JPH01275601A - Cellulose particle - Google Patents

Abstract

PURPOSE:To reduce the pressure loss and improve the selectivity and the amount of adsorption when used as plasma protein adsorbent, by specifying the ranges of the number-average particle diameter, the particle diameter distribution and the partition coefficient of cellulose particles. CONSTITUTION:A cellulose material (e.g., cellulose acetate), preferably, purified cellulose, is dissolved in a solvent (e.g., a liquid mixture of dimethyl sulfoxide with propylene glycol) to obtain a polymer solution. The resulting solution is spouted into a gas phase as uniform droplets and the droplets are flow over such a distance as to become nearly spherical, and are brought into contact with a coagulant to produce cellulose particles wherein the number-average particle diameter is 300-600mum, 95% or more of them are in the range of + or -10% of the number-average particle diameter, and the partition coefficient is 0.3 or more for the particles having a molecular weight of 10,000 or below and 0.005 or less for the particles having a molecular weight of 100,000 or above.

Description

[Detailed description of the invention] [Industrial application field] The present invention has a specific number average particle size and a narrow particle size distribution.
and relates to cellulosic particles having a specific partition coefficient.

[Prior Art/Problems to be Solved by the Invention] Cellulose-based materials such as cellulose, regenerated cellulose, and cellulose derivatives have characteristics such as relatively low nonspecific adsorption of blood cell components and plasma proteins. Therefore, cellulosic materials, especially those coated with a number average particle size of 6
Activated carbon particles of about 0G to 1500a+ are used to selectively remove plasma proteins and the like from blood vessels. However, cellulosic particles themselves have never been used for this purpose.

On the other hand, dispersion methods and spray methods are known as methods for producing spherical polymer particles.

In the dispersion method, a dilute solution of a polymer dispersed in small droplets in a dispersion medium containing a surfactant is solidified by exerting the solvent (see Japanese Patent Application Laid-open No. 58-24480), or this dispersion is The polymer particles can be changed by gradually adding small droplets of a coagulating agent to the polymer and solidifying it (see Japanese Patent Application Laid-open No. 159801/1983). In addition to converting particles with a broad size distribution, this method requires washing with not only water but also organic solvents to remove solvent, dispersion medium, and surfactant from the solidified droplets.

In the spray method, polymer particles are obtained by spraying a polymer solution into a coagulant.

These particles also have a wide particle size distribution and are relatively large in size (see Japanese Patent Laid-Open No. 129788/1983).

When cellulose-based particles are produced as the spherical polymer particles and used in place of activated carbon particles coated with a cellulose-based material, adsorption efficiency may be improved if the cellulose-based particles contain many particles with small particle sizes. When used as an adsorbent in the form of a column, pressure loss increases, leading to problems such as hemolysis, and the molecular weight cut off becomes less sharp, resulting in poor selectivity.

Furthermore, if the cellulose-based particles contain many large particles, the specific surface 1j1 (total particle surface area per unit volume of particles) of the particles becomes small, resulting in a problem that the adsorption rate decreases.

[Means for Solving the Problems] The present invention was made in order to solve the problems such as the wide particle size distribution of cellulose particles, which is the cause of the above problems, and the number average particle size is 300 to 600. It is within the captivity,
95% or more of the particles are within ±10% of the number average particle size,
The present invention relates to cellulose particles having a distribution coefficient of 063 or more for molecular weights of 10.000 or less and 0.05 or less for molecular weights of 100.000 or more.

[Example] The cellulose-based particles of the present invention are composed of cellulose-based materials such as cellulose, regenerated cellulose, and cellulose derivatives. Therefore, when the cellulose-based particles are used for purposes such as selectively removing plasma proteins from blood, blood cell components and plasma Non-specific adsorption of proteins is reduced. Also, when used for purposes such as chromatographic separation of biochemical substances, non-specific adsorption of proteins is reduced.

The cellulose refers to so-called natural cellulose, such as pulp obtained by removing lignin and hemicellulose from defatted cotton fibers, hemp fibers, and wood, and pulp obtained by further refining the bulb. Representative examples include purified cellulose, but are not limited to these.

The cellulose derivatives are derived from cellulose, such as those in which some or all of the hydroxyl groups of cellulose have been esterified or etherified, and those in which some of the hydroxyl groups of cellulose have been esterified and some have been etherified. It is something that has been induced.

Specific examples of cellulose in which some or all of the hydroxyl groups have been esterified include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose nitro, cellulose sulfate, cellulose phosphate, cellulose acetate butyrate, cellulose nitrate, and cellulose cellulose. Examples include, but are not limited to, dithiocarboxylic acid esters (viscose rayon).

Specific examples of cellulose in which some or all of the hydroxyl groups are etherified include methylcellulose, ethylcellulose, benzylcellulose, tritylcellulose, cyanethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, oxyethylcellulose, etc. , but not limited to these.

Furthermore, the regenerated cellulose refers to cellulose obtained by molding cellulose into a cellulose derivative that can be easily molded in one piece, and then regenerating the cellulose by hydrolysis or the like.

Among the cellulose-based materials constituting the cellulose-based particles, purified cellulose is preferable because it has fewer impurities and leaves less undissolved matter when dissolved, and cellulose esters such as cellulose acetate and cellulose propionate are preferable when used in various solvents. As a result, the range of selection of various manufacturing conditions during particle production is widened, and it is easy to adjust the particle distribution coefficient, skin layer thickness, pore size in the internal network structure, etc. to achieve the desired result. This is preferable because cellulose-based particles can be produced, and it is even more preferable because it can be easily converted into regenerated cellulose particles by hydrolysis.

The cellulose-based particles of the present invention are spherical particles (a concept that includes not only spherical particles but also elliptical bodies of rotation with a minor axis/long axis of up to about 0.8), The number average particle diameter (in the case of an elliptical rotating body, the volume average particle diameter, that is, determined as the cube root of the value obtained by multiplying the square of the major axis by the minor axis) is in the range of 300 to eoo Jl, and 95% The above particles are within ±10% of the number average particle diameter, and the distribution coefficient is 0.3 or more for molecules m to, ooo or less, and 0.05 or less for molecules 1 too, ooo or more. On the surface of such cellulose-based particles, there is usually a skin layer with a thickness of 10 pores or less, and the inside consists of a network structure having pores of 0.1 to 10 pores.

Further, the porosity of the particles is about 50 to 95%.

Figures 1 and 2 show the skin layer of the cellulose-based particles of the present invention (the whitish layer that exists diagonally from about 1/3 from the upper left to about 1/2 from the upper left in Figure 1). This is an example of an electron micrograph (15,000x magnification) observing the surface portion of

When the number average particle diameter is less than Boo -, especially albumin (molecular! 58,000
) When used as an adsorbent for adsorbing and removing plasma proteins with smaller molecular weights by direct blood perfusion, the pressure loss increases and problems such as hemolysis are more likely to occur. Further, when the thickness exceeds 600 um, the specific surface area becomes small and the adsorption speed becomes low, so that the amount of adsorption and removal of unnecessary substances becomes small in relation to the amount of blood circulation.

In addition, the proportion of particles within ±10% of the number average particle diameter is 95%.
If the amount is less than
Hemolysis may occur more easily.

Furthermore, the distribution coefficient is 0 for molecular QIs below 0.000.
．． 3 or more, 0.05 for molecular weight 100,000 or more
If the following range is exceeded, the selectivity when used as an adsorbent for the adsorbent described above will decrease, and substances with molecular weights higher than albumin will be easily adsorbed, or conversely, the adsorption rate will be significantly reduced. This tends to cause problems such as insufficient adsorption and removal of unnecessary substances.

Note that if the size of the network structure inside the cellulose particles is less than 0.1ρ, when used as an adsorbent for an adsorbent, not only will the rate of adsorption of the unnecessary substances in the blood decrease, There is a tendency that these unnecessary substances are not adsorbed and removed sufficiently. In addition, if the value exceeds 10, the mechanical strength will not be sufficient, and the particles will tend to be easily deformed or crushed during filling into columns or transportation, and if such deformation occurs, This results in increased pressure loss and a tendency for microscopic debris to enter the blood.

Next, the method for producing cellulose particles of the present invention will be explained.

The cellulose-based particles of the present invention can be obtained by dissolving a polymer solution in which cellulose, cellulose derivatives, etc. ) can be manufactured by applying.

The solvent used when preparing the polymer solution is
Solvents for cellulose, such as an aqueous cuprammonium solution, a mixture of dimethyl sulfoxide and formamide, and an aqueous calcium thiocyanate solution; and solvents for cellulose acetate, a typical cellulose derivative, such as dimethyl sulfoxide, dimethyl formamide, and dimethyl acetamide. , N-methyl-2-pyrrolidone, acetone, and the like.

These solvents include methanol, ethanol, ethylene glycol, and propylene in order to adjust the thickness of the skin layer and the size of the pores in the internal network structure of the resulting cellulose particles to adjust the distribution coefficient. Glycol, glycerin, water, inorganic salts, polyethylene glycol, polyvinylpyrrolidone, etc. may also be added.

The polymer solution prepared in this way is ejected into the gas phase as uniform droplets using a device such as that described in Japanese Patent Application Laid-Open No. 82-191038, and is ejected into a gas phase over a flying distance to form a spherical shape. After being flown, it is brought into contact with a coagulant.

The cellulose-based particles produced in this manner are approximately perfectly spherical particles.

The coagulant is made of a polymeric non-solvent, and preferably has a surface tension such that it dissolves in the solvent constituting the droplets and naturally wets the droplets.

Specific examples of such coagulants include water, a mixture of water and the aforementioned good solvent or non-solvent, and a mixture of water and a surfactant.

Generally, when the concentration of the polymer in the polymer solution is high, the proportion of non-solvent is low, and a coagulating liquid with strong coagulating power, such as water, is used, the pores of the skin layer become smaller (the distribution coefficient becomes smaller).

The cellulose-based particles of the present invention obtained in this way have a specific average particle size, a specific particle size distribution, and a specific distribution coefficient, so they can be used as fillers for chromatography, as carriers for enzyme immobilization, and as affinity particles. chromatography carrier,
It can be used as an adsorbent for direct blood perfusion, and when used in these applications, it is excellent in terms of pressure drop, selectivity, adsorption rate, etc.

Next, the cellulose particles of the present invention will be explained based on Examples, but it goes without saying that the present invention is not limited to these Examples.

In an example, cellulose acetate was dissolved in a mixed solution of dimethyl sulfoxide/propylene glycol in a weight ratio of 476 so that the concentration was 12.5% (weight %, the same applies hereinafter).

Parallel plate-like electrodes with a width of 5 aa and a length of 25 mm in the direction of droplet travel are installed at a distance of 2011 mm in front of the nozzle, and a parallel plate electrode with a width of 5 aa and a length of 25 mm in the direction of droplet travel is installed between the electrode and the nozzle.
A DC voltage of 0.0 cm was applied. Diameter 2 provided on this nozzle
The solution maintained at 145° C. was discharged from the 50° orifice at a linear velocity of 7.8 m/sec while applying vibration of 385011z to form uniform droplets of the solution, which were flown through the air for about 31°. Thereafter, the particles were solidified by entering a 10% aqueous methanol solution at 23° C. to obtain particles of cellulose diacetate.

The obtained cellulose diacetate particles were put into a 0.8% aqueous sodium hydroxide solution at 50°C, stirred for 2 hours, recovered, neutralized and washed with water to obtain 100% regenerated cellulose particles. I got it.

The number average particle size of the obtained regenerated cellulose particles was measured by the following method, and found to be 430ρ, which was within ±5% of the number average particle size.

After replacing the liquid in the obtained regenerated cellulose particles with ethanol, they were subjected to critical point drying with carbon dioxide gas (using Hitachi's critical point dryer HCP-2), gold was evaporated, and then they were dried using a scanning electron microscope. Upon observation, as shown in Figure 1, a skin layer with a thickness of about 0.2 -
From part 3 to about 1/2 of the way from the top of the left end, there is a whitish layer (the surface part) that exists diagonally, and as shown in Figure 2, the inside is porous with a pore size of about 0.2 to 2 mm. It had a mesh-like structure.

The partition coefficients of the particles for dextran of molecules tito, ooo, and 110.000 were measured by the following method and were 0.67 and 0, respectively.

The regenerated cellulose particles have an inner diameter of 1411% and a length of 7 (to)
When we filled a column with 30 units/ml of heparin and poured a fresh cow's surface while keeping it at 37℃, we gradually increased the flow rate and measured the pressure drop.As the linear velocity increased, the pressure drop was almost linear. Although the pressure loss increased, gc+e/m
Even when it was 1n, it was 50mm and 11g, and even if it was operated continuously for 1 hour, this value hardly changed, and direct blood perfusion was possible.

The regenerated cellulose particles were reacted with epichlorohydrin and then with n-hexylamine to obtain n-hexylamine-immobilized cellulose particles. When the selectivity of these particles was measured using the method below, the adsorption rates for lysozyme and albumin were 7396% and 8%, respectively.
Met.

(Number average particle size and particle size distribution) Optical microscopic images of hundreds of particles (approximately 500 to 1000 particles) are processed using an image processing device (Ruzetx, manufactured by Nireco).

(Partition coefficient (Kav)) Partition chromatography was performed using aqueous solutions of dextran and pullulan with various molecular weights, and the elution curve was determined using the formula: The amount of eluate corresponding to the peak position of the elution curve, Vt is the column volume, and ve is determined from the eluate ti) corresponding to the peak position of the sample elution curve.

(Selectivity) 1) Lysozyme and albumin were each added at 3 tsg/m in 0.025M phosphate buffer adjusted to H7.4.
Cellulose-based particles on which a ligand adsorbable to plasma proteins is immobilized so that the sedimentation volume is 1 volume per 6 volumes of each solution dissolved at a concentration of 1 and 7.3 mg/ml. After shaking at 37°C for 2 hours, the concentration of the supernatant was measured to determine the adsorption rate of each.

Stock solution concentration - Supernatant solution concentration Adsorption rate (%) - X100 Stock solution concentration (judgment of possibility of direct blood perfusion) Fresh side of cow with 30 units/ml of heparin added
Insulated at 7℃ and filled with particles, length 7〔, inner diameter 14m.
The linear velocity was set to 8 while gradually increasing the flow rate to the 5φ column.
cm/sin, and during this time the pressure loss is 1
It was judged that direct blood perfusion was possible if the number did not exceed 100 ail1.

Comparative Example 1 Pressure drop was measured in the same manner as in Example 1 using commercially available regenerated cellulose particles with a number average particle size of 450 and 89% of particles within ±10% of the number average particle size. Linear speed is 2cm/sln and pressure loss is already 1100avlr
After that, the pressure loss became even larger, so the experiment was stopped.

Comparative Example 2 Regenerated cellulose particles with a number average particle size of 270 particles and 100% of particles within ±5% of the number average particle size were obtained in the same manner as in Example 1 by changing the conditions for forming uniform droplets. . When the pressure drop was measured using these particles in the same manner as in Example 1, it was found that the pressure drop was 100a+a+H at a linear velocity of 5 cm/sin.
It exceeded g.

Comparative Example 3 In the same manner as in Example 1, n-hexylamine was immobilized on commercially available regenerated cellulose particles having molecular weights ILQ and QOQ and a distribution coefficient of 0.3 for dextran, and the adsorption rate of lysozyme and albumin was measured. The results were 24% and 58%, respectively.

[Effects of the Invention] Since the cellulose-based particles of the present invention have a specific number average particle size, a specific particle size distribution, and a specific distribution coefficient, they can be used for adsorption to selectively remove plasma proteins from blood. Cellulose-based particles for body use, especially when used for purposes such as adsorption and removal of plasma proteins with a molecular weight smaller than albumin, by direct blood perfusion, are selected because pressure loss is small and problems such as hemolysis are less likely to occur. Effects such as improved properties and increased adsorption amount are achieved.

[Brief explanation of the drawing]

Figure 1 is a photograph for explaining the structure of the cellulose-based particles of the present invention, and is a photograph showing the vicinity of the surface of the particle cross section (the skin layer on the surface and the network structure inside thereof) magnified 15,000 times. is a photograph for explaining the internal structure of the cellulose-based particles of the present invention obtained in Example 1, and is a photograph in which the cross section of the particles is enlarged 15,000 times. Figure 1 Procedural amendment stamp button 1
1 Description of the case Patent Application No. 105346 filed in 1988 2 Name of the invention Cellulose-based particles 3 Person making the amendment Relationship to the case Patent applicant Address 3-2-4 Nakanoshima, Kita-ku, Osaka Name Name
(094) Kanebuchi Chemical Industry Co., Ltd. Representative Masato Niino 2-Ko ε Name 5 Subject of amendment (1) Contents of amendment to column 5 of “Detailed explanation of the invention” of the specification (1) Page 2 of the specification Correct "exhibit" in line 12 to "volatize". (2) "Undissolved matter" on page 6, line 14 is corrected to "undissolved matter." (3) r5g, 000J on page 8, line 8, r67.000
Corrected to ~68.0OOJ. (4) "Formamide" on page 10, line 11 is corrected to "paraformaldehyde." (5) Correct "shaking temperature" in line 5 of page 1B to "shaking". that's all

Claims (1)

[Claims] 1 The number average particle size is in the range of 300 to 600 μm, and 9
5% or more of the particles are within ±10% of the number average particle diameter, and the distribution coefficient is 0.3 or more for a molecular weight of 10,000 or less,
Cellulose particles having a molecular weight of 0.05 or less with respect to a molecular weight of 100,000 or more.