Method for producing microcapsule and apparatus for producing microcapsule

Abstract

To provide a microcapsule production method enabling easy control of particle diameters and a microcapsule production apparatus that allows easy manufacture of microcapsules adjusted to a desired particle size range.SOLUTION: A method for producing microcapsules comprises: a step of growing a droplet of a first solution while keeping it in contact with a discharge port of a discharge head that holds the first solution, while controlling the distance between the discharge port and the liquid surface of a second solution stored in a storage section; and a step of contacting the droplet with the second solution without scattering, thereby forming a microcapsule covered with a hydrogel membrane, wherein the first solution contains a first substrate and the second solution contains a second substrate that reacts with the first substrate to form a hydrogel.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing microcapsules. [Background technology]

[0002] Encapsulation technology has been used to produce microparticles (microcapsules) containing desired substances. For example, microcapsules containing cells have been investigated for application in medical fields such as cell transplantation therapy by using biocompatible hydrogels as the encapsulating material for the cells.

[0003] A known method for producing microcapsules involves ejecting a first polymer electrolyte solution containing a first polymer electrolyte from the tip of a needle and contacting the resulting microdroplets with a second polymer electrolyte solution containing a second polymer electrolyte to form a polymer film on the droplet surface, thereby obtaining microcapsules (see, for example, Patent Document 1).In the invention described in Patent Document 1, by adding a predetermined substance such as cells to the first polymer electrolyte solution, microcapsules encapsulating the added predetermined substance are obtained. Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention described in Patent Document 1, when the first polymer electrolyte solution is ejected from the tip of the needle, a voltage is applied to the needle to strongly charge the droplets that are formed. This causes the charged droplets to fly, suppresses the droplets from coalescing during flight, and produces microcapsules of uniform size.

[0005] However, in the invention described in Patent Document 1, the size of the droplets is determined by electrostatic repulsion and surface tension, so if the particle size needs to be adjusted, a lot of trial and error is required.

[0006] Furthermore, if the particle size of the microcapsules to be produced is to be increased, it is necessary to adjust the particle size of the ejected droplets to be larger. However, since the droplets are strongly charged, electrostatic repulsion can cause them to break into smaller particles during flight, making it difficult to produce microcapsules with large particle sizes.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a method for producing microcapsules that allows easy control of particle size, and a microcapsule production apparatus that allows easy production of microcapsules whose particle size is controlled within a desired range. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present invention provides a method for producing microcapsules, which includes the steps of: growing droplets of a first solution while the nozzle of a nozzle of a nozzle head that holds the first solution is in contact with the liquid surface of a second solution stored in a storage section, while controlling the distance between the nozzle and the liquid surface of the second solution; and contacting the droplets with the second solution without causing them to fly, to form microcapsules covered with a hydrogel membrane, wherein the first solution contains a first substrate, and the second solution contains a second substrate that reacts with the first substrate to form the hydrogel. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing microcapsules that allows easy control of particle size, and also to provide a microcapsule production device that allows easy production of microcapsules whose particle size is controlled within a desired range. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a microcapsule manufacturing apparatus 1 of this embodiment. [Figure 2] FIG. 2 is a partially enlarged view of the microcapsule manufacturing apparatus 1. [Figure 3]FIG. 3 is an explanatory diagram illustrating the operation of the manufacturing apparatus 1. [Figure 4] FIG. 4 is an explanatory diagram illustrating the operation of the manufacturing apparatus 1. [Figure 5] FIG. 5 is an explanatory diagram illustrating the operation of the manufacturing apparatus 1. [Figure 6] FIG. 6 is a diagram showing a modified example of the ejection head. [Figure 7] FIG. 7 is a diagram showing a modified example of the ejection head. [Figure 8] FIG. 8 is an enlarged photograph of the obtained microcapsules MC. DETAILED DESCRIPTION OF THE INVENTION

[0011] The microcapsule manufacturing method and microcapsule manufacturing apparatus according to this embodiment will be described below with reference to Figures 1 to 7. In all the following figures, the dimensions and proportions of the components have been changed as appropriate to make the drawings easier to understand.

[0012] In the following explanation, an xyz Cartesian coordinate system is set, and the positional relationship of each component is explained with reference to this xyz Cartesian coordinate system. Here, a specific direction in a horizontal plane is defined as the x direction, a direction perpendicular to the x direction in the horizontal plane is defined as the y direction, and a direction perpendicular to both the x and y directions (i.e., the vertical direction) is defined as the z direction.

[0013] In addition, the vertically upward direction is the +z direction, and the vertically downward direction is the -z direction. In the following explanation, the "upper" in "upper" and "upper surface" and the "lower" in "lower" and "lower surface" have the same meaning.

[0014] Furthermore, in the following description, "planar view" refers to viewing an object from above (+z direction), and "planar shape" refers to the shape of an object viewed from above.

[0015] "Microcapsule MC" In the microcapsule manufacturing apparatus and method of this embodiment, droplets of a first solution L1 containing a first substrate are formed and then brought into contact with a second solution L2 containing a second substrate that reacts with the first substrate to form a hydrogel, thereby producing microcapsules MC in which a core C is covered with a hydrogel membrane HM (see FIG. 1).

[0016] The first solution L1 also contains a substance dissolved or dispersed therein that is to be encapsulated in the resulting microcapsules MC. Such a substance contained in the first solution L1 and intended to be encapsulated in the microcapsules MC may be referred to hereinafter as the "encapsulated substance." As a result, the resulting microcapsules MC become particles that contain (encapsulate) the encapsulated substance.

[0017] (1st substrate, 2nd substrate) The first substrate and the second substrate are not particularly limited as long as they form a crosslinked structure and gel when mixed together, and can be appropriately selected depending on the purpose.

[0018] Specific examples of the first substrate include biopolymers such as collagen, elastin, gelatin, and fibroin; coagulation factors such as fibrinogen; adhesion factors such as fibronectin, laminin, and recombinant peptides; metal salts of polysaccharide compounds such as alginic acid and gellan gum; and synthetic polymers such as polylactic acid and polyethylene glycol. These may be used alone or in combination of two or more.

[0019] Specific examples of the second substrate include polysaccharides, polyvalent metal salts, fibrinogen, thrombin, fibronectin, laminin, recombinant peptides, chitosan, chitin, tetrafunctional polyethylene glycol (Tetra-PEG), etc. These may be used alone or in combination of two or more.

[0020] It is advisable to carry out a preliminary experiment in advance to determine the combination of the first substrate and the second substrate that will give a hydrogel with the desired physical properties.

[0021] The resulting hydrogel is preferably a material that functions as a scaffold for cell culture. For example, when sodium alginate is used as the first substrate and a calcium salt such as calcium chloride is used as the second substrate, the resulting hydrogel (calcium alginate) is a material that can be used as a cell scaffold for research purposes and is preferred.

[0022] The solvent (dispersion medium) of the first solution L1 is not particularly limited as long as it is an aqueous solution that can dissolve the first substrate and dissolve or disperse the encapsulated substance. When cells are used as the encapsulated substance, the dispersion medium can be a known buffer solution such as phosphate buffered saline or Hank's balanced salt solution, or a culture medium suitable for the cells used.

[0023] The solvent (dispersion medium) of the second solution L2 is not particularly limited as long as it is an aqueous solution that can dissolve the second substrate and dissolve or disperse the encapsulated substance. The solvent (dispersion medium) of the second solution L2 can be the same as the solvent (dispersion medium) of the first solution L1 described above.

[0024] (cell) A representative example of the encapsulated substance contained in the first solution L1 is cells. By using cells as the encapsulated substance, the resulting microcapsules MC become hydrogel particles encapsulating cells.

[0025] There are no particular restrictions on the type of cells, and they can be selected appropriately depending on the purpose. All cells can be used, regardless of taxonomic classification, for example, karyotic cells, prokaryotic cells, multicellular organism cells, or unicellular organism cells.

[0026] Examples of eukaryotic cells include animal cells, insect cells, plant cells, and fungi. These may be used alone or in combination of two or more. Among these, animal cells are preferred, and when the cells form cell aggregates, adhesive cells that adhere to each other and have such cell adhesiveness that they cannot be isolated without physicochemical treatment are more preferred.

[0027] There are no particular limitations on the adhesive cells, and they can be appropriately selected depending on the purpose. Examples include differentiated cells and undifferentiated cells.

[0028] Examples of differentiated cells include hepatocytes, which are parenchymal cells of the liver; stellate cells; Kupffer cells; vascular endothelial cells; endothelial cells such as meatal endothelial cells and corneal endothelial cells; fibroblasts; osteoblasts; osteoclasts; periodontal ligament-derived cells; epidermal cells such as epidermal keratinocytes; tracheal epithelial cells; digestive tract epithelial cells; cervical epithelial cells; epithelial cells such as corneal epithelial cells; mammary gland cells; pericytes; muscle cells such as smooth muscle cells and cardiac muscle cells; kidney cells; pancreatic islet cells of Langerhans; nerve cells such as peripheral nerve cells and optic nerve cells; chondrocytes; bone cells, etc. The adhesive cells may be primary cells directly collected from tissues or organs, or may be cells that have been passaged for several generations.

[0029] The undifferentiated cells are not particularly limited and can be appropriately selected depending on the purpose. Examples include undifferentiated cells such as embryonic stem cells and pluripotent stem cells such as mesenchymal stem cells that have the ability to differentiate into different types; unipotent stem cells such as vascular endothelial progenitor cells that have the ability to differentiate into a single type; and iPS cells.

[0030] The above-mentioned cells may form a cell mass (spheroid).

[0031] The microcapsules MC obtained in this manner have a core-shell structure in which the first solution L1 is encapsulated as the core C and the hydrogel membrane HM encases the core C. Since the core C contains the first substrate, the first substrate of the core C may also solidify (gel) by reacting with the second substrate.

[0032] The microcapsule manufacturing apparatus of this embodiment can suitably form the above-mentioned microcapsules MC.

[0033] [Microcapsule manufacturing equipment] Fig. 1 is a schematic diagram of a microcapsule manufacturing apparatus 1 of this embodiment. Fig. 2 is a partial enlarged view of the microcapsule manufacturing apparatus 1. As shown in Figs. 1 and 2, the microcapsule manufacturing apparatus 1 has a discharge unit 10, a storage unit 30, a placement unit 40, and a control unit 50. In the following description, the microcapsule manufacturing apparatus may be simply referred to as the "manufacturing apparatus."

[0034] <Discharge head> The ejection head 110 ejects the first solution L1 held in the ejection head 110 to form droplets DR.

[0035] The discharge section 10 may have only one or more discharge heads 110. The discharge section 10 shown in Fig. 1 has three discharge heads 110a, 110b, and 110c. The three discharge heads 110a, 110b, and 110c are collectively referred to as a discharge unit 110L.

[0036] The ejection heads 110a, 110b, and 110c may have the same configuration or may have different configurations.

[0037] The three ejection heads 110a, 110b, and 110c are arranged in a direction (x direction in the drawing) that intersects with the ejection direction of the liquid ejected from the ejection head 110 (-z direction in the drawing).

[0038] As shown in FIG. 2, the ejection head 110A includes a liquid holding portion 111, a nozzle plate (film-shaped member) 112, and a vibration member 113.

[0039] The space surrounded by the liquid holding portion 111 and the nozzle plate 112 is a liquid chamber 110S of the ejection head 110A. A first solution L1 is held in the liquid chamber 110S.

[0040] The amount of the first solution L1 held in the liquid chamber 110S is not particularly limited. For example, the amount of the first solution L1 held in the liquid chamber 110S may be approximately 1 μl to 1 ml. When an expensive liquid such as a cell suspension is discharged from the manufacturing apparatus 1, the amount of the first solution L1 held in the liquid chamber 110S may be approximately 1 μl to 200 μl.

[0041] The ejection heads 110a, 110b, and 110c shown in FIG. 1 may each hold the same first solution L1, or may each hold a different first solution L1.

[0042] (liquid holding part) The liquid holder 111 is a tubular member with both ends in the z direction open. The liquid holder 111 may be, for example, a cylindrical member. Examples of materials for the liquid holder 111 include metals such as stainless steel, nickel, and aluminum, plastics (resin materials) such as ABS, polycarbonate, and fluororesin, ceramics such as silicon dioxide, alumina, and zirconia, and silicon.

[0043] One end of the liquid holding unit 111, that is, the lower end, is covered and blocked by a nozzle plate 112. The other end of the liquid holding unit 111, that is, the upper end, is open to the atmosphere. When the upper part of the liquid holding unit 111 is open to the atmosphere, the first solution L1 held in the liquid holding unit 111 is less likely to be pressurized when droplets are ejected. Therefore, when cells are contained in the first solution L1, damage to the cells can be suppressed.

[0044] (Nozzle plate (film-like member)) The nozzle plate 112 is a film-like member having ejection ports 112x. A cylindrical nozzle 115 extending downward (in the -z direction) is provided on the lower surface 112a of the nozzle plate 112. The nozzle has an open tip 115a that communicates with the liquid holding portion 111 (liquid chamber 110S). The nozzle tip 115a is the ejection port 112x of the nozzle plate 112.

[0045] There are no particular limitations on the planar shape, size in plan view, material, and structure of the nozzle plate 112, and they can be selected appropriately depending on the purpose.

[0046] Examples of the planar shape of the outer edge of the nozzle plate 112 include a circle, an ellipse, a rectangle, a square, a diamond, etc. For example, if the shape of the outer edge of the nozzle plate 112 is a circle, the nozzle plate 112 becomes an annular member.

[0047] If the nozzle plate 112 is too thick, it will be difficult to vibrate, and if it is too thin, the vibration will be difficult to stop, reducing the stability of droplet ejection. Therefore, the thickness of the nozzle plate 112 is preferably 5 μm to 500 μm, and more preferably 20 μm to 100 μm.

[0048] As an example, the nozzle plate 112 may be a circular member having a diameter of 20 mm and an average thickness of 0.05 mm.

[0049] The nozzle plate 112 is not supported at its end on the discharge port 112x side and can vibrate up and down. When the nozzle plate 112 vibrates at its end on the discharge port 112x side, it applies a downward force to the first solution L1 near the discharge port 112x, forming droplets DR at the discharge port 112x.

[0050] If the nozzle plate 112 is made of a material that is too soft, it will vibrate easily and it will be difficult to immediately stop the vibrations when no ink is being ejected. Therefore, it is preferable to use a material that has a certain degree of hardness.

[0051] Furthermore, when the first solution L1 to be discharged is a dispersion of cells, it is preferable that the material of the nozzle plate 112 is low in cytotoxicity and that cells do not easily adhere to it. As such a material, a highly hydrophilic material is preferable.

[0052] Such materials include, for example, metals, ceramics, and polymeric materials.

[0053] More specifically, examples of the material for the nozzle plate 112 include stainless steel, nickel, aluminum, silicon dioxide, alumina, zirconia, ABS, polycarbonate, fluororesin, etc. Furthermore, a composite material can be used in which the surface of the nozzle plate 112 formed from a material other than the above-mentioned materials is coated with the above-mentioned metal, ceramics, or synthetic phospholipid polymer that mimics a cell membrane (for example, Lipidure manufactured by NOF Corporation).

[0054] There are no particular limitations on the number of the discharge ports 112x arranged, the arrangement pattern, the interval (pitch), the opening shape, the opening size, etc., and these can be selected appropriately depending on the purpose.

[0055] The opening shape of the discharge port 112x can be selected appropriately depending on the purpose. Examples of the opening shape of the discharge port 112x include a circle, an ellipse, a rectangle, etc. Among these, a circle is preferable as the opening shape of the discharge port 112x.

[0056] The average opening diameter of the discharge port 112x is not particularly limited and can be appropriately selected depending on the purpose. When the first solution L1 to be discharged is a dispersion liquid, the opening shape of the discharge port 112x is preferably at least twice the maximum diameter of the dispersoids, in order to prevent the dispersoids, such as cells, dispersed in the first solution L1, from clogging the discharge port 112x.

[0057] When the particle is an animal cell, particularly a human cell, the average opening diameter of the outlet 112x is preferably 10 μm or more and 1000 μm or less.

[0058] The size of human cells varies depending on the cell type, but is generally between 5 μm and 50 μm. Furthermore, when the dispersoid is a cell cluster (spheroid), the size of the cell cluster is several tens of μm to several mm. Therefore, by setting the size of the discharge port 112x as described above and providing the discharge port 112x with an average opening diameter appropriate for the cells to be discharged, clogging of the discharge port can be suppressed.

[0059] It should be noted that while a larger opening diameter of the discharge ports 112x allows relatively large cell aggregates to be discharged, the larger the opening diameter, the more difficult it is to achieve stable discharge. By setting the average opening diameter of the discharge ports 112x to 1000 μm or less, a large number of cell aggregates can be stably discharged. Furthermore, to achieve stable discharge, it is preferable that the upper limit of the average opening diameter of the discharge ports 112x be 200 μm or less.

[0060] Furthermore, the smaller the opening diameter of the discharge port 112x, the more likely shear stress is applied to the cells or cell aggregates passing through the discharge port 112x. Therefore, it is preferable that the average opening diameter of the discharge port 112x is large.

[0061] The position of the discharge ports 112x in the nozzle plate 112 is not particularly limited and can be appropriately selected depending on the purpose. For example, the discharge ports 112x may be located at the center of the nozzle plate 112 when viewed from above, or at a position other than the center of the nozzle plate 112 when viewed from above.

[0062] Furthermore, the number of outlets 112x in the nozzle plate 112 may be one or more. A nozzle plate 112 having multiple outlets 112x can be suitably employed in a cylindrical liquid holding portion 111. In the nozzle plate 112 exposed to the internal space of the liquid holding portion 111, the multiple outlets 112x should be arranged at an equal distance from the central axis of the liquid holding portion 111. By arranging them in this manner, the vibration state of each outlet 112x in the nozzle plate 112 becomes equivalent, and it becomes possible to simultaneously eject droplets from the multiple outlets 112x.

[0063] Note that the nozzle plate 112 having the plurality of ejection ports 112x can be used in liquid holding portions other than cylindrical ones. As long as the vibration state of the nozzle plate 112 at the plurality of ejection ports 112x is equivalent, the nozzle plate 112 can be used in liquid holding portions of various shapes. For example, in the case of an elliptical cylindrical liquid holding portion, if ejection ports are provided at positions that overlap with the focal points in the xy cross section (rectangle) of the liquid holding portion, the vibration state at each ejection port becomes equivalent, and liquid droplets can be ejected simultaneously.

[0064] Similarly, when the liquid holding section is a rectangular tube, an xy cross section of the liquid holding section is assumed, an outlet is provided at an arbitrary point on the cross section, and an outlet is provided at a position that is symmetrical (line symmetric, point symmetric) to the arbitrary point on the cross section, thereby making the vibration state at each outlet equivalent.

[0065] (nozzle) The nozzle 115 may be formed by processing the nozzle plate 112, or may be formed by forming a cylindrical part using the same material as the nozzle plate 112 and then attaching it to the nozzle plate 112.

[0066] The tip 115a of the nozzle 115 may be subjected to a water-repellent treatment, so that the tip 115a is liquid-repellent to the first solution L1. There are no particular limitations on the type of water-repellent treatment as long as it does not impair the effects of the invention, and any known method can be used.

[0067] (Excitation member) The vibration member 113 vibrates the nozzle plate 112 based on the input electric signal, and discharges the first solution L1 from the discharge ports 112x. The discharged first solution L1 forms droplets DR at the tips 115a of the nozzles 115.

[0068] The vibration member 113 is installed on the lower surface 112 a of the nozzle plate 112 .

[0069] There are no particular limitations on the shape, size, material, and structure of the vibration member 113, and they can be selected appropriately depending on the purpose.

[0070] There are no particular limitations on the shape or arrangement of the vibration member 113 as long as it does not impair the effects of the invention, and it can be designed appropriately to match the shape of the nozzle plate 112. For example, if the nozzle plate 112 has a circular planar shape, it is preferable to provide the vibration member 113 concentrically around the discharge port 112x.

[0071] Examples of the vibrating member 113 include a piezoelectric element and an electromagnetic solenoid, with a piezoelectric element being preferred. The piezoelectric element may have a structure in which electrodes for applying a voltage are provided on the upper and lower surfaces of a piezoelectric material, for example. In this case, by applying a voltage between the upper and lower electrodes of the piezoelectric element from the control unit 50, a compressive stress is applied in the lateral direction of the film surface, and the nozzle plate 112 can be vibrated in the vertical direction of the film surface.

[0072] The piezoelectric material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include lead zirconate titanate (PZT), bismuth iron oxide, metal niobate, barium titanate, or any of these materials to which a metal or a different oxide has been added. Among these, lead zirconate titanate (PZT) is preferred.

[0073] The vibration mode of the piezoelectric element is not particularly limited and can be appropriately selected depending on the purpose, and examples include longitudinal mode, bend mode, etc. A longitudinal mode piezoelectric element is, for example, a stacked type piezoelectric element stacked in the z direction, which expands in the vertical direction (z direction) and contracts in the horizontal directions (x and y directions) when a voltage is applied.

[0074] Furthermore, as a bend mode piezoelectric element, for example, a bimorph type piezoelectric element can be used, in which the piezoelectric element is deformed and bent by applying a voltage, and the position of one end of the piezoelectric element is displaced.

[0075] <Transportation section> The transport section 120 includes a first moving section 121 and a second moving section 122 .

[0076] (First moving part) First moving section 121 has support member 121a and linear moving section 121b. First moving section 121 is a pair of members provided at the +x side end and the -x side end of second moving section 122. First moving section 121 corresponds to the distance adjustment member of the present invention.

[0077] The support member 121a is a rectangular member when viewed from the +y direction, and supports the second moving part 122.

[0078] The linear moving part 121b is a long member extending in the z direction. The linear moving part 121b moves the support member 121a up and down in the z direction. For example, a known linear actuator equipped with a stepping motor as a drive source can be used as the linear moving part 121b.

[0079] The first moving part 121 moves the support member 121a in the z direction, thereby moving the discharge unit 110L supported by the second moving part 122 in the z direction. The first moving part 121 is used to adjust the distance between the discharge port 112x (the tip 115a of the nozzle 115) of the discharge head 110A and the liquid surface S of the second solution L2 stored in the storage part 30, which will be described later.

[0080] (Second moving part) The second moving portion 122 has a support member 122a and a linear moving portion 122b.

[0081] The support member 122a is a rectangular member when viewed from the +y direction, and supports the discharge unit 110L.

[0082] The linear moving portion 122b is a long member extending in the x direction. The linear moving portion 122b moves the support member 122a horizontally in the x direction. Both ends of the linear moving portion 122b are supported by the support members 121a of the first moving portion 121, respectively.

[0083] The linear movement portion 122b may be, for example, a known linear actuator equipped with a stepping motor as a drive source.

[0084] The second moving section 122 moves the support member 122a in the x direction, thereby moving the discharge unit 110L supported by the support member 122a in the x direction.

[0085] Reservoir The reservoir 30 is disposed in the ejection direction of the droplets DR and stores the second solution L2. The reservoir 30 is a container that is open upward (in the +z direction). The reservoir 30 may be, for example, a shallow container such as a petri dish or a deep container such as a beaker.

[0086] The material of the reservoir 30 is not particularly limited, and organic materials such as synthetic resins, inorganic materials such as glass, metal materials, and the like can be used as appropriate.

[0087] The storage unit 30 may have a stirring device for stirring the stored second solution L2. This can suppress precipitation and aggregation of the microcapsules MC formed in the second solution L2. A known configuration can be used as the stirring device.

[0088] <<Placement section>> The storage unit 30 is placed on the placement unit 40. The placement unit 40 has an x-stage 41, a y-stage 42, and a base 43.

[0089] The x-stage 41 supports and fixes the storage unit 30. The x-stage 41 also moves the storage unit 30 horizontally in the x direction.

[0090] The y-stage 42 moves the x-stage 41 horizontally in the y direction. The base 43 supports the y-stage 42 .

[0091] The mounting unit 40 can employ a known structure known as an xy stage.

[0092] Control Unit The control unit 50 generates electrical signals to operate each unit of the manufacturing apparatus 1 and supplies them to control each unit. The control unit 50 generates drive signals to be supplied to, for example, the discharge unit 10 and the placement unit 40 and supplies them to each unit to control the operation of each unit.

[0093] 3 to 5 are explanatory diagrams illustrating the operation of the manufacturing apparatus 1. Device control by the control unit 50 will be described with reference to FIGS.

[0094] 3, the control unit 50 adjusts the height position of the discharge head 110A in the z direction using the first moving unit 121 (see FIG. 1). The control unit 50 operates the first moving unit 121 in accordance with the diameter (particle size) of the microcapsules MC to be produced, and adjusts the separation distance H between the tip 115a of the nozzle 115 of the discharge head 110A and the liquid surface S of the second solution L2 in the storage unit 30.

[0095] 4, the control unit 50 operates the vibration member 113 to discharge the first solution L1 from the discharge port 112x. The first solution L1 forms a droplet DR at the tip 115a of the nozzle 115. As the first solution L1 continues to be discharged from the discharge port 112x, the droplet DR at the tip 115a grows.

[0096] When the tip 115a of the nozzle 115 is treated with a water-repellent coating, the droplet DR can grow larger than when the tip 115a is not treated with a water-repellent coating.

[0097] Next, as shown in FIG. 5, when the diameter of the droplet DR grows to reach the separation distance H, the droplet DR comes into contact with the liquid surface S of the second solution L2 without flying.

[0098] When the droplet DR comes into contact with the liquid surface S of the second solution L2, the first substrate contained in the droplet DR (first solution L1) reacts with the second substrate contained in the second solution L2 to form a hydrogel film HM on the surface of the droplet DR. At the same time, a force is applied to the droplet DR to pull it into the second solution L2, and the droplet DR detaches from the tip 115a of the nozzle 115.

[0099] The inventors have experimentally confirmed that these phenomena occur the moment the droplets DR come into contact with the liquid surface S of the second solution L2. The diameter W of the resulting microcapsules MC is approximately equal to the separation distance H, or becomes slightly smaller than the separation distance H due to shrinkage from the droplets DR.

[0100] Furthermore, when the control unit 50 continues to operate the vibration member 113, microcapsules MC are formed one after another from the resulting droplets DR. The diameter of each of the obtained microcapsules MC is controlled by the separation distance H.

[0101] As a result, the particle size of the obtained microcapsules MC is controlled.

[0102] [Method of manufacturing microcapsules] The method for manufacturing microcapsules can be suitably carried out by using the manufacturing apparatus 1. The method for manufacturing microcapsules includes a step of growing droplets DR of the first solution L1 while keeping them in contact with the discharge outlets 112x, while controlling the separation distance H between the discharge outlets 112x of the discharge head 110A that holds the first solution L1 and the liquid surface S of the second solution L2 stored in the storage section 30, and a step of bringing the droplets DR into contact with the second solution L2 without causing them to fly, to form microcapsules MC covered with a hydrogel film HM.

[0103] As described above, the first solution L1 contains a first substrate, and the second solution L2 contains a second substrate that reacts with the first substrate to form a hydrogel.

[0104] The first solution L1 may contain dispersoids that are dispersed in the first solution L1. By using either or both of cells and spheroids as such dispersoids, microcapsules encapsulating cells or spheroids can be produced.

[0105] It should be noted that the apparatus used for carrying out the above-described manufacturing method is not limited to the manufacturing apparatus 1 described above, as long as it is possible to carry out the above-described manufacturing method.

[0106] According to the above-described method for producing microcapsules, it is easy to control the particle size of the produced microcapsules.

[0107] Furthermore, the microcapsule manufacturing apparatus described above makes it possible to easily manufacture microcapsules whose particle diameters are controlled within a desired range.

[0108] (Variation) 6 and 7 are explanatory diagrams of a microcapsule manufacturing apparatus according to a modified example, showing a modified ejection head.

[0109] The ejection head 110B shown in FIG. 6 includes a liquid holding portion 116, a nozzle 115, and a pressure device 118.

[0110] The liquid holding portion 116 is a cylindrical member that extends in the z direction and has both ends in the z direction that are closed. The inside of the liquid holding portion 116 is a liquid chamber 110S that stores the first solution L1.

[0111] A through-hole communicating with the liquid chamber 110S is provided in the lower surface of the liquid holding portion 116, and a nozzle 115 is connected to the through-hole. A tip 115a of the nozzle 115 is an outlet 116x for discharging the first solution L1.

[0112] A pressurizing device 118 that pressurizes the space of the liquid chamber 110S is connected to the liquid holding portion 116. The operation of the pressurizing device 118 is controlled by the control portion 50, and the pressurizing device 118 increases the internal pressure of the liquid chamber 110S. For example, an air pump can be used as the pressurizing device 118.

[0113] When the space in the liquid chamber 110S is pressurized, the gas occupying the space pushes down the first solution L1, causing the first solution L1 to be discharged from the nozzle 115 and form droplets DR at the tip 115a of the nozzle 115.

[0114] With such a discharge head 110B, it is possible to continuously apply pressure to the first solution L1, and therefore it is easier to continue to apply pressure to the first solution L1 and form droplets DR compared to the discharge head 110A that uses the vibration member 113. Therefore, with a manufacturing device having the discharge head 110B, it is easier to stably manufacture microcapsules MC.

[0115] 7 includes a liquid holding portion 116 and a pressurizing device 118. The liquid holding portion 116 of the ejection head 110C has, on its lower surface (the outer surface of the ejection head) 116a, a first region AR1 having a closed ring shape that surrounds the ejection port 116x, and a second region AR2 inside the first region AR1. The first region AR1 is treated with a water-repellent finish and is more hydrophobic than the second region AR2.

[0116] When the first solution L1 is discharged from the outlet 116x using this discharge head 110C, droplets DR grow at the outlet 116x. At this time, even if the first solution L1 spreads in the second region AR2 on the lower surface 116a, it is repelled by the first region AR1.

[0117] As a result, the droplet DR growing at the discharge port 116x grows in contact with the boundary between the first area AR1 and the second area AR2 without spreading beyond the second area AR2.

[0118] Even with a manufacturing device using the above-described discharge heads 110B and 110C, microcapsules can be manufactured by adjusting the distance between the discharge port and the liquid surface S of the second solution L2 in the storage section 30, forming droplets DR with the discharge head, and bringing the droplets DR into contact with the liquid surface S without flying. The microcapsules manufactured in this manner have particle diameters controlled to a desired range.

[0119] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention. [Example]

[0120] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0121] A confirmation experiment was carried out by configuring a manufacturing device having the discharge head shown in Fig. 6. In the following description, the reference numerals used in the description of the above embodiment will be used as appropriate.

[0122] A discharge head 110B equipped with a nozzle having an opening diameter of 160 μm was prepared, and the liquid chamber 110S of the discharge head 110B was made pressurizable by air pressure. Also, a 35 mm cell culture dish was used as the reservoir 30.

[0123] A 2.5% sodium alginate solution was used as the first solution L1, and a 109 mmol% calcium chloride aqueous solution was used as the second solution L2. In the first solution L1, 65 μm resin particles were suspended at a concentration of 0.5% as a model of cells (spheroids).

[0124] After adjusting the distance between the tip 115a of the nozzle 115 of the ejection head 110B and the liquid surface S of the second solution L2 in the storage section 30 to 1 mm, the liquid chamber 110S of the ejection head 110B was pressurized to eject the first solution L1 from the nozzle 115.

[0125] A high-speed camera (FASTCAM, manufactured by Photron) was used to observe under magnification the state of the tip of the nozzle 115. It was possible to confirm that the first solution L1 formed droplets DR at the tip 115a of the nozzle 115, and that when the droplets DR came into contact with the second solution, the droplets DR were instantly drawn into the second solution L2, and microcapsules MC were formed.

[0126] Figure 8 is an enlarged photograph of the obtained microcapsules MC. In Figure 8, it can be seen that resin particles are encapsulated in the microcapsules MC. The microcapsules were flattened into ellipses in a planar view, but all of them were uniform in size, with a major axis length of approximately 800 μm and a minor axis length of approximately 700 μm, confirming that microcapsules with controlled particle size and shape were obtained.

[0127] From the above results, it was confirmed that the present invention is useful.

[0128] The present invention includes the following aspects.

[0129] [1] A method for producing microcapsules, comprising: a step of growing droplets of a first solution while keeping them in contact with the outlet of a discharge head that holds the first solution, while controlling the distance between the outlet and the liquid surface of a second solution stored in a storage section; and a step of contacting the droplets with the second solution without causing them to fly, to form microcapsules covered with a hydrogel membrane, wherein the first solution contains a first substrate, and the second solution contains a second substrate that reacts with the first substrate to form the hydrogel.

[0130] [2] The method for producing microcapsules according to [1], wherein the first solution contains a dispersoid dispersed in the first solution.

[0131] [3] The method for producing microcapsules according to [2], wherein the dispersoid is either a cell or a spheroid, or both.

[0132] [4] An apparatus for manufacturing microcapsules covered with a hydrogel membrane obtained by reaction between a first substrate and a second substrate, the apparatus comprising: an ejection head for ejecting a first solution containing the first substrate from an outlet at the tip of a nozzle; a storage section arranged opposite the tip of the nozzle for storing a second solution containing the second substrate; a distance adjustment member for adjusting the distance between the tip of the nozzle and the liquid surface of the second solution; and a control section for causing the distance adjustment member to adjust the distance according to the diameter of the microcapsules to be manufactured.

[0133] [5] The microcapsule manufacturing apparatus according to [4], wherein the tip of the nozzle is water-repellent.

[0134] [6] An apparatus for manufacturing microcapsules covered with a hydrogel film obtained by reaction between a first substrate and a second substrate, the apparatus comprising: an ejection head for ejecting a first solution containing the first substrate from an ejection outlet; a storage section arranged opposite the ejection outlet and for storing a second solution containing the second substrate; a distance adjustment member for adjusting the distance between the ejection outlet and the liquid surface of the second solution; and a control section for causing the distance adjustment member to adjust the distance according to the diameter of the microcapsules to be manufactured, wherein the ejection head has a first closed-ring region surrounding the ejection outlet on the outer surface of the ejection head and a second region inside the first region, and the first region is more hydrophobic than the second region. [Explanation of symbols]

[0135] 1... manufacturing apparatus, 30... storage section, 50... control section, 110, 110a to 110c, 110A, 110B, 110C... ejection head, 112x, 116x... ejection port, 115... nozzle, 1115a... tip, 116a... lower surface (outer surface of ejection head), AR1... first region, AR2... second region, DR... droplet, H... separation distance, HM... membrane, L1... first solution, L2... second solution, MC... microcapsule, S... liquid surface, W... diameter [Prior art documents] [Patent documents]

[0136] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-201350

Claims

1. a step of growing droplets of the first solution while being in contact with the discharge port of a discharge head that holds the first solution, while controlling a separation distance between the discharge port and a liquid surface of the second solution stored in a storage section; and contacting the droplets with the second solution without causing them to fly, thereby forming microcapsules covered with a hydrogel membrane, the first solution comprises a first substrate; The second solution comprises a second substrate that reacts with the first substrate to form the hydrogel.

2. The method for producing microcapsules according to claim 1 , wherein the first solution contains a dispersoid dispersed in the first solution.

3. The method for producing microcapsules according to claim 2 , wherein the dispersoid is either one or both of a cell and a spheroid.

4. An apparatus for producing microcapsules covered with a hydrogel membrane obtained by reacting a first substrate with a second substrate, a discharge head that discharges the first solution containing the first substrate from a discharge port at the tip of a nozzle; a reservoir arranged opposite to the tip of the nozzle and configured to store a second solution containing the second substrate; a distance adjusting member for adjusting a distance between the tip of the nozzle and a liquid surface of the second solution; a control unit that causes the distance adjustment member to adjust the separation distance in accordance with the diameter of the microcapsules to be manufactured.

5. 5. The microcapsule manufacturing apparatus according to claim 4, wherein the tip of the nozzle is water-repellent.

6. An apparatus for producing microcapsules covered with a hydrogel membrane obtained by reacting a first substrate with a second substrate, a discharge head configured to discharge a first solution containing the first substrate from a discharge port; a reservoir disposed opposite the discharge port and configured to store a second solution containing the second substrate; a distance adjusting member for adjusting a distance between the discharge port and a liquid surface of the second solution; a control unit that causes the distance adjustment member to adjust the separation distance in accordance with the diameter of the microcapsules to be manufactured, the ejection head has a first region in a closed ring shape that surrounds the ejection port on an outer surface of the ejection head, and a second region inside the first region, An apparatus for manufacturing microcapsules, wherein the first region is more hydrophobic than the second region.

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