Method for manufacturing a biomolecular detector, a biomolecular detector, and a method for detecting biomolecules

Abstract

This invention provides a method for manufacturing an inexpensive biomolecular detector with low sensitivity variability, a biomolecular detector, and a method for detecting biomolecules using the biomolecular detector. [Solution] The method for manufacturing a biomolecule detector according to the embodiment comprises the steps of: preparing a solution in which carbon oxide nanotubes having carboxyl groups are dispersed in a solvent; forming a thin film made of the carbon oxide nanotubes on the surface of the filter material by suction filtration of the solution from the back side of the filter material; and binding an antibody that selectively captures biomolecules to the carboxyl groups of the carbon oxide nanotubes in the thin film.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a biomolecular detector, a biomolecular detector, and a method for detecting biomolecules. [Background technology]

[0002] As one method for detecting antigen-antibody reactions (specific adsorption reactions, immune reactions), Patent Document 1 describes the use of a biosensor in which carbon oxide nanotubes are immobilized on a gold electrode by a spray method, and antibodies are bound to the carbon oxide nanotubes.

[0003] However, gold electrodes are expensive, making it difficult to reduce the cost of biosensors. Furthermore, the carbon oxide nanotubes immobilized on the gold electrodes are not uniform, resulting in significant sensitivity variations between biosensors. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-123411 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention provides a method for manufacturing an inexpensive biomolecular detector with low sensitivity variability, a biomolecular detector, and a method for detecting biomolecules using the biomolecular detector. However, the present invention is not limited to this purpose, and may also be aimed at purposes corresponding to the effects of the configurations of each embodiment described later. [Means for solving the problem]

[0006] The method for producing a biomolecular detector according to the present invention is: A step to prepare a solution in which carbon oxide nanotubes having carboxyl groups are dispersed in a solvent, The process involves forming a thin film made of carbon oxide nanotubes on the surface of the filter material by suction filtration of the solution from the back side of the filter material, The process involves attaching an antibody that selectively captures biomolecules to the carboxyl group of the carbon oxide nanotube in the thin film, It is equipped with.

[0007] In the method for producing the biomolecular detector, After the step of binding the antibody to the carboxyl group of the carbon oxide nanotube, The process may further include a step of bonding inert molecules to the carbon oxide nanotubes.

[0008] In the method for producing the biomolecular detector, The method may further include the steps of applying a conductive paste to a first portion of the thin film to form a first electrode, and applying a conductive paste to a second portion of the thin film to form a second electrode.

[0009] In the method for producing the biomolecular detector, A step of forming a first electrode and a second electrode on the surface of an insulating substrate, A step of fixing the filter material to the insulating substrate such that a first portion of the thin film contacts the first electrode and a second portion of the thin film contacts the second electrode, It may also be provided.

[0010] The biomolecule detection method according to the present invention is The biomolecular detector manufactured by the above method for manufacturing a biomolecular detector is immersed in a solution in which biomolecules are dissolved, A step of measuring the DC resistance between the first electrode and the second electrode of the biomolecular detector, It is equipped with.

[0011] The biomolecular detector according to the present invention is filter media and A thin film made of carbon oxide nanotubes is directly fixed on the filter material, A first electrode covering the first portion of the thin film, a second electrode covering the second portion of the thin film; comprising An antibody that selectively captures biomolecules is bound to the carboxyl groups of the carbon nanotube oxide in the thin film.

[0012] Also, in the biomolecule detector, The filter medium may be filter paper, filter cloth, or sponge.

[0013] Also, in the biomolecule detector, The density of the carbon nanotube oxide in the thin film may be in the range of 0.1 to 2.6 μg / cm 2 of. [Advantages of the Invention]

[0014] According to the present invention, it is possible to provide a method for manufacturing a biomolecule detector that is inexpensive and has little variation in sensitivity, a biomolecule detector, and a method for detecting biomolecules using the biomolecule detector. [Brief Description of the Drawings]

[0015] [Figure 1] It is a flowchart for explaining a method for manufacturing a biomolecule detector according to an embodiment. [[ID=�6]] [Figure 2] It is a diagram for explaining the suction filtration step according to an embodiment. [Figure 3] It is an example of a photograph showing an oxidized CNT thin film formed on a filter medium by suction filtration according to an embodiment. [Figure 4] (a) is an example of a SEM image of the surface of filter paper, and (b), (c), and (d) are examples of SEM images of the surfaces of oxidized CNT thin films with different film formation amounts. [Figure 5] (a), (b), and (c) are examples of SEM images of the cross-sections of filter paper on which oxidized CNT thin films with different film formation amounts are formed. [Figure 6] It is a graph showing the relationship between the film formation amount of oxidized CNT and the resistance of the oxidized CNT thin film. [Figure 7](a) is a plan view of the biomolecular detector according to the embodiment, and (b) is a cross-sectional view along line II in (a). [Figure 8] This is a flowchart illustrating a method for detecting biomolecules using a biomolecular detector according to this embodiment. [Figure 9] This graph shows the IV characteristics of a biomolecular detector, with the cortisol concentration in solution as a parameter. [Figure 10] This graph shows the relationship between the cortisol concentration in a solution and the DC resistance between the electrodes of a biomolecular detector. [Figure 11] This graph shows the relationship between the melatonin concentration in a solution and the DC resistance between the electrodes of a biomolecular detector. [Figure 12] (a) and (b) are diagrams illustrating the change in resistance of a biomolecular detector due to the adsorption of an antigen onto an antibody. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, components having equivalent functions are denoted by the same reference numerals. Also, the drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thickness of each layer, etc., may differ from those in reality.

[0017] <Method for manufacturing a biomolecular detector> Referring to the flowchart in Figure 1, an example of a method for manufacturing a biomolecular detector according to this embodiment will be described.

[0018] Step S11: Carbon nanotubes are subjected to an oxidation treatment to form oxide carbon nanotubes having carboxyl groups. This oxidation treatment is carried out, for example, by dispersing the carbon nanotubes in hydrogen peroxide, heating, and then stirring. Oxide carbon nanotubes are hydrophilic.

[0019] The carbon nanotubes used in this step are single-walled carbon nanotubes, but they are not limited to single-walled carbon nanotubes; double-walled carbon nanotubes or multi-walled carbon nanotubes may also be used. Note that oxidized carbon nanotubes are also called oxidized CNTs or ox-CNTs.

[0020] Step S12: Prepare a solution in which the carbon oxide nanotubes formed in Step S11 are dispersed in a solvent (hereinafter also referred to as the "CNT solution"). The CNT solution can be prepared, for example, by washing the oxidized CNTs obtained in Step S11 with ultrapure water, freeze-drying them, and mixing them with a mixed solution of ethanol and 2-propanol. The dispersibility of the CNTs may be improved by stirring the CNT solution with an ultrasonic homogenizer.

[0021] Step S13: The solution prepared in Step S12 is filtered by suction from the back side of the filter material to form (fix and adsorb) a thin film made of carbon oxide nanotubes on the surface of the filter material. Figure 2 shows the suction filtration performed in Step S13. A suction funnel 200 is connected to the upper opening of the suction bottle 100 via a rubber stopper 150. The filter material 11 is placed inside the suction funnel 200. In this embodiment, the filter material 11 is filter paper. The filter paper used in this step is, for example, a membrane filter made of polyvinylidene fluoride (PVDF).

[0022] The suction bottle 100 is connected to a vacuum device 300, such as an aspirator. When the vacuum device 300 operates, the inside of the suction bottle 100 is depressurized. As a result, the CNT solution poured into the suction funnel 200 is drawn in from the back side of the filter material 11. Consequently, a thin film of oxide CNT 12 is formed on the surface of the filter material 11. The thin film of oxide CNT 12 is a thin film containing oxide carbon nanotubes. The amount of the CNT thin film 12 formed can be adjusted by changing the amount of CNT solution poured into the suction funnel 200. In this application, the CNT thin film 12 is also simply referred to as a thin film.

[0023] Figure 3 is an example photograph showing a thin film of carbon oxide nanotubes (CNTs) formed on the filter medium 11 by suction filtration. In this example, the CNT solution in the suction funnel 200 was subjected to suction filtration at a suction pressure of 80 kPa for 30 seconds to deposit a thin film of carbon oxide nanotubes on the filter medium 11.

[0024] The filter material can be any material that allows the solvent to pass through but prevents carbon oxide nanotubes from passing through, such as filter cloth or sponge.

[0025] Step S14: The filter material 11, on which the oxide CNT thin film 12 has been formed on its surface, is processed into a predetermined shape and fixed to a support member (see support member 15 described later). For example, the filter material 11 is cut into a rectangle (strip shape) and fixed to the support member. The filter material 11 is fixed to the support member using tape such as Kapton tape, adhesive, etc.

[0026] Step S15: A conductive paste is applied to one end (first portion) of the carbon oxide thin film 12 to form the first electrode, and a conductive paste is applied to the other end (second portion) of the carbon oxide thin film 12 to form the second electrode. That is, electrodes are formed by applying conductive paste to both ends of the carbon oxide thin film 12 on the rectangular filter material 11 processed in step S14. For example, silver paste is used as the conductive paste.

[0027] Furthermore, the first and second electrodes also function as reinforcing members that reinforce the laminate consisting of the filter material 11 and the carbon oxide nanotube (CNT) thin film 12. The locations where the first and second electrodes are formed do not need to be limited to the edges of the CNT thin film 12; they can be formed in any location that is spaced apart from each other.

[0028] Step S16: An antibody that selectively captures biomolecules (antigens) is bound to the carboxyl group of the carbon oxide nanotube in the oxidized CNT thin film 12. In this embodiment, as an example of a sensor for measuring cortisol, an anti-cortisol antibody was immobilized on oxidized CNT using an EDC / NHS reaction. Specifically, the carboxyl group is reacted with EDC to form an O-osylisourea intermediate. The unstable O-osylisourea intermediate reacts with NHS to form a relatively stable NHS ester terminus on the carboxyl group.

[0029] Because the NHS ester terminus formed in this way is highly reactive with amino groups, it is possible to chemically bond primary amines, such as protein molecules containing amino groups, to the NHS ester terminus via amide bonds. By binding the amino group of an antibody to oxidized carbon nanotubes (CNTs) in this way, antibodies such as anti-cortisol antibodies can be immobilized on oxidized CNTs. Note that the antibody immobilized on oxidized CNTs is not limited to anti-cortisol antibodies; other antibodies such as anti-melatonin antibodies may also be used.

[0030] Step S17: A blocking treatment is performed in which an inert molecule (blocking material) is bound to the oxidized CNT. Specifically, an inert molecule is bound to the NHS ester end that is not bound to the antibody in Step S16. For example, triethylene glycolamine (Amino-PEG), a type of primary amine, is used as the blocking material. By performing the blocking treatment, it is possible to suppress the binding of residual NHS ester ends to unexpected molecules (non-specific adsorption) which would reduce the sensitivity of the biosensor.

[0031] The biomolecular detector according to the embodiment is manufactured through the steps described above. Note that the above manufacturing method is merely an example, and various modifications are possible. For example, step S15, in which electrodes are formed, may be performed before step S14, in which the filter material 11 is processed. Also, the processing of the filter material 11 in step S14 may be omitted. Furthermore, step S17 may be omitted.

[0032] In step S15, electrodes were formed by applying a conductive paste to the filter material 11, but this embodiment is not limited to this method. For example, an insulating substrate (not shown), such as a glass plate, may be prepared, and a first electrode and a second electrode may be formed on the surface of this insulating substrate. The first electrode and the second electrode may be formed, for example, as parallel lines. Each electrode may also be formed by applying a conductive paste. After that, the filter material 11 is fixed to the insulating substrate such that a first portion of the carbon oxide thin film 12 (for example, one end of the carbon oxide thin film 12) contacts the first electrode and a second portion of the carbon oxide thin film 12 (for example, the other end of the carbon oxide thin film 12) contacts the second electrode. The filter material 11 is fixed to the insulating substrate by tape or adhesive.

[0033] Here, images of the surface and cross-section of the carbon oxide nanotube (CNT) thin film 12 taken by scanning electron microscopy (SEM) are shown in Figures 4 and 5, respectively. Figures 4(b), (c), and (d) are examples of images of the surface of the carbon oxide nanotube (CNT) thin film 12 with different amounts of deposited CNTs. Figure 4(a) is an example of an SEM image of the surface of the filter paper (filter material 11). As can be seen from Figure 4(b), in the sample with a deposited amount of 50 μg, the fibers of the filter paper were visible behind the carbon oxide nanotube. As can be seen from Figure 4(c), in the sample with a deposited amount of 100 μg, the fibers of the filter paper were hidden by the carbon oxide nanotube and were no longer visible.

[0034] Figures 5(a), (b), and (c) are examples of SEM images of cross-sections of filter media 11 with a thin film of carbon oxide nanotubes (ox-CNTs) formed on its surface. In all samples, it was confirmed that the filter paper layer and the carbon oxide nanotube (ox-CNT) layer were separated, and that the filter paper fibers and carbon oxide nanotubes were intricately intertwined at the boundary between the two layers. Furthermore, there was no significant difference in the thickness of the carbon oxide nanotube thin film 12 regardless of the amount of carbon oxide nanotube deposited. From this, it is considered that the density of carbon oxide nanotubes increases as the amount of deposited film increases.

[0035] Furthermore, Figure 6 shows the measurement results illustrating the relationship between the resistance / sheet resistance of the CNT oxide thin film 12 and the amount of CNTs deposited. The resistance R of the CNT oxide thin film 12 was measured using the four-terminal resistance measurement method. Subsequently, the sheet resistance ρ was calculated from the width of the sample and the distance between terminals. s The value was calculated. Here, the filter material 11 on which the oxide CNT thin film 12 was formed was cut into a rectangle with a width of 2 mm, and the distance between the terminals to which the voltage was applied was set to 5 mm. As can be seen from Figure 6, there is an inverse relationship between the amount of oxide CNT film formed and the sheet resistance. From this, it can be concluded that the oxide CNT film was formed uniformly.

[0036] The biomolecular detector manufactured by the manufacturing method of this embodiment can form a uniform carbon nanotube (CNT) thin film 12 on the filter material 11 by suction filtration. This makes it possible to easily obtain a biomolecular detector 10 with little variation (i.e., stable sensitivity).

[0037] Furthermore, since the carbon oxide nanotube (CNT) thin film 12 is directly fixed to the filter material 11 without the need for an adhesive solvent such as a polymer, the conductivity of the CNT thin film 12 is increased, allowing for high-precision detection of the antigen.

[0038] Furthermore, in the biomolecular detector of this embodiment, oxidized carbon nanotubes (CNTs) penetrate deep into the fibers of the filter material 11, and antibodies are immobilized on these oxidized CNTs. Therefore, compared to conventional biomolecular detectors with antibodies immobilized on gold electrodes, this embodiment has the advantage of producing a larger amount of antibody and preventing saturation of the antigen-antibody reaction even at high antigen concentrations. As a result, the biomolecular detector of this embodiment can detect antigens over a wide concentration range, including high concentrations. This can also be seen from the graph in Figure 10, which will be described later.

[0039] Furthermore, since the biomolecular detector 10 of this embodiment uses a filter material 11 such as filter paper, it is significantly less expensive and lighter than those using expensive gold electrodes. Therefore, according to this embodiment, an inexpensive and disposable biosensor can be provided.

[0040] <Biomolecular Detector> The biomolecular detector 10 manufactured by the above manufacturing method will be described with reference to Figures 7(a) and 7(b). Figure 7(a) is a plan view of the biomolecular detector 10 according to the embodiment, and Figure 7(b) is a cross-sectional view along line II in Figure 7(a).

[0041] The biomolecular detector 10 according to this embodiment comprises a filter medium 11, a carbon oxide nanotube (CNT) thin film 12 made of carbon oxide nanotubes and directly fixed on the filter medium 11, an electrode 13 covering a first portion of the CNT thin film 12, an electrode 14 covering a second portion of the CNT thin film 12, and a support member 15 supporting the filter medium 11. The phrase "directly" fixed the CNT thin film 12 on the filter medium 11 means that the CNT thin film 12 is fixed to the filter medium 11 without the use of an adhesive or binder such as a polymer.

[0042] In this embodiment, the filter material 11 is filter paper, but it is not limited to this; it may also be filter cloth or sponge. By using such materials, it is possible to make the biomolecular detector 10 a flexible biosensor.

[0043] Antibodies that selectively capture biomolecules are bound to the carboxyl groups of the carbon oxide nanotubes in the oxidized CNT thin film 12. The antibody is, for example, an anti-cortisol antibody, but is not limited to this; other antibodies such as anti-melatonin antibodies may also be used.

[0044] Furthermore, antibodies do not necessarily need to be immobilized on the carbon oxide nanotubes coated with electrodes 13 and 14. That is, antibodies that selectively capture biomolecules are bound to the carboxyl groups of at least the carbon oxide nanotubes in the carbon oxide thin film 12 that are not coated with electrodes 13 and 14.

[0045] Electrodes 13 and 14 are made of a conductive paste such as silver paste. In this embodiment, as shown in Figures 7(a) and 7(b), electrodes 13 and 14 are formed at the left and right ends of a rectangular sample (filter material 11 and oxide CNT thin film 12), respectively.

[0046] The support member 15 is, for example, a resin substrate made of Teflon (registered trademark), a glass substrate, or an acrylic plate. The filter material 11 is fixed to the support member 15 by tape such as Kapton tape, adhesive, etc.

[0047] <Methods for detecting biomolecules> Next, the biomolecule detection method according to the embodiment will be described with reference to the flowchart in Figure 8.

[0048] Step S21: The biomolecular detector 10 is immersed in a solution containing dissolved biomolecules. Due to the antigen-antibody reaction, the biomolecules in the solution are adsorbed onto the antibody on the oxidized CNT thin film 12. The solution used in this step is, for example, a cortisol solution of a predetermined concentration.

[0049] Step S22: Remove the biomolecular detector 10 from the solution. After removal, it is desirable to wash the biomolecular detector 10 with distilled water and remove any water droplets from electrodes 13 and 14 with a blower.

[0050] Step S23: Measure the DC resistance between electrodes 13 and 14 of the biomolecular detector 10. This measurement allows you to obtain the IV characteristics.

[0051] Step S24: Estimate the concentration of biomolecules in the solution based on the DC resistance value measured in Step S23. As will be explained later with reference to the graphs (Figures 10 and 11), there is a positive correlation between the concentration of biomolecules and DC resistance. Therefore, by investigating the relationship between the concentration of biomolecules and DC resistance in advance, it is possible to estimate the concentration of biomolecules in the solution based on the value of DC resistance. Note that the estimation in this step may be performed by a person (measurer) or by an information processing device such as a tablet terminal, smartphone, or personal computer.

[0052] The biomolecule detector 10 can be used repeatedly. That is, after measuring the DC resistance, the biomolecule detector 10 is immersed in an acidic solution with a pH of about 3 to remove the antigen adsorbed to the antibody from the antibody. Then, after washing with distilled water, it is immersed in another solution.

[0053] The graph of FIG. 9 shows the I-V characteristics of the biomolecule detector 10 with the cortisol concentration in the solution as a parameter. The cortisol concentrations are 0, 10 -14 、10 -13 、10 -12 、10 -11 、10 -10 、10 -9 mol / L. After immersing the biomolecule detector 10 in seven types of solutions, the I-V characteristics obtained by measuring the DC resistance are shown.

[0054] As can be seen from this result, the DC resistance of the biomolecule detector 10 immersed in a cortisol solution with a predetermined concentration is almost a constant value, and the DC resistance increases as the cortisol concentration increases. The graph of FIG. 10 shows the relationship between the cortisol concentration in the solution and the DC resistance between the electrodes 13 and 14 of the biomolecule detector 10. As can be seen from FIG. 10, according to the biomolecule detector 10, antigens can be detected over a wide concentration range from 10 -15 ~10 -10 mol / L.

[0055] The graph of FIG. 11 shows the relationship between the melatonin concentration in the solution and the DC resistance between the electrodes 13 and 14 of the biomolecule detector 10. As can be seen from FIG. 11, according to the biomolecule detector 10, antigens can be detected over a wide concentration range from 10 -14 ~10 -5 mol / L.

[0056] The following are possible reasons why the DC resistance between electrodes 13 and 14 of the biomolecular detector 10 increases as the cortisol and melatonin concentrations increase. Specifically, as schematically shown in Figure 12(a), when no antigen (cortisol, melatonin, etc.) is adsorbed onto antibody A on carbon oxide nanotube C, a relatively large current flows due to the conductivity of the carbon oxide nanotube and the hopping conduction of carriers (electrons) between the carbon oxide nanotubes. On the other hand, as schematically shown in Figure 12(b), when antigen B is adsorbed onto antibody A on carbon oxide nanotube C, the hopping conduction is inhibited by the antibody to which the antigen is adsorbed, resulting in a decrease in current and an increase in DC resistance.

[0057] Incidentally, if the amount of carbon oxide (CNT) deposited is excessive, the density of the CNT thin film 12 increases, resulting in the antibody being immobilized only on the surface of the CNT thin film 12. This reduces the antibody density per unit area, lowering the sensitivity of the biomolecular detector 10. Therefore, it is desirable that the amount of CNT deposited is not excessive. According to our own studies and experiments, the amount of CNT deposited is 2.6 μg / cm². 2 The following is preferable. Regarding the lower limit of the amount of carbon nanotubes (CNTs) deposited, from the viewpoint of ensuring sensitivity, the amount of CNTs deposited is 0.1 μg / cm³. 2 Preferably, it is 0.35 μg / cm³. 2 It is even more preferable that the above conditions are met.

[0058] <Effects and Effects of Biomolecular Detection Methods Using Biomolecular Detectors> In the biomolecule detection method according to this embodiment, an inexpensive biomolecule detector 10 is used, and the DC resistance between electrodes 13 and 14 of the biomolecule detector 10 is measured. Therefore, compared to methods using biomolecule detectors with gold electrodes or electrochemical impedance spectroscopy (EIS), which requires relatively expensive impedance measuring instruments and takes a long time to obtain measurement results, this method allows for inexpensive, simple, and rapid detection of biomolecules.

[0059] Furthermore, while cortisol was detected in this embodiment, the target of detection is not limited to this. By changing the identification protein, it is possible to apply this to biosensors that can detect various targets such as viruses.

[0060] Based on the above description, those skilled in the art may conceive of additional effects and various modifications of the present invention, but the embodiments of the present invention are not limited to the individual embodiments described above. Components from different embodiments may be combined as appropriate. Various additions, modifications, and partial deletions are possible without departing from the conceptual idea and spirit of the present invention derived from the claims and their equivalents. [Explanation of Symbols]

[0061] 10 Biomolecular detectors 11 Filter media 12. Oxide CNT thin film 13, 14 electrodes 15 Support member 100 suction bottles 150 rubber stoppers 200 suction funnels 300 Pressure Reducing Device A antibody B. Antigen (biomolecule) C carbon oxide nanotubes

Claims

1. A step to prepare a solution in which carbon oxide nanotubes having carboxyl groups are dispersed in a solvent, The process involves forming a thin film made of carbon oxide nanotubes on the surface of the filter material by suction filtration of the solution from the back side of the filter material, The process involves attaching an antibody that selectively captures biomolecules to the carboxyl group of the carbon oxide nanotube in the thin film, A method for manufacturing a biomolecular detector, comprising the above.

2. After the step of binding the antibody to the carboxyl group of the carbon oxide nanotube, A method for producing a biomolecular detector according to claim 1, further comprising the step of bonding an inert molecule to the carbon oxide nanotube.

3. The method for manufacturing a biomolecular detector according to claim 1, further comprising the steps of applying a conductive paste to a first portion of the thin film to form a first electrode, and applying a conductive paste to a second portion of the thin film to form a second electrode.

4. A step of forming a first electrode and a second electrode on the surface of an insulating substrate, A step of fixing the filter material to the insulating substrate such that a first portion of the thin film contacts the first electrode and a second portion of the thin film contacts the second electrode, A method for manufacturing a biomolecular detector according to claim 1, further comprising:

5. A biomolecular detector manufactured by the method of claim 3 or 4 is immersed in a solution in which biomolecules are dissolved; A step of measuring the DC resistance between the first electrode and the second electrode of the biomolecular detector, A method for detecting biomolecules, comprising the following features.

6. The method for detecting biomolecules according to claim 5, further comprising the step of estimating the concentration of biomolecules in the solution based on the measured DC resistance.

7. filter media and A thin film made of carbon oxide nanotubes is directly fixed on the filter material, A first electrode covering the first portion of the thin film, A second electrode covering the second portion of the thin film, Equipped with, A biomolecular detector in which an antibody that selectively captures biomolecules is bound to the carboxyl group of the carbon oxide nanotube in the thin film.

8. The biomolecular detector according to claim 7, wherein the filter material is filter paper, filter cloth, or sponge.

9. The density of the carbon oxide nanotubes in the thin film is 0.1 to 2.6 μg / cm³. ２ A biomolecular detector according to claim 7 or 8, which is within the range of the biomolecular detector.

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