JP2003043031A - Blood filtering unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blood filtering unit capable of separating plasma or serum from a small amount of whole blood efficiently. SOLUTION: In the blood filtering unit, glass fiber-filter paper is filled into a vessel that has at least two openings and has a diameter of approximately 1 cm or less so that the ratio of length/diameter is 1/2 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hemofiltration unit for filtering plasma or serum from whole blood using glass fiber filter paper as a main filter material. More specifically, the present invention provides efficient plasma or serum (hereinafter, “plasma etc.”) from a small amount of whole blood sample.
A) is separated.

[0002]

2. Description of the Related Art The types and concentrations of constituents in blood such as metabolites, proteins, lipids, electrolytes, enzymes, antigens and antibodies are measured using plasma or the like as a sample. Centrifugation and filtration are known as methods for separating plasma and the like from whole blood, but centrifugation takes time and effort. Especially when a small number of specimens are to be processed promptly or in the field, etc., the centrifugal method using electricity as a power source and requiring a centrifugal separator is not suitable, and the filtration method is preferable.

For this filtration method, several methods have been publicly known, in which a column is filled with glass fiber filter paper, whole blood is injected from one side of the column, and pressure or pressure is applied to obtain plasma or the like from the other side. (JP-B-44-14673, JP-A-2-208565, JP-A-4-208856, JP-B-5-52463, etc.).

Furthermore, the applicant of the present invention, as a blood filtration unit capable of efficiently separating plasma and the like, combines a filter material with glass fiber filter paper and a microporous membrane and provides a sealing member on the plasma outlet side of the filter material to provide a filter material. An application was filed for a blood filtration unit having a narrow opening area (Japanese Patent Laid-Open No. 9-1969).
No. 11, etc.).

The present applicant has completed a blood filtration unit based on these inventions and is commercially available under the trade name of Fuji Dry Chem Plasma Filter. With this blood filtration unit, it is possible to easily obtain the amount of plasma or the like required for analyzing many items by an automatic analyzer by using a dry analysis element (for example, Fuji Drychem manufactured by Fuji Photo Film).

However, the above-mentioned hemofiltration unit cannot be said to have a sufficiently high efficiency of separating plasma or the like from whole blood even if the dead volume part of the unit is removed. , Need a significant amount of whole blood.
In many cases, in order to reduce the burden on subjects whose health condition is not good, especially infants and elderly people, it is preferable that the blood collection amount is small, and it is preferable to keep the blood collection amount to about 1 ml or less.
For this purpose, a technique for more efficiently separating plasma or the like from whole blood is desired.

Conventionally, when separating plasma or the like from whole blood using a glass fiber filter paper, it has been considered that the glass fiber filter paper functions as a so-called volumetric filtration material (for example, Japanese Patent Laid-Open No. 61-038608). That is, large components (for example, white blood cells and red blood cells) in blood are captured relatively early by the voids formed inside the glass fiber, not on the surface of the glass fiber filter paper, and liquid components such as plasma are It was thought to sew through the gap and flow away to be separated from whole blood. Therefore, it is considered to be advantageous to increase the total volume of the glass fiber filter paper in order to increase the amount of plasma or the like to be filtered, but in this case, the plasma etc. remaining inside the glass fiber filter paper also increases, so There was a problem that the amount of blood plasma was not increased as desired.

[0008]

The object of the present invention is to use glass fiber filter paper as the main filtering material,
Particularly, it is to provide a hemofiltration unit that efficiently separates plasma and the like from about 1 ml or less of whole blood.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors focused on the mechanism of separating plasma and the like from whole blood and clarified it. As a result, surprisingly, the red blood cells are not caught in the voids of the glass fiber filter paper, but are temporarily wrapped around the glass fibers, especially the glass fibers having a diameter of about 2 μm or less, which makes the glass cells more viscous than plasma and the like. It was found that there was a difference in the moving speed inside the fiber filter paper. That is, in blood filtration using glass fiber filter paper, it was found that plasma and the like were not separated by volumetric filtration but by a liquid chromatographic mechanism. FIG. 1 shows a situation in which red blood cells are wrapped around the thin glass fibers in the glass fiber filter paper.

The present invention has been made on the basis of such knowledge regarding the separation mechanism, and has an average diameter of about 2 μm.
A glass fiber filter paper containing about 10% to about 90% of the following glass fibers was used as a main filtering material, and the shape thereof was selected, whereby a hemofiltration unit with good separation efficiency could be completed.

That is, in the present invention, glass fibers having an average diameter of about 2 μm or less are used as the main component of the filter medium in an amount of about 10% to about 90%.
%, And a length / diameter of about ½ or more and a diameter of about 10 mm or less.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION If separation is carried out by a liquid chromatographic mechanism as described above, it is considered that the separation efficiency will be improved by making the channel longer. However, if the entire volume of the glass fiber filter paper becomes large, it becomes difficult or impossible to filter a small amount of whole blood, especially about 1 ml or less of whole blood. Therefore, it is preferable that the cross-sectional area of the glass fiber filter paper is set to a certain value or less, and the length of the flow path (the thickness of the glass fiber filter paper) to the cross-sectional area of the glass fiber filter paper is set to a certain value or more. This value can be determined experimentally. For example, when GF / D (glass fiber filter paper manufactured by Whatman) is used, in the case of a circle, the diameter is about 1 cm.
It is preferable that the length is less than or equal to (or the cross-sectional area is about 0.79 cm ² or less) and the length / diameter ratio is equal to or more than 1/2. In the case of a circle, the diameter is about 0.8 cm or less (or the cross-sectional area is about 0.
It is further preferred that the length / diameter ratio is about 1.2 / 2 or more at 50 cm ² or less). In order to obtain a flow path having a required length, it is preferable to stack a plurality of glass fiber filter papers, but it is also possible to wind the glass fiber filter papers in a roll shape for use.

In this case, the total volume of glass fiber filter paper suitable for processing about 1 ml of whole blood sample is 1100 mm.
^{Is 3} . If it exceeds this, the amount of plasma and the like remaining in the filter paper increases, which is not preferable. For smaller amounts of analyte, the preferred total volume of glass fiber filter paper decreases in proportion to the amount of analyte.

The glass fiber filter paper is usually composed of two kinds of glass fiber groups having different average diameters. GF / D above
Contains about 55% of glass fibers having an average diameter of about 2 μm or less. Since the glass fiber filter paper is produced by a papermaking method, it is understood that the distribution of glass fibers having different thicknesses cannot be controlled inside the glass fiber filter paper and they are uniformly distributed.

The density of the glass fiber filter paper is 0.02 to 0.5.
g / cm ³ or so, preferably 0.03 to 0.2 g / cm ³
Degree, particularly preferably about 0.05 to 0.13 g / cm ³ , and the retained particle size is about 0.6 to 9 μm, particularly 1 to 5 μm.
It is preferably about m.

In order to prepare a blood filtration unit using such a glass fiber filter paper, it is preferable to store the glass fiber filter paper in a container having a fixed shape. This container may have at least two openings for sucking whole blood and taking out filtered plasma or the like. There is no restriction on the cross-sectional shape of the glass fiber filter paper, and it may be any shape such as circular, rectangular, hexagonal, etc. However, circular shape is preferable from the viewpoint of ease of manufacturing, and rectangular shape is preferable from the point of not discarding the waste part of the glass fiber filter paper .

On the outlet side of the filtered plasma of the glass fiber filter paper,
It is preferable to install a microporous membrane having a hydrophilic surface to capture the red blood cells that pass through the glass fiber filter paper and come out to the surface. This microporous membrane has a pore size smaller than the retained particle size of the glass fiber filter paper and 0.2 μm or more, preferably 0.3.
Approximately about 5 μm, more preferably about 0.5 to 3 μm. Further, it is preferable that the porosity is high,
Specifically, a porosity of about 40% to about 95%, preferably about 50% to about 95%, more preferably about 70% to about 95% is suitable. Examples of microporous membranes include polysulfone membranes, fluorine-containing polymer membranes, cellulose acetate membranes and the like, with polysulfone membranes being preferred. The thickness of the microporous membrane is about 0.05 to 0.5 mm, especially 0.1.
It may be about 0.3 mm, and usually one microporous membrane may be used. However, a plurality of sheets can be used if necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0019]

EXAMPLES Example 1 Inner diameters of 3.5 mm, 4.5 mm, 7.5 mm and 11.
Glass tubes of 5 mm and 14.5 mm were prepared, and GF / D (glass fiber filter paper manufactured by Whatman) was placed in the glass tubes.
The filter papers were packed so that the total volume was close to each other. At the tip of this glass tube, whole blood (Hct
45% value) was inserted into about 1.1 ml and aspirated using a peristaltic pump. At this time, the scale of the peristaltic pump was adjusted so that the moving speed of the liquid in the glass fiber filter paper was almost the same.

Suction was terminated immediately before the whole sample blood was sucked into the lower end of each glass tube. At this time, the positions of the upper and lower ends of the filtered plasma accumulated on the upper end of the glass fiber filter paper were photographed by a video equipped with a micro CCD camera. The observation magnification was between about 1.2 times and 1.5 times. Output to the printer after shooting. The length of the plasma part was measured using this output image, and the volume of plasma obtained from this and the inner diameter of the glass tube was calculated.

The experimental conditions and results are shown in Table 1. From this result, when the inner diameter of the glass tube, that is, the diameter of the glass fiber filter paper is about 10 mm or less and the length of the glass fiber filter paper / the diameter of the glass fiber filter paper is about 5/10 or more, the plasma recovery rate is improved,
It proves to be preferable to filter plasma from a small amount of whole blood.

[0022]

[Table 1]

[0023]

INDUSTRIAL APPLICABILITY With the filtration unit of the present invention, plasma and the like can be efficiently separated from a small amount of whole blood by filtration.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing a state in which red blood cells are entangled in glass fibers. 1a is x1,
000, FIG. 1b is x10,000.

Continued front page    (72) Inventor Yuji Mihara             Fuji Photo, 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture             Within Film Co., Ltd. (72) Inventor Kikuo Hirai             3-11-46 Izumi, Asaka-shi, Saitama Prefecture             Shin Film Co., Ltd. (72) Inventor Kaoru Terashima             3-11-46 Izumi, Asaka-shi, Saitama Prefecture             Shin Film Co., Ltd. F-term (reference) 2G045 AA01 BB05 CA25 HB02 HB05

Claims (2)

[Claims] 1. A diameter of about 1 having at least 2 openings.
A blood filtration unit in which a glass fiber filter paper is filled so that the length / diameter is 1/2 or more in a container of cm or less. 2. The total volume of glass fiber filter paper is about 1100 m.
The hemofiltration unit according to claim 1, which has a m ³ or less.