JP7709899B2 - Method for manufacturing sample-loading plate - Google Patents

Description

The present invention relates to a sample loading plate for loading samples and a method for manufacturing the same.

Matrix Assisted Laser Desorption/Ionization (MALDI) is known as one of the mass spectrometry ionization methods that can rapidly and accurately diagnose pathogens and bacteria.

The MALDI method is a method for analyzing analytes that do not easily absorb laser light or are easily damaged by laser light. The sample is mixed in advance with a substance (matrix) that easily absorbs laser light and is easily ionized, and the sample is ionized by irradiating it with laser light.

In mass spectrometry using the MALDI method, a metal plate called a target plate (hereafter referred to as the "sample loading plate") is generally placed inside the device on which the analyte and matrix are mixed in advance and liquefied with a solvent (hereafter referred to as the "sample"). The sample loaded on the sample loading plate is irradiated with laser light for a predetermined period of time to desorb and ionize the sample. At this time, a voltage is applied to the metal sample loading plate, and an electric field is applied to the desorbed and ionized sample, making it easier for the desorbed and ionized sample to fly toward the acceleration electrode.

The sample loading plate has multiple sample placement areas for loading samples, and multiple samples to be measured are dropped onto the designated sample loading areas, dried (crystallized), and then placed inside the mass spectrometer. The sample loading plate is then moved so that the laser can be irradiated onto the multiple samples.

For example, Patent Document 1 discloses a technique for retaining a dropped sample on a sample loading section by modifying the surface of the sample loading section on a sample loading plate to be hydrophilic, forming a hydrophilic modified layer.

JP 2021-57148 A

The sample loading plate is transported for drying or the like with a liquid sample loaded on the sample loading section of the sample loading plate. During this process, the sample loading plate may not be held horizontally but may be tilted or vibrations may be applied during transport. In the case of the sample loading plate, the tilting or vibrations of the sample loading plate may cause the sample that should be held on the sample loading section to fall off the sample loading section or the sample to spread wetly to areas other than the sample loading section, making it impossible to properly analyze the sample. In response to this problem, attempts have been made to make the sample loading section hydrophilic, but for example, in mass spectrometry using the MALDI method or the like, laser light is irradiated onto the sample, which places restrictions on the material of the sample loading section, and there have been problems in ensuring sufficient hydrophilicity to hold the sample on the sample loading section.

The present invention was made in consideration of the above problems, and aims to provide a sample loading plate capable of properly holding a sample on the sample loading section, and a method for manufacturing the same.

The sample loading plate is provided with a sample loading section having a hydrophilic surface on a substrate, and a hydrophilic member having a higher hydrophilicity than the hydrophilic surface is partially embedded in the hydrophilic surface. The hydrophilic surface may be a rough surface having a rougher surface than the surface of the substrate surrounding the sample loading section. The sample loading section is formed by blasting a part of the substrate, and the hydrophilic member may be a projecting material used in the blasting. The sample loading section may be a well having a bottom portion and a side portion. The surface of the substrate surrounding the sample loading section may be provided with a water-repellent film.
In addition, a method for manufacturing a sample-loading plate having a sample-loading section on a substrate with a hydrophilic surface includes a blasting process step of projecting a hydrophilic member having a higher hydrophilicity than the hydrophilic surface onto the hydrophilic surface to form the sample-loading section, the blasting process step being a process of embedding the hydrophilic member in the hydrophilic surface. The blasting process step may be a process of roughening the surface roughness of the hydrophilic surface. The method may include a water-repellent film forming process of forming a water-repellent film on the surface of the substrate before or after the blasting process.

The sample loading plate and manufacturing method of the present invention make it possible to provide a sample loading plate that can properly hold the sample loaded on the sample loading section.

FIG. 1 is a diagram showing an embodiment of a sample loading plate of the present invention. 2 is a schematic cross-sectional view illustrating a state in which a sample is placed on a sample placement portion of the sample loading plate in the present invention. FIG. 1 is a schematic diagram showing a method for producing a sample-loading plate according to the present invention. FIG. 13 shows a sample loading plate according to another embodiment of the present invention. 5A to 5C are schematic diagrams showing a method for manufacturing a sample loading plate according to another embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the scale and number of each structure may differ from the actual shape and structure in order to make each component easier to understand. Figure 1 shows one embodiment of a sample-loading plate of the present invention, where (a) is a plan view of the sample-loading plate and (b) is a cross-sectional view taken along line A-A in (a).

The sample-loading plate 10 shown in Figure 1 comprises a plurality of wells 6 having a bottom portion 6a and a side portion 6b on a substrate 1. The wells 6 are sample-loading portions for holding samples containing an analyte on the substrate 1, and a hydrophilic material 5 having hydrophilic properties is partially embedded in the surfaces of the bottom portion 6a and the side portion 6b of the wells 6. The substrate 1 is made of a hydrophilic and conductive material, for example, a metal such as stainless steel, aluminum, or an aluminum alloy, and is a roughly rectangular flat plate with an outer dimension of about 120 mm x 80 mm and a thickness of about 2 mm. The wells 6 formed in the substrate 1 are 0.8 mm in diameter and 0.1 mm deep. The arithmetic mean roughness Ra of the surface of the substrate 1 excluding the well 6 is 0.1 μm, the arithmetic mean roughness Ra of the bottom surface 6a of the well 6 is 2.0 μm, and the arithmetic mean roughness Ra of the side surface 6b is 2.5 μm, so that the well 6 has a rougher surface than the rest of the substrate 1, and the side surface 6b of the well 6 is rougher than the bottom surface 6a. The hydrophilic member 5 is made of particles of silicon dioxide, aluminum oxide, or titanium oxide with a particle size of, for example, about 27 to 74 μm, which is more hydrophilic than the substrate 1, and is embedded in the well 6 with part of its outer surface exposed to the outside.

Figure 2 is a cross-sectional view showing the state in which a sample is loaded on the sample loading plate 10. The sample 30 dropped into the well 6, which is the sample loading portion, spreads radially due to gravity and surface tension, and the spreading stops when the surface free energy between the sample 30 and the well 6 and the surface of the substrate 1 around it is balanced. Here, in the sample loading plate 10 of this embodiment, the bottom surface 6a and side surface 6b of the well 6 have a rougher surface than the surface of the substrate 1 around the well 6, and are more hydrophilic than the surroundings of the well 6 of the substrate 1, so that the effect of holding the sample 30 in the well 6 (anchor effect) is high. Furthermore, in this embodiment, a hydrophilic member 5 is embedded in the bottom surface 6a and side surface 6b of the well 6 so that a part of its surface is exposed to the outside. The hydrophilic member 5 is a member that is more hydrophilic than the surface of the substrate 1 (and the surface of the well 6), and by embedding it in the well 6, the surface exposed area of the sample loading portion is increased compared to when the hydrophilic member 5 is not embedded, and in addition to the well 6 being rough, a higher anchor effect is achieved. In addition, by using a photocatalyst such as titanium oxide for the hydrophilic member 5, it is possible to obtain stable hydrophilicity over the long term (anchor effect).

Next, the manufacturing method of the sample-loading plate 10 will be described with reference to the drawings. FIG. 3 is a schematic diagram showing the manufacturing method of the sample-loading plate 10. The sample-loading plate 10 shown in FIG. 1 is manufactured by the following steps.

[Substrate preparation process: FIG. 3(a)]
First, prepare the substrate 1. In this embodiment, the substrate 1 has an outer dimension of about 120 mm×80 mm and a thickness of about 2 mm. The substrate 1 is preferably made of, for example, stainless steel, aluminum, or an aluminum alloy.

[Blast processing step: Figure 3(b)]
Next, a well 6, which is a sample loading portion, is formed in the substrate 1 by blasting (see FIG. 3(c) for the state after processing). In this process, a hydrophilic member 5 is projected from a nozzle 4 of a blasting device onto the substrate 1 to form a well 6, roughen the surface of the well 6, and embed the hydrophilic member 5 in the bottom portion 6a and side portion 6b of the well 6. The well 6 is formed by scraping the substrate 1 with the hydrophilic member 5 projected from the nozzle 4. The projection speed, projection distance, projection angle, etc. of the hydrophilic member 5 onto the substrate 1 are determined so that a part of the hydrophilic member 5 projected from the nozzle 4 is embedded in the surface of the bottom portion 6a and side portion 6b of the well 6 and remains on the surface of the well 6. In this embodiment, the hydrophilic member 5 is projected at an angle with respect to the substrate 1. Therefore, the amount of the hydrophilic member 5 embedded in the side portion 6b is greater than that of the bottom portion 6a, and as a result, the hydrophilicity of the side portion 6b is higher than that of the bottom portion 6a. The well 6 thus formed by the blasting process has a rough surface with a larger surface roughness of the bottom portion 6a and the side portion 6b than that of the substrate 1, and the side surface 6b is rougher than the bottom surface 6a by projecting the hydrophilic member 5 at an angle. In this process, the hydrophilic member 5 is embedded in the well 6 at the same time as the well 6 is formed, and the sample loading portion can be formed more efficiently than when each of these processes is performed as a separate process. In this process, a mask having an opening may be placed at a position corresponding to the well 6 of the substrate 1, and the hydrophilic member 5 may be projected from the nozzle 4. This allows for more accurate processing.

[Cleaning step: FIG. 3(c)]
Finally, the sample-loading plate 10 is washed with a washing solution to remove the hydrophilic material 5 that is not embedded but adheres to the surfaces of the bottom portion 6a and side portion 6b of the wells 6. In this washing step, most of the hydrophilic material 5 embedded in the wells 6 is not removed because it is embedded in the wells 6 with sufficient energy. Through the above steps, the sample-loading plate 10 of this embodiment is obtained.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows a sample loading plate 20 of the present invention, where (a) is a plan view of the sample loading plate, and (b) is a cross-sectional view of A-A in (a). Note that the same reference numerals are used for configurations similar to those in the previously described embodiment, and descriptions of overlapping configurations will be omitted. The sample loading plate 20 in this embodiment includes a well 6 serving as a sample loading portion on a substrate 1, a hydrophilic member 5 embedded in the surface of the bottom portion 6a and the side portion 6b of the well, and a water-repellent film 2. The water-repellent film 2 is formed on the entire surface of the substrate 1 except for the well 6, and the well 6 is surrounded by the water-repellent film 2. The water-repellent film 2 is, for example, a water-repellent material containing carbon (C), fluorine (F) or silicon (Si), or a composite water-repellent material thereof, and has a thickness of, for example, 5 nm. In this embodiment, the well 6 is surrounded by a water-repellent film 2, which has the advantage that the spread of the sample 30 can be reduced compared to the sample loading plate 10, thereby reducing the risk of the sample coming into contact with each of the multiple sample loading sections.

Next, the manufacturing method of the sample-loading plate 20 will be described with reference to the drawings. FIG. 5 is a schematic diagram showing the manufacturing method of the sample-loading plate 20 of the present invention. The sample-loading plate 20 shown in FIG. 4 is manufactured by the following steps. Note that some of the explanations of the steps that are the same as those in the manufacturing method of the sample-loading plate 10 shown in FIG. 3 may be omitted.

[Water-repellent film formation process: FIG. 5(a)]
First, the substrate 1 is prepared, and the water-repellent film 2 is formed on the entire surface of one surface of the substrate 1. The water-repellent film 2 is formed by a film forming method such as vacuum deposition.

[Mask placement process: FIG. 5(b)]
Next, a mask 3 having an opening is placed on the surface of the substrate 1 on which the water-repellent film 2 is formed. The mask 3 having an opening is a metal mask 3 or a mask 3 made of a resist film formed using a known photolithography technique. The opening of the mask 3 is an area including the wells 6 of the sample-loading plate 20, and corresponds to a projection area of the hydrophilic member 5 onto the substrate 1, which will be described later. In this embodiment, the mask 3 is used when forming the wells 6, but the hydrophilic member 5 may be projected onto the substrate 1 without using the mask 3.

[Blast processing process: Fig. 5 (c-1), Fig. 5 (c-2)]
Next, a hydrophilic material 5 is projected from a nozzle 4 onto positions (openings of the mask 3) corresponding to the wells 6 of the substrate 1 (see FIG. 5(c-1)). In this process, the water-repellent film 2 is removed from the area where the wells 6 are to be formed, and the wells 6 are formed with rough bottom and side surfaces 6a and 6b, and at the same time, the hydrophilic material 5 is embedded in the wells 6 (see FIG. 5(c-2) for the state after processing).

[Cleaning step: FIG. 5(d)]
Finally, the mask 3 placed on the substrate 1 is removed, and the sample-loading plate 20 is washed with a washing solution to remove the hydrophilic material 5 that is not embedded but adheres to the surfaces of the bottom portion 6a and side portion 6b of the wells 6. In this washing, most of the hydrophilic material 5 embedded in the wells 6 is not removed because it is embedded in the wells 6 with sufficient energy. The sample-loading plate 20 of this embodiment is obtained by the above steps.

The sample-loading plate and the method for manufacturing the sample-loading plate of the present invention have been described above based on the examples, but any modification can be made within the scope of the technical concept of the present invention. For example, in the method for manufacturing the sample-loading plate 20, the well 6 is formed after the water-repellent film 2 is formed on the substrate 1, but the water-repellent film 2 may be formed around the well 6 by placing a mask covering the well 6 after the well 6 is formed. Also, the sample loading portion is a well 6 with a bottom portion 6a and a side portion 6b, but the sample loading portion may be a cone-shaped sample loading portion with an inclined surface toward the center of the sample loading portion.

REFERENCE SIGNS LIST 1 Substrate 2 Water-repellent film 3 Mask 4 Nozzle 5 Projection material 6 Well 6a Bottom surface 6b Side surface 10, 20 Sample-loading plate 30 Sample

Claims (3)

A method for manufacturing a sample loading plate having a sample loading portion having a hydrophilic surface on a substrate, comprising the steps of:
a blasting process step of projecting a hydrophilic member having a higher hydrophilicity than the hydrophilic surface onto the hydrophilic surface to form the sample loading section;
A method for manufacturing a sample-loading plate, wherein the blast processing step is a step of embedding the hydrophilic material in the hydrophilic surface. 2. The method for manufacturing a sample-loading plate according to claim 1 , wherein the blast processing step is a step of roughening the surface roughness of the hydrophilic surface. 3. The method for manufacturing a sample-loading plate according to claim 1 , further comprising a water-repellent film forming step of forming a water-repellent film on the surface of the substrate before or after the blast processing step.