JP2005172779A - Method and apparatus for measuring bacteria, virus and toxic substance by irradiation with electromagnetic wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device for inspecting food by irradiating the food with an electromagnetic wave with a specific wavelength possessed by the DNA structure of food, modified protein, bacteria or a virus, and an inspection method using it. <P>SOLUTION: This food inspection device has a variable wavelength electromagnetic wave generating means capable of irradiating food with the electromagnetic wave with a frequency of 0.1-10 THz inherent to the constituent element of the food and a detection means for the electromagnetic wave with the frequency of 0.1-10 THz. At least a part of a food sample processed into a predetermined shape is irradiated with the electromagnetic wave to measure the intensity of the transmitted or reflected electromagnetic wave. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for measuring bacteria and toxic substances using electromagnetic wave irradiation.

In recent years, terahertz electromagnetic waves (1 THz = 10 ¹² Hz), whose application has attracted attention, hit the boundary between the frequency of light and the frequency of radio waves. The frequency of light is approximately 30 to 1000 THz, whereas the frequency of radio waves such as microwaves and millimeter waves has a frequency of 0.1 THz or less.

  The THz waveband fills this frequency gap. In the generation of terahertz, terahertz using a semiconductor crystal such as terahertz time-domain spectroscopy (THz-TDS), terahertz parametric oscillator (THz-TPO), or GaP based on the principle method. A terahertz electromagnetic wave generation method using a semiconductor device such as differential frequency generation (THz-difference generation; THz-DFG) or a p-type germanium laser or a quantum cascade laser has been realized.

In particular, in the difference frequency generation using GaP, generation of a terahertz electromagnetic wave having a variable wavelength and a high output is realized in an unparalleled range of 0.15 to 7 THz (see, for example, Non-Patent Document 1).
T.A. Tanabbe, K .; Suto, J. et al. Nishizawa, T .; Kimura, K .; Saito, Journal of Applied Physics 93, 4610 (2003)

  Bacteria, that is, bacteria and viruses, cause food spoilage and alteration due to their presence, and when certain bacteria and viruses grow abnormally in vivo, various diseases are caused in the human body.

  There are various types of bacteria that cause such infections, such as Staphylococcus, Streptococcus, Legionella, Vibrioaceae, anaerobic bacteria, spirochetes, rickettsia, and chlamydia. These microorganisms parasitize host tissues and produce toxins as they grow, causing inflammation in the human body. Recently, a new type of pneumonia SARS (severe acute respiratory syndrome) caused by the growth of the pathogen coronavirus is prevalent and has become a social problem.

  In addition, as represented by shellfish poisons, there are many secondary cases in which plankton with toxins in seawater accumulates in shellfish, and humans who ingest it cause poisoning.

  In recent years, terrorism has worsened and so-called bioterrorism has been used in cases where biochemical weapons are used. Untracks reaches a fatality rate of 100% within 5 to 7 days with an amount of 1 millionth of a gram or less. (Anthrax) and botulinum toxin that can cause death within 36 hours after paralysis of respiratory muscles.

  In general, these infections are often judged by secondary effects of the human body such as fever, vomiting, abdominal pain, or dyspnea. For example, in SARS, a fever of a passenger is taken as a thermal image (thermography) at the airport. An example of using a fever to detect is new to memory.

  Tests relating to infectious diseases as described above take several days until results are obtained because screening tests (immunobiochemical tests) and more detailed confirmation tests (immunohistochemical tests) are performed. Since these inspections require time, or because there is always a need for expert and qualified personnel and an environment that can handle various reagents, there was no other way than sending samples to remote locations and waiting for inspection results. . In view of the above problems, it is necessary for doctors or medical personnel to quickly and accurately detect bacteria and viruses in contact with infected persons (without sending samples to remote locations), regardless of the analysis specialist's hands. There is.

  The present invention has been made to eliminate the above-mentioned disadvantages of the prior art, and irradiates bacteria and viruses with terahertz electromagnetic waves to obtain absorption spectrum information peculiar to bacteria and viruses. It is an object of the present invention to provide a method and apparatus for identifying a type of bacteria or virus by performing pattern recognition based on the pattern recognition.

  In order to solve the above-mentioned problems, the present invention is characterized by a natural vibration at 0.1 to 10 THz, which is peculiar to DNA structures of bacteria and toxic substances, or protein degeneration caused by bacteria-generated toxins or bacterial parasites. Equipped with a variable wavelength electromagnetic wave generator for irradiating terahertz electromagnetic waves with a frequency equal to the number, and measuring the intensity of the terahertz electromagnetic waves transmitted or reflected through the sample using a detector having sensitivity in the frequency band to obtain spectral information . This spectrum is so-called fingerprint information of the substance to be measured, and pattern recognition is performed based on spectrum information of a standard sample measured in advance to identify bacteria.

  In addition, the present invention proposes a cell structure of a sample confinement system that takes into consideration prevention of diffusion into the atmosphere or the environment, which are bacteria and toxic substances. With this method, for example, a biological sample containing moisture has a problem of attenuation of terahertz electromagnetic waves, and has a sample thinned cell structure for measurement in a state of being thinned to an arbitrary thickness (for example, about 10 μm). Furthermore, in order to realize a very small amount of sample analysis, a pipe-type sample confinement type waveguide cell is used.

  The natural vibration frequency band of bacteria and toxic substances is approximately 0.1 to 10 THz, and each has a characteristic fingerprint spectrum related to the type of bacteria or virus, that is, the structure factor. However, this zone has never been used to test for bacteria and toxic substances. The present invention can realize a new detection method and apparatus by using this band, and enables simple and rapid inspection.

  The method and apparatus for measuring bacteria and toxic substances using electromagnetic radiation according to the present invention is equal to the natural frequency corresponding to the structure of bacteria or viruses that grow in DNA structures, denatured proteins, foods, etc. of bacteria and toxic substances. Since the substance can be identified from the absorption characteristics by irradiating the electromagnetic wave with the frequency, detection of bacteria and viruses and detection of toxins can be performed quickly and easily. Furthermore, since it can respond also to detection of anthrax, botulinum toxin, etc., the present invention provides an apparatus and method effective for bioterrorism countermeasures.

  Bacteria, viruses and toxic substances are enclosed in a sample to be measured as shown in FIG. 2, and a terahertz electromagnetic wave having a predetermined frequency is irradiated by an apparatus as shown in FIG. The type can be identified.

A schematic diagram of a measurement system for bacteria and toxic substances using electromagnetic wave irradiation according to the present invention is shown in FIG. As the variable wavelength electromagnetic wave generator 1, a differential frequency terahertz wave generator using a GaP crystal is used. When a LiNbO ₃ crystal is used instead of the GaP crystal, a terahertz electromagnetic wave of 0.7 THz to 2.5 THz can be obtained due to difference frequency generation or parametric oscillation. Furthermore, as the variable wavelength electromagnetic wave generator 1, a Gunn diode, a tannet diode, or an electronic device such as a p-type germanium laser or a quantum cascade laser can be used.

  In particular, in the difference frequency generation using GaP, generation of a terahertz electromagnetic wave having a variable wavelength and a high output is realized in an unparalleled range of 0.15 to 7 THz. In this method, a YAG laser having a wavelength of 1.064 μm is used as the first pump light, and an optical parametric oscillator (OPO) equipped with an injection seeding device is used as the second pump light source, that is, the wavelength tunable light source.

  Such OPO can be prevented from wavelength degeneration by being excited by the third harmonic of the YAG laser, that is, light having a wavelength of 355 nm, and the line width of the OPO can be narrowed by the effect of injection seeding. For this reason, the line width of the terahertz electromagnetic wave generated as the difference frequency is similarly reduced.

  As a second method, a Cr: FORSTERITE (Cr-added olivine) laser can be used as pump light. Since this laser uses the Cr level, the line width is extremely narrow compared to OPO without injection seeding. The Cr: FORSTERITE laser is excited by using a YAG laser having a wavelength of 1.064 μm, but it is highly efficient because it does not use the third harmonic unlike the above-mentioned OPO. The wavelength tunable range of the Cr: FORSTERITE laser is the range from 1.15 μm to 1.35 μm, two Cr: FORSTERITE lasers are used as pump light sources, one is a fixed wavelength, and the other is used as a wavelength tunable pump light source, Difference frequency can be generated without injection seeding.

  The terahertz electromagnetic wave generated from the variable wavelength electromagnetic wave generator 1 is radiated into free space, and a condensing system is configured by the lens 2 and the like. The material of the lens needs to be a material that transmits terahertz electromagnetic waves, and quartz, polyethylene, or a cycloolefin polymer resin material that transmits terahertz electromagnetic waves is used. Sample 3 is usually pulverized into a powder, dried, mixed with Teflon or polyethylene powder, and processed into a pellet. The size of the pellet is about 10 mmφ, and the thickness is 0.1 mm to 5 mm. The analysis point of the sample 3 is determined by movement and adjustment on the x and y axes. As the detector 4, a pyroelectric detector having a wide wavelength sensitivity characteristic, a bolometer, or the like is used. The signal detected by the detector is processed and stored as spectrum information by the signal processing unit 5.

  Since the sample 3 in FIG. 1 is composed of bacteria and toxic substances, a cell structure of a sample confinement method in consideration of preventing diffusion into the atmosphere or the environment is indispensable.

  FIG. 2 shows a cell structure of the sample confinement method. (1) has a planar cell structure, and (2) has a waveguide cell structure. The planar cell structure includes a planar cell 32, a sample 31, and a cap 33. The planar cell 32 and the cap are made of a material that is transparent to terahertz electromagnetic waves such as quartz, Teflon, polyethylene, or resin. For example, in a biological sample containing moisture, attenuation of terahertz electromagnetic waves becomes a problem by this method. However, when the thickness of the sample is reduced to, for example, about 10 μm, transmission characteristics can be measured even when moisture is present.

  Furthermore, in order to realize a very small amount of sample analysis, a pipe-type sample confinement type waveguide cell is used. As shown in FIG. 2B, a small amount of sample 61 is placed in a waveguide type cell 62 as shown. As the waveguide type cell 62, for example, a quartz tube having an inner diameter of 0.1 mm to 1 mmφ and a length of about 1 cm and having an inner surface coated with gold is used. The terahertz electromagnetic wave irradiated from one of the waveguide type cells is reflected multiple times in the tube, so that a very small amount of the sample 61 is efficiently irradiated, thereby enabling high sensitivity analysis. Further, in this structure, a cap 63 is provided to prevent the sample (for example, powder) from diffusing into the atmosphere or the environment.

  FIG. 3 is a schematic diagram of a measurement system for bacteria and toxic substances using electromagnetic wave irradiation, which is characterized by detecting reflection of a sample to be measured. This method is used when the sample 3 has poor terahertz electromagnetic wave transmission, and is effective when it is difficult to obtain a spectrum through transmission. The terahertz electromagnetic wave generated from the variable wavelength electromagnetic wave generator 1 is radiated into free space, and a condensing system is configured by the lens 2 and the like. The terahertz electromagnetic wave that has passed through the mirror 6 is irradiated on the surface of the sample 3 and reflected, and the terahertz electromagnetic wave reflected by the mirror 6 is detected by the detector 4. Since the reflected terahertz electromagnetic wave retains the absorption characteristic peculiar to the structure near the surface of the sample 3, the substance can be identified as in the case of the transmission characteristic (shown in FIG. 1). The analysis point of the sample 3 is determined by movement and adjustment on the x and y axes.

  A trial production process of the planar cell structure shown in FIG. 2 (1) is shown in FIG. Since the sample 37 contains bacteria and toxic substances, a process that takes into consideration prevention of diffusion into the atmosphere or the environment is used. For the planar cell 32 and the cap material 33, quartz, polyethylene, Teflon, or a cycloolefin polymer-based special resin, which is a material transparent to terahertz electromagnetic waves, is used. The planar cell 32 has, for example, a 10 μm recess, and has a structure that is devised so that the thickness of the sample to be measured is determined by the depth of the recess. (1) The recess is formed in advance with a predetermined depth by etching or the like. (2) Next, the paste-like liquid sample 37 is supplied from the sample supply device 38, but it is necessary to supply it in excess of the amount filling the recess. Here, even if the liquid sample is a powder, the same steps can be taken. As shown in (3), a sample to be measured having a constant thickness can be formed by scanning the surface with a constant force with a clean and hard flat blade 39, and finally a cap 33 as shown in (4). Install.

  By automating the process by the above method, diffusion of bacteria and toxic substances into the atmosphere or the environment can be prevented, and safe sample preparation becomes possible. In addition, since a thinned sample can be prepared, even when the transmittance of terahertz electromagnetic waves is extremely lowered in a sample containing a lot of moisture, the absorption characteristic peculiar to a substance can be measured by thinning the sample.

  Furthermore, this sample preparation method is suitable for quantitative evaluation because the thickness of the sample can always be constant. Regarding quantitative evaluation, since the amount of terahertz electromagnetic wave absorption changes according to the film thickness of the sample, it is necessary to make the sample thickness constant.

  A trial production process of the waveguide type cell structure shown in (2) of FIG. 2 is shown in FIG. The waveguide type cell 62 uses, for example, a quartz tube having an inner diameter of 0.1 mm to 1 mmφ and a gold coating on the inner surface of about 1 cm. First, the tip is immersed in a terahertz electromagnetic wave permeable cap material 63 ′ and a predetermined thickness is used. A cap 63 having a film thickness is formed at one end of the waveguide type cell 62. As the cap material 63 ', a paste or a paste containing a solvent or a solvent is used. Next, in order to enclose the liquid sample material 61 ′ inside the waveguide type cell 62, the waveguide type cell 62 whose one end is sealed with a cap material is used as the sample material 61 ′ in a vacuum environment. The sample 61 is enclosed in the waveguide type cell 62 by dipping (vacuum impregnation) and then pressurizing the environment with nitrogen pressure (pressure impregnation). Thereafter, the sample material 61 'adhering to the outside of the waveguide type cell 62 and the like is removed by a liquid draining process and a post-processing process. When the sample material 61 ′ is powder, the sample 61 can be sealed in the waveguide type cell 62 by pressure bonding without performing vacuum impregnation and pressure impregnation. Next, the cap 63 is formed at the open end by the same process as the cap forming step, and the waveguide type cell structure is completed through the cleaning step.

  FIG. 6 is a schematic view of a measurement system for bacteria and toxic substances using electromagnetic wave irradiation, and includes a culture vessel. When the number of certain types of bacteria is very small, it is effective to increase the number of bacteria by culturing and analyze with high accuracy. In the figure, reference numeral 71 denotes a terahertz electromagnetic wave transmission type culture vessel, which is made of a material such as quartz, polyethylene, Teflon, or a cycloolefin polymer-based special resin. The culture material 72 to which the latest is applied is sealed in the culture vessel 71 in a predetermined environment. This culture container is analyzed in the measurement system after a predetermined process by the culture apparatus 73. Image information can also be obtained from the measurement of the spectrum corresponding to each colony and the reflection intensity at the time of irradiation with a terahertz electromagnetic wave of a predetermined frequency. Therefore, the output of the detector 4 and the positions of the x, y, and z stages can be processed by the signal processing unit 5 to obtain image information at a predetermined frequency. Although the measurement system shown in FIG. 6 is a reflection type, it goes without saying that a transmission measurement system can be realized by installing the detector 4 below the sample 3.

  As described above, according to the present invention, an electromagnetic wave having a frequency equal to the natural frequency inherent to bacteria and toxic substances can be irradiated, and the substance can be identified from its absorption characteristics. Therefore, bacteria and toxic substances using electromagnetic wave irradiation can be identified. This measurement method and apparatus can quickly and easily detect bacteria and viruses and detect toxins, and thus is highly likely to be widely applied in the fields of medicine and biochemistry.

  It is a figure which shows the measuring method and apparatus of bacteria and a toxic substance using permeation | transmission of electromagnetic waves.   It is a figure which shows the cell structure of a sample confinement system, (1) planar type cell structure, and (2) waveguide type cell structure.   It is a figure which shows the measuring method and apparatus of bacteria and a toxic substance using reflection of electromagnetic waves.   It is a figure which shows the trial manufacture process of a planar cell structure.   It is a figure which shows the trial manufacture process of a waveguide type cell structure.   It is the schematic of the measurement system of bacteria and a toxic substance using the irradiation of electromagnetic waves including culture | cultivation of bacteria.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable wavelength electromagnetic wave generator 2 ... Lens 3 ... Sample 4 ... Detector 5 ... Signal processing part 6 ... Mirror 7 ... X, y, z movement stage 31, 61 ... Sample 32 ... Planar cell 33, 63 ... Cap 37 ... Liquid sample 38 ... Sample supply device 39 ... Blade 61 '... Sample material 63' ... Cap material 71 ... Culture container 72 ... Culture quality 73 ... Culture device

Claims (6)

  A sample containing at least one of bacteria, viruses and toxic substances has a variable wavelength electromagnetic wave generating means capable of irradiating an electromagnetic wave, and an electromagnetic wave detecting means having the frequency, and irradiates at least a part of the sample with an electromagnetic wave having a predetermined frequency. And measuring a transmission or reflection intensity, a method and an apparatus for measuring bacteria, viruses and toxic substances.   A frequency sweep of the electromagnetic wave or a part of the electromagnetic wave or a selection program of several frequencies to measure the frequency characteristic (spectrum) of the electromagnetic wave absorption of the sample, a value at a certain point, or an absorption characteristic in a certain frequency range, A method and apparatus for measuring bacteria, viruses and toxic substances, characterized by identifying the types of bacteria, viruses and toxic substances by pattern recognition in comparison with frequency characteristics of bacteria, viruses and toxic substances.   Bacteria, virus and toxic substance, characterized in that the sample has a planar cell structure having a cap film structure that covers the sample using a material that is substantially transparent to electromagnetic waves and processed into a predetermined film thickness using a recess Measuring method and apparatus.   Bacteria characterized in that the sample is a waveguide-type cell structure having a cap structure that covers the sample while being placed in a tube-like structure whose inner surface is covered with metal using a material that is substantially transparent to electromagnetic waves, Method and apparatus for measuring viruses and toxic substances.   As the variable wavelength electromagnetic wave generating means, a difference frequency generator using a GaP crystal is used, a YAG laser having a wavelength of 1.064 μm is used as the first pump light, and an optical parametric oscillator (OPO) is used as the second pump light source. A method and apparatus for measuring bacteria, viruses and toxic substances.   In the difference frequency generator using a GaP crystal as the variable wavelength electromagnetic wave generating means, two Cr: FORSTRITE lasers are used as pump light sources, one is a fixed wavelength and the other is used as a wavelength variable pump light source. Method and apparatus for measuring bacteria, viruses and toxic substances.

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