Optical measurement method, optical measurement system and test kit

Abstract

The present disclosure relates to an optical measurement method, an optical measurement system, and a test kit. The optical measurement method includes: a preparation step of preparing an optical measurement apparatus, a reaction cell in the optical measurement apparatus containing a sample containing magnetic particles each having a substance specifically bound to a target substance fixed thereto; a magnetic field application step of applying a magnetic field to the magnetic particles by a magnetic field application unit; a stop step of stopping application of the magnetic field after a first time elapses from initiation of application of the magnetic field; a test value acquisition step of acquiring a test value based on an amount of light detected by a light detection unit after the stop step; and a determination step of determining one of presence or absence of the target substance in the sample based on the test value.

Description

Technical Field

[0001] The embodiments disclosed in this specification and accompanying drawings relate to optical measurement methods, optical measurement systems, and test kits. Background Technology

[0002] In the field of biosensors, there exists an optical measurement method in which an optical measurement system using a transparent substrate optically measures a target substance (such as an antigen) contained in a sample and determines the presence of the target substance in the sample. This optical measurement method utilizes the change in detection signal that occurs when carrier particles, on which a first substance specifically bonded to the target substance is immobilized, settle on the detection surface of a translucent substrate.

[0003] Generally speaking, when using particle detection to identify target substances, there is a method to separate particles that are bonded to the target substance from those that are not.

[0004] Japanese Patent Publications Nos. 2012-215553, 2021-135236, and 2023-71397 describe a method in which, in the aforementioned optical measurement method, magnetic particles are deposited onto a detection surface on which a second material specifically bonded to a target material is fixed, and then a magnetic field is applied in a direction away from the detection surface. In the methods described in Japanese Patent Publications Nos. 2012-215553, 2021-135236, and 2023-71397, the magnetic particles capturing the target material are held aloft by the second material bonded to the detection surface by the target material, thus remaining on the detection surface even after a magnetic field is applied in a direction away from the detection surface. Simultaneously, magnetic particles that do not capture the target material move away from the detection surface along the magnetic field and thus separate from the magnetic particles that capture the target material, thereby enabling the detection of the target material using particles.

[0005] Currently, there is a need for measurement methods to determine the presence of a target substance in a short time, and the techniques described in Japanese Patent Publication No. 2012-215553, Japanese Patent Publication No. 2021-135236 and Japanese Patent Publication No. 2023-71397 have room for improvement in shortening measurement time. Summary of the Invention

[0006] That is, this disclosure relates to providing an optical measurement method that can determine the presence of a target substance using particles in a short time.

[0007] According to one aspect of this disclosure, an optical measurement method using an optical measurement apparatus is provided, the optical measurement apparatus comprising: a substrate including an optical waveguide; a reaction cell disposed on the substrate and having a detection surface formed at a bottom portion by a portion of the surface of the optical waveguide; a magnetic field application unit configured to apply a magnetic field to magnetic particles dispersed in a sample contained within the reaction cell and to generate a magnetic force on the magnetic particles in a direction toward the detection surface; and a light detection unit configured to allow light to enter the optical waveguide and detect light emitted from the substrate after reflection from the detected surface, the optical measurement method including: The method includes: a preparation step, which prepares an optical measurement device, wherein a reaction tank in the optical measurement device contains a sample containing magnetic particles, each magnetic particle having a substance specifically bonded to a target substance fixed on it; a magnetic field application step, which applies a magnetic field to the magnetic particles via a magnetic field application unit; an application stop step, which stops applying the magnetic field after a first time elapsed since the application of the magnetic field was initiated; a test value acquisition step, which acquires a test value based on the amount of light detected by a light detection unit after the application stop step; and a determination step, which determines the presence or absence of the target substance in the sample based on the test value.

[0008] In addition, according to another aspect of this disclosure, an optical measurement system is provided, comprising: a substrate including an optical waveguide; a reaction cell disposed on the substrate and having a detection surface formed by a portion of the surface of the optical waveguide at a bottom portion; a magnetic field application unit configured to apply a magnetic field to magnetic particles dispersed in a sample contained within the reaction cell and generate a magnetic force on the magnetic particles in a direction toward the detection surface, each magnetic particle having a substance specifically bonded to a target substance fixed thereon; a light detection unit configured to allow light to enter the optical waveguide and detect light emitted from the substrate after reflection from the detected surface; an application stop unit configured to stop the application of the magnetic field after a first time has elapsed since the application of the magnetic field was initiated; a test value acquisition unit configured to acquire a test value based on the amount of light detected by the light detection unit after the magnetic field is stopped by the application stop unit; and a determination unit configured to determine the presence or absence of the target substance in the sample based on the test value.

[0009] Furthermore, according to another aspect of this disclosure, a test kit for use in the aforementioned optical measurement method is provided, the test kit comprising: magnetic particles having a substance specifically bonded to a target substance fixed on the magnetic particles; a substrate including an optical waveguide; and a reaction cell disposed on the substrate and having a detection surface at the bottom portion formed by a portion of the surface of the optical waveguide, wherein the substance bonded to the target substance is not fixed on the detection surface.

[0010] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is by way of example. Attached Figure Description

[0011] Figure 1 This is a functional block diagram illustrating a configuration example of an optical measurement system according to an embodiment.

[0012] Figure 2 This is a schematic diagram illustrating an example configuration of an optical measurement system according to an embodiment.

[0013] Figure 3 This is a cross-sectional view used to illustrate an example of the structure of magnetic particles.

[0014] Figure 4 This is a flowchart illustrating the processing steps of the optical measurement method according to an embodiment.

[0015] Figure 5A This is a schematic diagram illustrating the behavior of magnetic particles when a magnetic field is applied to a negative specimen that does not contain the target substance.

[0016] Figure 5B It is a diagram used to illustrate the behavior of magnetic particles when a magnetic field is applied to a positive specimen containing the target substance.

[0017] Figure 6 This is a graph used to illustrate an example of how signal strength changes over time. Detailed Implementation

[0018] The embodiments of the optical measurement method, optical measurement system, and test kit according to the present disclosure are described in detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a functional block diagram illustrating a configuration example of an optical measurement system 100 according to an embodiment of the present disclosure.

[0020] The optical measurement system 100 is a system for measuring a target substance using optical methods.

[0021] There are no particular restrictions on the target substance, as long as it is a substance that can be detected by the optical measurement system 100. Examples include influenza virus, adenovirus, and respiratory syncytial virus (RSV), as well as antigens of coronaviruses such as COVID-19.

[0022] like Figure 1 As shown, the optical measurement system 100 includes an optical measurement device 110, a signal processing device 120, an input device 130, an output device 140, and a storage device 150.

[0023] The optical measuring device 110 performs optical measurements under the control of the signal processing device 120 and transmits the measurement results to the signal processing device 120 for processing to determine the presence or absence of a target substance. The input device 130 is for the operator to input instructions for operating the signal processing device 120, and the output device 140 is for outputting the results processed by the signal processing device 120 to the operator. The storage device 150 is for storing various pieces of information, such as measurement data.

[0024] The optical measuring device 110, signal processing device 120, input device 130, output device 140 and storage device 150 are connected to each other via signal lines so that signals can be transmitted and received therebetween.

[0025] Input device 130 receives various input operations from the operator and converts the received input operations into operation signals. These operation signals are then supplied to signal processing device 120. As an input device 130, for example, a physical switch, touch panel, touchpad, joystick, keyboard, mouse, etc., can be used. As an input device 130, a voice input device that recognizes the operator's speech sensed by a microphone and converts the speech into operation signals can also be used.

[0026] Output device 140 outputs various types of information received from signal processing device 120. As output device 140, for example, a liquid crystal display (LCD), a cathode ray tube (CRT) display, an organic electroluminescent display (organic EL display; OLED), a plasma display, or any other display can be appropriately used. Output device 140 can also be a projector. Additionally, output device 140 may also include a sound-generating device, such as a speaker.

[0027] Storage device 150 is a device for storing various types of information. Examples of storage device 150 may include read-only memory (ROM), random access memory (RAM), hard disk drive (HDD), solid-state drive (SSD), and integrated circuit storage devices. Storage device 150 may also be a drive that reads various types of information from portable storage media such as flash memory, CD-ROM, or DVD, and writes various types of information to them. Storage device 150 is not necessarily required to be implemented as a single storage device. For example, storage device 150 may be implemented as multiple storage devices. Storage device 150 may also be replaced by cloud storage.

[0028] Storage device 150 may store one or more programs for performing the optical measurement method according to this disclosure. For example, the program may be pre-stored in storage device 150, or it may be stored in a non-transitory storage medium, distributed, and read from the non-transitory storage medium for installation in storage device 150. For example, the program may also be downloaded from a network for installation in storage device 150.

[0029] like Figure 1 As shown, the optical measurement device 110 includes a substrate 111, a reaction tank 112, a magnetic field application unit 113, a light detection unit 114, and an application stop unit 115. The signal processing device 120 includes a magnetic field control unit 121, an optical control unit 122, a test value acquisition unit 123, a determination unit 124, and a communication unit 125.

[0030] Figure 2 This is a schematic diagram illustrating an example of the specific configuration of the optical measurement device 110 and the signal processing device 120 among the various devices used to form the optical measurement system 100. Figure 2 The image shows an optical measurement device 110 with a reaction tank 112 mounted on a substrate 111. Figure 2 The illustration of the stop unit 115 is omitted in the text.

[0031] The substrate 111 is a support mechanism that can be attached to and detachably supports the reaction tank 112. The attachment and detachment of the reaction tank 112 from the substrate 111 are detected by electrical, magnetic, or mechanical means. Figure 2 As shown, the substrate 111 includes a base portion 111a, an optical waveguide 111b disposed on the base portion 111a, a protective film 111c covering a portion of the surface of the optical waveguide 111b, and a grating 111d disposed at the interface between the base portion 111a and the optical waveguide 111b.

[0032] A reaction tank 112 is disposed on a substrate 111 and has a detection surface 111e formed at its bottom portion by a portion of the surface of an optical waveguide 111b. A frame 112a, forming part of the housing of the reaction tank 112, is formed on a protective film 111c to surround the detection surface 111e. The frame 112a is formed, for example, from a resin (such as acrylonitrile-butadiene-styrene (ABS)) in a generally cuboid shape and can be colored black for light-shielding purposes. A droplet orifice 112b is formed in the frame 112a and communicates with the interior of the reaction tank 112 via a flow path. The reaction tank 112 also includes a cap (not shown) configured to cover the droplet orifice 112b.

[0033] The magnetic field application unit 113 is configured to apply a magnetic field to the magnetic particles 201 dispersed in the sample contained in the reaction tank 112, and generate a magnetic force on the magnetic particles 201 in the direction toward the detection surface 111e. In this embodiment, the magnetic field application unit 113 is disposed at a position facing the base portion 111a, such that the substrate 111 is located between the magnetic field application unit 113 and the reaction tank 112.

[0034] The photodetector unit 114 is a functional unit that performs optical detection and includes a light source 114a and a photodetector 114b. The light source 114a illuminates the substrate 111 (base portion 111a) with light L1 so that the light enters the optical waveguide 111b, and the photodetector 114b detects the light L2 emitted from the substrate 111 after reflection from the surface 111e being detected. The photodetector 114b also generates a photodetection signal representing the intensity of the detected light L2.

[0035] In this configuration, two gratings 111d are positioned in front of and behind the detection surface 111e in the direction of light propagation within the optical waveguide 111b. One grating 111d is used to allow light to enter the optical waveguide 111b, and the other is used to exit the optical waveguide 111b. That is, the grating 111d has a structure that reflects (diffuses) light and is configured such that light entering the optical waveguide 111b exits the optical waveguide 111b after being reflected by the detection surface 111e.

[0036] The light source 114a, the grating 111d, and the optical waveguide 111b form an optical system for light detection in the optical measurement system 100, and the optical system may also include optical components, such as additionally configured lenses.

[0037] The application stop unit 115 is a mechanism for stopping the application of the magnetic field performed by the magnetic field application unit 113.

[0038] The signal processing device 120 is connected to each of the magnetic field application unit 113, the light source 114a, the photodetector 114b, and the application stop unit 115 so that communication can be made therebetween.

[0039] The base portion 111a is a light-transmitting component and is made of, for example, alkali-free glass. An optical waveguide 111b is formed on the upper surface of the base portion 111a.

[0040] As an example, planar optical waveguide 111b can be used as optical waveguide 111b. For example, optical waveguide 111b can be formed of thermosetting resin (such as phenolic resin, epoxy resin, or acrylic resin), or it can be formed of photocurable resin or alkali-free glass. Optical waveguide 111b is transmissive to a predetermined light and is preferably made of a resin, for example, with a refractive index higher than that of the base portion 111a. A portion of the surface of optical waveguide 111b forms a detection surface 111e (sensing area), and the detection surface 111e refers to the area on the surface of optical waveguide 111b where near-field light (evanescent light) can occur.

[0041] The protective film 111c is, for example, a resin film with a low refractive index.

[0042] As a light source 114a, a red laser diode is used as an example, but a laser diode of another color can be used, or a light-emitting diode can be used. The light L1 emitted from the light source 114a can be shaped to be approximately parallel by an additionally provided lens or the like. As a photodetector 114b, a photodiode can be used, for example.

[0043] The magnetic field applying unit 113 may include, for example, a permanent magnet or an electromagnet. For example, when using an electromagnet, the magnetic field applying unit 113 may maintain a specific magnetic field state by including processing circuitry with magnetic field control functionality.

[0044] The application stop unit 115 may have a suitable configuration depending on the specific configuration of the magnetic field application unit 113. For example, when the magnetic field application unit 113 is a permanent magnet, the application stop unit 115 may be a mechanism for moving the permanent magnet to a position where the magnetic field influence from the permanent magnet is negligible. For example, when the magnetic field application unit 113 is an electromagnet, the application stop unit 115 may be a mechanism for interrupting the current used to generate magnetic force. Although this embodiment is directed to an example in which the optical measurement device 110 includes the application stop unit 115, the function of the application stop unit 115 may be implemented by the function of the magnetic field control unit 121 included in the signal processing device 120.

[0045] The signal processing device 120 is a processor that serves as the control center of the optical measurement system 100. The signal processing device 120 executes programs stored in the storage device 150, thereby realizing the functions corresponding to the programs, namely, the functions of the magnetic field control unit 121, the optical control unit 122, the test value acquisition unit 123, the determination unit 124, and the communication unit 125.

[0046] This embodiment describes an example in which the corresponding functions mentioned above are implemented by a single physical processor, but this disclosure is not limited thereto. For example, the signal processing device 120 can be configured by combining multiple independent processors, and the corresponding functions mentioned above can be implemented by the respective processors executing programs.

[0047] Signal processing device 120 may be a computer (or CPU, microcontroller unit (MPU), etc.), or it may be a device including, for example, circuitry (such as an ASIC) that implements one or more functions. Signal processing device 120 may also include amplifiers, A / D converters, field-programmable gate array (FPGA) chips, etc., for performing amplification and digital conversion processing on the analog electrical signal output by photodetector 114b through the functions of the verification value acquisition unit 123. Details of the functions mentioned above included in signal processing device 120 are described later.

[0048] Next, the magnetic particle 201 that can be used in the optical measurement method according to this disclosure will be described.

[0049] There are no particular limitations on the structure of the magnetic particles, and magnetic particles 201 with suitable structures can be appropriately used depending on the purpose and measurement environment, such as the target substance to be measured, the sample containing the target substance, or the device to be used. Examples of the structures of magnetic particles 201 include structures in which magnetic nanoparticles are dispersed in resin or silica particles serving as a core, structures in which magnetic nanoparticles are fixed as a shell structure on the surface layer of the core particles, and structures in which magnetic nanoparticles are clustered to form secondary particles.

[0050] Figure 3 This is a cross-sectional view illustrating the structure of a magnetic particle 201 on which a substance specifically bonded to a target material is fixed. On the surface of the magnetic particle 201, a substance 301 specifically bonded to the target material is fixed. Furthermore, in... Figure 3 On the outermost surface of the magnetic particle 201 shown, a hydrophilic layer 302 formed of resin is formed to suppress non-specific adsorption caused by proteins in the specimen. Substances 301 that specifically bind to the target substance in the specimen are bonded to the hydrophilic layer 302 on the outermost surface of the magnetic particle 201 and are configured such that when each substance 301 captures the target substance, the magnetic particles 201 aggregate with each other through the target substance.

[0051] Examples of mechanisms for agglomerating magnetic particles 201 to form aggregates may include: when the target substance is an antigen, using an antibody as a substance 301 specifically bonded to the target substance, and forming an immune complex in which the target substance is sandwiched between antibodies. Furthermore, to suppress non-specific adsorption between magnetic particles 201, in addition to the substance 301 specifically bonded to the target substance, any hydrophilic polymer may be immobilized on the surface of each magnetic particle 201.

[0052] The combination of the target substance and the substance 301 specifically bound to the target substance is not limited to the antigen and antibody combination mentioned above. Examples of other combinations include combinations of sugars and lectins, combinations of nucleotide chains and their complementary nucleotide chains, and combinations of ligands and receptors.

[0053] The magnetic particles 201 are not particularly limited, and can be appropriately selected according to the purpose of detecting target substances, and can also be used in the optical measurement methods according to this disclosure. The particle size and specific gravity of the magnetic particles 201 are also not particularly limited, but the specific gravity of the magnetic particles 201 is preferably greater than the specific gravity of the sample in which the magnetic particles 201 are dispersed. Specifically, for example, the particle size can be set to 0.1 μm or larger and 3.0 μm or smaller, and the specific gravity can be set to about 1.05 or larger and about 3.00 or smaller. The relationship between the particle size and specific gravity of the magnetic particles 201 is important. When the specific gravity is high, the particle size can be reduced, and when the specific gravity is low, the particle size can be increased. However, even when the specific gravity is low, magnetic particles 201 with an excessively large particle size may be unsuitable. Therefore, it is preferable to appropriately select magnetic particles 201 with suitable particle size and specific gravity based on, for example, the specific gravity of the sample in which the magnetic particles 201 are dispersed and the conditions of the apparatus to be used (such as the magnetic field strength applied by the magnetic field application unit 113).

[0054] Next, a process for performing the optical measurement method according to this disclosure by the optical measurement system 100 according to an embodiment will be described. In the following description, it is assumed that the target substance is an antigen, and that the substance 301 immobilized on the magnetic particle 201 is an antibody. Furthermore, it is assumed that the magnetic particle 201 used herein is a magnetic particle 201 formed by containing magnetic material inside its core.

[0055] Figure 4 This is a flowchart illustrating the processing procedure for optical measurements performed by the optical measuring device 110. Regarding the magnetic particles 201 in the reaction tank 112, Figure 5A This is a diagram illustrating the behavior of magnetic particles 201 in the case of a negative specimen, and Figure 5BThis is a diagram used to illustrate the behavior of magnetic particles 201 in the case of a positive specimen. Figure 6 It is a graph used to show the time-varying signal intensity of the optical detection signal during measurement processing. Figure 6 The graph shown has a vertical axis indicating the signal strength [in arbitrary units] of the light detection signal and a horizontal axis indicating the time [in seconds]. Figure 6 The thick line indicates the temporal change in signal intensity of positive samples containing the target substance. Figure 6 The thin line indicates the time-varying signal intensity of a negative sample that does not contain the target substance.

[0056] First, in the preparation step of step S401, an optical measurement device 110 is prepared. The reaction tank 112 in the optical measurement device 110 contains a sample containing magnetic particles 201. Each magnetic particle is fixed with a substance 301 specifically bonded to the target substance.

[0057] Specifically, a sample containing the target substance is introduced into a reaction vessel 112, and the sample is further mixed with magnetic particles 201, each of which has a substance 301 specifically bonded to the target substance. Thus, simultaneously with the introduction of the sample, the bonding (antigen-antibody reaction) between the target substance and the substance 301 specifically bonded to the target substance is initiated.

[0058] Samples introduced into reaction tank 112 can be prepared, for example, by immersing a sterile swab with the collected specimen attached into an extraction buffer tube and agitating the swab together. This extraction buffer is formed from a solution containing a surfactant. In this case, the extraction buffer tube refers to a tube made of resin or glass.

[0059] There are no particular restrictions on the specific method for mixing the sample and magnetic particles 201 in the reaction tank 112, but mixing can be performed as follows.

[0060] Examples may include a configuration in which magnetic particles 201 are fixed to a filter to be attached to an extraction buffer tube containing the collected sample, and the sample and magnetic particles 201 are mixed when a worker drips the sample into the reaction tank 112.

[0061] As another example, a configuration can be adopted in which magnetic particles 201 are held by a sealing membrane on a detection surface 111e positioned at the bottom surface of the reaction tank 112. The sealing membrane is formed of a material containing at least one water-soluble substance, and allows the water-soluble substance to dissolve rapidly and the magnetic particles 201 to be dispersed in the sample when the sample is introduced into the reaction tank 112. The material used for the water-soluble substance can be selected from well-known excipients, such as sugars, starches, celluloses, and inorganic salts.

[0062] Subsequently, in the optical system activation step of step S402, the optical system in the optical measurement device 110 is activated. In response to receiving a trigger for activating the optical system, the optical measurement device 110 activates the optical system under the control of the optical control unit 122 included in the signal processing device 120. The activation time of the optical system can optionally be set. Specifically, the activation time of the optical system can be, for example, the time when the lid of the reaction tank 112 is closed after the sample is introduced into the reaction tank 112, or the time after a preset time has elapsed after the lid is closed. The activation time of the optical system can also correspond to the time when a trigger for activating the optical system is received (such as an instruction to activate the optical system input by an operator from the input device 130 to the communication unit 125 of the signal processing device 120).

[0063] In step S402, the optical control unit 122 controls the light source 114a to allow light L1 to enter the substrate 111. The light L1 entering the substrate 111 passes through the base portion 111a and is reflected or diffracted by the grating 111d to enter and propagate through the optical waveguide 111b. Then, light L2 exits from the substrate 111 after being reflected or diffracted by the grating 111d. The photodetector 114b detects the light L2 exiting the substrate 111 and generates a photodetection signal representing the amount (intensity) of the detected light L2. The photodetection signal is output to the signal processing device 120. The optical system activation step of step S402 can also be performed after the application of the magnetic field is initiated in the subsequent magnetic field application step of step S403.

[0064] Subsequently, in the magnetic field application step S403, under the control of the magnetic field control unit 121 included in the signal processing device 120, the magnetic field application unit 113 applies a magnetic field to the magnetic particles 201. In the optical measurement method according to this disclosure, during measurement, the magnetic field application unit 113 applies a magnetic field to the magnetic particles 201 in the reaction tank 112, thereby generating a magnetic force in the direction toward the detection surface 111e.

[0065] Figure 5A This is a diagram illustrating the behavior of magnetic particles 201 when a magnetic field is applied to a negative specimen that does not contain the target substance. Figure 5B It is a diagram used to illustrate the behavior of magnetic particles when a magnetic field is applied to a positive specimen containing the target substance.

[0066] like Figure 5A and Figure 5B As shown, reaction tank 112 is filled with sample. Magnetic particles 201 and antigen 231 (target substance) are suspended in the sample, and antibodies are bonded to magnetic particles 201. The bottom surface of reaction tank 112 is a detection surface 111e formed by a portion of the surface of optical waveguide 111b.

[0067] In negative samples, magnetic particles 201 are in a dispersed state and approach the detection surface 111e under the influence of a magnetic field, such as... Figure 5A As shown in the diagram. At this point, its speed is set to "v'". Simultaneously, in the positive sample, where two or more magnetic particles 201 are bonded together by antigen 231 and aggregated, the magnetic particles 201 are attracted towards the detection surface 111e under the influence of the magnetic field, as shown... Figure 5B As shown in the diagram. Its velocity is set to "v". The comparison between velocity "v" and v' yields v>v', and it can be said that the magnetic particles 201 aggregated by antigen 231 have a faster sedimentation velocity. That is, the magnetic particles 201 deposit on the detection surface 111e earlier, and the decrease in the optical detection signal becomes more significant.

[0068] In this embodiment, the strength of the magnetic field applied by the magnetic field applying unit 113 can be a strength that causes individual magnetic particles 201 to move, but preferably a magnetic field strength that moves substantially only the aggregated magnetic particles 201 and hardly moves any individual magnetic particles 201. By selecting a magnetic field that moves only the aggregated magnetic particles 201, the detection signal attributed to the individual magnetic particles 201 can be suppressed, thus enabling a more accurate test. That is, by selecting a magnetic field strength that selectively moves only the aggregated magnetic particles 201, the aggregated magnetic particles 201 can be moved more selectively to the detection surface 111e, thereby enabling the determination of positive or negative with higher accuracy.

[0069] The timing of applying the magnetic field in step S403 can be optionally controlled. For example, the application of the magnetic field can be initiated immediately upon activating the timing of the optical system in step S402. Alternatively, the magnetic field can be applied after maintaining a constant magnetic field strength (which could be a zero magnetic field where no magnetic field is applied) for the time during which the magnetic particles 201 capture the antigen 231 in the specimen, thereby achieving higher sensitivity by increasing the probability of capturing the antigen 231. In this case, the optimal time for maintaining a constant magnetic field strength (e.g., a zero magnetic field) can be appropriately selected according to the type of antigen 231 and the desired sensitivity characteristics.

[0070] Subsequently, in the application stop step of step S404, after a first time has elapsed since the application of the magnetic field was initiated, the application of the magnetic field is stopped under the control of the magnetic field control unit 121.

[0071] When a magnetic field is applied, the magnetic particles 201 that reach the detection surface 111e are deposited in a bead-like form on the detection surface 111e due to the characteristics of the magnetic material. When the magnetic field is stopped, the magnetic particles 201 connected in a bead-like form become loose, and the number of magnetic particles 201 in contact with the detection surface 111e increases, thereby causing a further significant decrease in the optical detection signal.

[0072] The first time of applying the magnetic field from initiation to cessation can be appropriately set according to the physical characteristics of the sample, the type of magnetic particles 201 to be used, the type of target substance, its expected concentration level, etc.

[0073] Subsequently, in the test value acquisition step of step S405, the signal processing device 120 causes the test value acquisition unit 123 to acquire a test value based on the amount of light detected by the light detection unit 114 after the application of the stopping magnetic field in the application stopping step. After acquiring the test value in step S405, the optical control unit 122 can stop the illumination of light L1 from the light source 114a.

[0074] After the application of the magnetic field is stopped, the aforementioned test value can be obtained after a predetermined time (second time) has elapsed until the magnetic particles 201 connected in a bead-like form become loose and come into contact with the detection surface 111e. That is, the test value obtained by the test value acquisition unit 123 can be based on the amount of light detected by the light detection unit 114 after the second time has elapsed since the application of the magnetic field was stopped in the application stopping step.

[0075] The test value acquired by the test value acquisition unit 123 can be a value corresponding to the amount of light detected by the light detection unit 114. For example, the test value can be the signal strength itself of the light detection signal representing the intensity of light L2 generated by the light detector 114b.

[0076] In addition, the test value can be presented as a value corresponding to the difference between the amount of light L2 detected by the light detection unit 114 and the predetermined reference light amount.

[0077] The reference light intensity can be, for example, the intensity of light L2 detected by photodetector 114b when the light undergoes total internal reflection in the optical waveguide. This reference light intensity can be obtained, for example, by measuring the intensity of light L2 after the reaction tank 112 has been pre-filled with water. Alternatively, the intensity of light L2 detected by photodetector 114b when the reaction tank 112 is empty can be used as the reference light intensity.

[0078] Additionally, the optical measurement method according to this disclosure may further include a reference value acquisition step, which acquires the amount of light detected by the light detection unit 114 before the magnetic field application step or after a third time elapsed since the application of the magnetic field as a reference value. In this case, a third time may optionally be set. However, when the time elapsed since the application of the magnetic field becomes longer, the magnetic particles 201 in the sample begin to settle on the detection surface 111e, and the acquired amount of light becomes unsuitable as a reference value. Accordingly, the third time is preferably as short as possible, and for example, the third time may be set to zero.

[0079] For example, the test value could be a value indicating the degree of change in the amount of light detected by the light detection unit 114 after the stop step is applied, relative to the reference value acquired in the reference value acquisition step. In this case, the degree of change in the amount of light L2 detected by the light detector 114b relative to the reference value could be, for example, a difference or a ratio.

[0080] The signal strength of the light detection signal transmitted from the photodetector 114b to the signal processing device 120, the light detection signal representing the amount (intensity) of light L2, and the test value obtained based on the signal strength can be stored in the storage device 150.

[0081] Storage device 150 can record information about defective optical detection signals, for example, in cases where samples are improperly introduced into reaction tank 112 or where the sample contains interfering substances or abnormal specimens. Inspection value acquisition unit 123 can be configured to output measurement errors when applicable.

[0082] Subsequently, in the determination step of step S406, the determination unit 124 of the signal processing device 120 determines the presence or absence of the target substance in the sample based on the test value obtained by the test value acquisition unit 123.

[0083] In the optical measurement method according to this disclosure, the velocity difference between magnetic particles 201 aggregated by the target substance and individually dispersed magnetic particles 201 moving toward the detection surface 111e is utilized, as described above. That is, when the sample contains the target substance, the magnetic particles 201 settle onto the detection surface 111e earlier than when the sample does not contain the target substance. Therefore, the presence or absence of the target substance in the sample is determined based on the fact that the signal intensity of the optical detection signal detected by the optical detection unit 114 after the application of the magnetic field is stopped has a significantly smaller value for positive samples than for negative samples.

[0084] The optical measurement method according to this disclosure does not require the step of applying a magnetic field to generate a magnetic force in a direction away from the detection surface 111e in order to separate the magnetic particles 201 from the detection surface 111e, a step that is essential in optical measurement methods according to related art. As a result, the determination of the presence or absence of a target substance using the magnetic particles 201 can be achieved in a shorter time.

[0085] Furthermore, unlike related technologies, in the optical measurement method according to this disclosure, the magnetic particles 201 not bonded to the target material are not separated from the magnetic particles 201 bonded to the detection surface 111e by using magnetic force to pull the magnetic particles 201 away from the detection surface 111e. Therefore, in the optical measurement equipment used in the optical measurement method according to this disclosure, it is not required to fix the material bonded to the target material onto the detection surface 111e. Accordingly, measurements can be performed using simple and low-cost equipment. In this disclosure, "the material specifically bonded to the target material is not fixed on the detection surface" indicates that the detection surface, which originally did not have the material, was not processed to fix the material.

[0086] The following describes a specific example of the determination performed by the determination unit 124.

[0087] When the reaction tank 112 is empty and no sample is contained therein, when light L1 is emitted from the light source 114a, the light propagating through the optical waveguide 111b is not totally reflected by the detection surface 111e, and evanescent light (leakage light) is generated at the detection surface 111e. In this case, the signal strength of the optical detection signal has a lower value than in the case of total reflection.

[0088] When the detection surface 111e is covered by the sample, the light propagating through the optical waveguide 111b is totally reflected by the detection surface 111e, and the signal intensity of the optical detection signal increases. Therefore, in Figure 6 In the process, the light signal intensity of both positive and negative signals increases sharply at time 0.

[0089] exist Figure 6 In this context, the time point at which the amount of light L2 detected by the photodetector 114b reaches its maximum value when the detection surface 111e is completely covered by the sample is set as the reference time point, and the signal intensity of the photodetector signal at this reference time point is shown as the reference signal.

[0090] When magnetic particles 201 settle onto the detection surface 111e, the rate at which light propagating through the optical waveguide 111b is totally reflected by the detection surface 111e decreases, and the intensity of the light signal generated by the photodetector 114b also decreases. That is, in this embodiment, the number of magnetic particles 201 in the sample settled on the detection surface 111e due to the magnetic field increases over time, therefore the intensity of light L2 detected by the photodetector 114b tends to decrease over time.

[0091] At this point, as described above, in the positive sample, the magnetic particles 201 agglomerate through the target material, resulting in a greater migration velocity toward the detection surface 111e. Therefore, the positive signal exhibits a significantly lower signal intensity detected after the application of the magnetic field is stopped compared to the negative signal. Accordingly, positive and negative samples can be distinguished, such as... Figure 6 As shown in the image.

[0092] Additionally, for example, in Figure 6 In the example shown, when the difference in signal intensity between the value of a positive or negative signal and a reference signal is used as the test value, the test value changes in the increasing direction—that is, in the direction opposite to the direction of the intensity of light L2—as the intensity of light L2 detected by the light detection unit 114 decreases. Accordingly, in this case, positive and negative samples can be distinguished based on the fact that the positive signal exhibits a significantly larger test value than the negative signal.

[0093] When distinguishing between positive and negative samples based on test values, a predetermined threshold can be used. That is, the determination step S406 may include determining the presence or absence of the target substance in the sample based on the test value obtained in step S405 and the predetermined threshold.

[0094] Specifically, for example, when the signal intensity of the light detection signal representing the intensity of light L2 generated by the photodetector 114b is used as the test value, a positive result can be determined when the test value drops below a predetermined threshold, and a negative result can be determined when the test value exceeds the predetermined threshold. Figure 6 As shown in the image.

[0095] In addition, for example, when the difference between the signal intensity of the light detection signal to be measured and the signal intensity of the reference signal is used as the test value, the specimen can be determined to be positive when the test value exceeds a predetermined threshold, and the specimen can be determined to be negative when the test value drops below the predetermined threshold.

[0096] The threshold can be set to any value based on experience. The threshold can be pre-stored in storage device 150.

[0097] The determination process may include performing the determination by using reference information relating to the relationship between the time elapsed since the reference time point and the test value.

[0098] In this context, the reference information can be information obtained in advance using samples with known concentrations of the target substance. That is, for example, the reference information may include information related to test values ​​for samples (negative samples) where the concentration of the target substance is less than a predetermined value. Alternatively, for example, the reference information may include information related to test values ​​for samples (positive samples) where the concentration of the target substance is equal to or greater than a predetermined value.

[0099] Alternatively, for example, the reference information could be transformation information about a sample containing a specific concentration of the target substance, which is obtained through computer simulation prediction.

[0100] Reference information can be pre-stored in storage device 150 as a lookup table (LUT) or mathematical expression.

[0101] The determination unit 124 can perform the determination based on the correspondence between the test value and the reference information.

[0102] Examples of performing determination using reference information obtained from positive samples include: obtaining test values ​​using a sample containing a target substance at the detection limit, and using the obtained test values ​​as a reference for determination. That is, the value of the test value obtained for a positive sample is set as a threshold, and a positive or negative determination can be output when the test value obtained for an actual sample exceeds (or falls below) the threshold.

[0103] The reference information may also include information relating to the test values ​​of each of multiple samples having different concentrations of the target substance. In this case, the determining unit 124 can not only determine whether a result is positive or negative, but also estimate the concentration range of the target substance contained in the sample by performing a comparison between the test values ​​obtained for multiple positive samples with different concentrations and the test values ​​obtained for the actual sample.

[0104] Examples of performing determinations based on reference information obtained from negative samples include: obtaining test values ​​using samples containing target substances at concentrations below the detection limit, and using the obtained test values ​​for determination. That is, a threshold is set based on the test values ​​obtained for negative samples, and a positive or negative determination can be output when a test value exceeding (or falling below) the threshold is obtained.

[0105] After the positive or negative determination is performed in step S406, in the result output step of step S407, the determined result is sent by the communication unit 125 to the output device 140, and the determined result is output to the operator. Specifically, the signal processing device 120 outputs the test value and the determined result based on the test value to the output device 140 in any mode (in any layout in the case of an image).

[0106] The optical measurement performed by the optical measuring device 110 is thus terminated.

[0107] The test kit according to this disclosure is used in the aforementioned optical measurement method and includes magnetic particles 201 on which a substance specifically bonded to a target substance is fixed, a substrate 111 having an optical waveguide 111b, and a reaction tank 112. As described above, the reaction tank 112 is provided on the substrate 111 and has a detection surface 111e at the bottom portion, which is formed from a portion of the surface of the optical waveguide 111b and on which no substance bonded to the target substance is fixed.

[0108] Any of the above embodiments merely indicates a specific example for carrying out the invention, and the technical scope of the invention should not be interpreted in a limiting manner because of those embodiments. That is, the invention can be carried out in various forms without departing from the technical spirit or the main features of the invention. For example, an embodiment in which a portion of the configuration of any embodiment is added to another embodiment, or an embodiment in which a portion of the configuration of any embodiment is replaced by a portion of the configuration of another embodiment, is also understood to be an embodiment to which the invention can be applied.

[0109] According to this disclosure, an optical measurement method can be provided that enables the determination of the presence of a target substance using particles in a short time.

[0110] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. An optical measurement method using optical measuring equipment, The optical measurement device includes: A substrate, the substrate including an optical waveguide; A reaction tank is disposed on a substrate and has a detection surface at the bottom portion formed by a portion of the surface of an optical waveguide; A magnetic field applying unit is configured to apply a magnetic field to magnetic particles dispersed in a sample contained in a reaction tank and to generate a magnetic force on the magnetic particles in the direction toward the detection surface. as well as A photodetector unit is configured to allow light to enter an optical waveguide and detect the light emitted from the substrate after reflection from the surface being detected. The optical measurement method includes: The preparation step prepares the optical measuring device, wherein the reaction tank in the optical measuring device contains a sample containing magnetic particles, and each magnetic particle is fixed with a substance specifically bonded to the target substance. The magnetic field application step involves applying a magnetic field to the magnetic particles via a magnetic field application unit. An application stop step is performed, wherein the application of the magnetic field is stopped after a first time elapsed since the application of the magnetic field was initiated; The test value acquisition step acquires a test value based on the amount of light detected by the light detection unit after the stop step is applied; and The determination step is based on the test value to determine the presence or absence of the target substance in the sample.

2. The optical measurement method according to claim 1, wherein the test value includes a value based on the amount of light detected by the light detection unit after a second time elapsed from the time the application of the magnetic field is stopped in the application stopping step.

3. The optical measurement method according to claim 1, wherein the test value presents a value corresponding to the amount of light detected by the photodetector unit.

4. The optical measurement method according to claim 1, wherein the test value presents a value corresponding to the difference between a predetermined reference light quantity and the amount of light detected by the light detection unit after the application of the stop step.

5. The optical measurement method according to claim 1 further includes a reference value acquisition step, wherein the reference value acquisition step acquires the amount of light detected by the light detection unit before the magnetic field application step or after a third time elapsed from the application of the magnetic field as a reference value. The test value represents the degree of change in the amount of light detected by the light detection unit relative to the reference value after the stop step is applied.

6. The optical measurement method according to claim 1, wherein the substance specifically bonded to the target substance is not fixed on the detection surface.

7. The optical measurement method of claim 1, wherein the determining step comprises performing the determination by using reference information relating to the relationship between the time elapsed from the reference time point and the test value.

8. The optical measurement method according to claim 7, wherein the reference information includes information related to the test value of a sample in which the concentration of the target substance is less than a predetermined value.

9. The optical measurement method of claim 7, wherein the reference information includes information relating to test values ​​of samples in which the concentration of the target substance is equal to or greater than a predetermined value.

10. The optical measurement method according to any one of claims 1 to 9, wherein the determining step includes performing the determination based on a test value and a predetermined threshold.

11. The optical measurement method of claim 9, wherein the reference information includes information relating to the test value of each of a plurality of samples having mutually different concentrations of the target substance.

12. The optical measurement method according to claim 1, wherein the magnetic particles comprise particles having the property of agglomeration through the target material.

13. The optical measurement method of claim 12, wherein the magnetic field application step comprises applying a magnetic field strength for selectively moving and condensing magnetic particles.

14. An optical measurement system, comprising: A substrate, the substrate including an optical waveguide; A reaction tank is disposed on a substrate and has a detection surface at the bottom portion formed by a portion of the surface of an optical waveguide; A magnetic field application unit is configured to apply a magnetic field to magnetic particles dispersed in a sample contained in a reaction vessel and generate a magnetic force on the magnetic particles in the direction toward the detection surface, wherein each magnetic particle is fixed with a substance specifically bonded to the target substance. A light detection unit is configured to allow light to enter an optical waveguide and detect the light emitted from the substrate after reflection from the surface being detected. An application stop unit is configured to stop the application of the magnetic field after a first time has elapsed since the application of the magnetic field was initiated; A test value acquisition unit is configured to acquire a test value based on the amount of light detected by the light detection unit after the magnetic field is stopped by the applied stopping unit; as well as A determining unit is configured to determine the presence or absence of a target substance in a sample based on a test value.

15. The optical measurement system of claim 14, wherein the material bonded to the target material is not fixed on the detection surface.

16. A test kit for use in the optical measurement method according to any one of claims 1 to 9 and 11 to 13, the test kit comprising: Magnetic particles, wherein a substance specifically bonded to a target substance is fixed on the magnetic particles; A substrate, the substrate including an optical waveguide; as well as The reaction tank is disposed on a substrate and has a detection surface at the bottom portion formed by a portion of the surface of an optical waveguide, on which no material bonded to the target material is fixed.

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