Delivery composite particle, method for producing the same, and production kit therefor

Abstract

To provide a liquid marble-like particle with enhanced mechanical strength.SOLUTION: The delivery composite particle of the present disclosure comprises a gel particle comprising a delivery target substance and a hydrophobic particle covering the gel particle, the viscosity of the gel particle at 20°C being 4500 mPa s or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composite particle for delivery, a method for producing the same, and a kit for producing the same. [Background technology]

[0002] Liquid marbles are materials in which liquid droplets are encapsulated by hydrophobic particles. They are expected to be used as delivery carriers or capsules, or for applications such as microbial culture, and research and development of liquid marbles has been actively pursued in recent years.

[0003] For example, Patent Document 1 discloses a liquid marble containing a biocatalyst, water, and a thickener, in which a liquid for liquid marble having a viscosity of 400 mPa·s to 4,000 mPa·s at 25°C is encapsulated in external particles. An example of the thickener disclosed is a polysaccharide.

[0004] Patent Document 2 discloses liquid marbles in which an organic solvent (tetraethylpentamine or polyethyleneimine) is encapsulated in hydrophobic silica nanoparticles, and also discloses that the liquid marbles can be used as CO2 capture materials. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-27274 [Non-patent literature]

[0006] [Non-Patent Document 1] NATURE COMMUNICATIONS (2019) 10:1854 Summary of the Invention [Problem to be solved by the invention]

[0007] The liquid marble of Patent Document 1 has low mechanical strength and issues with handling. The liquid marble of Patent Document 2 contains an organic solvent such as polyethyleneimine as the encapsulated liquid, which poses issues with biocompatibility. Furthermore, the liquid encapsulated in the liquid marble of Patent Document 2 is not gelled, which raises concerns about low mechanical strength.

[0008] One aspect of the present invention aims to realize liquid marble-like particles with improved mechanical strength. [Means for solving the problem]

[0009] As a result of extensive research, the inventors discovered that composite particles obtained by gelling a liquid and coating the gel particles with hydrophobic particles have improved mechanical strength, leading to the completion of the present invention.

[0010] In order to solve the above-mentioned problems, one embodiment of the present invention provides a composite particle for delivery, which comprises gel particles containing a delivery target and hydrophobic particles that coat the gel particles, and the viscosity of the gel particles at 20°C is 4500 mPa·s or more.

[0011] Furthermore, a method for producing composite particles for delivery according to one embodiment of the present invention includes a preparation step of preparing a gel particle preparation liquid by adding a delivery target to a solution containing a gelling agent, and a coating step of coating the surfaces of droplets of the gel particle preparation liquid with hydrophobic particles and then gelling the droplets, or gelling the droplets of the gel particle preparation liquid to obtain gel particles and then coating the surfaces of the gel particles with hydrophobic particles. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to provide liquid marble-like particles having improved mechanical strength. [Brief explanation of the drawings]

[0013] [Figure 1]FIG. 10 is a diagram showing the observation results of Composite Particle 1 of Evaluation Example 2 after being left to stand for 48 hours. [Figure 2] FIG. 1 shows the results of observation of the composite particle for delivery (containing a blue pigment) of Evaluation Example 3 after being left to stand for 48 hours. [Figure 3] FIG. 1 shows the results of observation of the composite particle for delivery (containing a red dye) of Evaluation Example 3 after being left to stand for 48 hours. DETAILED DESCRIPTION OF THE INVENTION

[0014] One aspect of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments and examples obtained by appropriately combining the technical means disclosed in the embodiments and examples are also included in the technical scope of the present invention. Furthermore, in this specification, "A to B" means A or more and B or less, unless otherwise specified.

[0015] [Delivery Composite Particles] A composite particle for delivery according to one embodiment of the present invention comprises gel particles and hydrophobic particles.

[0016] (gel particles) The gel particles contained in the composite particle for delivery according to one embodiment of the present invention contain a delivery target. Examples of the delivery target include microorganisms such as bacteria, cells, supplements, drugs, pigments, proteins, enzymes, antibodies, etc. One type of delivery target may be used alone, or two or more types may be used in combination in any ratio.

[0017] The content of the substance to be delivered in the gel particles can be appropriately selected depending on the type of substance to be delivered and the intended use of the composite particle for delivery.

[0018] The viscosity of the gel particles at 20°C is 4500 mPa·s or more. When the viscosity of the gel particles is within this range, the mechanical strength of the composite particles for delivery is improved. In order to further improve the mechanical strength of the composite particles for delivery, the viscosity of the gel particles at 20°C is preferably 10000 mPa·s or more, more preferably 20000 mPa·s or more, and even more preferably 40000 mPa·s or more. There is no particular upper limit to the viscosity of the gel particles at 20°C, but it may be, for example, 1,000,000 mPa·s or less.

[0019] In this specification, the "viscosity of gel particles at 20°C" refers to the viscosity at 20°C measured with a Brookfield rotational viscometer 48 hours after the start of gelation to prepare the gel particles.

[0020] When the gel particles contain gelatin or collagen, "48 hours after initiation of gelation to prepare the gel particles" refers to 48 hours after initiation of gelation of the solution containing gelatin or collagen. For example, gelation of the solution containing gelatin or collagen is initiated by applying an external force, such as by changing the temperature of the solution containing gelatin or collagen.

[0021] In terms of high biodegradability and the ability to utilize reversible reactions, the gel particles are preferably physically crosslinked gel particles, and more preferably contain a physical crosslinking agent that induces the formation of physical crosslinks. In this specification, "physical crosslinking" refers to crosslinking by non-covalent bonds and is different from crosslinking by covalent bonds. Examples of crosslinking by non-covalent bonds include crosslinking by hydrogen bonds, ionic bonds, or intermolecular interactions.

[0022] Examples of the physical cross-linking agent include gelatin, collagen, polyvinyl alcohol, etc. In terms of improving biocompatibility, the gel particles preferably contain gelatin or collagen. In terms of further improving the mechanical strength of the composite particle for delivery, the concentration of gelatin or collagen is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the gel particles. There is no particular upper limit to the concentration of gelatin or collagen, and the concentration of gelatin or collagen may be a saturated concentration.

[0023] Examples of the shape of the gel particles include spherical, true spherical, polyhedral, and needle-like shapes.

[0024] (hydrophobic particles) The hydrophobic particles contained in the composite particle for delivery according to one embodiment of the present invention coat the gel particles. Coating of the gel particles with hydrophobic particles includes an embodiment in which the entire or partial surface of the gel particles is covered. The hydrophobic particles that coat the gel particles may be used alone or in combination of two or more types in any ratio.

[0025] In this specification, the term "hydrophobic particles" includes particles whose constituent material itself is hydrophobic, and particles whose surfaces have been subjected to a hydrophobic treatment.

[0026] Examples of materials constituting the hydrophobic particles include inorganic particles such as silica, calcium carbonate, and talc; organic particles such as silicone resin and cellulose; etc. In terms of mechanical strength, the hydrophobic particles are preferably silica particles, and more preferably hydrophobic silica particles whose surfaces have been subjected to a hydrophobic treatment.

[0027] The average particle size of the hydrophobic particles can be appropriately selected depending on the intended use of the composite particles for delivery, and may be, for example, from 0.05 μm to 1000 μm.

[0028] Examples of the shape of the hydrophobic particles include spherical, true spherical, polyhedral, needle-like, etc. The hydrophobic particles may be porous or hollow.

[0029] (Other ingredients) The composite particle for delivery according to one embodiment of the present invention may contain other components in addition to the gel particles and hydrophobic particles, such as a coating agent for covering the hydrophobic particles.

[0030] (Applications of composite particles for delivery) The composite particle for delivery according to one embodiment of the present invention has high mechanical strength and can be used in various technical fields, for example, as a system for delivering medicines, supplements, or cells to target sites in the body.

[0031] [Method for producing composite particles for delivery] The present invention also includes a method for producing composite particles for delivery according to one aspect of the present invention, which includes a preparation step of preparing a gel particle preparation solution and a coating step.

[0032] (Preparation process) In the preparation step, a substance to be delivered is added to a solution containing a gelling agent to prepare a gel particle preparation solution. Examples of the substance to be delivered have already been described, and will not be repeated here.

[0033] Examples of gelling agents include physical cross-linking agents such as gelatin or collagen.

[0034] The gel particle preparation solution may be prepared so that the gel former is present in an amount of preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the gel particles to be prepared. There is no particular upper limit to the concentration of the gel former, and the concentration of the gel former may be a saturated concentration.

[0035] Examples of solvents used in the solution containing the gelling agent include aqueous solvents. Examples of aqueous solvents include water and buffer solutions. The solvents used in the solution containing the gelling agent may be used alone or in combination of two or more in any ratio.

[0036] The amount of solvent used in the solution containing the gelling agent can be appropriately selected depending on the type and content of the gelling agent and the object to be delivered.

[0037] When the gelling agent contains gelatin or collagen, it is preferable to use gelatin or collagen swollen with an aqueous solvent, as this makes the gelatin or collagen more easily soluble in the gel particle preparation solution. The solvent used for swelling may be the same as or different from the solvent used in the solution containing the gelling agent. The swelling temperature and swelling time can be appropriately selected depending on the type, amount, or temperature of the solvent used for swelling, the amount of gelatin or collagen to be swollen, etc. The swelling temperature may be, for example, 10°C to 40°C. The swelling time may be, for example, 1 hour or longer.

[0038] When the gelling agent contains gelatin or collagen, the temperature at which the gel particle preparation solution is prepared is preferably 40° C. or higher, more preferably 45° C. or higher, and even more preferably 50° C. or higher, in order to facilitate dissolution of the gelatin or collagen in the gel particle preparation solution. Furthermore, the temperature at which the gel particle preparation solution is prepared is preferably 80° C. or lower, more preferably 70° C. or lower, and even more preferably 60° C. or lower, in order to maintain the physical properties of the gelatin or collagen or the delivery target.

[0039] (Coating process) The coating step is a step (i) of coating the surfaces of droplets of the gel particle preparation solution with hydrophobic particles and then gelling the droplets, or a step (ii) of gelling the droplets of the gel particle preparation solution to obtain gel particles and then coating the surfaces of the gel particles with hydrophobic particles. Examples and preferred embodiments of hydrophobic particles have already been described, so they will not be repeated here.

[0040] The droplets can be formed in the coating step by a known method. Examples of the droplet formation method include forming droplets using a droplet dropping device such as a dropper, burette, or shower head; forming droplets by spraying using a spray nozzle; and forming droplets by ejecting droplets using an inkjet head. The size of the droplets can be appropriately selected depending on the type and amount of the delivery target and the application of the composite particle for delivery.

[0041] When the coating step is step (i), the surfaces of the droplets of the gel particle preparation solution can be coated with hydrophobic particles by contacting the hydrophobic particles with the surfaces of the droplets of the gel particle preparation solution. Examples of methods for contacting the hydrophobic particles with the surfaces of the droplets of the gel particle preparation solution include a method of spraying the hydrophobic particles onto the surfaces of the droplets of the gel particle preparation solution, and a method of dripping droplets of the gel particle preparation solution onto the hydrophobic particles.

[0042] As a method for dropping droplets of the gel particle preparation solution onto the hydrophobic particles, for example, a method may be mentioned in which a plate on which the hydrophobic particles are arranged is tilted and droplets of the gel particle preparation solution are dropped onto the surface on which the hydrophobic particles are arranged. As the dropped droplets slide down the surface of the tilted plate, they come into contact with the hydrophobic particles, and the droplets are coated with the hydrophobic particles.

[0043] When the coating step is step (i), the temperature of the droplets to be coated with hydrophobic particles is preferably a temperature at which the droplets are in a sol state, and more preferably a temperature at which a gel particle preparation liquid is prepared.

[0044] When the coating step is step (i), the droplets coated with hydrophobic particles can be gelled by applying an external force such as a temperature change. When gelatin or collagen is used as the gelling agent, the droplets coated with hydrophobic particles can be gelled by leaving them standing at preferably 35° C. or less, more preferably 30° C. or less, and even more preferably 25° C. or less. The standing period may be, for example, 24 hours or more.

[0045] When the coating step is step (ii), the surfaces of the gel particles can be coated with hydrophobic particles, for example, by the following procedure: injecting droplets of a gel particle preparation liquid into a mold and allowing it to gel in the mold to prepare gel particles (for example, by setting the mold temperature to 35°C or less); coating the surfaces of the gel particles with hydrophobic particles.

[0046] When the coating step is step (ii), the surfaces of gel particles can also be coated with hydrophobic particles, for example, by the following procedure: preparing gel particles by gelling droplets of a gel particle preparation solution (for example, by lowering the temperature of the gel particle preparation solution to 35°C or below); arranging gel particles on hydrophobic particles; and coating the surfaces of the gel particles with hydrophobic particles.

[0047] The method for producing composite particles for delivery according to one embodiment of the present invention may include other steps in addition to the preparation step and the coating step, such as a step of selecting or recovering gel particles whose surfaces are coated with hydrophobic particles.

[0048] One aspect of the present invention includes composite particles for delivery manufactured by the method for manufacturing composite particles for delivery according to one aspect of the present invention. From the viewpoint of improving the mechanical strength of the composite particles for delivery, it is preferable that the viscosity of the gel particles in the composite particles for delivery at 20°C is 4500 mPa s or more.

[0049] [Production kit for composite particles for delivery] Another aspect of the present invention is a kit for producing a composite particle for delivery according to one aspect of the present invention. The kit includes hydrophobic particles. The kit may also include a gelling agent. Examples and preferred embodiments of the hydrophobic particles and the gelling agent have already been described, and therefore will not be repeated here.

[0050] As used herein, the term "kit" refers to a package containing containers (e.g., bottles, tubes, vials, etc.) containing specific materials. A production kit according to one embodiment of the present invention may be in a form in which each material contained therein exists independently, or in a form in which multiple materials are mixed (e.g., in the form of a composition). A production kit according to one embodiment of the present invention preferably includes instructions for using each material.

[0051] The production kit according to one embodiment of the present invention may further include, in addition to the hydrophobic particles and the gelling agent, materials for preparing the composite particles for delivery (for example, a solvent).

[0052] 〔summary〕 The composite particle for delivery according to aspect 1 of the present invention comprises a gel particle containing a delivery target and a hydrophobic particle that coats the gel particle, and the viscosity of the gel particle at 20°C is 4500 mPa·s or more.

[0053] The composite particle for delivery according to the second aspect of the present invention may be a gel particle obtained by physically crosslinking the gel particles in the first aspect.

[0054] In the composite particle for delivery according to aspect 3 of the present invention, in the above aspect 1 or 2, the gel particle may contain gelatin or collagen.

[0055] The composite particle for delivery according to aspect 4 of the present invention may be the same as that according to aspect 3, wherein the concentration of the gelatin or collagen is 3% by mass or more relative to 100% by mass of the gel particle.

[0056] The composite particles for delivery according to Aspect 5 of the present invention are any one of Aspects 1 to 4, and the hydrophobic particles may be silica particles.

[0057] A method for producing composite particles for delivery according to aspect 6 of the present invention includes a preparation step of preparing a gel particle preparation solution by adding a delivery target to a solution containing a gelling agent, and a coating step of coating the surfaces of droplets of the gel particle preparation solution with hydrophobic particles and then gelling the droplets, or gelling the droplets of the gel particle preparation solution to obtain gel particles and then coating the surfaces of the gel particles with hydrophobic particles.

[0058] A seventh aspect of the present invention relates to the method for producing composite particles for delivery in the sixth aspect, wherein the viscosity of the gel particles at 20° C. may be 4500 mPa·s or more.

[0059] A production kit according to an eighth aspect of the present invention is a production kit for producing the composite particle for delivery according to any one of the first to fifth aspects, which contains hydrophobic particles.

[0060] The production kit according to Aspect 9 of the present invention is in accordance with Aspect 8, and may further include a gel-forming agent. [Example]

[0061] In the examples, room temperature refers to 15° C. to 30° C. Unless otherwise specified, % refers to % by mass.

[0062] [Evaluation Example 1] Evaluation of viscosity of gel particles After preparing 10 mg / mL, 20 mg / mL, 50 mg / mL, or 100 mg / mL gelatin aqueous solutions, the gelatin was allowed to swell in water for 1 hour. After swelling, the gelatin in each gelatin aqueous solution was dissolved in a 60°C water bath. After dissolving the gelatin, each gelatin aqueous solution was returned to room temperature to initiate gelation. 48 hours after the start of gelation, the viscosity of each gelled solution was measured. The viscosity measurement conditions are as follows:

[0063] <Viscosity measurement conditions> Measurement equipment: Brookfield rotational viscometer (manufactured by Eiko Seiki Co., Ltd.) ·Measurement temperature 20℃ (water bath) Measurement speed: 1.5 rpm, 6 rpm or 60 rpm

[0064] The viscosity of each gelled aqueous gelatin solution was measured and the results are shown in Table 1.

[0065] [Table 1]

[0066] In Table 1, "cP" is the unit of viscosity, where 1 cP = 1 mPa·s. "%" indicates the torque value. A value within the range of 10 to 100% indicates that the measured value is accurate.

[0067] In Table 1, "NA" indicates that the spindle combination was poor and data could not be obtained. "ERROR" indicates that the viscosity of the gelatin solution was too high and measurement was not possible with the current spindle.

[0068] As shown in Table 1, gels were formed at 20°C in 50 mg / mL and 100 mg / mL gelatin aqueous solutions, demonstrating their suitability for the production of composite particles for delivery. Note that the viscosity shown in the 100 mg / mL measurement results is the viscosity calculated from the spindle and rotation speed.

[0069] <Evaluation Example 2> Evaluation of the mechanical strength of composite particles for delivery Gelatin was used as a gelling agent. Gelatin was weighed out so that the gelatin concentration was 10% by mass, and MilliQ water was added to prepare a gelatin aqueous solution. This gelatin aqueous solution corresponds to a 100 mg / mL gelatin aqueous solution. After preparing the gelatin aqueous solution, the gelatin was swollen in MilliQ water for 1 hour. After swelling, the gelatin in the gelatin aqueous solution was dissolved in a water bath at 60°C.

[0070] Silica particles (manufactured by Fuji Silysia Chemical Ltd.) were placed on a metal plate, which was then tilted and fixed. A droplet of a 60°C gelatin aqueous solution was then dropped onto the surface on which the hydrophobic silica particles were placed. The dropped droplet slid down the inclined surface, producing a composite particle precursor in which the droplet was coated with hydrophobic silica particles. The prepared composite particle precursor was returned to room temperature to initiate gelation, and left to stand for 48 hours to obtain composite particle 1. Control composite particles were also prepared to which no gelling agent was added.

[0071] The mechanical strength of Composite Particle 1 was confirmed immediately after the start of gelation and after being left to stand for 48 hours. Immediately after the start of gelation, both the control composite particle and Composite Particle 1 were so strong that they would be crushed if pinched firmly with the fingers. After being left to stand for 48 hours, the control composite particle broke when picked up with tweezers, while Composite Particle 1 could be pinched with tweezers, as shown in Figure 1, demonstrating its high mechanical strength.

[0072] <Evaluation Example 3> Preparation of composite particles for delivery Gelatin was used as a gel-forming agent. Gelatin was weighed out to be 10% by mass, and MilliQ water was added to prepare a gelatin aqueous solution. After preparing the gelatin aqueous solution, the gelatin was swollen in water for 1 hour. After swelling, the gelatin in the gelatin aqueous solution was dissolved in a water bath at 60°C. After dissolution of the gelatin, a blue dye (BCG: Bromocresol Green) or a red dye (Eosin Yellow) was added to the gelatin aqueous solution as a delivery target to be 0.1% by mass, thereby preparing a gel particle preparation solution.

[0073] As in Evaluation Example 2, a composite particle precursor for delivery was prepared by tilting the metal plate on which the hydrophobic silica particles were arranged and dripping droplets of the gel particle preparation solution at 60°C onto the surface on which the hydrophobic silica particles were arranged. The prepared composite particle precursor for delivery was returned to room temperature to initiate gelation, and left to stand for 48 hours to obtain composite particles for delivery.

[0074] The observation results of the composite particle for delivery after standing for 48 hours are shown in Figure 2 (blue dye) and Figure 3 (red dye). The upper figures in Figures 2 and 3 show the observation results of the composite particle for delivery after standing for 48 hours, and the lower figures show cross-sectional views of the composite particle for delivery after standing for 48 hours.

[0075] As shown in Figures 2 and 3, it was confirmed that the dye, which is the target substance for delivery, is encapsulated in the composite particles for delivery. [Industrial Applicability]

[0076] The composite particle for delivery according to one embodiment of the present invention has high mechanical strength and can therefore be used in pharmaceuticals, supplements, regenerative medicine products, and the like.

Claims

1. Gel particles containing a substance to be delivered; and hydrophobic particles that coat the gel particles, The composite particle for delivery, wherein the viscosity of the gel particle at 20°C is 4500 mPa·s or more.

2. The composite particle for delivery according to claim 1 , wherein the gel particles are physically crosslinked gel particles.

3. The composite particle for delivery according to claim 1 , wherein the gel particle comprises gelatin or collagen.

4. The composite particle for delivery according to claim 3 , wherein the concentration of the gelatin or collagen is 3% by mass or more relative to 100% by mass of the gel particle.

5. The composite particle for delivery according to claim 1 , wherein the hydrophobic particle is a silica particle.

6. a preparation step of adding a delivery target to a solution containing a gelling agent to prepare a gel particle preparation solution; a coating step of coating the surfaces of droplets of the gel particle preparation solution with hydrophobic particles and then gelling the droplets, or gelling the droplets of the gel particle preparation solution to obtain gel particles and then coating the surfaces of the gel particles with hydrophobic particles.

7. The method according to claim 6, wherein the viscosity of the gel particles at 20°C is 4500 mPa·s or more.

8. A production kit for producing the composite particle for delivery according to any one of claims 1 to 5, which contains hydrophobic particles.

9. The manufacturing kit according to claim 8 , further comprising a gelling agent.

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