Method for producing magnetic polymer particles

Abstract

To provide a production method capable of producing magnetic polymer particles having a more uniform shape which are polymers containing a structural unit derived from a hydrophobic aromatic compound.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 containing a structural unit derived from a hydrophobic aromatic compound in an organic solvent and an aqueous solvent containing at least one selected from the group consisting of 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 at a temperature of 0°C or more and 50°C or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Magnetic polymer particles are widely used in the fields of life sciences, such as for the recovery or detection of DNA or viruses, and in the fields of clinical testing using chemiluminescence immunoassays, and research and development of magnetic polymer particles themselves is being actively conducted.

[0003] For example, Non-Patent Document 1 discloses a method for producing magnetic polystyrene particles by an emulsion evaporation method, and 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 literature]

[0004] [Non-Patent Document 1] Hai et al., J. Phys., 2009, 187, 012009. [Non-Patent Document 2] Okassa et al., Eur. J. Pharm. Biopharm., 2007, 67, 31-38. Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique described in Non-Patent Document 1 has a problem in that it is prone to forming anisotropic particles that are inconvenient in practical use, such as rugby ball-shaped particles. In addition, the technique described in Non-Patent Document 2 is a technique that targets a specific biodegradable polymer, and no method for producing magnetic polymer particles that can be applied to other polymers has been considered.

[0006] An object of one aspect of the present invention is to provide a production method capable of producing magnetic polymer particles having a more uniform shape from a polymer containing structural units derived from a hydrophobic aromatic compound. [Means for solving the problem]

[0007] In order to solve the above problems, a method for producing magnetic polymer particles according to one embodiment of the present invention includes an emulsification step of preparing an emulsion by emulsifying a dispersion in which magnetic particles and a polymer containing a structural unit derived from a hydrophobic aromatic compound are dispersed in an organic solvent with an aqueous solvent containing at least one selected from the group consisting of water and hydrophilic organic solvents, and a formation step of removing at least a portion of the organic solvent contained in the dispersion from the emulsion at a temperature of 0°C or higher and 50°C or lower to form magnetic polymer particles. Effect of the Invention

[0008] According to one aspect of the present invention, there is provided a production method capable of producing magnetic polymer particles having a more uniform shape from a polymer containing structural units derived from a hydrophobic aromatic compound. [Brief description of the drawings]

[0009] [Figure 1] 1 is an optical photograph of the magnetic polymer particle dispersion of Example 1. [Diagram 2] 1 is an optical photograph of the magnetic polymer particle dispersion of Example 1. [Diagram 3] 3 is a scanning electron microscope (SEM) image of the magnetic polymer particles of Example 2. [Figure 4] 1 is an EDX map of the magnetic polymer particles of Example 2. [Diagram 5] 1 is an optical photograph of the magnetic polymer particle dispersion of Example 2. [Figure 6] 1 is a graph showing the absorption spectrum of the magnetic polymer particle dispersion of Example 2. [Figure 7] 1 is a graph showing the relative absorbance of the magnetic polymer particle dispersion of Example 2. [Figure 8]1 is a graph showing the particle size distribution and zeta potential of the magnetic polymer particles of Examples 2-1 and 2-4. [Figure 9] The magnetic collection measurement results of the magnetic polymer particles of Example 2-3 are shown in Figure 9, where the left side is a graph showing the relative absorbance at each time point relative to the absorbance of the supernatant at the start of the measurement, and the right side is an optical photograph of the dispersion at each time point. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Method of producing magnetic polymer particles] As a result of intensive research, the inventors have discovered that in the production of magnetic polymer particles containing as a matrix a polymer that includes structural units derived from a hydrophobic aromatic compound, by carrying out an emulsion evaporation method within a specific temperature range, it is possible to obtain magnetic polymer particles having a more uniform shape than those obtained by conventional techniques, and have completed the present invention.

[0011] That is, the method for producing magnetic polymer particles according to one embodiment of the present invention includes an emulsification step of preparing an emulsion by emulsifying a dispersion in which magnetic particles and a polymer containing a structural unit derived from a hydrophobic aromatic compound are dispersed in an organic solvent with an aqueous solvent containing at least one selected from the group consisting of water and hydrophilic organic solvents, 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 at a temperature of 0° C. or higher and 50° C. or lower. Hereinafter, the method for producing magnetic polymer particles according to one embodiment of the present invention may be abbreviated as "this production method".

[0012] In this specification, the term "magnetic polymer particles" refers to polymer particles having magnetic particles encapsulated therein.

[0013] [Dispersion process] The present manufacturing method may further include a dispersion step in which the magnetic particles and the polymer are dispersed in an organic solvent to prepare a dispersion liquid prior to the emulsification step. The type and amount of each component such as the 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 emulsification step. The polymer is preferably used in the form of a fluid in order to dissolve it uniformly in the organic solvent.

[0014] For example, the magnetic particles and the polymer are added to the organic solvent in any order or simultaneously, and then stirred. In order to disperse the magnetic particles more uniformly, a shear mixer that generates high shear force may be used, or the magnetic particles may be ultrasonically treated before mixing. In addition, other components such as a surfactant may be appropriately added to the organic solvent.

[0015] [Emulsification process] This manufacturing method includes an emulsification step, which is a step of preparing an emulsion by emulsifying a dispersion liquid in which magnetic particles and a polymer are dispersed in an organic solvent with an aqueous solvent. The emulsification step forms an emulsion that includes a dispersed phase composed of the dispersion liquid and a continuous phase composed of the aqueous solvent.

[0016] (dispersion) The dispersion 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, the polymer is typically dissolved in the organic solvent as a form of dispersion.

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

[0018] The magnetic particles are preferably coated with a long-chain fatty acid, because they have high dispersibility in both organic solvents and polymers. In this specification, the long-chain fatty acid refers to a saturated or unsaturated fatty acid having 6 or more carbon atoms in the entire fatty acid. Examples of long-chain fatty acids include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, linolenic acid, linoleic acid, oleic acid, and 5-phenylvaleric acid.

[0019] From the viewpoint of high dispersibility in polymers, the number average particle size of the magnetic particles is preferably 0.1 nm or more, more preferably 1 nm or more, and from the viewpoint of high dispersibility in polymers, the number average particle size 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 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, based on 100% by mass of the dispersion. The higher the content of magnetic particles within this range, the higher the magnetic particle content and the stronger the magnetic polymer particles that are obtained. The content of 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, based on 100% by mass of the dispersion. The lower the content of magnetic particles within this range, the lower the solution viscosity and the more uniform the emulsion can be formed.

[0021] In the present production method, commercially available magnetic particles may be used. An example of a commercially available magnetic particle coated with a long-chain fatty acid is biomedical magnetic nanoparticle EMG1400 manufactured by Ferrotec Corporation.

[0022] (polymer) The polymer contained in the dispersion contains a structural unit derived from a hydrophobic aromatic compound. Magnetic polymer particles containing a polymer containing a structural unit derived from a hydrophobic aromatic compound are less susceptible to degradation by enzymes and the like compared to biodegradable polymers such as PLGA, and therefore have been put to practical use in the field of clinical diagnosis. On the other hand, in the prior art, it was difficult to produce such 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 degradation by enzymes and the like, with a more uniform shape and little 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 relatively inexpensive and have biocompatibility, and are therefore preferred. 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 preferred, and styrene is even more preferred, in terms of ease of producing spherical particles. In other words, it is even more preferred that the polymer contains polystyrene.

[0024] Examples of styrene derivatives include alkyl styrenes such as methyl styrene, ethyl styrene, propyl styrene, t-butyl styrene, cyclohexyl styrene, dodecyl styrene, and dimethyl styrene; halogenated styrenes such as monochlorostyrene, dichlorostyrene, monobromostyrene, and dibromostyrene; alkoxy styrenes such as methoxy styrene, ethoxy styrene, propoxy styrene, and butoxy styrene; carboxy styrenes such as carboxy styrene; amino styrenes such as 4-amino styrene, dimethyl amino styrene, and diethyl amino styrene; hydroxy styrenes; and isomers thereof.

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

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

[0027] The polymer may contain structural units derived from other monomers other than the hydrophobic aromatic compound. Examples of the other monomers include polymerizable unsaturated carboxylic acids such as itaconic acid, maleic acid, and fumaric acid; polymerizable unsaturated sulfonic acids or salts thereof such as sodium styrenesulfonate; polymerizable carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, ethylene glycol-di-methacrylic acid ester, and tribromophenyl methacrylate; unsaturated carboxylic acid amides such as methacrylonitrile, methacrylamide, N-methylol methacrylamide, methylene bis methacrylamide, butadiene, isoprene, vinyl acetate, vinylpyridine, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, and vinyl bromide; polymerizable unsaturated nitriles; vinyl halides; and conjugated dienes.

[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 even more preferably 90% by mass or more, based on 100% by mass of the polymer, in order to obtain high-strength magnetic polymer particles. 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 even more preferably 10000 or more. The weight average molecular weight of the polymer is preferably 1000000 or less, more preferably 800000 or less, and even 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 even 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 size produced. The content of the polymer in the dispersion is preferably 20% by mass or less, more preferably 10% by mass or less, and even 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] The polymer may be a commercially available polymer or a polymer obtained by a known polymerization method. The polymer is typically used in the form of a fluid so as to be uniformly dispersed or dissolved in an organic solvent.

[0032] (Organic solvent) The organic solvent contained in the dispersion liquid is not limited as long as it is an organic solvent that the magnetic particles disperse in and the polymer dissolves in. The organic solvent is preferably a hydrophobic organic solvent, in that it has 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. 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 polymer particles are produced 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. 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) The dispersion may further contain other components in addition to the magnetic particles, the polymer, and the organic solvent. Examples of the other components include a surfactant, a physiologically active substance, and the like. Of these, it is preferable that the dispersion further contains a surfactant. By using a dispersion containing a surfactant, the variation in particle size of the obtained magnetic polymer particles is reduced.

[0037] Examples of the surfactant include anionic surfactants, nonionic surfactants, etc. Examples of the surfactant include fatty acids such as stearic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, linoleic acid, linoleic acid, oleic acid, 5-phenylvaleric acid, or salts thereof, etc.; amphiphilic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, etc.; 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 even 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 improved the dispersion stability of the generated magnetic polymer particles in the aqueous solution can be expected. The content of the surfactant in the dispersion is preferably 20% by mass or less, more preferably 10% by mass or less, and even 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 reduced the aggregation of the generated magnetic polymer particles can be.

[0039] (Water-based solvent) The aqueous solvent is a solution containing at least one selected from the group consisting of water and hydrophilic organic solvents, and forms a continuous phase in the emulsion prepared in the emulsification step.

[0040] The aqueous solvent may contain only one or both of water and a hydrophilic organic solvent, but preferably contains both. By using an aqueous solvent containing water and a hydrophilic organic solvent, the particle size variation of the obtained magnetic polymer particles is reduced, and the magnetic particle content of the magnetic polymer particles is improved.

[0041] Examples of hydrophilic organic solvents include alcohols, ethers, ketones, and nitriles. Examples of alcohols include methanol, ethanol, propanol, isopropyl alcohol, tert-butyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol, ethylene glycol, and propylene glycol. Examples of ethers include dimethoxyethane and diethylene glycol. Examples of ketones include acetone, methyl ethyl ketone, and diethyl ethene. Examples of nitriles include acetonitrile and acrylonitrile. 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. Furthermore, 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, and 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 more stable the emulsion formed is.

[0044] (SP value of each component) The SP value of the polymer contained in the dispersion (also called the 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. In addition, the SP value δ of the polymer P is preferably 10.0 or less, more preferably 9.5 or less. P When the molecular weight falls within this range, the polymer contained in the dispersed phase of the emulsion is less likely to leak into the continuous phase constituted by the aqueous solvent, so that the particle size of the obtained magnetic polymer particles can be more precisely controlled.

[0045] SP value δ of the organic solvent contained in the dispersion O is preferably 8.0 or more, more preferably 8.5 or more. In addition, the SP value δ of the organic solvent O is preferably 10.0 or less, more preferably 9.5 or less. OWhen the SP value δ is within such a range, the polymer is easily dissolved in the organic solvent during the preparation of the dispersion, and after the formation of the emulsion, the organic solvent is easily removed from the emulsion by evaporation or the formation of a precipitate layer. O is shown in Table 1 below.

[0046] SP value δ of hydrophilic organic solvents contained in aqueous solvents HO is preferably 10 or more, more preferably 14 or more. In addition, 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 the SP value δ is within this range, the particle size of the obtained magnetic polymer particles becomes more uniform, and the magnetic particle content in the magnetic polymer particles is improved. HO is shown in Table 1 below.

[0047] [Table 1]

[0048] SP value δ of the organic solvent contained in the dispersion O and the SP value of the polymer δ P Difference δ O -δ P The difference in SP value δ is preferably within the range of ±1.0, and more preferably within the range of ±0.5. O -δ P When the molecular weight falls within this range, the polymer is easily dissolved in an organic solvent during preparation of a dispersion.

[0049] SP value δ of the organic solvent contained in the dispersion O and the SP value δ of the hydrophilic organic solvent contained in the aqueous solvent HO The difference between the SP value of water, δ, is preferably within the range of ±10, and more preferably within the range of ±6. W , SP value of the polymer δ P, SP value of organic solvent δ O , and the SP value δ of the hydrophilic organic solvent HO is δ W ≧δ HO ≧δ O ≧δ P , and the relationship is preferably such. When the difference in SP value is within such a range and the SP value is in such a relationship, the hydrophilic organic solvent is not only highly water-soluble but also has a certain degree of affinity for the organic solvent in the dispersion liquid, and has a lower affinity for the polymer. Therefore, a small amount of the hydrophilic organic solvent is dissolved in the dispersed phase in the emulsion, and the polymer with low affinity for the hydrophilic organic solvent aggregates in the dispersed phase by globule transition. The aggregation makes the particle size of the magnetic polymer particles obtained uniform, and the magnetic particles in the dispersed phase are encapsulated in the polymer during aggregation, thereby improving the magnetic particle content in the magnetic polymer particles.

[0050] In this specification, the SP value can be calculated in accordance with the description of the solubility parameter δ in the Applied Chemistry Handbook (1973 edition) edited by the Chemical Society of Japan and Polymer Handbook (4th edition, edited by Johannnes Brandrup and EH Immergut, 1998).

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

[0052] The amount of the dispersion liquid used per 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 more the amount of the dispersion liquid used within this range, the more uniformly the polymer can be dispersed. The amount of the dispersion liquid used per 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 less the amount of the dispersion liquid used within this range, the easier it is to form an emulsion.

[0053] (Operation of the emulsification process) The emulsification step can be carried out by using a known method for emulsifying the above-mentioned dispersion liquid and the aqueous solvent. For example, the emulsification method includes a method of mixing the dispersion liquid and the aqueous solvent and stirring the mixture using an ultrasonic irradiation device, a mixer, or a stirrer.

[0054] (irradiation process) Among the emulsification methods, it is preferable to use an ultrasonic irradiation device because it is possible to obtain a dispersed phase having a uniform particle size. In other words, it is preferable that the emulsification step includes an irradiation step of irradiating a mixture of the dispersion liquid and the aqueous solvent with ultrasonic waves.

[0055] In the irradiation step, the ultrasonic irradiation time 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. The ultrasonic irradiation time is preferably 1800 seconds or less, more preferably 1000 seconds or less. The shorter the irradiation time within this range, the less localized heating in the solution due to ultrasonic irradiation is, and the less anisotropic particle formation is.

[0056] In the irradiation step, the intensity of the ultrasonic waves is preferably 100 mW / cm 2 More preferably, it is 1000 mW / cm 2 The higher the intensity within this range, the shorter the irradiation time for forming an emulsion. The intensity of the ultrasonic waves is preferably 100,000 mW / cm 2 or less, more preferably 50,000 mW / cm2 Within this range, lower intensities reduce localized heating in the solution and reduce the formation of anisotropic particles.

[0057] (cooling process) The emulsification step preferably includes a cooling step of cooling the mixture of the dispersion and the aqueous solvent. The cooling step reduces the temperature rise of the mixture caused by the operation of emulsifying the mixture, such as ultrasonic treatment, and thus allows the formation of the emulsion to be suitably controlled. The cooling step can be carried out by 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 may be carried out simultaneously with the operation. For example, in the emulsification step, the above-mentioned irradiation step and cooling step may be carried out simultaneously.

[0059] In the cooling step, the mixture is preferably cooled to 10° C. or less, more preferably 5° C. or less. Within this range, the lower the cooling temperature, the less localized heating in the solution and the less the formation of anisotropic particles. In the cooling step, the lower limit of the mixture temperature is, for example, 0° C. or more.

[0060] [Formation process] This manufacturing method includes a forming step after the emulsifying step. The forming 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 forming 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, are aggregated to form magnetic polymer particles. At this time, the removal of the organic solvent and the aggregation of the polymer proceed in a suitable balance, so that magnetic polymer particles having a uniform shape are obtained.

[0061] (Formation process operation) The formation step can be carried out, for example, by leaving the emulsion to stand. By leaving it to stand, at least a part of the organic solvent of the dispersion liquid constituting the dispersed phase moves into the continuous phase with the passage of time. The moved organic solvent is removed from the emulsion by either evaporating and moving further into the gas phase, or by precipitation to form a precipitate layer separated from the emulsion, or by both. Here, whether evaporation or precipitation occurs is determined according to the temperature of the emulsion and the type of organic solvent.

[0062] The temperature of the emulsion is 0°C or higher and 50°C or lower. By carrying out the formation process within this temperature range, the removal of the organic solvent proceeds under mild conditions, so that the removal rate is suitably controlled and the shape of the resulting particles becomes uniform. The temperature of the emulsion is preferably 10°C or higher, and more preferably 20°C or higher. The higher the temperature within this range, the faster the organic solvent is removed, and the magnetic polymer particles are formed in a shorter time. The temperature of the emulsion is 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 organic solvent is removed, and the magnetic polymer particles having a more uniform shape are formed. The temperature of the emulsion may be adjusted to the above-mentioned preferred range by leaving the emulsion at room temperature (for example, 20°C to 30°C), and may be adjusted by heating or cooling the emulsion as necessary.

[0063] The time for which the emulsion is allowed to stand, i.e., the standing time, is preferably 5 hours or more, more preferably 10 hours or more. 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, but for example, the standing time is 24 hours or less.

[0064] The emulsion may be allowed to stand either at normal pressure (1 atm) or under reduced pressure.

[0065] The formation step can also be performed by shaking instead of leaving the emulsion to stand. For example, the emulsion can be shaken for 5 hours or more and 24 hours or less.

[0066] [Other steps] The present production method may include other steps in addition to the above-mentioned dispersing step, emulsifying step, and forming step. Examples of the other steps include a refining step, a modifying step, and the like.

[0067] The purification step is a step of purifying the magnetic polymer particles after the formation step. The purification step may be carried out, for example, by recovering the magnetic polymer particles from the emulsion by magnet-assisted collection, centrifugation or filtration, and then washing the magnetic polymer particles with water or the like, and redispersing them in a solvent such as water.

[0068] The modification step is a step of modifying the surface of the magnetic polymer particles after the formation step. The modification step may be performed, for example, by adding a modifier to the recovered magnetic polymer particles. The modifier may be selected depending on the application of the magnetic polymer particles. Examples of the modifier include ionic polymers, labeled antibodies, fluorescent substances, etc.

[0069] [Magnetic polymer particles] The magnetic polymer particles according to one embodiment of the present invention are particles in which magnetic particles are encapsulated in polymer particles, and are typically produced by the production method according to one embodiment of the present invention described above.

[0070] The average particle size 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, even 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 size of the magnetic polymer particles is the number average particle size.

[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 even more preferably 80 w / w% or more. The higher the content of magnetic particles within this range, the stronger the magnetism of the magnetic polymer, making it easier to recover using a magnet or the like. 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 even 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] The magnetic polymer particles may contain other components, in addition to the magnetic particles and polymer, such as surfactants, bioactive substances, etc.

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

[0074] Aspect 1: A method for producing magnetic polymer particles, comprising: an emulsification step of preparing an emulsion by emulsifying a dispersion in which magnetic particles and a polymer containing structural units derived from a hydrophobic aromatic compound are dispersed in an organic solvent with an aqueous solvent containing at least one selected from the group consisting of water and hydrophilic organic solvents; and a formation step of removing at least a portion of the organic solvent contained in the dispersion from the emulsion at a temperature of 0°C or higher and 50°C or lower to form magnetic polymer particles.

[0075] Aspect 2: The method for producing magnetic polymer particles of aspect 1, wherein the polymer contains structural units derived from at least one hydrophobic aromatic compound selected from the group consisting of styrene, vinylnaphthalene, divinylbenzene, vinyltoluene, vinylnaphthalene, vinylanthracene, vinylpyridine, thiophene, and derivatives thereof.

[0076] Aspect 3: The method of producing magnetic polymer particles of aspect 1 or 2, wherein the polymer comprises polystyrene.

[0077] Aspect 4: The method for producing magnetic polymer particles according to any one of Aspects 1 to 3, wherein the temperature is 10°C or higher and 40°C or lower.

[0078] Aspect 5: The method for producing magnetic polymer particles according to any one of Aspects 1 to 4, wherein the aqueous solvent contains water and a hydrophilic organic solvent.

[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 dispersion liquid further comprises a surfactant.

[0081] Aspect 8: The method for producing magnetic polymer particles of any one of aspects 1 to 7, wherein the emulsification step includes an irradiation step of irradiating a mixture of the dispersion liquid and the aqueous solvent with ultrasonic waves, and a cooling step of cooling the mixture.

[0082] Aspect 9: In the irradiation step, the ultrasonic irradiation time is from 1 second to 1800 seconds, and the ultrasonic intensity is 100 mW / cm 2 More than 100000mW / cm 2 A method for producing the magnetic polymer particles of embodiment 8, which is as follows:

[0083] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of 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

[0084] [Example 1] Examination of emulsion preparation conditions Magnetic polymer particles were produced under different conditions of dispersion composition and ultrasonic treatment time.

[0085] A magnetic particle dispersion was prepared by dispersing 1.02 mg of polystyrene (SP value 9.0) and 4.23 mg of iron oxide nanoparticles (EMG1400, Ferrotec Corporation, d = 10 nm, coating agent: long-chain fatty acid) in 0.44 mL of chloroform. 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% MeOH, with the remainder being water, and the mixture was cooled on ice while being heated at an intensity of 9375 mW / cm. 2 The ultrasonic waves were irradiated for 10 to 600 seconds.

[0086] After ultrasonic treatment, it was visually determined whether an emulsion of the dispersed phase and the continuous phase was formed from the mixture. The mixture was then left to stand at normal pressure (1 atm) and room temperature (25°C) for 16 hours. The mixture was centrifuged (5000g, 15 min), 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 Figures 1 and 2. In Figures 1 and 2, the darker the color of the solution after redispersion, the greater the amount of magnetic polymer particles obtained, or the greater the amount of magnetic particles contained in the magnetic polymer particles, or both.

[0087] As shown in Figures 1 and 2, magnetic polymer particles were not obtained from the samples in which emulsion formation was not observed, while in each sample in which emulsion formation was observed, a brownish-brown solution containing magnetic polymer particles was obtained after redispersion. In addition, when a mixed solvent containing MeOH, a hydrophilic organic solvent, and water was used as the aqueous solvent, magnetic polymer particles were obtained with a shorter ultrasonic treatment time than when pure water was used. In addition, the longer the ultrasonic treatment time, the more the mixed liquid was emulsified and the more magnetic polymer particles were obtained. Among them, if the ultrasonic treatment time was 300 seconds or more, emulsification proceeded sufficiently, so in the following examples, a condition of 300 seconds of ultrasonic treatment time was adopted.

[0088] [Example 2] Production and evaluation of magnetic polymer particles Magnetic polymer particles were produced under conditions with different compositions of the dispersion liquid and the aqueous solvent, and their physical properties were evaluated.

[0089] (Example 2-1) A magnetic particle dispersion was prepared by dispersing 1.02 mg of polystyrene (SP value 9.0) and 4.23 mg of iron oxide nanoparticles (EMG1400, Ferrotec Corporation, d = 10 nm, coating agent: long-chain fatty acid) in 0.44 mL of chloroform. After adding 0.44 mL of the magnetic particle dispersion to 4 mL of water as an aqueous solvent, the mixture was cooled on ice and heated at an intensity of 9375 mW / cm. 2 The emulsion was then irradiated with ultrasonic waves for 300 seconds to emulsify. The emulsion was then allowed to stand for 16 hours at normal pressure (1 atm) and room temperature (25°C). The emulsion was centrifuged (5000g, 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.

[0090] (Example 2-2) The 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.

[0091] (Example 2-3) The magnetic polymer particles of Example 2-3 were obtained in the same manner as in Example 2-1, except that a 4 v / v % MeOH aqueous solution was used instead of water as the aqueous solvent.

[0092] (Examples 2-4) The magnetic polymer particles of Example 2-4 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, and a 4 v / v% aqueous MeOH solution was used instead of water as the aqueous solvent.

[0093] [Evaluation example 1] SEM observation Each magnetic polymer particle obtained in Example 2 was observed using an electron microscope. SEM images were taken using an electron microscope JSM-7800F Prime (JEOL) at an acceleration voltage of 10.0 kV and a magnification of 30,000 times. The taken SEM image is shown in Figure 3. Furthermore, in the taken SEM image, the uniformity of the particle shape was visually judged, and if the proportion of spherical particles and nearly spherical particles was higher than that in Figure 3 of Non-Patent Document 1, it was evaluated as being uniform. The judgment results are shown in Table 2.

[0094] As shown in FIG. 3, the magnetic polymer particles of each Example had a uniform particle shape and no anisotropy was observed.

[0095] [Evaluation Example 2] Elemental analysis An elemental analysis of each of the magnetic polymer particles obtained in Example 2 was carried out using a transmission electron microscope (JEM-F200, manufactured by JEOL Ltd.) The measured EDX (Energy Dispersive X-ray Spectroscopy) map is shown in FIG.

[0096] As shown in Figure 4, elemental iron (Fe) was observed in the regions corresponding to the magnetic polymer particles in each example, indicating that the resulting magnetic polymer particles contained the iron oxide nanoparticles used in their preparation.

[0097] [Evaluation Example 3] Optical property analysis An optical photograph of each magnetic polymer particle dispersion obtained in Example 2 is shown in Figure 5. The absorption spectrum of each dispersion was measured using a microplate reader (Infinite (registered trademark) M200 PRO; Tecan Group Ltd.). The measurement results of the absorption spectrum are shown in Figure 6. The relative absorbance at a wavelength of 400 nm of each magnetic polymer particle dispersion obtained in Example 2 to the absorbance of the magnetic polymer particle dispersion of Example 2-1 is shown in Figure 7.

[0098] As shown in FIG. 6, in each Example, absorbance at a wavelength of 400 nm was observed, indicating the presence of iron oxide contained in the magnetic particles. Also, as shown in FIG. 7, the magnetic polymer particle dispersions of Examples 2-3 and 2-4 showed higher relative absorbance than those of Examples 2-1 and 2-2. This suggests that the use of an aqueous mixed solvent of water and a hydrophilic solvent improves the content of magnetic particles in the magnetic polymer particles compared to the use of water. Also, the magnetic polymer particle dispersions of Examples 2-2 and 2-4 showed higher relative absorbance than those of Examples 2-1 and 2-3, respectively. This suggests that the content of magnetic particles in the magnetic polymer particles is improved by dispersing a surfactant in the magnetic particle dispersion compared to the case where the surfactant is not used.

[0099] [Evaluation Example 4] Analysis of physicochemical properties The particle size distribution and zeta potential of the magnetic polymer particles obtained in Examples 2-1 and 2-4 were measured using a Zeta Potential / Particle Size / 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. The particle size distribution of the magnetic polymer particles obtained in Examples 2-2 and 2-3 was also 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 2-2 to 2-4, especially Example 2-4, the variation in number-average particle size was reduced compared to Example 2-1. This shows that the use of an aqueous mixed solvent of water and a hydrophilic solvent and the dispersion of a surfactant in the magnetic particle dispersion liquid improves the variation in particle size between samples. The polydispersity index (PDI) values ​​shown in Table 2 show that the variation in particle size within one sample is also improved in a similar manner. In addition, the zeta potential shown in FIG. 8 shows that the surfaces of the magnetic polymer particles are negatively charged.

[0101] [Evaluation Example 5] Analysis of magnetic particle content The magnetic particle content of the magnetic polymer particles obtained in Examples 2-1 and 2-4 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 Examples 2-1 and 2-4. It was also 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 performed.

[0105] [Evaluation Example 6] Analysis of magnetic attraction In order to analyze the magnetic collection of the magnetic polymer particles obtained in Example 2-3, the magnetic polymer particle dispersion was placed on a neodymium magnet (dimensions: 10 mm x 10 mm x 10 mm, surface magnetic flux density: 0.42 T) and on a non-magnetic tabletop, and the change over time in the amount of magnetic polymer particles contained in the supernatant was measured. The measurement results are shown in Figure 9. The left side of Figure 9 is a graph showing the relative absorbance at each time point to the absorbance of the supernatant at the start of the measurement at a wavelength of 400 nm, and the right side of Figure 9 is an optical photograph of the dispersion at each time point.

[0106] As shown in FIG. 9, the magnetic polymer particles were rapidly accumulated in the dispersion placed on the magnet. This demonstrated that the magnetic polymer particles obtained in the examples are suitable for recovery using magnetism. Furthermore, in the dispersion placed on the table, the amount of magnetic polymer particles contained in the supernatant was almost constant. This demonstrated that the magnetic polymer particles obtained in the examples have excellent dispersion stability. [Industrial Applicability]

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

Claims

1. An emulsification step of emulsifying a dispersion liquid in which magnetic particles and a polymer containing a structural unit derived from a hydrophobic aromatic compound are dispersed, and an aqueous solvent containing at least one selected from the group consisting of water and a hydrophilic organic solvent to prepare an emulsion liquid; A forming step of removing at least a part of the organic solvent contained in the dispersion liquid from the emulsion liquid at a temperature of 0°C or higher and 50°C or lower to form magnetic polymer particles; A method for producing magnetic polymer particles, comprising:

2. The polymer contains a structural unit derived from at least one hydrophobic aromatic compound selected from the group consisting of styrene, vinylnaphthalene, divinylbenzene, vinyltoluene, vinylnaphthalene, vinylanthracene, vinylpyridine, thiophene, and derivatives thereof; The method for producing magnetic polymer particles according to Claim 1.

3. The polymer contains polystyrene; The method for producing magnetic polymer particles according to Claim 1.

4. The temperature is 10°C or higher and 40°C or lower; The method for producing magnetic polymer particles according to any one of Claims 1 to 3.

5. The aqueous solvent contains water and a hydrophilic organic solvent; The method for producing magnetic polymer particles according to any one of Claims 1 to 3.

6. The organic solvent contained in the dispersion liquid is a hydrophobic organic solvent; The method for producing magnetic polymer particles according to any one of Claims 1 to 3.

7. The dispersion liquid further contains a surfactant; The method for producing magnetic polymer particles according to any one of Claims 1 to 3.

8. The emulsification step includes: An irradiation step of irradiating ultrasonic waves to a mixture of the dispersion liquid and the aqueous solvent; A cooling step of cooling the mixture; and includes: The method for producing magnetic polymer particles according to any one of Claims 1 to 3.

9. 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 100000 mW / cm ２ or less. The method for producing magnetic polymer particles according to Claim 8.

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