JPS60172313A - Material and process for removing endotoxin - Google Patents

Abstract

PURPOSE:To remove endotoxin in a relatively large amt. of aq. liquid efficiently and without causing clogging by using porous hollow short fiber consisting of polyolefin and having a particular structure. CONSTITUTION:The polyolefin porous hollow fiber to be used has a microlaminar structure comprising microfibrils 1 and oblong fine pores 3 constituted of knots 2 connected almost perpendicularly to said microfibrils 1 and interposing said knots 2. The above described hollow fibers are cut to short fibers. Further, the hollow short fibers have >=20vol% porosity measured by Hg porosimeter, and the surface is made hydrophilic. The short fibers are packed in a cylindrical body, and aq. liquid contg. endotoxin at 4-9pH and 0-80 deg.C is passed through the cylindrical body.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to an endotoxin removal material and a removal method that can easily and efficiently remove endotoxins from an aqueous liquid.

(b) Prior Art There are various compounds found in nature as pyrogenic substances (pyrothicones), but the main component of pyrothicones present in water is bobolisasocalide, which is present on the cell membranes of Gram-negative bacteria. , called endotoxin. Therefore,
Pyrocicon is generally considered to be the same term as bacterial endotoxin.

If even a small amount of endotoxin enters the blood, it can cause fever, chills, shock, etc. and is extremely dangerous, so the removal of endotoxin from various pharmaceutical products such as hospital water, pharmaceutical industry water, infusions, and vaccines is an important issue. Conventionally, precise distillation methods, reverse osmosis membrane methods, adsorption methods, etc. have been used to remove endotoxins from water. However, the distillation method has a high energy cost, and endotoxin cannot be sufficiently removed by one distillation. The reverse osmosis membrane method requires large-scale equipment, requires a high-pressure pump, and requires laborious operations such as membrane cleaning management.

In conventional adsorption methods, adsorbents such as activated carbon are used, but the removal effect is not sufficient. For example, JP-A-52-102414
The issue describes a method for adsorption and removal of endotoxin using olefin polymers. This method uses microspheres, powders, or fibers such as olefin polymers as endotoxin adsorbents, or adsorption is carried out through nonwoven fabrics or microporous films of the polymers. Although these spherical, powdery, and fibrous materials have endotoxin adsorption ability, the effect is not great and it is difficult to completely remove endotoxin from the liquid to be treated from human feet. In addition, adsorption through a microporous film is likely to cause clogging due to impurities and fine fibers in the water, and it is difficult to completely remove endotoxin from a large amount of liquid to be treated due to adsorption capacity and the like.

When attempting to remove endotoxins from blood, plasma, and serum, reverse osmosis membranes and ultrafiltration membranes cannot be used because they do not permeate high molecular compounds such as proteins. In particular, the removal of endotoxins from blood containing blood cells is completely performed using the membrane permeation method.
Impracticable.

Furthermore, the polyolefin membrane described in JP-A No. 52-102414 is also capable of permeating proteins such as albumin with relatively low molecular weight, but it is difficult to filter blood sputum proteins, and as mentioned above, I'm blind to this. Furthermore, although an endotoxin adsorbent made of immobilized polymyxin has been proposed in JP-A-58-13519, it has not been put to practical use due to concerns about side effects of the polymyxin itself.

(c) Purpose of the Invention The purpose of the present invention is to provide a removal material and method that can remove endotoxin from a relatively large amount of aqueous liquid with greater efficiency than the conventional methods described above and without causing clogging. There is something to do.

Another object of the present invention is to provide a removal material and method that can efficiently remove endotoxins from plasma and serum, and especially from whole blood containing blood cells.

(d) Structure of the Invention The material for removing endotoxins in an aqueous liquid according to the present invention has a large number of strip-shaped microscopic particles formed by nodules in which microfibrils arranged in the vertical direction are connected at approximately right angles to the microfibrils. Consisting of polyolefin porous hollow short fibers having a micro-laminated structure in which pores are interconnected in the thickness direction of the membrane and having a porosity of 20% by volume or more as measured by a mercury porosimeter, the porous hollow short fibers are It is characterized by a hydrophilic surface.

Furthermore, in the method for removing endotoxins in an aqueous liquid according to the present invention, a column filled with the above-mentioned removal material is filled with PI (4
~9. It is characterized by allowing an endotoxin-containing aqueous liquid at a temperature of 0°C to 80°C to pass through.

(*) Effects of the invention According to the present invention, surprisingly, JP-A-52-1'024
Compared to the method shown in No. 14, significantly higher endotoxin removal performance is exhibited, and it becomes possible to easily remove endotoxin from a large amount of aqueous liquid. In addition, it has become possible to reliably remove endotoxins in the blood, blood vessels, and serum, increasing the possibility of practical application to the treatment of endotoxemia.

(f) Specific description of the constitution of the invention The porous polyolefin hollow short fibers used in the present invention have a large number of nodules formed by microfibrils arranged in the longitudinal direction and knots connected at almost right angles to the microfibrils. It has a microlaminated structure in which strip-shaped micropores are interconnected in the thickness direction of the fiber. The porosity of the hollow short fibers measured with a mercury porosimeter must be 20% by volume or more. If the porosity is 20% by volume, the removal of endotoxin will be insufficient. In particular, it is preferable that the porosity is 40% by volume or more from the viewpoint of endotoxin removal ability. 'Porous polyolefin fibers with the above-mentioned special structure can be produced by melt-spinning a polymer such as polypropylene or polyethylene using a special nozzle for manufacturing hollow fibers, and producing highly oriented crystalline unstretched hollow fibers. Thread (fine structure called "hard elastane ink fiber")
It is manufactured by appropriately controlling each process condition in the main process of cold stretching and then hot stretching.

As the polyolefin, polyethylene, polypropylene, and copolymers containing these as main components are preferably used, and blends of these polymers mixed with other polymers in small proportions can also be used.

Next, the special microstructure of the polyolefin porous fiber used in the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a schematic diagram of one plane of a laminated structure of strip-shaped micropores, in which (1) is a microfibril, (2) is a nodule connected almost at right angles to the microfibril in (1),
(3) is a rectangular micropore, and the rectangular micropore (3) constituted by microfibrils and nodules has a product IZ structure via each nodule.

Further, the laminated structure of micropores means that the fibers are laminated in the longitudinal direction of the hollow fibers in one plane via the knots, and at the same time, the planes having such a structure are laminated in the thickness direction of the wall membrane of the hollow fibers.

Next 1. The polyolefin porous hollow fibers having a special structure obtained as described above are cut into short fibers. The fiber length is desirably 1"0IIIL11 or less; if it is longer than 10 mm, the endotoxin removal ability becomes insufficient. Therefore, the fiber length is particularly preferably 51 or less.

The inner diameter of the hollow short fibers is preferably 5 μm to 1000 μm. If it is less than 5 μm, the hollow effect becomes unclear, and if it exceeds 1000 μm, the hollow effect decreases and the endotoxin removal effect decreases. Particularly preferably, it is 30μI11 to 400μm.

The wall thickness of the hollow short fibers is preferably 3 μm to 150 μm. 3
If it is less than μm, the endotoxin removal ability is insufficient;
Further, if the thickness exceeds 150 μm, it becomes difficult to uniformly form the special film structure of the present invention.

Polyolefin porous hollow fibers are usually formed into continuous filaments, but they may be cut into short fibers by cutting with a cutter or by crushing under cooling. In this case, even if the fiber length is not uniform, the main part (70%
above) is within the range specified above. It is desirable that the cut end has a hollow hole shape from the viewpoint of endotoxin removal efficiency, but it can also be used in a closed state.

Further, the shape of the hollow fiber may be a completely circular hollow shape,
It may have a semicircular shape or a shape in which the hollow fibers are partially destroyed.

It is necessary that the polyolefin porous hollow short fibers used in the present invention be made hydrophilic. Normally, it is thought that making the adsorbent hydrophilic reduces the adsorption ability of lipophilic substances, and is also expected to be disadvantageous for the removal of entodo-1; In this case, surprisingly, the endotoxin removal ability is extremely low without hydrophilization, so hydrophilization is essential. Hydrophilization is
A liquid that has an affinity for polyolefins and is miscible with water, or that water? This can be carried out by infiltrating the short fibers into a solution. As an example of the body for hydrophilization,
Examples include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and ethylene glycol, dimethyl formaldehyde, dimethyl sulfoxide, dioxane, and various surfactants.

The endotoxin removing material of the present invention can be used by being dispersed in an aqueous liquid, or it can be packed in a column and the aqueous liquid is passed through the column. The latter method is particularly effective when treating large amounts of aqueous liquids, and is also effective for removing endotoxins in blood or blood vessels.

The temperature of the aqueous liquid from which endo-1-xin is to be removed is 0°C ~
At 80°C, the pH is 4-9. If it is outside this range, endotoxin removal will not be performed efficiently. And blood,
Alternatively, when removing endotoxin in plasma or serum, the temperature is preferably 0°C to 42°C.

The endotoxin removal material of the present invention has a surprisingly large endotoxin removal effect compared to conventional adsorption and removal materials. for example,
When comparing the same polypropylene, (1) diameter 2mm
polypropylene beads, (2) polypropylene fibers with a fineness of 10 sol cut to length 31, and (3
) The inner diameter of the present invention is 190 μm, the wall thickness is 25 μM, the porosity is 45
Capacity%, bubble point 12.5kg/cJ, fiber length 3
30 each of II1m porous polypropylene hollow short fibers
Pack 0■ into a column with a diameter of 0.5 am and 1 mj! /min
Tap water (endotoxin concentration 2.7 / m1i) at a flow rate of
When injected, the endotoxin in the permeate water is removed by 18% compared to the raw water in case (1), and 1.5% in case (2).
% removed, whereas in the case of the present invention in 3), 87%
has been removed. Furthermore, when polypropylene powder was used in the same manner as above, only 15% of the endotoxin was removed.

The details of why the endotoxin remover of the present invention exhibits such a remarkable effect compared to conventional adsorbents are not yet clear, and considering that the endotoxin removal ability of fine polymer powder is low, it is difficult to explain why the endotoxin removal agent of the present invention exhibits such a remarkable effect compared to conventional adsorbents. I can't explain it. It is presumed that the special structure in which microfibrils are laminated in a complex manner (as mentioned above) contributes to the efficient removal of endotoxin. From subunits with a molecular weight of 1,000 to 20,000 to micelles with a molecular weight of several million.
It is known that the endotoxin removal agent of the present invention exhibits a structure that is extremely advantageous for adsorption in accordance with such molecular weight distribution of endotoxin.

The reason why the endotoxin removing material of the present invention is less effective if it is not subjected to hydrophilic treatment is thought to be because the aqueous liquid does not come into sufficient contact with the above-mentioned special structure in the non-hydrophilic state.

(g) Examples Hereinafter, the present invention will be specifically described with reference to Examples.

Example 1 Density 0.968 g/cl, melt index 5.
The high-density polyethylene No. 5 was spun at a spinning temperature of 165° C. using a hollow fiber spinneret having a double tube structure. The obtained unstretched hollow fibers were annealed at 112° C. and then cold-stretched by 50% at room temperature. Subsequently, hot stretching was performed at 100° C. so that the total stretching ratio was 3.8 times. Further, it was heat set at a fixed length at 113° C., and then cut into short fibers using a cutting machine.

The obtained porous hollow short polyethylene fibers have a large number of strip-shaped micropores in the thickness direction of the membrane, which are formed by nodules in which microfibrils arranged in the longitudinal direction are connected at almost right angles to the microfibrils. It has an interconnected micro-laminated structure, and the porosity measured with a water root porosimeter is 6.
0 volume foot%, bubble point was 4.8 kg/cm. The hollow short fibers had an inner diameter of 270 μm, a wall thickness of 55 μm, and a length of 2 mm.

70 mg of the hollow short fibers obtained in this way
% ethanol and then washed with water to make it hydrophilic. The short fibers were packed in a column with a diameter of 5 mm, and the temperature was 24°C.
H6.5 tap water (endotoxin concentration 2.70nll)
? / ml: Measurements were made using a synthetic substrate (by Seikagaku Corporation (a) Pyrodic) at a flow rate of 1 mj! Water was passed at a rate of /min. The water that has passed through the column is lQ, m 7! Table 1 shows the results of measuring the endotoxin concentration using the collected synthetic substrate method.

Example 2 Polypropylene ([r1]- in Tetralin at 135°C
1,40) was spun at a spinning temperature of 260°C using a hollow fiber spinneret having a double tube structure. The obtained undrawn yarn was
After annealing at 45°C, it was stretched under conditions of cold stretching (room temperature)/hot stretching (145°C) -12/88 and a total stretching ratio of 21.2 times. The drawn hollow fibers were then heat set at 155° C. and then cut into short fibers using a cutter. The obtained polypropylene porous hollow short fibers have microfibrils arranged in the longitudinal direction, and a large number of strip-shaped micropores formed by nodules connecting the microfibrils at almost right angles to the microfibrils in the thickness direction of the membrane. It has an interconnected micro-layered structure with a porosity of 45% by volume as measured by a mercury porosimeter.
, the bubble point is 12. '5 kg/eel. The hollow short fibers have an inner diameter of 190 μm and a wall thickness of 25 μm.
The length was 2 mm.

200 mg of the hollow short fibers thus obtained were made hydrophilic in the same manner as in Example 1, and then filled in a column and passed with tap water in the same manner as in Example 1. Table 1 shows the results of measuring the endotoxin concentration of the water that passed through the column.

Comparative Example 1 Polypropylene beads (shell polypropylene 5820
, diameter approximately 2 mm) 40 (1 mg was treated to make it hydrophilic in the same manner as in Example 1, and then tap water was passed through the column in the same manner as in Example 1. The endotoxin concentration of the water that passed through the column was measured. The results are shown in Table 1.

Comparative Example 2 Polypropylene fibers having a fineness of 10 denier were cut into 2 mm lengths, 3001 cm were made hydrophilic in the same manner as in Example 1, and then packed in a column and tap water was passed therethrough. Table 1 shows the results of measuring the endotoxin flow rate of the water that passed through the column.

Comparative Example 3 High-density polyethylene fine powder (Hizenox 2208J, manufactured by Mitsui Petrochemicals Co., Ltd.) 200 mg After being made hydrophilic in the same manner as in Example 1, it was packed in a column and tap water was passed through it.

Table 1 shows the results of measuring the endotoxin concentration of the water that passed through the column.

Example 3 150 g of polyethylene porous hollow short fibers similar to Example 1
was packed into a column with a diameter of 5 can, and after hydrophilizing with 70% ethanol, tap water at a temperature of 20°C, PH, 6.5
! Water was passed continuously at a rate of /min. The endotoxin concentration in tap water was measured by the synthetic filament method in the same manner as in Example 1, and 4.
It was 7ng/ml. Total water flow ff12.000
When the endotoxin concentration of the column permeated water after p was measured, it was 0.09 ng/ml, indicating that the polyethylene porous hollow short fibers still maintained good endo-1 to toxin removal ability.

Example 4, Comparative Example 4.5 +1 to distilled water for injection that does not contain enF' l-1-syn
゜Co110111-84 Mountain endotoxin (D
(manufactured by Fco) was dissolved to a concentration of 1 On8/mβ to prepare a test solution.

The temperature of the test solution was maintained at 20°C, I'116.5.

Polyethylene porous hollow short fiber 200 similar to Example 1
Pack ■ into a 5mm0 column and add 1mff of the fiber liquid after hydrophilization.
Water was passed through at a flow rate of /min. Table 2 shows the measurement results of endodocin in 10 mβ of the treatment solution (Example 4).

Next, the polyethylene undrawn hollow fiber filtered according to Example 1 was cut into 21 pieces, and the endotoxin removal ability was measured in the same manner as in Example 4. This unstretched hollow fiber has an inner diameter of 3
It had a wall thickness of 68 μm, no microporous structure in which microfibrils were stacked, and the porosity measured with a mercury porosimeter was 2% by volume or less. The measurement results are shown in Table 2 (Comparative Example 4).

Furthermore, the endotoxin removal ability of the same polypropylene short fibers as in Comparative Example 2 was measured in the same manner, and the results are shown in Table 2 (Comparative Example 5).

Below is the margin Table 2 Table 8 11N □ Raw water end toxin Treated water end well (ng/m 1 ) Toxin 渭odonail import/rrl) Fruit tJ mochi row 4 10 0.08 Upper tJm row 4 10' 9. 4 ■ Tsubo row 5 10 9.4 Example 5 Comparative example 6.7 Polypropylene porous hollow short fibers similar to Example 2 15
0 g was packed into a column with a diameter of 5 cm, and after hydrophilic treatment, tap water with a temperature of 21°C and a pH of 6.5 was added to Q, 57! It was passed continuously at a speed of /min. Table 3 shows the increase in pressure loss and endotoxin concentration when the cumulative water flow rate was 2000β (Example 5).

Next, a porous polypropylene film (Celgard (trade name) 2500 manufactured by Celanese) was set in a filter with a diameter of IQ cm, and after making it hydrophilic by pouring 70% ethanol into it, tap water was continuously poured at O, lJ/min. The water was running. The filter became clogged with the integrated water flow titll ff and became unusable (Comparative Example 6).

The polypropylene porous hollow fibers produced in the same manner as in Example 2 were bent into a loop shape without cutting them into short fibers, and the ends were adhesively sealed with polyurethane resin and then cut to effect effective filtration. The filter module had an area of 0.3%, a housing diameter of 5 cm, and a length of 39 cm.

After making this filter hydrophilic, use the same tap water as in Example 5.
, water was passed in a continuous manner at a rate of 5ff/min.

Table 3 shows the increase in pressure loss and endotoxin concentration when the cumulative water flow was m2000 p (Comparative Example 7).

Below is the margin O CO> When raw water is filtered using a polypropylene porous hollow fiber as a filter, it is possible to remove endo-1-nidocine, but the clogging is significant and tap water is 20007! Filtering is difficult under tap water pressure during filtration.

In the case of a polyzolopyrene porous film, passing only a small amount of tap water causes it to clog and become unusable.

In contrast, the method of the present invention successfully removed endotoxins from the tap water of Person 7 with little clogging (Example 6).

Human blood ＼valine (1000u/m 1!)
Collect bacteria into a syringe containing 0.1m f, centrifuge 1Ti
Plasma was fractionated by microcentrifugation (2500 rpm, 5 min). A 120 ng/ml aqueous solution of Ecoli 111-134 was added to the plasma, and 12 n
Plasma with pH 7.4 containing g/nu endotoxin was prepared. This plasma was placed in a column packed with polyethylene porous hollow short fibers 12 (1#) similar to those in Example 1 at 25°C.
The endotoxin concentration in the plasma after treatment was measured at 3 mA/min and 30°C.

The analysis was performed by pretreating the specimen with perchloric acid and using a synthetic substrate method (Pyrobink). As a result, the endotoxin concentration in plasma after treatment was 0. There was log/mi%. However, as a result of this treatment, almost no change in the composition of plasma protein components was observed.

Example 7, Comparative Example 8 Using the same polypropylene porous hollow short fibers as in Example 2, an attempt was made to remove endotoxin from plasma in the same manner as in Example 6. As a result, the endotoxin concentration of blood-1i containing 12 ng/ml of endotoxin was 0.00 ng/ml after treatment.
08 ng/mj+. Moreover, almost no change in plasma protein composition was observed as a result of this treatment.

On the other hand, a filter and seal having an effective filtration area of IQQ-cnT was prepared using the same polypropylene porous hollow fiber as in Example 2. ``When this filter was used to filter a human dish similar to that used in Example 8 at a rate of 0.3 ml/mrn, the filter immediately became clogged and only a small amount of plasma could be filtered. Analysis of the filtrate also showed that the plasma albumin/γ-globulin ratio increased significantly, indicating that α-globulin was blocked by the membrane. The relationship between endotoxin concentration and fever is 1. Until now, this has been done using the Japanese Pharmacopoeia rabbit test, but a method using bacterial pyrodic (Seikagaku Kogyo Co., Ltd.) has been developed that can be used to measure endotoxin concentrations in water and plasma (including serum). . Experimental data showing good agreement between endotoxin concentrations in rabbit tests and pyrodic tests can be found in many technical papers. This pyrodic endotoxin analysis method was adopted in the examples in the Kikiri book.

[Brief explanation of the drawing]

No. 11a is a schematic diagram of one plane of a stacked structure of strip-shaped micropores. d31 figure

Claims (1)

[Claims] 1. A large number of strip-shaped 7JX holes formed by knots in which microfibrils arranged in the longitudinal direction are connected at approximately right angles to the microfibrils. It consists of polyolefin porous hollow short fibers that have a micro-laminated structure connected to the pores and have a porosity of 20% by volume or more as measured by a mercury porosimeter, and the surface of the porous hollow short fibers is made hydrophilic. A material for removing endotoxins from aqueous liquids. 2. The fiber length of the polyolefin porous hollow short fiber is 10
2. The material for removing endotoxins in an aqueous liquid according to claim 1, which has a particle size of less than 1 mm. 3. The fiber length of the polyolefin porous hollow short fiber is 5.
The material for removing endotoxins in an aqueous liquid according to claim 1, which has an LI of 1 m or less. 4. The endotoxin removing material according to claim 1, which has a shape in which the hollow short fibers are crushed. 5. The inner diameter of the polyolefin porous hollow short fiber is 5 μm
The material for removing endotoxins in an aqueous liquid according to any one of claims 1 to 3, wherein the material has a wall thickness of 3 to 150 μm. 69. The material for removing endotoxins in an aqueous liquid according to any one of claims 1 to 5, wherein the polyolefin is polyethylene. 7. The material for removing endotoxins in an aqueous liquid according to any one of claims 1 to 5, wherein the polyolefin is polypropylene. 8. It has a microlaminated structure in which a large number of strip-shaped micropores formed by nodules in which microfibrils arranged in the longitudinal direction are connected at almost right angles to the microfibrils are interconnected in the thickness direction of the membrane. The porosity measured by a mercury porosimeter was 20% by volume, and a cylindrical body (man-lam) filled with polyolefin porous short fibers whose surface was made hydrophilic was heated at a pH of 4 to 9 and a temperature of 0 to 80 degrees Celsius. A method for removing endotoxin in an aqueous liquid, the method comprising passing through an aqueous liquid containing endotoxin. 9. The method for removing endotoxin from an aqueous liquid according to claim 8, wherein the aqueous liquid is blood. 10. Aqueous liquid is bloodff! The method for removing endotoxin from an aqueous liquid according to claim 8, which is serum. 11. The endotoxin removal method according to claim 9 or 10, wherein the temperature of the aqueous liquid is 0°C to 42°C.