter time. Also, the temperature of the emulsion is preferably 50 °C or lower, more preferably 40 °C or lower, and even more preferably 30 °C or lower. The lower the temperature within this range, the more suitably the rate at which the organic solvent is removed is controlled, and magnetic polymer particles having a more uniform shape are formed. The temperature of the emulsion may be adjusted to the above preferable range by allowing the emulsion to stand still at room temperature (for example, 20 °C to 30 °C), or may be adjusted by heating or cooling the emulsion as necessary.

[0063] The time for allowing the emulsion to stand still, that is, the standing time, is preferably 5 hours or longer, and more preferably 10 hours or longer. The longer the standing time within this range, the more the organic solvent is removed from the emulsion. The upper limit of the standing time is not particularly limited. For example, the standing time is 24 hours or less.

[0064] The standing still of the emulsion may be carried out at normal pressure (1 atmosphere) or under reduced pressure.

[0065] The forming process can also be carried out by shaking instead of standing still. For example, the emulsion may be shaken for 5 hours or longer and 24 hours or shorter.

[0066] 〔Other Processes〕 In addition to the dispersion process, emulsification process, and formation process described above, this manufacturing method may include other processes. Examples of other processes include a purification process, a modification process, and the like.

[0067] The purification process is a process of purifying magnetic polymer particles after the formation process. The purification process may be performed, for example, by collecting magnetic polymer particles from the emulsion by integration using a magnet, centrifugation, or filtration, then washing the magnetic polymer particles with water or the like, and redispersing them in a solvent such as water.

[0068] The modification process is a process of modifying the surface of magnetic polymer particles after the formation process. The modification process may be performed, for example, by adding a modifier to the collected magnetic polymer particles. The modifier can be selected according to the use of the magnetic polymer particles. Examples of the modifier include ionic polymers, labeled antibodies, fluorescent substances, and the like.

[0069] 〔Magnetic Polymer Particles〕 The magnetic polymer particles according to one aspect of the present invention are particles in which magnetic particles are encapsulated in polymer particles, and are typically manufactured by the manufacturing method according to one aspect of the present invention described above.

[0070] The average particle diameter of the magnetic polymer particles is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.1 μm or more and 1.0 μm or less, still more preferably 0.1 μm or more and 0.5 μm or less, and even more preferably 0.1 μm or more and 0.3 μm or less. In this specification, the average particle diameter of the magnetic polymer particles is the number average particle diameter.

[0071] The content of magnetic particles in the magnetic polymer particles is preferably 50 w / w% or more, more preferably 70 w / w% or more, and still more preferably 80 w / w% or more. The higher the content of magnetic particles within this range, the stronger the magnetism exhibited by the magnetic polymer, and the easier it is to recover using a magnet or the like. Also, the content of magnetic particles in the magnetic polymer particles is preferably 99 w / w% or less, more preferably 95 w / w% or less, and still more preferably 90 w / w% or less. The lower the content of magnetic particles within this range, the higher the dispersion stability of the magnetic polymer particles.

[0072] In addition to magnetic particles and a polymer, the magnetic polymer particles may contain other components such as a surfactant and a physiologically active substance.

[0073] 〔Summary〕 As understood from the above description, the present invention includes the following aspects.

[0074] Aspect 1: An emulsification step of emulsifying a dispersion in which magnetic particles and a polymer are dispersed in an organic solvent and an aqueous solvent containing water and a hydrophilic organic solvent to prepare an emulsion, and a forming step of removing at least a part of the organic solvent contained in the dispersion from the emulsion to form magnetic polymer particles. A method for producing magnetic polymer particles, comprising:

[0075] Aspect 2: The method for producing magnetic polymer particles according to Aspect 1, wherein the SP value of the hydrophilic organic solvent is 10 or more.

[0076] Aspect 3: The method for producing magnetic polymer particles according to Aspect 1 or 2, wherein the hydrophilic organic solvent is an alcohol having 1 to 6 carbon atoms.

[0077] Aspect 4: The method for producing magnetic polymer particles according to any one of Aspects 1 to 3, wherein the hydrophilic organic solvent is methanol.

[0078] Aspect 5: The method for producing magnetic polymer particles according to any one of Aspects 1 to 4, wherein the concentration of the hydrophilic organic solvent in the aqueous solvent is 1% by volume or more and 20% by volume or less.

[0079] Aspect 6: The method for producing magnetic polymer particles according to any one of Aspects 1 to 5, wherein the organic solvent contained in the dispersion liquid is a hydrophobic organic solvent.

[0080] Aspect 7: The method for producing magnetic polymer particles according to any one of Aspects 1 to 6, wherein the polymer contains a structural unit derived from a hydrophobic aromatic compound.

[0081] Aspect 8: The method for producing magnetic polymer particles according to any one of Aspects 1 to 7, wherein the dispersion liquid further contains a surfactant.

[0082] Aspect 9: The method for producing magnetic polymer particles according to any one of Aspects 1 to 8, wherein the emulsification step includes an irradiation step of irradiating ultrasonic waves to a mixture of the dispersion liquid and the aqueous solvent, and a cooling step of cooling the mixture.

[0083] Aspect 10: In the irradiation step, the irradiation time of ultrasonic waves is 1 second or more and 1800 seconds or less, and the intensity of ultrasonic waves is 100 mW / cm 2 or more and 100,000 mW / cm 2 or less. The method for producing magnetic polymer particles according to Aspect 9.

[0084] 〔Supplementary Note〕 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Examples

[0085] 〔Example 1〕Examination of Emulsion Preparation Conditions Magnetic polymer particles were produced under conditions where the composition of the dispersion liquid and the ultrasonic treatment time were different.

[0086] 1.02 mg of polystyrene (SP value 9.0) and 4.23 mg of iron oxide nanoparticles (EMG1400, manufactured by Ferrotec Corporation, d = 10 nm, coating agent: long-chain fatty acid) were dispersed in 0.44 mL of chloroform to prepare a magnetic particle dispersion. 0.44 mL of the magnetic particle dispersion was added to 4 mL of an aqueous solvent containing 0 v / v% to 20 v / v% of MeOH and the balance water, and then the mixture was irradiated with ultrasonic waves of intensity 9375 mW / cm 2 for 10 seconds to 600 seconds while being ice-cooled.

[0087] After the ultrasonic treatment, it was visually determined whether an emulsion of the dispersed phase and the continuous phase was formed from the mixture. Next, the mixture was allowed to stand at normal pressure (1 atm) and room temperature (25 °C) for 16 hours. The mixture was subjected to centrifugation (5000 g, 15 minutes), the supernatant was removed, and the precipitate was redispersed in water. The preparation conditions and optical photographs of the dispersions obtained under each condition are shown in FIGS. 1 and 2. In FIGS. 1 and 2, the darker the color of the solution after redispersion, the more magnetic polymer particles were obtained, or the more magnetic particles were contained in the magnetic polymer particles, or both.

[0088] As shown in FIGS. 1 and 2, magnetic polymer particles were not obtained from the samples in which emulsion formation was not observed, while a brown solution containing magnetic polymer particles was obtained after redispersion in each sample in which emulsion formation was observed. Further, when a mixed solvent containing MeOH, which is a hydrophilic organic solvent, and water was used as the aqueous solvent, magnetic polymer particles were obtained with ultrasonic treatment for a shorter time compared to the case where pure water was used. Also, the longer the ultrasonic treatment time, the more emulsified the mixture became and the more magnetic polymer particles were obtained. In particular, when the ultrasonic treatment time was 300 seconds or more, the emulsification proceeded sufficiently, so the condition of an ultrasonic treatment time of 300 seconds was adopted in the subsequent examples.

[0089] Example 2: Production and Evaluation of Magnetic Polymer Particles Magnetic polymer particles were produced under conditions where the composition of each of the dispersion and the aqueous solvent was different, and their physical properties were evaluated.

[0090] (Example 2-1) 1.02 mg of polystyrene (SP value 9.0) and 4.23 mg of iron oxide nanoparticles (EMG1400, manufactured by Ferrotec Corporation, d = 10 nm, coating agent: long-chain fatty acid) were dispersed in 0.44 mL of chloroform to prepare a magnetic particle dispersion. After adding 0.44 mL of the magnetic particle dispersion to 4 mL of a 4 v / v% MeOH aqueous solution as an aqueous solvent, while cooling the mixture on ice, ultrasonic waves with an intensity of 9375 mW / cm 2 were irradiated for 300 seconds to emulsify. Next, the emulsion was allowed to stand at normal pressure (1 atm) and room temperature (25 °C) for 16 hours. The emulsion was subjected to centrifugation (5000 g, 15 minutes), the supernatant was removed, and the precipitate was redispersed in 3 mL of water to obtain the magnetic polymer particles of Example 2-1 as a dispersion.

[0091] (Example 2-2) Magnetic polymer particles of Example 2-2 were obtained using the same method as in Example 2-1, except that 0.045 mg of stearic acid (SA) was further dispersed in the preparation of the magnetic particle dispersion.

[0092] (Reference Example 2-1) Magnetic polymer particles of Reference Example 2-1 were obtained using the same method as in Example 2-1, except that water was used instead of a 4 v / v% MeOH aqueous solution as the aqueous solvent.

[0093] [Evaluation Example 1] SEM Observation Each of the magnetic polymer particles obtained in Example 2 was observed using an electron microscope. The SEM images were acquired using an electron microscope JSM-7800F Prime (JEOL) under the conditions of an acceleration voltage of 10.0 kV and a magnification of 30,000 times. The acquired SEM images are shown in Figure 3. Also, in the acquired SEM images, the uniformity of the particle shape was visually determined, and if the ratio of spherical particles and substantially spherical particles was higher than that in Figure 3 of Non-Patent Document 1, it was evaluated as uniform. The determination results are shown in Table 2.

[0094] As shown in Figure 3, in the magnetic polymer particles of each example and reference example, the particle shape was uniform and no anisotropy was observed.

[0095] [Evaluation Example 2] Elemental Analysis Elemental analysis of each magnetic polymer particle obtained in Example 2 was performed using a transmission electron microscope (JEM-F200, manufactured by JEOL Ltd.). The measured EDX (Energy Dispersive X-ray Spectroscopy) map is shown in Fig. 4.

[0096] As shown in Fig. 4, in each example and reference example, iron element (Fe) was observed in the region corresponding to the magnetic polymer particles. From this, it was shown that the obtained magnetic polymer particles contain the iron oxide nanoparticles used in the preparation.

[0097] 〔Evaluation Example 3〕Optical property analysis Optical photographs of each magnetic polymer particle dispersion obtained in Example 2 are shown in Fig. 5. Also, the absorption spectra of each dispersion were measured using a microplate reader (Infinite (registered trademark) M200 PRO; Tecan Group Ltd.). The measurement results of the absorption spectra are shown in Fig. 6. Fig. 7 shows the relative absorbance of each magnetic polymer particle dispersion obtained in Example 2 with respect to the absorbance of the magnetic polymer particle dispersion of Reference Example 2-1 at a wavelength of 400 nm.

[0098] As shown in Fig. 6, in each example, absorption at a wavelength of 400 nm indicating the presence of iron oxide contained in the magnetic particles was observed. Also, as shown in Fig. 7, the magnetic polymer particle dispersions of Examples 2-1 and 2-2 showed higher relative absorbance compared to Reference Example 2-1. From this, it was suggested that by using an aqueous mixed solvent of water and a hydrophilic solvent, the content of magnetic particles in the magnetic polymer particles is improved compared to the case of using water. Also, the dispersion of the magnetic polymer particles of Example 2-2 showed higher relative absorbance compared to Example 2-1. From this, it was suggested that by dispersing a surfactant in the magnetic particle dispersion, the content of magnetic particles in the magnetic polymer particles is improved compared to the case of not using it.

[0099] 〔Evaluation Example 4〕Analysis of physicochemical properties The particle size distribution and zeta potential of the magnetic polymer particles obtained in Reference Example 2-1 and Example 2-2 were measured using a zeta potential, particle size, and molecular weight measurement system ELSZ-2000 (Otsuka Electronics Co., Ltd.). The particle size distribution measurement was based on the dynamic light scattering (DLS) method. The measurement results are shown in Fig. 8 and Table 2. Also, for the magnetic polymer particles obtained in Example 2-1, the particle size distribution was measured in the same manner. The number average particle size calculated from the particle size distribution is shown in Table 2. The numerical range indicated by "±" in Table 2 represents the standard deviation of the measurement results for three samples prepared by the same method.

[0100] As shown in Fig. 8 and Table 2, in Examples 2-1 and 2-2, particularly in Example 2-2, the variation in the number average particle size was reduced compared to Reference Example 2-1. From this, it was shown that by using an aqueous mixed solvent of water and a hydrophilic solvent and by dispersing a surfactant in the magnetic particle dispersion, the variation in particle size between samples was improved. From the values of the polydispersity index (PDI) shown in Table 2, it was also shown that the variation in particle size within one sample was similarly improved. Also, from the zeta potential shown in Fig. 8, it can be seen that the surface of the magnetic polymer particles is negatively charged.

[0101] 〔Evaluation Example 5〕Analysis of magnetic particle content The magnetic particle content of the magnetic polymer particles obtained in Reference Example 2-1 and Example 2-2 was measured using a thermogravimetric analyzer (TG8120; Rigaku Corporation). The measurement results are shown in Table 2.

[0102] As shown in Table 2, it was shown that magnetic polymer particles were produced in Reference Example 2-1 and Example 2-2. Also, it was shown that the content was improved by using an aqueous mixed solvent of water and a hydrophilic solvent.

[0103]

Table 2

[0104] In Table 2, "-" indicates that the measurement was not carried out.

[0105] Evaluation Example 6: Analysis of Agglomeration Magnetism To analyze the agglomeration magnetism of the magnetic polymer particles obtained in Example 2-1, the time change in the amount of magnetic polymer particles contained in the supernatant was measured when the magnetic polymer particle dispersion was placed on a neodymium magnet (dimensions: 10 mm × 10 mm × 10 mm, surface magnetic flux density: 0.42 T) and when it was placed on a non-magnetic tabletop. The measurement results are shown in Fig. 9. The left side of Fig. 9 is a graph showing the relative absorbance at each time point with respect to the absorbance of the supernatant at the start of measurement at a wavelength of 400 nm, and the right side of Fig. 9 is an optical photograph of the dispersion at each time point.

[0106] As shown in Fig. 9, in the dispersion placed on the magnet, the magnetic polymer particles were rapidly accumulated. From this, it was shown that the magnetic polymer particles obtained in the examples are suitable for recovery using magnetism. Also, in the dispersion placed on the tabletop, the amount of magnetic polymer particles contained in the supernatant was almost constant. From this, it was shown that the magnetic polymer particles obtained in the examples are excellent in dispersion stability. Industrial Applicability

[0107] The magnetic polymer particles produced by the production method of the present invention can be used in the field of life sciences such as the recovery or detection of DNA or viruses, or in the field of clinical tests using chemiluminescence immunoassay or the like.

Claims

1. An emulsifying step of preparing an emulsion by emulsifying a dispersion in which magnetic particles and a polymer are dispersed in an organic solvent and an aqueous solvent containing water and a hydrophilic organic solvent; A forming step of removing at least a part of the organic solvent contained in the dispersion from the emulsion to form magnetic polymer particles. A method for producing magnetic polymer particles, comprising:

2. The SP value of the hydrophilic organic solvent is 10 or more. The method for producing magnetic polymer particles according to Claim 1.

3. The hydrophilic organic solvent is an alcohol having 1 to 6 carbon atoms. The method for producing magnetic polymer particles according to Claim 1.

4. The hydrophilic organic solvent is methanol. The method for producing magnetic polymer particles according to Claim 1.

5. The concentration of the hydrophilic organic solvent in the aqueous solvent is 1% by volume or more and 20% by volume or less. The method for producing magnetic polymer particles according to any one of Claims 1 to 4.

6. The organic solvent contained in the dispersion is a hydrophobic organic solvent. The method for producing magnetic polymer particles according to any one of Claims 1 to 4.

7. The polymer contains a structural unit derived from a hydrophobic aromatic compound. The method for producing magnetic polymer particles according to any one of Claims 1 to 4.

8. The dispersion further contains a surfactant. The method for producing magnetic polymer particles according to any one of Claims 1 to 4.

9. The emulsifying step includes: An irradiation step of irradiating ultrasonic waves to a mixture of the dispersion and the aqueous solvent; A cooling step of cooling the mixture. The method for producing magnetic polymer particles according to any one of Claims 1 to 4.

10. In the irradiation step, the irradiation time of the ultrasonic wave is 1 second or more and 1800 seconds or less, and the intensity of the ultrasonic wave is 100 mW / cm ２ or more and 100,000 mW / cm ２ or less. The method for producing magnetic polymer particles according to Claim 9.

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