JP2009162537A - Composite particle having polysaccharide on surface, composite particle colloid, analytical reagent using the same, and composite particle manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide composite particles, polysaccharide modifying composite particles having biomolecules on their particle surfaces, capable of preventing the occurrence of nonspecific adsorption except the occurrence of the specific bonding of the intended biomolecules and preventing the occurrence of aggregation in the process of surface treatments and thereafter when the composite particles are manufactured and having high dispersion stability, to provide a composite particle colloid, to provide an analytical reagent having excellent reproducibility of measurement results, high reliability, and a high signal-to-noise ratio, to provide a composite particle manufacturing method capable of being executed through the use of a general-purpose experimental apparatus at normal temperatures and normal pressures without requiring any special apparatus such as a high-pressure homogenizer, and to provide a silica composite particle manufacturing method capable of preventing the occurrence of nonspecific adsorption and having excellent dispersion stability. <P>SOLUTION: In silica particle/polysaccharide/biomolecule composite particles, polysaccharide is adsorbed to the surfaces of silica particles, and biomolecules are adsorbed or covalently bonded to the surfaces of the silica particles and the outside of the polysaccharide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composite particle having a high dispersion stability obtained by adsorbing a polysaccharide on the particle surface, a composite particle colloid, an analytical reagent using the composite particle, and a method for producing the composite particle. Furthermore, the present invention relates to composite particles, composite particle colloids, analytical reagents using the same, and methods for producing composite particles that prevent the occurrence of non-specific adsorption other than the specific binding of the intended biomolecules.

In recent years, fine particles of about several nm to 1 μm have been applied to various fields and attracted attention. For example, porous silica particles and zeolite particles used for adsorbents and catalysts, carbon black used for pigments, metal oxide particles, inorganic compound particles, metal nanoparticles used for conductive materials, and resin reinforcing agents. There are a wide variety of materials and applications of particles such as silica particles. Further, semiconductor nanoparticles and silica particles encapsulating a fluorescent substance are expected to be applied to fluorescent reagents as new fluorescent labeling agents, particularly in the bio field. In addition, silica particles encapsulating a dye at a high concentration have a high molar extinction coefficient, and are expected to be applied to highly sensitive coloring reagents.
Labeling reagents such as fluorescent reagents and coloring reagents are those in which proteins and DNA are bound to the surfaces of fluorescent particles or coloring particles, and the interaction of these proteins and DNA with specific biomolecules enables detection of biomolecules, It is used for quantification and staining.
In order to use fluorescent particles or colored particles as labeling reagents, surface modification that satisfies the following problems is required.
(1) Introduction of functional groups for binding biomolecules (2) Stabilization of dispersion in buffer (3) Prevention of non-specific adsorption

Hereinafter, the problems (1) to (3) will be specifically described.
(1) Introduction of functional group for binding biomolecules In order to integrate silica particles and biomolecules to function stably, it is necessary to bind the silica particles and biomolecules irreversibly. For this purpose, it is necessary to covalently bond silica particles and biomolecules, not ionic bonds or physicochemical adsorption.
Protein has an amino group, a carboxyl group, a thiol group, and the like. In addition, DNA can be given an amino group or a thiol group by terminal modification. Therefore, if an amino group, a carboxyl group, a thiol group or the like is introduced into the silica particles, it is possible to covalently bond the silica particles and the biomolecules using a crosslinking agent or a condensing agent.
(2) Dispersion stabilization in a buffer solution The DLVO theory is known as a modeled representation of attractive and repulsive forces that act on the aggregation and dispersion of particles. This explains the agglomeration / dispersion of particles by electrostatic repulsive force and van der Waals force between particles (for example, see Non-Patent Document 1).
Biomolecules are often used in an aqueous solution having a high ion concentration such as physiological saline. In an aqueous solution with a high ion concentration, the ions weaken the electrostatic repulsion of the silica particles due to the shielding effect, so that the particles tend to aggregate. In order to stably disperse particles even in an aqueous solution having a high ion concentration, it is necessary to apply a repulsive force other than an electrostatic repulsive force.
There is a solid repulsive force that acts as a repulsive force between particles in addition to the electrostatic repulsive force. This works as a repulsive force between particles by repelling molecular chains with degrees of freedom. Therefore, the dispersion stability of the particles can be improved by introducing molecular chains having a high degree of freedom into the particle surface.
(3) Prevention of non-specific adsorption In order for labeled particles such as fluorescent particles to function as a fluorescent reagent, biomolecules bound to labeled particles such as fluorescent particles selectively bind to the target by specific binding or the like. It is necessary. If non-specific binding to a biomolecule other than the target or adsorption to the substrate occurs, the sensitivity, accuracy, and reliability of the measurement will decrease accordingly.
In order to reduce non-specific adsorption, it is necessary to impart steric repulsion as well as improvement in dispersion stability.

From the above viewpoint, surface modification is required for application of labeled particles such as fluorescent particles. Particle surface modification methods include silane coating with a silane coupling agent, incorporation into polymer beads, entrapment in lipid bilayers, and attachment of small molecules via thiol groups. It is known (for example, see Patent Documents 1 to 3). However, the method of coating with a silane coupling agent is limited to applicable particles such as inorganic particles, metal particles, and silica particles. In addition, sufficient dispersion stability cannot be obtained simply by coating with silane. It is. The method of incorporating the polymer beads is costly and has a problem that the particle size increases. Although the method of encapsulating in a lipid bilayer has high dispersion stability in water, the lipid bilayer itself is unstable, and thus has a problem in terms of long-term dispersion stability. Also regarding the method of binding a small molecule through a thiol group, applicable particles are limited to metals.
In addition, the inventors have filed a patent application regarding a surface modification method in which a cationic polymer and an anionic polymer are alternately laminated on the particle surface using electrostatic attraction (Japanese Patent Application No. 2007-64205).
Fumio Kitahara, Kunio Furusawa, Masataka Ozaki, Hiroyuki Oshima, “Zeta Potential Zeta Potential: Physical Chemistry of Fine Particle Interfaces”, Scientist, 1995 JP 2003-11505 A JP 2004-77389 A JP 2006-131771 A

In view of the above problems, an object of the present invention is a polysaccharide-modified composite particle having a biomolecule on the particle surface, preventing the occurrence of nonspecific adsorption other than the specific binding of the intended biomolecule, It is an object of the present invention to provide a composite particle and a composite particle colloid having a high dispersion stability without agglomeration during the surface treatment process during the production of the composite particle and thereafter.
Another object of the present invention is to provide an analytical reagent having excellent reproducibility of measurement results, high reliability, and a high signal / noise ratio. Another object of the present invention is to provide a method for producing composite particles that does not require a special apparatus such as a high-pressure homogenizer, and can be performed using a general-purpose experimental apparatus at normal temperature and normal pressure.
Furthermore, an object of the present invention is to provide a method for producing composite particles that prevents the occurrence of non-specific adsorption and has excellent dispersion stability.

The above problems have been achieved by the following means.
(1) A silica particle / polysaccharide / biomolecule composite particle in which a polysaccharide is adsorbed on the surface of a silica particle and a biomolecule is adsorbed or covalently bonded to the surface of the silica particle and the outside of the polysaccharide;
(2) The biomolecule is at least one selected from the group consisting of antigens, antibodies, DNA, RNA, sugars, sugar chains, ligands, receptors, peptides, and chemical substances (1) Composite particles according to
(3) The composite particles according to (1) or (2), wherein the silica particles have an average particle diameter of 1 nm to 1 μm, and the polysaccharide has a weight average molecular weight of 1,000 to 1,000,000.
(4) The composite particles according to any one of (1) to (3), wherein the absolute value of ζ potential in pure water at pH 7 is 1 to 70 mV,
(5) The composite particle according to any one of (1) to (4), wherein the polysaccharide is alginic acid or dextran,
(6) A composite particle colloid in which the composite particles of silica particles / polysaccharide / biomolecule according to any one of (1) to (5) are dispersed in a dispersion medium,
(7) The composite particle colloid according to (6), wherein the dispersion medium is a buffer solution,
(8) An analytical reagent using the composite particle colloid according to (6) or (7),

(9) Silica having a step of producing silica particles / polysaccharide composite particles in which the polysaccharide is adsorbed on the surface of the silica particles by mixing silica particles and polysaccharide in a basic solution. Production method of particle / polysaccharide / biomolecule composite particle (10) The production method according to (9), wherein the basic solution is an aqueous ammonia solution,
(11) Adsorption or covalent bond formation between the surface of the silica particles and the polysaccharide and the biomolecule is carried out in the presence or absence of a condensing agent or a crosslinking agent in the composite particles of the silica particles / polysaccharide. The method for producing a composite particle of silica particles / polysaccharide / biomolecule according to (9) or (10), which is performed by mixing a colloid and a solution of the biomolecule,
(12) The method for producing composite particles of silica particles / polysaccharide / biomolecule according to any one of (9) to (11), wherein the polysaccharide is alginic acid or dextran,

(13) Silica particles / polysaccharides / polysaccharide / polysaccharide adsorbed on the surface of silica particles having an average particle diameter of 1 nm to 1 μm, and further biomolecules adsorbed or covalently bonded to the surface of the silica particles and to the outside of the polysaccharide A biomolecule composite particle, wherein the biomolecule is at least one selected from the group consisting of antigen, antibody, DNA, RNA, sugar, sugar chain, ligand, receptor, peptide, and chemical substance; Composite particles, wherein the polysaccharide is alginic acid or dextran,
(14) A composite particle colloid obtained by dispersing the composite particles according to (13) in a dispersion medium,
(15) An analytical reagent using the composite particle colloid according to (14),
(16) 0.01% by mass to 1% by mass of a colloid in which silica particles having an average particle diameter of 1 nm to 1 μm are dispersed and 0.5 parts by mass or more of alginic acid or dextran with respect to 100 parts by mass of the silica particles. A silica particle / polysaccharide / biomolecule composite particle comprising a step of producing a silica particle / polysaccharide composite particle mixed in an aqueous ammonia solution and adsorbing the alginic acid or dextran on the surface of the silica particle And (17) providing silica particles / polysaccharide composite particles in which polysaccharides are adsorbed on the surface of silica particles.

Since the composite particles of the present invention are formed by adsorbing polysaccharides on the surface of silica particles, the dispersion stability of the composite particles can be improved by the protective colloid action of the polysaccharides.
The composite particle of the present invention prevents nonspecific adsorption by a low molecular weight compound or a high molecular compound, nonspecific adsorption to a substrate or a container, has excellent dispersion stability, and has high ionic strength such as physiological saline. Aggregation hardly occurs even in colloids.
Here, “non-specific adsorption” refers to adsorption that does not follow rules other than specifically binding to a specific functional group or ligand, and refers to an adsorption phenomenon other than intended.

Since the composite particle colloid of the present invention uses the composite particle, it prevents nonspecific adsorption other than the specific binding of the intended biomolecule, has excellent dispersion stability, and has high ionic strength such as physiological saline. Aggregation hardly occurs even with water-dispersed colloids.
The analytical reagent of the present invention uses the composite particle colloid that prevents non-specific adsorption other than the specific binding of the intended biomolecule and has excellent dispersion stability, so that the measurement results are highly reproducible and reliable. Highly sensitive analysis of extremely small target samples with high signal / noise ratio is possible.
The method for producing composite particles of the present invention can be carried out at room temperature and normal pressure, and can carry out surface adsorption of polysaccharides without using special equipment such as a high-pressure homogenizer or chemicals. In addition, since surface treatment of the silica particles is enhanced by performing the surface treatment under basic conditions, the polysaccharide can be adsorbed on the surface of the silica particles even if the polysaccharide has no charge.
The method for producing composite particles of the present invention can provide composite particles that hardly cause aggregation even in an aqueous dispersion having high ionic strength such as physiological saline. Moreover, the composite particle which can suppress the nonspecific adsorption | suction of the low molecular compound and high molecular compound with respect to particle | grains and the nonspecific adsorption | suction with respect to the board | substrate and container of particle | grains can be provided. Furthermore, functional groups for the adsorption or binding of biomolecules can also be introduced.

First, the silica particle / polysaccharide / biomolecule composite particle of the present invention will be described.
The composite particle of silica particles / polysaccharide / biomolecule of the present invention is formed by adsorbing polysaccharide on the surface of the silica particle and further adsorbing or covalently bonding the biomolecule on the surface of the silica particle and outside of the polysaccharide.
In the present invention, “adsorption” means chemical or physical bonding based on the affinity between silicon atom and oxygen atom, electrostatic attraction (Coulomb force acting between positive and negative charges), van der Waals force or hydrophobicity. This refers to integration through sexual interaction.
In the present invention, the silica particles used are not particularly limited, and may be silica particles obtained by any arbitrary preparation method. Examples thereof include silica particles prepared by the sol-gel method described in Journal of Colloid and Interface Science, 159, 150-157 (1993).

It is particularly preferred to use silica particles containing a functional compound obtained according to the method for preparing fluorescent dye compound-containing colloidal silica particles described in International Publication No. 2007 / 074722A1.
Here, specific examples of the functional compound include fluorescent dye compounds, light absorbing compounds, magnetic compounds, radiolabeled compounds, pH sensitive dye compounds, and the like.
Specifically, the silica particle containing the functional compound is a product obtained by reacting the functional compound with a silane coupling agent, and covalently bonding, ionic bonding, or other chemical bonding or adsorption. It can be prepared by condensation-polymerizing one or two or more silane compounds to form a siloxane bond. As a result, silica particles in which the organosiloxane component and the siloxane component are bonded by siloxane are obtained.
Preferred embodiments of the method for preparing silica particles containing the functional compound include N-hydroxysuccinimide (NHS) ester group, maleimide group, isocyanate group, isothiocyanate group, aldehyde group, paranitrophenyl group, diethoxy. The functional compound having an active group such as a methyl group, an epoxy group, or a cyano group, and a silane coupling agent having a substituent (for example, an amino group, a hydroxyl group, or a thiol group) that reacts with the active group. The product obtained by reacting and covalently bonding can be prepared by polycondensing one or more silane compounds to form a siloxane bond. The case where APS is used as the silane coupling agent and TEOS is used as the silane compound is illustrated below.

  Specific examples of the functional compound having the active group include 5- (and -6) -carboxytetramethylrhodamine-NHS ester (trade name, manufactured by emp Biotech GmbH), DY550-NHS represented by the following formulae, respectively. Examples thereof include fluorescent dye compounds having an NHS ester group such as ester or DY630-NHS ester (both trade names, manufactured by Dynamics GmbH).

  Specific examples of the silane coupling agent having a substituent include γ-aminopropyltriethoxysilane (APS), 3- [2- (2-aminoethylamino) ethylamino] propyl-triethoxysilane, N-2 ( Examples thereof include silane coupling agents having an amino group such as (aminoethyl) 3-aminopropylmethyldimethoxysilane and 3-aminopropyltrimethoxysilane. Of these, APS is preferable.

  The silane compound to be polycondensed is not particularly limited, but includes tetraethoxysilane (TEOS), γ-mercaptopropyltrimethoxysilane (MPS), γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane ( APS), 3-thiocyanatopropyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3- [2- (2-aminoethylamino) ethylamino] propyl-tri Mention may be made of ethoxysilane. Among these, TEOS is preferable from the viewpoint of forming the siloxane component inside the silica particles, and MPS or APS is preferable from the viewpoint of forming the organosiloxane component inside the silica particles.

When prepared as described above, spherical or nearly spherical silica particles can be produced. The nearly spherical silica particles specifically have a shape in which the ratio of the major axis to the minor axis is 2 or less.
In order to obtain silica particles having a desired average particle size, ultrafiltration is performed using an ultrafiltration membrane such as YM-10, YM-100 (both trade names, manufactured by Millipore), and the particle size is large. It is possible to remove particles that are too small or too small, or to centrifuge at an appropriate gravitational acceleration and collect only the supernatant or precipitate.

The polysaccharide used in the present invention is an anionic polysaccharide or a charge-neutral polysaccharide from the viewpoint of keeping negative the zeta potential of the resulting silica particles / polysaccharide composite particles and silica particle / polysaccharide / biomolecule composite particles. It is preferable.
The anionic polysaccharide and the charge-neutral polysaccharide are not particularly limited, and examples include alginic acid, dextran, hyaluronic acid, cellulose, heparin, and the like. Among them, the anionic polysaccharide is alginic acid. Preferably, the neutral polysaccharide is preferably dextran. The molecular weight of these polysaccharides is not particularly limited, but is preferably 1,000 to 1,000,000, more preferably 20,000 to 100,000 (in the present invention, unless otherwise specified, the molecular weight is the weight average molecular weight). The polymer compound is a polydisperse system and does not necessarily have the same molecular weight or particle weight, so the value obtained by measuring the molecular weight is the average molecular weight averaged in some form. There are the following three types: 1) number average molecular weight Mn, 2) weight average molecular weight Mw, 3) Z average molecular weight Mz, and a relationship of Mn <Mw <Mz is established. ).

Examples of biomolecules that are adsorbed or covalently bonded to the outside of the polysaccharide include antigens, antibodies, DNA, RNA, sugars, sugar chains, ligands, receptors, peptides, and chemical substances.
Here, a ligand refers to a substance that specifically binds to a protein, such as a substrate that binds to an enzyme, a coenzyme, a regulatory factor, a hormone, or a neurotransmitter, as well as a low molecular weight molecule or ion. Also includes high molecular weight materials.
The chemical substances are not limited to natural organic compounds, but include artificially synthesized physiologically active compounds and environmental hormones.

In this invention, it is preferable that the average particle diameter of the said silica particle to be used is 1 nm-1 micrometer, and it is more preferable that it is 20 nm-500 nm.
The average particle size of the composite particles of the present invention is not particularly limited, but is preferably 1 nm to 1 μm.
In the present invention, the average particle size is calculated from the total projected area of 50 silica particles or composite particles randomly selected from an image such as a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Alternatively, the area occupied by the composite particles is obtained by an image processing apparatus, and the average value of the diameters of the circles corresponding to the value obtained by dividing the total occupied area by the number of selected silica particles or composite particles (50 particles) (corresponding to the average circle) (Diameter).
The average particle diameter is an average particle diameter of particles composed of only primary particles, unlike the “particle size by dynamic light scattering method” described later, which is a concept including secondary particles formed by aggregation of primary particles.

In the present invention, the “particle size by the dynamic light scattering method” of the composite particles is measured by the dynamic light scattering method, and unlike the average particle size, not only the primary particles but also the primary particles are aggregated. This is a concept including the secondary particles, and serves as an index for evaluating the dispersion stability of the composite particles.
An example of the measuring device is Zetasizer Nano (trade name; manufactured by Malvern). This method measures the time fluctuation of the light scattering intensity by the light scatterer such as fine particles, calculates the Brownian motion velocity of the light scatterer from the autocorrelation function, and derives the particle size distribution of the light scatterer from the result. Is.
The variation coefficient of the particle size distribution, the so-called CV value, is not particularly limited, but is preferably 10% or less, more preferably 8% or less.
In the present specification and claims, monodisperse means a particle group having a CV value of 15% or less.

Next, the ζ potential of the composite particles of the present invention will be described.
Charge separation occurs at the interface when the dispersion medium comes into contact with the colloidal particles moving relative to the dispersion medium. At this time, ions having a sign opposite to that of the particles gather on the particle surface to form a layer. This is called an electric double layer. In a region close enough to the particle surface, ions with opposite charges are strongly attracted to the surface and have no mobility, so they are called stationary phases. The ions outside it have mobility and are called diffusion layers. The contact surface between the fixed layer and the diffusion layer is called a sliding surface. The potential of the sliding surface when the potential in a region where the charge is sufficiently far away from the particle is defined as zero is ζ potential (hereinafter sometimes simply referred to as “zeta potential”). Electric potential.
The zeta potential is an index for evaluating the dispersion stability, cohesiveness, surface modification and the like of colloidal particles. That is, since the colloidal particles are charged and the magnitude of the electrostatic repulsion due to the charging corresponds to the magnitude of the absolute value of the zeta potential, the magnitude of the absolute value of the zeta potential is It is an index of the dispersion stability of particles (see, for example, Fumio Kitahara, Kunio Furusawa, Masataka Ozaki, Hiroyuki Oshima, “Zeta Potential Zeta Potential: Physical Chemistry of Fine Particle Interface”, Scientist, 1995).
Further, when the colloidal particles are negatively charged, the zeta potential becomes a negative value, while when the colloidal particles are positively charged, the zeta potential becomes a positive value.
The composite particles of the present invention preferably have an absolute value of ζ potential in pure water of pH 7 of 1 to 70 mV, and more preferably 45 to 55 mV.
If the absolute value is too small, aggregates are easily formed. If the absolute value is too large, nonspecific adsorption increases due to electrostatic interaction.
As the zeta potential measuring device, Zetasizer Nano (trade name, manufactured by Malvern), ELS-Z1 (trade name, manufactured by Otsuka Electronics Co., Ltd.), NICOMP 380ZLS (trade name, manufactured by IBC) and the like can be used.

Next, the composite particle colloid of the present invention will be described.
The composite particle colloid of the present invention is obtained by dispersing the composite particles of the present invention in a dispersion medium.
The dispersion medium for the composite particle colloid is not particularly limited as long as it uniformly disperses the composite particles, and is preferably a hydrophilic solvent, for example, water, methanol, ethanol, a mixed solvent of water and methanol, Buffers such as a mixed solvent of water and ethanol, PBS (phosphate buffered saline), Tris buffer, HEPES buffer and the like can be mentioned.
Even in the case of using the composite particles of the present invention in a buffer solution such as PBS (phosphate buffered saline), Tris buffer solution, HEPES buffer solution containing negative ionic species with high adsorptivity, The ionic species are adsorbed to the composite particles by electrostatic attraction, the electrostatic repulsive force is weakened, and the composite particles do not aggregate.
The composite particle colloid of the present invention may contain an arbitrary blocking agent such as polyethylene glycol (PEG) and serum albumin (BSA) from the viewpoint of further preventing the above-mentioned non-specific adsorption.

Next, the analysis reagent of the present invention will be described.
The analytical reagent of the present invention is achieved by using the composite particle colloid and imparting a label such as fluorescence, light absorption, magnetism, radiation, pH sensitivity to the composite particle contained in the composite particle colloid. . As a method for imparting the label to the composite particles, as described above, silica particles containing the functional compound such as a fluorescent dye compound, a light absorbing compound, a magnetic compound, a radiolabeled compound, and a pH sensitive dye compound are used. Examples include a method for producing the composite particles.
Specific examples of the analysis reagent of the present invention include a biomolecule detection reagent, a biomolecule quantification reagent, a biomolecule separation reagent, a biomolecule recovery reagent, or an immunostaining reagent.
The composite particles contained in the composite particle colloid of the present invention can target biomolecules or bioactive substances that recognize the biomolecules, and detect and quantify the target biomolecules or bioactive substances. It can be an analytical reagent to be separated or recovered. When the molecular recognition between the biomolecule and the target biomolecule or physiologically active substance is an antigen-antibody reaction, an immunostaining reagent using the composite particle colloid can be used.
Here, molecular recognition refers to (1) hybridization between DNA molecules or DNA-RNA molecules, (2) antigen-antibody reaction, (3) reaction between enzyme (receptor) and substrate (ligand), etc. A specific interaction between molecules.

Next, the manufacturing method of the composite particle of this invention is demonstrated.
The method for producing a composite particle of silica particles / polysaccharide / biomolecule of the present invention is a silica particle / polysaccharide formed by adsorbing the polysaccharide on the surface of the silica particle by mixing the silica particle and the polysaccharide in a basic solution. And a step of producing the composite particles (hereinafter simply referred to as “step of adsorbing the polysaccharide on the surface of the silica particles”).
In the method for producing composite particles of the present invention, the silica particles to be used are preferably silica particles obtained by an arbitrary preparation method such as the sol-gel method described above, and as described above, in International Publication No. 2007 / 074722A1. Silica particles containing a functional compound obtained according to the described preparation method are particularly preferred. Preferred specific examples, molecular weights, etc. of the polysaccharide are as described above.
In the method for producing composite particles of the present invention, the basic solution is not particularly limited as long as it contains a basic substance, and examples thereof include ammonia water, an aqueous sodium hydroxide solution, and an aqueous potassium hydroxide solution.
The concentration of the basic substance in the mixed solution in the step of adsorbing the polysaccharide on the surface of the silica particles is preferably 0.01% by mass to 5% by mass when the basic substance is ammonia. More preferably, the content is 1% by mass to 1% by mass. When the basic substance is sodium hydroxide or potassium hydroxide, it is preferably 0.001% by mass to 0.5% by mass, and more preferably 0.01% by mass to 0.1% by mass. .

Although the reason why the polysaccharide is adsorbed on the surface of the silica particles is not clear, the basic solution dissociates part of the siloxane bonds existing on the surface of the silica particles and activates the surface of the silica particles, and the oxygen atoms of the polysaccharide It is considered that the activated silicon atoms on the surface of the silica particles cause adsorption or bonding.
In the method for producing composite particles of the present invention, the amount of the polysaccharide to be mixed with the silica particles is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the silica particles, and with respect to 100 parts by mass of the silica particles. 1 to 50 parts by mass is more preferable, and 5 to 20 parts by mass is more preferable.
Further, the concentration of the silica particles in the mixed solution in the step of adsorbing the polysaccharide on the surface of the silica particles is not particularly limited as long as the concentration of the particles is stably dispersed, but may be 10% by mass or less. Preferably, it is 0.2-5 mass%.
In the step of adsorbing the polysaccharide on the surface of the silica particles, the mixing time when the silica particles and the polysaccharide are mixed under basic conditions is preferably 15 minutes to 24 hours per mixing operation. The temperature of the mixed solution during mixing is preferably 0 ° C to 60 ° C.
After the adsorption reaction, the particles can be separated from the polysaccharide not adsorbed on the silica particles by centrifugation or ultrafiltration.
To confirm whether the polysaccharide has been adsorbed or not, measure the solution obtained by removing particles from the mixture by centrifugation or ultrafiltration using HPLC (high performance liquid chromatography), and quantify the decrease in the polysaccharide. Can be done. The column and detector used for HPLC are not particularly limited, but TSKgel G3000PWXL (manufactured by Tosoh Corporation) can be used as the column, and Shodex RI SE-61 (manufactured by Showa Denko) can be used as the detector.

In the step of adsorbing the polysaccharide on the surface of the silica particles, the procedure for mixing the colloid of the silica particles, the polysaccharide, and the basic solution is not particularly limited, and the polysaccharide is mixed with the colloid of the silica particles. The basic solution may be mixed, the colloid of silica particles may be mixed with the basic solution, and then the polysaccharide may be mixed, or the mixed solution of the polysaccharide and the basic solution may be mixed with the basic solution. It may be added to the colloid of silica particles.
Further, in the step of adsorbing the polysaccharide on the surface of the silica particles, after mixing the colloid of silica particles, the polysaccharide and the basic solution, the mixture is centrifuged to precipitate the silica particles, A step of removing the clear liquid, adding a dispersion medium, a polysaccharide and a basic solution thereto and mixing them again may be included. The step of centrifuging the mixed solution to precipitate the silica particles, removing the supernatant, adding the dispersion medium, polysaccharide and basic solution thereto and mixing again may be repeated a plurality of times.

  In the present invention, it is possible to introduce a functional group to the surface of the composite particle of silica particles / polysaccharide by adsorbing the polysaccharide on the surface of the silica particles. For example, by adsorbing alginic acid or hyaluronic acid, a carboxyl group is introduced on the surface of the composite particle of silica particles / polysaccharide, and by adsorbing dextran or cellulose, the surface of the composite particle of silica particle / polysaccharide is adsorbed. A hydroxyl group is introduced. Utilizing these functional groups, covalent bonds can be formed between the composite particles and the biomolecules in the presence of a condensing agent or a crosslinking agent.

In the method for producing a composite particle of silica particles / polysaccharide / biomolecule of the present invention, the surface of the silica particle and / or the polysaccharide and the biomolecule may be complexed in the presence or absence of a condensing agent or a crosslinking agent. It is preferably carried out by mixing a colloid of the composite particles of silica particles / polysaccharide and a solution of the biomolecule below.
Here, “composite” refers to integration by adsorption or covalent bond formation.
Specifically, by mixing the colloid of the composite particles of silica particles / polysaccharide and the solution of the biomolecules in the absence of a condensing agent or the like, the biomolecules can be obtained on the surface of the silica particles and / or It can be adsorbed with the polysaccharide.
Further, the biomolecule can be covalently bonded to the functional group of the polysaccharide directly by a condensing agent or via a crosslinking agent.
Specific examples of the condensing agent or cross-linking agent used include N- (6-maleimidocaproyloxy) succinimide (EMCS), glutaraldehyde, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC) and the like. Can be mentioned.
There are no particular restrictions on the reaction conditions such as the number of equivalents of the condensing agent or cross-linking agent used for conjugation, the type of colloidal dispersion medium, the type and volume of the solvent of the biomolecule solution, and the reaction temperature. Absent.
After the complexing, separation of the composite particles and the biomolecules that are not complexed with the silica particles can be performed by centrifugation or ultrafiltration.
After complexing the surface of the silica particles and the polysaccharide and the biomolecule, from the viewpoint of further preventing the above-mentioned non-specific adsorption, a blocking treatment such as PEG or BSA may be performed. Good.
Whether or not the biomolecules are complexed can be confirmed by analyzing the biomolecules contained in the solution obtained by removing particles from the mixed solution by centrifugation or ultrafiltration using a general protein quantification method (for example, UV method, Lowry method). , Bradford method), and the amount of the reduced biomolecule can be quantified.

Hereinafter, the present invention will be described in more detail based on examples. The present invention is not limited to these examples. Unless otherwise specified, in the following examples, “part” represents “part by mass”, “%” represents “mass%”, and “molecular weight” represents “weight average molecular weight”.
Reference Example (Preparation of silica particles used for production of composite particles of the present invention)
5.8 mg of 5- (and -6) -carboxytetramethylrhodamine succinimidyl ester (trade name, manufactured by emp Biotech GmbH) was dissolved in 1 ml of dimethylformamide (DMF). 2.6 μl of APS was added thereto and reacted at room temperature (23 ° C.) for 1 hour.
Ethanol 44.8 ml, TEOS 360 μl, distilled water 11.2 ml and 28% by mass ammonia water 800 μl were added to 150 μl of the obtained reaction solution, and the reaction was performed at room temperature for 24 hours.
The reaction solution was centrifuged for 30 minutes at a gravitational acceleration of 18000 × g, and the supernatant was removed. 4 ml of distilled water was added to the precipitated silica particles to disperse the particles, and the mixture was again centrifuged for 30 minutes at a gravitational acceleration of 18000 × g. This washing operation was further repeated twice to remove unreacted TEOS, ammonia and the like contained in the labeled silica nanoparticle dispersion, thereby obtaining 27.9 mg of silica particles having an average particle diameter of 26 nm. Yield about 31%.
FIG. 5 is a view showing an SEM photograph image of the obtained rhodamine-containing silica particles. In the figure, the spherical substance that appears white is the obtained rhodamine-containing silica particles.

Example 1 (Adsorption of alginic acid on the surface of rhodamine-containing silica particles)
In a 300 μl dispersion (dispersion medium distilled water) of rhodamine-containing silica particles (average particle size 26 nm) having a concentration of 33.4 mg / ml obtained by the same method as in the reference example, 590 μl of distilled water and a concentration of 10 mg / ml 100 μl of a sodium alginate aqueous solution (weight average molecular weight 70000) was added and well stirred with a stir bar. Subsequently, 10 μl of 1 M sodium hydroxide aqueous solution was added, and the colloid was stirred at room temperature (23 ° C.) for 1 hour. The resulting colloid was centrifuged for 30 minutes at a gravitational acceleration of 15,000 × G, and the supernatant was removed. 890 μl of distilled water was added thereto to redisperse the particles. Subsequently, 100 μl of 10 mg / ml sodium alginate aqueous solution was added and stirred well with a stir bar, then 10 μl of 1M sodium hydroxide aqueous solution was added and stirred for 1 hour. The colloid was centrifuged for 30 minutes at a gravitational acceleration of 15,000 × G. After removing the supernatant, 1 ml of distilled water was added to disperse the particles. Similarly, centrifugal separation twice and dispersion in distilled water were repeated to wash the particles, and the particles were dispersed in 1 ml of distilled water to obtain a colloid of rhodamine-containing silica particles / alginic acid composite particles (average particle size 26 nm) ( Yield 10.0 mg / ml x 1 ml).
(Dispersion stability test)
50 μl of the obtained colloid was put into a cuvette, and 850 μl of distilled water and 100 μl of 50 mM KH ₂ PO ₄ aqueous solution (pH 7.0) were further added. 100 μl of 10% by weight NaCl aqueous solution was added to this mixed solution, mixed lightly with a pipette, and allowed to stand at room temperature, and the time-dependent change in particle size distribution was measured by a dynamic light scattering method (Zetasizer Nano, manufactured by Malvern). ).
FIG. 1 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginic acid composite particles. The horizontal axis represents the particle size (nm) by the dynamic light scattering method, and the vertical axis represents the ratio (%) of the number of particles in each particle size. The same applies hereinafter.
As is apparent from FIG. 1, the particle size distribution of the colloid of rhodamine-containing silica particles / alginic acid composite particles hardly changed even after 24 hours. From this, it can be seen that the composite particles of the present invention are excellent in dispersion stability without forming a secondary particle and aggregating even in a dispersion medium containing a salt.

Example 2 (Adsorption of alginic acid on the surface of rhodamine-containing silica particles)
1 ml of a 10 mg / ml aqueous sodium alginate solution was added to 8.8 ml (dispersion medium distilled water) of a rhodamine-containing silica particle having a concentration of 10 mg / ml (average particle size 26 nm) obtained by the same method as in the Reference Example. In addition, the mixture was well stirred with a stirring bar. Subsequently, 200 μl of 28 mass% ammonia water was added, and the colloid was stirred at room temperature for 1 hour. The resulting colloid was centrifuged for 30 minutes at a gravitational acceleration of 15,000 × G, and the supernatant was removed. 8.8 ml of distilled water was added thereto to redisperse the particles. Subsequently, 1 ml of an aqueous sodium alginate solution having a concentration of 10 mg / ml was added, and after stirring well with a stirrer, 200 μl of 28% by mass of aqueous ammonia was added and stirred for 1 hour. The colloid was centrifuged at a gravitational acceleration of 15,000 × G for 30 minutes, and after removing the supernatant, 10 ml of distilled water was added to disperse the particles. Similarly, centrifugal separation twice and dispersion in distilled water were repeated to wash the particles, and the particles were dispersed in 1 ml of distilled water to obtain a colloid of rhodamine-containing silica particles / alginic acid composite particles (average particle size 26 nm) ( Colloid A, yield 8.8 mg / ml × 10 ml). When 900 μl of distilled water was added to 100 μl of colloid A to make 1 ml, and the zeta potential was measured using a zeta potential measuring device (Zeta Sizer Nano, manufactured by Malvern), the zeta potential was 51.4 mV.
(Dispersion stability test)
50 μl of colloid A was put in a cuvette, and further 850 μl of distilled water and 100 μl of 50 mM KH ₂ PO ₄ aqueous solution (pH 7.0) were added. 100 μl of 10% by weight NaCl aqueous solution was added to this mixed solution, mixed lightly with a pipette, and allowed to stand at room temperature, and the time-dependent change in particle size distribution was measured by a dynamic light scattering method (Zetasizer Nano, manufactured by Malvern). ).
FIG. 2 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginic acid composite particles.
As apparent from FIG. 2, the colloid of rhodamine-containing silica particles / alginic acid composite particles hardly changed the particle size distribution even after 24 hours. From this, it can be seen that the composite particles of the present invention are excellent in dispersion stability without forming a secondary particle and aggregating even in a dispersion medium containing a salt.

Example 3 (Conjugation of antibody to rhodamine-containing silica particles / alginate composite particles)
To the centrifuge tube, 1 mL of 50 mM KH ₂ PO ₄ (pH 6.5) and 9 mL of colloid (10 mg / mL) of rhodamine-containing silica particles / alginic acid composite particles (average particle size: 26 nm) were added and stirred gently. 1 mL (60 μg / mL) of an anti-hCG antibody (Anti-hCG clone codes / 5008, manufactured by Medix Biochemical) was added to the centrifuge tube with stirring, and the mixture was allowed to stand at room temperature for 1 hour. 0.55 mL of 1% by mass of PEG (polyethylene glycol, molecular weight 20000, manufactured by Wako Pure Chemical Industries, Ltd.) was added thereto and stirred gently, and 1.1 mL of 10% BSA was further added and stirred gently.
The mixed solution was centrifuged at 12,000 × G for 15 minutes, and about 1 mL of the supernatant was removed, and the precipitate was dispersed in the remaining supernatant. To this dispersion, 20 mL of a storage buffer (20 mM Tris-HCl (pH 8.2), 0.05% PEG 20,000, 1% BSA, 0.1% NaN ₃ ) was added, centrifuged again, and the supernatant was recovered. About 1 mL was left and removed, and the precipitate was dispersed in the remaining supernatant (colloid B). 900 μl of distilled water was added to 100 μl of colloid B to make 1 ml, and centrifuged at 15,000 × G for 30 minutes at a gravitational acceleration. After removing the supernatant, 1 ml of distilled water was added to disperse the particles. In the same manner, the mixture was further centrifuged once, and the particles were dispersed in 1 ml of distilled water. When the zeta potential was measured using the obtained colloid zeta potential measuring device (Zeta Sizer Nano, manufactured by Malvern), the zeta potential was 50.1 mV.

(Dispersion stability test)
10 μl of colloid B was placed in a cuvette, and further 890 μl of distilled water and 100 μl of 50 mM KH ₂ PO ₄ aqueous solution (pH 7.0) were added. 100 μl of 10% by weight NaCl aqueous solution was added to this mixed solution, mixed lightly with a pipette, and allowed to stand at room temperature, and the time-dependent change in particle size distribution was measured by a dynamic light scattering method (Zetasizer Nano, manufactured by Malvern). ).
FIG. 3 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginate / anti-hCG antibody composite particles.
As is apparent from FIG. 3, the colloid of rhodamine-containing silica particles / alginate / anti-hCG antibody composite particles (average particle size 26 nm) maintained dispersion even after 24 hours, and there was no significant change in the particle size distribution. From this, it can be seen that the composite particles of the present invention are excellent in dispersion stability without forming a secondary particle and aggregating even in a dispersion medium containing a salt.

(Molecular recognition test)
Subsequently, 100 μl of the obtained rhodamine-containing silica particles / alginate / anti-hCG antibody composite particle colloid (colloid B) was placed in one well of a 96-well microplate. Next, a solution (50 mM KH ₂ PO ₄ , pH 7.0) containing 1 mg / mL of an anti-IgG antibody (Anti Mouse IgG, manufactured by Dako) was prepared. FIG. 4 is a plan view of the strip 1 used in the molecular recognition test. Membrane 4 (Hi-Flow Plus 120 membrane, manufactured by MILLIPORE) coated with the above solution at a coating amount (about 1 mm width) of 0.75 μL / cm in a line shape at a position 3 about 15 mm from one end 2 is 5 mm wide. To be a strip 1 (length 25 mm).
The ends were immersed in rhodamine-containing silica particles / alginate / anti-hCG antibody composite particle colloid and allowed to stand for 1 hour.
As is clear from FIG. 4, it was confirmed that the portion 3 where the anti-IgG antibody was applied in a line was colored red, and rhodamine-containing silica particles / alginate / anti-hCG antibody composite particles were formed. Moreover, it turns out that the composite particle of this invention is suitable as an analysis reagent.

FIG. 1 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginic acid composite particles. FIG. 2 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginic acid composite particles. FIG. 3 is a graph showing the change over time in the particle size distribution of rhodamine-containing silica particles / alginate / anti-hCG antibody composite particles. 4 is a plan view of the strip used in the molecular recognition test of Example 3. FIG. FIG. 5 is a view showing an SEM photograph image of the silica particles obtained in the reference example.

Claims (17)

  A silica particle / polysaccharide / biomolecule composite particle in which a polysaccharide is adsorbed on the surface of a silica particle and a biomolecule is adsorbed or covalently bonded to the surface of the silica particle and the outside of the polysaccharide.   2. The biomolecule according to claim 1, wherein the biomolecule is at least one selected from the group consisting of antigens, antibodies, DNA, RNA, sugars, sugar chains, ligands, receptors, peptides, and chemical substances. Composite particles.   3. The composite particle according to claim 1, wherein the silica particle has an average particle diameter of 1 nm to 1 μm, and the polysaccharide has a weight average molecular weight of 1,000 to 1,000,000.   The composite particle according to any one of claims 1 to 3, wherein an absolute value of ζ potential in pure water at pH 7 is 1 to 70 mV.   The composite particle according to any one of claims 1 to 4, wherein the polysaccharide is alginic acid or dextran.   A composite particle colloid obtained by dispersing the silica particle / polysaccharide / biomolecule composite particle according to any one of claims 1 to 5 in a dispersion medium.   The composite particle colloid according to claim 6, wherein the dispersion medium is a buffer solution.   An analytical reagent comprising the composite particle colloid according to claim 6 or 7.   Silica particles / polysaccharides comprising a step of producing silica particles / polysaccharide composite particles in which the polysaccharides are adsorbed on the surfaces of the silica particles by mixing silica particles and polysaccharides in a basic solution. / Method for producing biomolecule composite particles.   The method according to claim 9, wherein the basic solution is an aqueous ammonia solution.   Adsorption or covalent bond formation between the surface of the silica particles and the polysaccharide and the biomolecule is performed in the presence or absence of a condensing agent or a crosslinking agent, and the colloid of the composite particles of the silica particles / polysaccharide and the The method for producing composite particles of silica particles / polysaccharide / biomolecule according to claim 9 or 10, wherein the method is performed by mixing with a biomolecule solution.   The method for producing composite particles of silica particles / polysaccharide / biomolecule according to any one of claims 9 to 11, wherein the polysaccharide is alginic acid or dextran.   Silica particles / polysaccharides / biomolecules formed by adsorbing polysaccharides on the surface of silica particles having an average particle diameter of 1 nm to 1 μm and further adsorbing or covalently binding biomolecules on the surface of the silica particles and outside the polysaccharides. It is a composite particle, and the biomolecule is at least one selected from the group consisting of antigen, antibody, DNA, RNA, sugar, sugar chain, ligand, receptor, peptide and chemical substance, and the polysaccharide is A composite particle characterized by being alginic acid or dextran.   A composite particle colloid obtained by dispersing the composite particles according to claim 13 in a dispersion medium.   An analytical reagent comprising the composite particle colloid according to claim 14.   A colloid in which silica particles having an average particle diameter of 1 nm to 1 μm are dispersed and 0.5 parts by mass or more of alginic acid or dextran with respect to 100 parts by mass of the silica particles in an aqueous solution of 0.01% by mass to 1% by mass. And a process for producing silica particles / polysaccharide / biomolecule composite particles, wherein the silica particles / polysaccharide composite particles are produced by adsorbing the alginic acid or dextran on the surface of the silica particles. . Silica particle / polysaccharide composite particles obtained by adsorbing polysaccharides on the surface of silica particles.