Patent ID: 12226716

DESCRIPTION OF EMBODIMENTS

Description will be made below with reference to the drawings regarding examples of the present invention. It should be noted that the invention according to the present application is not restricted to the examples described below.

EXAMPLES

The present invention relates to a three-dimensional filter structured to classify a target material mainly contained in a liquid in a size-selective and affinity-specific manner and a target cell capture method using the three-dimensional filter, and particularly to a three-dimensional filter, etc., structured to effectively capture target cells contained in a liquid.

FIG.1Ais a diagram showing target cell capture filter1and target cell capture filter21according to the present example. The target cell capture filter1and target cell capture filter21are each structured in a sheet shape before they are used. Furthermore, the target cell capture filter1and target cell capture filter21are each structured as an example of the “target cell capture filter” according to the appended claims.

The target cell capture filter1shown inFIG.1A(which will be referred to as a “compound3D filter1” hereafter) includes multiple different sets of concentric-circle-shaped (an example of “figure pattern” or “concentric circle” in the appended claims) notches3(an example of the “notches” in the appended claims) in a single face (an example of the “capture face” in the appended claims). On the other hand, the target cell capture filter21shown inFIG.1B(which will be referred to as an “equally spaced filter21” hereafter) has a single set of concentric-circle-shaped (an example of “figure pattern” or “concentric circle” in the appended claims) notches3. With such an arrangement including the notches3, this allows a part of the face to be elastically deformed in a direction that is orthogonal to the face itself, thereby providing a gap. With such an arrangement, the interval between the concentric notches becomes narrower closer to the outer side from the center thereof, such that the concentric gaps are positioned at regular intervals when the target cell capture filter21is elastically deformed under fluid force.

FIG.2is a graph showing results of measurement of capture density of target cells according to differences in notches of the target cell capture filters. Description will be made regarding the measurement. The measurement is made assuming that target cells are modified by nucleic acid aptamers beforehand, and biotin-avidin binding is used for binding to the filter. Specifically, nucleic acid aptamers terminally modified with biotin are introduced into a sample solution containing target cells, thereby binding the target cells and the nucleic acid aptamers. The filter is modified by avidin. Subsequently, the sample solution is introduced to the filter so as to capture the target cells by biotin-avidin binding. As shown inFIG.2, in comparison of the equally spaced filter21according to the present example with a conventional filter51, the equally spaced filter21has a target cell capture density improved by three times or more. Furthermore, it can be seen that the compound3D filter1has a target cell capture density improved by approximately 20 times as compared with the conventional filter51.

The target cell capture filters1and21have multiple notches3structured such that they are elastically deformed and form gaps, and at least part of the multiple notches3have the following features.(1) The number of such notches is plural.(2) There is a difference between the multiple notches in the shortest distance from the greatest deformation location of each notch to the outer edge5of the target cell capture filter. The multiple notches that have such features will be referred to as the “first notch group” (an example of the “first notch group” in the appended claims) hereafter.

Furthermore, the first notch group also has a feature as follows. That is to say, the first notch group exhibits an equal elastic deformation amount with respect to the impulse per unit area regardless of whether the notch is positioned in a center portion7that is a region including the center of the filter or in an outer edge portion9that is a region adjacent to the outer edge of the filter.

Here, the amount of deformation is represented by the area of a gap, and can be approximately represented by the product of the length of the gap and the distance of deformation.

Furthermore, in the target cell capture filter21, the notches3are designed to have the same length. Accordingly, the filter is formed with an increased rigidity as compared with the conventional filter51in which the length of the concentric-circle-shaped notch becomes longer closer to the outer side. With this, clogging readily occurs in the filter before deformation into a three-dimensional shape. This allows the target cell capture filter21to easily retain a capture target object. It is conceivable that this point also contributed to the improved capture ratio of target cells.

In contrast, in the target cell capture filter1, the circular-shaped notch is designed to have a length that is shorter as the size of the circular-shaped notch is smaller.

The cell capture filter according to the present example exhibits approximately the same level of elastic deformation at the center portion and the outer edge portion. This allows liquid to easily pass through uniformly over the entire face of the filter. Accordingly, the amount of the capture target object that comes in contact with the filter per unit area is approximately the same level regardless of whether it comes in contact with a central portion or an outer edge portion. This enables marked improvement in the capture ratio of the capture target object as compared to conventional filters.

It should be noted that description has been made in the present example regarding the target cell capture filter having a sheet shape. Also, the target cell capture filter may have a shape other than a sheet shape as long as it has a shape that has a capture face. For example, the target cell capture filter may have a thin-film shape. Also, the capture face is not restricted to being a flat face, and may be a curved face.

REFERENCE SIGNS LIST

Target cell capture filter1, Notch3, Outer edge5, Center portion7, Outer edge portion9, Target cell capture filter21.