Sensor

Abstract

To provide a technique that enables release of a target substance captured by a molecularly imprinted polymer.SOLUTION: A sensor for detecting a target substance is provided, the sensor comprising a detection unit including a membrane having a space for the target substance to enter and containing a molecularly imprinted polymer for capturing the target substance entering the space, and a release mechanism for releasing the target substance captured by the molecularly imprinted polymer from the molecularly imprinted polymer, where the release mechanism is a light irradiation device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to sensors. [Background technology]

[0002] Several proposals have been made to detect target substances using molecularly imprinted polymers. For example, Patent Document 1 discloses a field-effect transistor having a detection electrode on the surface of which a film of molecularly imprinted polymer is formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-061890 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to repeatedly use a sensor that uses a molecularly imprinted polymer, it is necessary to desorb the target substance captured by the molecularly imprinted polymer. In Patent Document 1, in the process of preparing a template for the target substance during the production of the molecularly imprinted polymer, a cyclic voltammetry technique is used to scan the potential applied between the working electrode and the counter electrode relative to the potential of the reference electrode, and the target substance is removed by reaching a potential at which the chemical bond is broken. However, if such a method is used as a desorption method for repeated use of the sensor, there is a risk that the molecularly imprinted polymer will deteriorate due to the exchange of electrons. Therefore, there is a need for another technique that can desorb the target substance captured by the molecularly imprinted polymer. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, a sensor for detecting a target substance is provided. The sensor includes a detection unit having a space for the target substance to enter and a membrane containing a molecular imprinted polymer that captures the target substance that has entered the space, and a desorption mechanism for desorbing the target substance captured by the molecular imprinted polymer from the molecular imprinted polymer, the desorption mechanism being a light irradiation device. According to this aspect of the sensor, the light irradiation device serves as the desorption mechanism, and the captured target substance can be made to absorb light, thereby changing its structure and electronic state, thereby reducing the interaction between the captured target substance and the molecular imprinted polymer. As a result, the target substance captured by the molecular imprinted polymer can be desorbed.

[0007] (2) In the sensor described in (1) above, the light irradiation device may irradiate ultraviolet light. With this type of sensor, the captured target substance absorbs ultraviolet light, which can significantly change the structure and electronic state of the captured target substance, thereby further reducing the interaction between the captured target substance and the molecularly imprinted polymer. As a result, the target substance can be easily released from the molecularly imprinted polymer.

[0008] (3) In the sensor described in (1) or (2), the molecular imprinted polymer may contain a structure that causes a photoisomerization reaction. According to this type of sensor, the molecular imprinted polymer contains a structure that causes a photoisomerization reaction. Therefore, the molecular imprinted polymer undergoes a structural change upon irradiation with light, thereby further reducing the interaction between the captured target substance and the molecular imprinted polymer. As a result, the target substance can be more easily released from the molecular imprinted polymer.

[0009] (4) In the sensor according to any one of (1) to (3), the target substance may be at least one selected from the group consisting of a virus, a bacterium, a microorganism, and a protein. In this sensor, the surface structure can be changed by changing the three-dimensional structure of the target substance, so that the target substance can be easily released from the molecularly imprinted polymer.

[0010] (5) The sensor according to any one of (1) to (4) above may be a field-effect transistor type sensor. According to this type of sensor, since it is a field-effect transistor type sensor, it is possible to suppress a decrease in detection sensitivity.

[0011] The present disclosure can be realized in various forms, for example, a method for manufacturing a sensor, a method for monitoring a target substance using a sensor, and the like. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view schematically illustrating the general configuration of a sensor. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating the general configuration of a sensor. [Figure 3] FIG. 2 is an explanatory diagram showing an example of a change in the electronic state of a target substance before and after light absorption. [Figure 4] FIG. 1 is an explanatory diagram showing how a target substance is desorbed from a molecularly imprinted polymer. [Figure 5] FIG. 10 is a cross-sectional view schematically showing the general configuration of a sensor according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] A. First embodiment FIG. 1 is a perspective view schematically illustrating the overall configuration of a sensor 100 according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically illustrating the overall configuration of the sensor 100. For convenience of illustration, FIGS. 1 and 2 illustrate only the essential components of the sensor 100. The sensor 100 detects a target substance contained in a sample. The sample is not particularly limited, but examples thereof include gases such as air and exhaled breath, and liquids such as water. The sensor 100 of this embodiment is a resistive sensor. The sensor 100 includes a detection unit 10 and a detachment mechanism 20. In the example illustrated in FIGS. 1 and 2, the detection unit 10 is disposed vertically below the detachment mechanism 20, and the detachment mechanism 20 is disposed vertically above the detection unit 10. The detection unit 10 and the detachment mechanism 20 are disposed opposite each other with a space between them.

[0014] The detection unit 10 has a membrane 12 containing a molecularly imprinted polymer (MIP). This molecularly imprinted polymer has a space 14 into which a target substance enters. This space 14 is formed according to the size and surface structure of the target substance by a method described below. The molecularly imprinted polymer recognizes and captures the target substance by chemically interacting with the target substance in this space 14. The chemical interaction is not particularly limited, but examples include hydrogen bonding.

[0015] The molecularly imprinted polymer is not particularly limited, but preferably has a non-covalent functional group in the main chain or branched chain. Examples of the non-covalent functional group include, but are not particularly limited to, an OH group. Examples of the molecularly imprinted polymer include, but are not particularly limited to, polypyrrole, polyaniline, acrylic polymers, photocurable polymers, and photosolubilizable polymers. The monomer for forming the molecularly imprinted polymer is not particularly limited, but preferably has a double bond for polymerization. The double bond may be present in the molecular chain or may be a double bond of an aromatic ring. Furthermore, from the viewpoint of the polymerization reaction, a monomer having an amino group is preferred. Therefore, the monomer for forming the molecularly imprinted polymer is preferably a compound having a double bond, an OH group, and an amino group.

[0016] Although one type of monomer may be used as the monomer for forming the molecularly imprinted polymer, it is preferable to use two or more types of monomers. When two or more types of monomers are used, a monomer without a non-covalent functional group may be included. The monomer for forming the molecularly imprinted polymer may be either water-soluble or water-insoluble, but a water-soluble monomer is preferable from the viewpoint of ease of handling. Specific examples of the monomer for forming the molecularly imprinted polymer include pyrrole, aniline, ortho-phenylenediamine, acrylamide, N,N'-methylenebisacrylamide, aminophenylboronic acid, aminophenol, aminobenzoic acid, and dopamine.

[0017] The target substance is not particularly limited, and examples thereof include substances with a three-dimensional structure, chemical substances, and fine particles. However, from the viewpoint of efficient desorption by the desorption mechanism 20, substances with a three-dimensional structure are preferable. Examples of substances with a three-dimensional structure include, but are not particularly limited to, viruses, fungi, microorganisms, proteins, antigens, and the like. Examples of fungi include, but are not particularly limited to, bacteria, fungi, and archaea. The viruses and fungi may be pathogenic to animals such as humans. Examples of microorganisms include, but are not particularly limited to, yeast and algae. Examples of proteins include, but are not particularly limited to, disease-related proteins and antibodies. Examples of chemical substances include, but are not particularly limited to, drugs and hormones. Examples of fine particles include, but are not particularly limited to, pollen, PM2.5, yellow sand, aerosols, and the like.

[0018] The target substance may be one or more types, but is preferably one type from the viewpoint of preventing a decrease in detection accuracy. In an embodiment in which two or more types of target substances are detected, two or more types of spaces 14 are also formed in the molecular imprinted polymer according to the target substances.

[0019] As shown in FIG. 2, the detection unit 10 of this embodiment further includes a pair of detection electrodes 18 and a substrate 19. When a target substance is captured in the space 14 formed in the molecularly imprinted polymer, the current flowing between the pair of detection electrodes 18 fluctuates, and the target substance can be detected based on this current value. The detection electrodes 18 are not particularly limited as long as they are conductive, and may be formed from, for example, metal, conductive carbon, conductive polymer, etc. Examples of metals include, but are not limited to, gold, silver, copper, aluminum, indium tin oxide (ITO), etc. The substrate 19 is not particularly limited, and may be formed from, for example, glass, ceramics, resin, etc. Examples of resins include, but are not limited to, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone, polycarbonate (PC), etc.

[0020] The desorption mechanism 20 desorbs the target substance captured by the molecularly imprinted polymer from the molecularly imprinted polymer. The desorption mechanism 20 in the present disclosure is a light irradiation device 22. The wavelength of the light 28 irradiated by the light irradiation device 22 is preferably 100 nm or more and 1000 nm or less. The light 28 irradiated by the light irradiation device 22 is not particularly limited, and examples thereof include visible light (visible light) and ultraviolet light (ultraviolet light). However, ultraviolet light is preferred from the viewpoint of enhancing the desorption effect. In other words, the desorption mechanism 20 is preferably an ultraviolet irradiation device capable of irradiating ultraviolet light. In the present disclosure, ultraviolet light refers to light having a wavelength of 10 nm or more and less than 400 nm, and visible light refers to light having a wavelength of 400 nm or more and 800 nm or less. The wavelength of the light 28 irradiated by the light irradiation device 22 may be set according to the light absorption band of the target substance. The light irradiation device 22 may irradiate light 28 in one wavelength range or may emit light 28 in two or more wavelength ranges.

[0021] The light irradiating device 22 serving as the desorption mechanism 20 is provided at a position where light 28 can reach the film 12 of the detection unit 10. More specifically, it is provided at a position where light 28 can reach the target substance captured in the space 14 formed in the molecularly imprinted polymer. The timing at which the light irradiating device 22 serving as the desorption mechanism 20 irradiates light 28 is not particularly limited, and light irradiating may be performed continuously or periodically. However, it is preferable to irradiate light when the target substance is captured in the detection unit 10. An example of a method of irradiating light when the target substance is captured is a method of irradiating light when a signal resulting from the capture of the target substance is detected in the detection unit 10.

[0022] FIG. 3 is an explanatory diagram showing an example of the change in the electronic state of a target substance before and after light absorption. FIG. 3 schematically shows electron-deficient sites and electron-rich sites in a chemical substance serving as a target substance. The state before light absorption corresponds to the ground state, and the state after light absorption corresponds to the transition state. The electron-deficient sites and electron-rich sites in the molecules of the target substance, i.e., the electronic state within the molecules, change before and after light absorption.

[0023] FIG. 4 is an explanatory diagram showing the desorption of a target substance 90 from a molecularly imprinted polymer film 12. In FIG. 4, the left side of the page shows the target substance 90 trapped in a space 14 formed in the molecularly imprinted polymer, and the right side shows the target substance 90 being desorbed by light irradiation. For ease of explanation, FIG. 4 also shows a schematic diagram of a functional group 13 in the molecularly imprinted polymer as an example of a group that interacts with the target substance 90. The target substance 90 changes its structure and electronic state upon absorbing light 28 irradiated from a light irradiation device 22, which serves as a desorption mechanism 20. As a result, the size and electronic configuration of the target substance 90 change, reducing its interaction with the functional group 13 of the molecularly imprinted polymer and resulting in desorption. Furthermore, if the target substance has a three-dimensional structure, the three-dimensional structure of the target substance can be changed by light irradiation, which in turn changes the surface structure of the target substance. As a result, the target substance can be easily desorbed from the molecularly imprinted polymer.

[0024] From the viewpoint of more easily releasing the target substance from the molecularly imprinted polymer, it is more preferable that the molecularly imprinted polymer contains a structure that undergoes a photoisomerization reaction. In the present disclosure, the term "structure that undergoes a photoisomerization reaction" refers to a structure whose molecular structure changes upon irradiation with light. When the molecularly imprinted polymer contains a structure that undergoes a photoisomerization reaction, light irradiation can induce structural changes in the molecularly imprinted polymer as well as the target substance, thereby further reducing the interaction between the captured target substance and the molecularly imprinted polymer. Monomers for forming a molecularly imprinted polymer having a structure that undergoes a photoisomerization reaction include, but are not limited to, monomers that exhibit cis-trans transition, monomers that exhibit polar-nonpolar transition, and monomers that exhibit ring-open-ring-closed transition. Monomers that exhibit cis-trans transition include, but are not limited to, azobenzene, etc. Monomers that exhibit polar-nonpolar transition include, but are not limited to, azobenzene, spiropyran, etc. Monomers that undergo a ring-opening-ring-closing transformation are not particularly limited, but examples thereof include spiropyran and diarylethene. As the monomers that undergo photoisomerization, one type of monomer may be used, or two or more types of monomers may be used. Note that a molecularly imprinted polymer containing a structure that undergoes a photoisomerization reaction returns to the structure before photoirradiation when photoirradiation is stopped or when it is irradiated with light of a wavelength different from that of the light irradiation wavelength used for elimination.

[0025] The light irradiation device 22 serving as the desorption mechanism 20 reduces the chemical interaction between the target substance 90 and the molecularly imprinted polymer by absorbing light 28 in the target substance 90 or the molecularly imprinted polymer, thereby suppressing deterioration of the molecularly imprinted polymer. Therefore, compared to an embodiment in which the target substance 90 is removed by, for example, using cyclic voltammetry, scanning the potential between the working electrode and the counter electrode relative to the potential of a reference electrode until the potential reaches a potential at which the chemical bond is broken, deterioration of the molecularly imprinted polymer due to electron exchange can be suppressed. As a result, a decrease in the detection accuracy of the sensor 100 can be suppressed. This enables the sensor 100 to be used repeatedly, and a shortened lifespan of the sensor 100 can be suppressed. Furthermore, compared to an embodiment in which the target substance 90 is removed using an organic solvent such as acetonitrile or a base such as sodium hydroxide, the use of an organic solvent or base can be omitted, thereby suppressing deterioration of the molecularly imprinted polymer. Furthermore, compared to an embodiment in which the target substance 90 is removed using an organic solvent, the environmental impact can be reduced. Furthermore, compared to an embodiment in which the target substance 90 is removed using an organic solvent, the use of the sensor 100 is not limited to places where an organic solvent can be used, so the range of use of the sensor 100 can be expanded.

[0026] The uses of the sensor 100 of this embodiment are not particularly limited, but may be applied to, for example, virus and bacteria monitoring, air quality monitoring, water quality management, food hygiene management, health management of humans, animals and plants, high sensitivity sensors, etc.

[0027] The method for manufacturing the detection unit 10 having the membrane 12 containing the molecularly imprinted polymer of this embodiment is not particularly limited, but it can be manufactured by the following method, for example. Hereinafter, an example of a method for manufacturing a molecularly imprinted polymer when the target substance 90 is Escherichia coli will be described. First, a substrate 19 including a pair of detection electrodes 18 with a gap of about 5 μm therebetween is washed with ethanol and ultrapure water, and then the potential is scanned from −0.7 V to +0.7 V five times in a solution containing 0.1 M LiClO4 and 50 mM pyrrole, thereby electropolymerizing pyrrole. Then, 1×10 4 After adding CFU / mL of E. coli to the electropolymerization cell, molecularly imprinted polymers were synthesized by scanning the potential at a scan rate of 100 mV / s for five more cycles. This was followed by ultrasonic cleaning in water for 5 minutes or by 1 × 10 -3 By incubating in a surfactant M, the E. coli used for template formation is removed from the molecularly imprinted polymer, whereby a detection unit 10 having a membrane 12 containing a molecularly imprinted polymer can be produced.

[0028] B. Second embodiment FIG. 5 is an explanatory diagram schematically illustrating the general configuration of a sensor 100a of a second embodiment. FIG. 5 shows a cross-sectional view similar to FIG. 2. The sensor 100a of the second embodiment differs from the sensor 100 of the first embodiment in that it is a FET-type sensor including a field-effect transistor (FET sensor) as the detection unit 10a. The other configurations, including the configuration of the detachment mechanism 20, are similar to those of the first embodiment, so similar configurations are denoted by the same reference numerals and detailed description thereof will be omitted. Note that the sensor 100a of the second embodiment is a so-called top-contact FET sensor, but is not limited to this and may be any FET sensor, such as a bottom-contact type or an extended-gate type.

[0029] The detection unit 10a includes a substrate 19, a gate electrode 31, a gate insulating layer 32, a channel 33, a source electrode 34, a drain electrode 35, and a film 12 containing a molecularly imprinted polymer. The gate electrode 31 is disposed on the substrate 19. The gate insulating layer 32 is disposed to cover the gate electrode 31. The channel 33 is disposed on the gate insulating layer 32. The source electrode 34 and the drain electrode 35 are disposed spaced apart from each other on the channel 33. The film 12 containing a molecularly imprinted polymer is disposed on the source electrode 34, the drain electrode 35, and the channel 33.

[0030] The gate electrode 31, source electrode 34, and drain electrode 35 are not particularly limited as long as they are conductive, and may be formed of, for example, metal, conductive carbon, conductive polymer, etc. The gate insulating layer 32 is not particularly limited as long as it is insulating, and may be formed of either an organic insulating material or an inorganic insulating material, but from the viewpoint of ease of handling, it is preferably formed of an organic insulating material. Examples of organic insulating materials include, but are not limited to, polymethyl methacrylate, polystyrene, polyvinylphenol, epoxy resin, phenolic resin, etc. The inorganic insulating material is not particularly limited to, but is limited to, oxides such as silicon dioxide, aluminum oxide, and titanium oxide, and nitrides such as silicon nitride, etc.

[0031] The channel 33 is not particularly limited and may be formed of either an organic or inorganic semiconductor. However, from the viewpoint of sensitivity, it is preferably formed of an organic semiconductor. Examples of organic semiconductors include, but are not limited to, pentacenes such as TIPS pentacene, anthradithiophenes such as TES-ADT, benzothienobenzothiophenes such as DPh-BTBT, phthalocyanines such as copper phthalocyanine, polythiophenes such as P3RT, and polythienothiophenes such as PBTTT. Examples of inorganic semiconductors include, but are not limited to, oxides of one or a mixture of two or more of indium, gallium, tin, and zinc. More specifically, examples of inorganic semiconductors include indium gallium zinc oxide (InGaZnO), In-Al-Zn-O, In-Sn-Zn-O, In-Zn-O, In-Sn-O, Zn-O, and Sn-O. Alternatively, the channel 33 may be formed of graphene instead of a semiconductor.

[0032] When a target substance is captured in the space 14 formed in the molecularly imprinted polymer, the electrical resistance in the channel 33 located adjacent to the membrane 12 containing the molecularly imprinted polymer changes, and as a result, the current value between, for example, the source electrode 34 and the drain electrode 35 changes, and the target substance can be detected based on this value.

[0033] C. Variations The configuration of the sensors 100, 100a in the above-described embodiments is merely an example and can be modified in various ways. For example, the sensors 100, 100a are not limited to resistive sensors or FET sensors, but may be any type of sensor, such as an impedance sensor or a QCM (quartz crystal microbalance) sensor. Furthermore, for example, in each of the above-described embodiments, the desorption mechanism 20 is disposed vertically above the detection unit 10, 10a. However, the position of the desorption mechanism 20 is not limited as long as the film 12 containing the molecularly imprinted polymer can be irradiated with light 28. For example, the desorption mechanism 20 may be disposed vertically below the detection unit 10, 10a, or may be disposed to the side of the detection unit 10, 10a. Furthermore, for example, the desorption mechanism 20 may be used in combination with a desorption mechanism having another mechanism for desorbing a target substance captured by the molecularly imprinted polymer. The desorption mechanism having other mechanisms is not particularly limited, but examples thereof include those that desorb by releasing a stimulating substance, those that desorb by heating or cooling, those that desorb by vibration, those that desorb by electrostatic repulsion of surface potential, etc. The stimulating substance may be, for example, at least one selected from the group consisting of ozone, hydroxyl radicals, and superoxide.

[0034] The present invention is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments and examples corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0035] 10, 10a...detection portion, 12...membrane, 13...functional group, 14...space, 18...detection electrode, 19...substrate, 20...desorption mechanism, 22...light irradiation device, 28...light, 31...gate electrode, 32...gate insulating layer, 33...channel, 34...source electrode, 35...drain electrode, 90...target substance, 100, 100a...sensor

Claims

1. A sensor for detecting a target substance, a detection unit having a space into which the target substance enters and a membrane containing a molecular imprinted polymer that captures the target substance that has entered the space; a desorption mechanism for desorbing the target substance captured by the molecular imprinted polymer from the molecular imprinted polymer; Equipped with the detachment mechanism is a light irradiation device; A sensor characterized by:

2. 2. The sensor of claim 1, The light irradiation device irradiates ultraviolet light. A sensor characterized by:

3. 3. The sensor according to claim 1, The molecularly imprinted polymer comprises a structure that undergoes a photoisomerization reaction. A sensor characterized by:

4. 3. The sensor according to claim 1, The target substance is at least one selected from the group consisting of a virus, a bacterium, a microorganism, and a protein. A sensor characterized by:

5. 3. The sensor according to claim 1, It is a field effect transistor type sensor, A sensor characterized by:

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