JP2020051830A - Inorganic fiber sheet for immobilizing test substance fluorescence sensor in fret method - Google Patents

Abstract

To provide an inorganic fiber sheet for immobilizing a test substance fluorescence sensor for use in an FRET (fluorescence resonance energy transfer) method that analyzes a test substance using FRET.SOLUTION: The present invention relates to a carrier for immobilizing a test substance fluorescence sensor having a wide detection range and capable of acquiring data with low background in an FRET method of analyzing a test substance, in which FRET method: uses a test substance fluorescence sensor that comprises a test substance binding part capable of specifically binding to the test substance and a first fluorescent substance; causes the test substance labeled with a second fluorescent substance to react with the test substance fluorescence sensor, or alternatively causes the test substance and a competitive substance bindable to the test substance binding part in competition with the test substance and labeled with the second fluorescent substance to react with the test substance fluorescence sensor; and analyzes a signal of fluorescence resonance energy transfer (FRET) generated by the interaction between the first fluorescent substance and the second fluorescent substance to thereby analyze the test substance.SELECTED DRAWING: None

Description

The present invention relates to an inorganic fiber sheet for fixing a test substance fluorescent sensor used in a FRET method for analyzing a test substance using fluorescence resonance energy transfer (FRET).
In this specification, the term "analysis" includes both "measurement" for quantitatively or semi-quantitatively determining the amount of a test substance and "detection" for determining the presence or absence of a test substance. It is.

  A method for analyzing a test substance using FRET is known (Patent Document 1). FRET means that two fluorescent substances, a donor channel (donor molecule or donor fluorescent molecule) which is a fluorescent energy donor and an acceptor channel (acceptor molecule or acceptor fluorescent molecule) which is a fluorescent energy acceptor, are present at adjacent positions. In this case, a non-radiative energy transfer phenomenon in which the energy is transferred to the acceptor channel non-radiatively by photoexcitation of the donor channel and the acceptor channel emits light.

In the FRET method, the presence or absence and amount of a test substance in a sample are determined by using a test substance fluorescent sensor having a test substance binding portion capable of specifically binding to the test substance and a first fluorescent substance. Can be analyzed.
For example, in non-competitive FRET, a test substance in a sample is labeled in advance with a second fluorescent substance, and the sample is reacted with a test substance fluorescent sensor. If the test substance is present in the sample, the test substance binds to the test substance binding part of the test substance fluorescent sensor, so that two fluorescent substances come close to each other, and when the donor fluorescent substance is optically excited in this state, the FRET phenomenon occurs. As a result, the fluorescence of the acceptor fluorescent substance is generated, so that the presence or absence and the amount of the test substance in the sample can be analyzed.

  On the other hand, in the competitive FRET, in addition to the sample that may contain the test substance, the second fluorescent substance can compete with the test substance and bind to the test substance binding part of the test substance fluorescent sensor. Prepare a competitor labeled with. When the sample, the competitor, and the analyte fluorescence sensor are reacted, the analyte in the sample competes with the competitor and binds to the analyte binding portion of the analyte fluorescence sensor. In the binding between the competitor and the test substance fluorescent sensor, the two fluorescent substances come close to each other, and when the donor fluorescent substance is optically excited in this state, the FRET phenomenon causes the acceptor fluorescent substance to emit fluorescence. On the other hand, the FRET phenomenon does not occur in the binding between the test substance having no fluorescent substance and the test substance fluorescent sensor. Since the amount of the competitor that binds to the test substance binding portion is inversely correlated with the amount of the test substance in the sample, the presence or absence and amount of the test substance in the sample and the amount The degree of competition between the test substance and the competitor for binding to the test substance binding portion can be analyzed.

  In the FRET method, it is possible to use the analyte fluorescence sensor immobilized on an appropriate carrier, and as the carrier, a flat plate such as a glass plate, particles such as agarose, and natural or synthetic fibers are known. (Patent Document 1).

JP-A-2013-232558

However, a flat carrier such as a glass plate has the drawback that the reaction field for immobilizing the analyte fluorescence sensor is small and the detection range is narrow.
Agarose particles, which are typical particle carriers, have a drawback that a fluorescent substance penetrates into the inside of the particles and the background becomes high. In addition, signals on individual particles had to be detected with a special device.
There are few studies on carriers for immobilization consisting of fibers. For example, it is known to use organic fibers such as cellulose ester in the FRET method in the gas phase (Japanese Patent Application Laid-Open No. 2010-14637). There is a possibility that the reagents used in the method may unintentionally react with the organic fiber or may penetrate into the organic fiber. It could go down.

  Therefore, an object of the present invention is to provide a carrier for immobilizing an analyte fluorescent sensor used in the FRET method, which has a wide detection range and can acquire data with a low background. Is to do.

The problem can be solved by the present invention described below:
[1] using a test substance fluorescence sensor including a test substance binding portion capable of specifically binding to a test substance and a first fluorescent substance,
The test substance labeled with the second fluorescent substance is allowed to react with the test substance fluorescent sensor, or the test substance and the test substance compete with the test substance and can bind to the test substance binding portion. And reacting a competitor labeled with a second fluorescent substance with the test substance fluorescent sensor,
A FRET method for analyzing the test substance by analyzing a signal of fluorescence resonance energy transfer (FRET) generated by an interaction between the first fluorescent substance and the second fluorescent substance,
An inorganic fiber sheet used in the FRET method, for fixing the fluorescence sensor of the test substance.
[2] The inorganic fibers constituting the inorganic fiber sheet are:
A silica fiber and a metal oxide other than the silica, and the metal oxide is present on the surface of the silica fiber, an inorganic fiber, the silicon on the surface of the inorganic fiber measured by ESCA analysis, The inorganic fiber sheet according to [1], wherein a ratio of the metal atom derived from the metal oxide (atomic%) to the atom (atomic%) is more than 0.00 and 0.70 or less.
[3] In the FRET method of [1], the fluorescence resonance energy transfer generated by the interaction between the first fluorescent substance and the second fluorescent substance contained in the test substance fluorescent sensor immobilized on the inorganic fiber sheet ( A method of analyzing a test substance by analyzing a signal of FRET).
[4] The method according to [1] above, wherein an inorganic fiber sheet is used as a carrier for fixing the analyte fluorescent sensor.
[5] (1) a test substance fluorescence sensor including a test substance binding portion capable of specifically binding to a test substance and a first fluorescent substance, and (2) carrying the test substance fluorescence sensor A fluorescence resonance energy transfer (FRET) analyzer including an inorganic fiber sheet.

  According to the inorganic fiber sheet of [1] of the present invention, since the surface area is large, a carrier for immobilization having a wide detection range can be provided. Further, according to the inorganic fiber sheet of the present invention, the reagents used in the FRET method, such as a fluorescent substance, can be prevented from reacting unintentionally with the fiber, and can be suppressed from penetrating into the fiber. It is possible to suppress a decrease in accuracy such as a narrow detection range and a high background in the analysis using the FRET method. As a result, it is possible to provide an immobilization carrier from which highly accurate data can be obtained.

  In addition, according to the inorganic fiber sheet of [2], which is a preferred embodiment of the present invention, the stability of the structure can be further improved, and further, a better handling property can be achieved. A more suitable carrier can be provided for immobilizing the analyte fluorescent sensor to be used.

Fluorescence observation images (upper figure) and transmission images (lower figure) in the same field of view of the FAM fluorescence-modified peptide-added Al-coated silica fiber nonwoven fabric prepared in Example 1 and the FAM fluorescence-modified peptide-added agarose beads prepared in Comparative Example 1. It is. 9 is an electron micrograph of the surface of the nonwoven fabric of the inorganic fiber nonwoven fabric prepared in Example 4. 9 is an electron micrograph of the fiber surface of the inorganic fiber nonwoven fabric prepared in Example 4. 9 is an electron micrograph of the nonwoven fabric surface of the inorganic fiber nonwoven fabric prepared in Example 5. 9 is an electron micrograph of the nonwoven fabric surface of the inorganic fiber nonwoven fabric prepared in Example 6. 9 is an electron micrograph of the surface of the nonwoven fabric of the inorganic fiber nonwoven fabric prepared in Example 7. 13 is an electron micrograph of the nonwoven fabric surface of the inorganic fiber nonwoven fabric prepared in Example 8. 9 is an electron micrograph of the surface of the nonwoven fabric of the inorganic fiber nonwoven fabric prepared in Comparative Example 3. It is an electron micrograph of the nonwoven fabric surface in the inorganic fiber nonwoven fabric prepared in Example 4 after performing ultrasonic treatment and drying. It is an electron micrograph of the nonwoven fabric surface in the inorganic fiber nonwoven fabric prepared in Example 5 after performing ultrasonic treatment and drying. It is an electron micrograph of the nonwoven fabric surface in the inorganic fiber nonwoven fabric prepared in Example 6 after performing ultrasonic treatment and drying. It is an electron micrograph of the nonwoven fabric surface in the inorganic fiber nonwoven fabric prepared in Example 7 after performing ultrasonic treatment and drying. It is an electron micrograph of the nonwoven fabric surface in the inorganic fiber nonwoven fabric prepared in Example 8 after performing ultrasonic treatment and drying. 9 is an electron micrograph of the nonwoven fabric surface of the inorganic fiber nonwoven fabric prepared in Comparative Example 3 after being subjected to ultrasonic treatment and dried.

  The inorganic fiber sheet of the present invention or the inorganic fiber sheet that can be used in the present invention (hereinafter, referred to as the inorganic fiber sheet in the present invention) is used for immobilizing a fluorescence sensor of a test substance used in the FRET method. It can be used as a carrier. In the present specification, the FRET method means a method of analyzing a test substance using FRET, and can be, for example, a non-competitive FRET method or a competitive FRET method in a liquid phase or a gas phase.

  More specifically, for example, a test substance fluorescent sensor including a test substance binding portion capable of specifically binding to a test substance and a first fluorescent substance was used, and labeled with a second fluorescent substance. The test substance reacts with the test substance fluorescent sensor, or the test substance competes with the test substance and can bind to the test substance binding portion, and the second fluorescent substance By reacting the labeled competitor with the analyte fluorescence sensor and analyzing a signal of fluorescence resonance energy transfer (FRET) generated by the interaction between the first fluorescent substance and the second fluorescent substance, The FRET method for analyzing the test substance can be mentioned.

The analyte fluorescence sensor fixed to the inorganic fiber sheet according to the present invention includes (1) an analyte binding portion capable of specifically binding to the analyte, and (2) a first fluorescent substance.
The “test substance binding portion” is not particularly limited as long as it is a substance that can specifically bind to a test substance (that is, a substance to be analyzed) that may be contained in a sample. Examples of the combination of the test substance and the test substance binding portion include a combination of an antigen and an antibody specific thereto (or an antibody fragment having an antigen recognition site), and a combination of an antibody and an antibody-binding protein (eg, protein A, protein G). , Protein L, etc.), a combination of a receptor and its ligand, a combination of biotin and avidin or streptavidin, a combination of an enzyme and its substrate, a histidine residue and a metal ion (eg, nickel, cobalt, copper) , Zinc, etc.).

  The “fluorescent substance” (including the first fluorescent substance and the second fluorescent substance) that can be used in the present invention is a fluorescent substance that can be a donor channel (donor molecule) or an acceptor channel (acceptor molecule) in FRET. There is no particular limitation as long as it is present, and examples of such a fluorescent substance include a fluorescent protein and a protein fluorescent labeling substance. Examples of such a fluorescent protein include fluorescent proteins such as CFP, YEP, GFP, RFP, BFP, and DsRed, and mutants of these fluorescent proteins may be used. Examples of such mutants include ECFP, EYFP, EGFP, ERFP, EBFP, and circular permutants thereof (circular permutants).

  Examples of the "protein fluorescent labeling substance" include low-molecular fluorescent substances. For example, naphthalene derivatives such as 1,5-IAEDANS, IAANS, and MIANS which are low-molecular fluorescent substances as donor channels (donor molecules); Pyrene derivatives such as pyrene maleimide and pyrene iodoacetamide; coumarin derivatives such as CPM, DCIA, DACIA, DACM (N- (7-dimethylamino-4-methylcoumarinyl) maleimide), MDCC, IDCC; and fluorescein isothiocyanate (FITC) Fluorescein maleimide, 5-iodoacetamide fluorescein, 5-bromomethylfluorescein, Oregon Green 488 maleimide, Oregon Green 488 iodoacetamide, etc. Alexa 488 Maleimide, Alexa 532 Maleimide, Alexa 546 Maleimide, Alexa 568 Maleimide, Alexa 594 Maleimide, Alexa 555 Maleimide, etc. Alexa Derivatives; BODIPY derivatives such as tetramethyl rhodamine maleimide, tetramethyl rhodamine iodoacetamide and rhodamine red maleimide; and Texas red derivatives such as Texas red maleimide and Texas red iodoacetamide. Low as a sceptor channel (acceptor molecule) Fluoroscein isothiocyanate (FITC), fluorescein maleimide, 5-iodoacetamide fluorescein, 5-bromomethyl fluorescein, Oregon Green 488 maleimide, Oregon Green 488 iodoacetamide, and other fluororesin derivatives; Alexa 488 maleimide, Alexa 532 Alexa derivatives such as maleimide, Alexa 546 maleimide, Alexa 568 maleimide, Alexa 594 maleimide, Alexa 555 maleimide, Alexa 633 maleimide, Alexa 647 maleimide, Alexa 660 maleimide, Alexa 680 maleimide, etc .; 545 Iodoacetamide, BODIP BODIPY derivatives such as Y530 / 550 iodoacetamide, BODIPY577 / 618 maleimide, BODIPY630 / 650 maleimide; rhodamine derivatives such as tetramethylrhodamine maleimide, tetramethylrhodamine iodoacetamide, rhodamine redmaleimide; Texas red maleimide, Texas red iodoacetamide And Texas red derivatives. Further, FAM (carboxyfluorescein hydrate) or the like can be used.

The binding between the first fluorescent substance and the test substance binding part, that is, the preparation of the test substance fluorescent sensor, is appropriately selected according to a combination of the selected fluorescent substance and the test substance binding part, according to a combination method known per se. For example, the first fluorescent substance can be chemically bonded to an amino group, an SH group, an aldehyde group, a carboxyl group, a hydroxyl group, or the like contained in or modified in the test substance binding portion. When the first fluorescent substance contains an NHS ester (amine-reactive), isocyanate (amine-reactive), maleimide (SH-reactive), hydrazide (aldehyde-reactive) or the like, a test substance having an amino acid sequence structure It is preferable because it can be easily bonded to the substance bonding portion.
When a fluorescent protein is used as the first fluorescent substance, a chimeric protein gene is prepared by adding or inserting a fluorescent protein gene to any site of the gene encoding the test substance binding portion, and using the gene. The test substance fluorescent sensor may be expressed in the cells.

  The “competitive substance” that can be used in the present invention is not particularly limited as long as it can compete with the test substance and bind to the test substance binding portion, and examples thereof include the test substance or an analog thereof. be able to.

  The labeling of the test substance with the second fluorescent substance or the labeling of the competitor with the second fluorescent substance can be performed by a known labeling method according to the combination of the selected fluorescent substance and the test substance or the competitor. The method can be appropriately selected. For example, the above-described method for bonding the first fluorescent substance and the test substance bonding portion can be used.

For example, in the non-competitive FRET method, after the test substance labeled with the second fluorescent substance is brought into contact with the test substance fluorescent sensor, or, for example, in the competitive FRET method, the test substance and the second Excitation light capable of exciting either one of the first fluorescent substance or the second fluorescent substance that functions as a donor channel after contacting the fluorescent substance-labeled competitor with the analyte fluorescent sensor; That is, using a desired light source, light in a range including the excitation maximum wavelength of the donor channel or a wavelength in the vicinity thereof is irradiated. As a light source, a monochromatic light such as a laser may be used in addition to a light source in which broad ultraviolet light or visible light is adjusted to a desired wavelength range using a filter or a spectroscope.
For example, as a laser light source when using CFP or DACM as a donor, in addition to a helium cadmium laser (442 nm), a blue diode laser (405 nm), an argon ion laser (457 nm), and an LD-excited solid-state laser (diode-pumped solid-state laser) ) (430 nm) and the like, and in the case of the two-photon excitation method, a pulse laser of about 800 nm can be used.
The wavelength of the laser light source can be appropriately adjusted so as to excite the fluorescent substance, and a laser light source having a longer wavelength than that described above may be employed according to the fluorescent substance to be used.

  The FRET signal, that is, the fluorescence, can be appropriately adjusted so as to be in a range including the fluorescence maximum wavelength of the donor channel and / or the acceptor channel or a wavelength in the vicinity thereof (for example, in the range of 200 to 800 nm). Can be analyzed by measuring the change in the fluorescence intensity. Furthermore, the quantification of the test substance in the sample can be calculated by preparing a calibration curve in advance using a test substance of known concentration according to a conventional method.

In the present invention, an inorganic fiber sheet is used as a carrier (hereinafter, sometimes referred to as a sensor-immobilizing carrier) for immobilizing the analyte fluorescent sensor used in the FRET method described above.
As the inorganic fiber sheet, a sheet-like fiber structure made of inorganic fibers can be used. Examples of the fiber structure include a fiber web, a nonwoven fabric, a woven fabric, and a knitted fabric. It is easy to adjust various configurations and physical properties such as the ratio and the distance between fibers, and the number of intersections of fibers where the reaction solution etc. unnecessarily accumulates can be reduced, so that data with a wide detection range and low background can be acquired. Inorganic fiber nonwoven fabrics are preferred because they can easily realize a carrier for immobilization. The inorganic fiber nonwoven fabric is manufactured by a known electrostatic spinning method, preferably by an electrostatic spinning method combining a sol-gel method and a neutralization spinning method, for example, a manufacturing method described in JP-A-2010-185164. be able to.

As the material of the constituent fibers of the inorganic fiber sheet, for example, SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , CeO ₂ , FeO, Fe ₃ O ₄ , Fe ₂ O ₃ , VO _{2 , V 2 O 5, SnO 2} , CdO, LiO 2, WO 3, Nb 2 O 5, Ta 2 O 5, In 2 O 3, GeO 2, PbTi 4 O 9, LiNbO 3, BaTiO 3, PbZrO 3, KTaO ₃ , Li ₂ B ₄ O ₇ , NiFe ₂ O ₄ , SrTiO _3, etc., and may be composed of a single component oxide or two or more components. . For example, it can be composed of two components of SiO ₂ —Al ₂ O ₃ .

  In the present invention, since the inorganic fiber sheet used as the carrier for immobilizing the sensor is a sheet-like fibrous structure, the immobilization carrier having a large surface area and a wide detection range can be provided. In addition, since the carrier is made of inorganic fibers, it is possible to suppress the infiltration of the fluorescent substance into the carrier, and to provide a carrier for immobilization capable of acquiring data with a low background.

  In the present invention, the inorganic fiber sheet used as the sensor-immobilizing carrier is not particularly limited as long as it is a sheet-shaped fiber structure made of inorganic fibers, but the inorganic fiber constituting the inorganic fiber sheet is not particularly limited. The system fiber is an inorganic fiber having a silica fiber and a metal oxide other than the silica, and the metal oxide is present on the surface of the silica fiber, wherein the inorganic fiber is measured by ESCA analysis. When the ratio of the metal atom derived from the metal oxide (atomic%) to the silicon atoms (atomic%) on the fiber surface is greater than 0.00 and 0.70 or less, "the inorganic fiber It is possible to provide an inorganic fiber sheet in which other metal oxides are not present in the form of webs at the intersections of each other, and as a result, the stability of the structure can be further increased, and further, Ri it is possible to achieve good handling properties, in order to immobilize the analyte fluorescent sensor using the FRET method, it is possible to provide a suitable carrier.

  The silica fiber that can constitute an inorganic fiber refers to a fiber in which the content of silica, which is silicon oxide, in the mass of the fiber component is 50 mass% or more. The greater the content of silica in the silica fiber, the more the structural stability and handleability of the inorganic fiber can be improved. Therefore, it is preferable that the silica fiber be substantially composed of only silica. The percentage of silica contained in the silica fiber can be calculated by subjecting it to an ESCA analysis method described later.

  Specifically, the silica fiber was subjected to an X-ray photoelectron spectroscopy analyzer (JPS-9010MK, JEOL (registered trademark)), and after performing a full element scan, a narrow scan was performed for the detected element and the element expected to be present. Is performed, it can be calculated based on the ratio of the measured value of the silicon atom (atomic%) to the measured value of another atom (atomic%).

  The crystalline state of the silica constituting the silica fiber can be appropriately selected, and may be in a form of crystalline or amorphous or a mixture of crystalline and amorphous. In particular, it is preferable that the silica fiber contains amorphous silica (hereinafter sometimes referred to as amorphous silica) because the silica fiber has excellent flexibility.

  The fiber length of the silica fiber can be appropriately selected, and may be a short fiber, a long fiber, or a continuous fiber having a fiber length of such a length that it is substantially difficult to measure the fiber length. The fiber length of the silica fiber is preferably a continuous length because an inorganic fiber or an inorganic fiber sheet having excellent flexibility can be provided. The silica fiber having a continuous length can be prepared by using a direct spinning method described later.

  The fiber diameter of the silica fiber can be appropriately selected. The fiber diameter of the silica fiber is preferably 3 μm or less, more preferably 2 μm or less, and preferably 1 μm or less so that the silica fiber has excellent flexibility and handling, and has a large surface area and a wide detection range. The lower limit of the fiber diameter is appropriately selected, but it is realistically 100 nm or more.

The “fiber length” and “fiber diameter” in the present invention can be measured based on a 5000 × electron micrograph of a fiber or a measurement object containing the fiber. When the measurement is difficult because the fiber length of the fiber is too long, it can be measured based on an electron micrograph at a magnification of less than 5000 times. When the measurement is difficult because the fiber diameter of the fiber is too small, it can be measured based on an electron micrograph at a magnification higher than 5000 times. When the cross-sectional shape of the fiber is non-circular, the diameter of a circle having the same area as the cross-sectional area is regarded as the fiber diameter.
The arithmetic average value of each fiber diameter at 50 points of the fibers measured as described above is defined as “average fiber diameter”, and the arithmetic average value of each fiber length is defined as “average fiber length”.

  The inorganic fiber sheet described below can be prepared using a silica fiber sheet configured to contain silica fiber.

The basis weight and thickness of the silica fiber sheet can be appropriately selected. Basis weight of the silica fiber sheet, most area of the area and weight of the wide surface (main surface) was measured, the value converted into weight per main surface 1 m ² and basis weight. In addition, when a load of 30 g / cm ² is applied on the main surface from the main surface of the silica fiber sheet to the other main surface, the length between the two main surfaces is measured by a high-precision digital length measuring machine. And its length as the thickness.

  Although the porosity of the silica fiber sheet can be appropriately selected, the porosity should be as high as 70% or more (bulk) so as to provide an inorganic fiber sheet which can be suitably used as a carrier for fixing a sensor. preferable. The preferred porosity is 75% or more, more preferably 80% or more, further preferably 85% or more, and further preferably 90% or more. The upper limit is not particularly limited, but is preferably 99.9% or less from the viewpoint of form stability.

The “porosity” can be calculated from the following equation.
P = [1-Wf / (V × SG)] × 100
Here, P represents the porosity (%), Wf represents the fiber weight (g), V represents the volume (cm ³ ), and SG represents the specific gravity of the fiber (g / cm ³ ).
For example, in the case of a sheet having a uniform thickness such as a nonwoven fabric, it can be calculated from the following equation.
P = [1−Wn / (t × SG)] × 100
Here, P represents the porosity (%), Wn represents the basis weight (g / m ² ), t represents the thickness (μm), and SG represents the specific gravity of the fiber (g / cm ³ ).

  The types of metals that can constitute other metal oxides can be appropriately selected depending on the application.For example, lithium, beryllium, boron, carbon, sodium, magnesium, aluminum, phosphorus, sulfur, potassium, calcium, scandium , Titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, cadmium, indium, tin, antimony, tellurium, cesium , Barium, lanthanum, hafnium, tantalum, tungsten, mercury, thallium, lead, bismuth, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium , Mention may be made of erbium, thulium, ytterbium, lutetium or the like.

As specific examples of other metal oxides, Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , CeO ₂ , FeO, Fe ₃ O ₄ , Fe ₂ O ₃ , VO ₂ , V ₂ O _{5 , SnO, SnO 2, SnO 3} , ZnO, CdO, LiO 2, WO 3, Nb 2 O 5, Ta 2 O 5, In 2 O 3, GeO 2, PbTi 4 O 9, LiNbO 3, BaTiO 3, PbZrO 3 , KTaO ₃ , Li ₂ B ₄ O ₇ , NiFe ₂ O ₄ , SrTiO _{3 and the} like. The other metal oxide may be composed of one component or may be composed of two or more components.

  In the present invention, the phrase "other metal oxide is present on the surface of the silica fiber" means that the other metal oxide covers the surface of the silica fiber over part or all of the surface of the silica fiber. And / or other metal oxides are present on the surface of the silica fiber in the form of fibrous, acicular, or particulate.

  The mode in which the other metal oxide is present on the surface of the silica fiber can be appropriately selected, but it is difficult for the other metal oxide to fall off from the fiber surface, and the other fiber is uniformly derived from the other metal oxide on the entire fiber surface. It is preferable that another metal oxide be present on a part or the entire surface of the silica fiber so as to cover the surface of the silica fiber, since an inorganic fiber exhibiting its function can be provided.

The aspect of the other metal oxide present on the surface of the silica fiber can be determined based on a 100,000 magnification electron micrograph of the inorganic fiber.
In addition, the ratio of the metal atom (atomic%) derived from another metal oxide to the silicon atom (atomic%) calculated by the ESCA analysis method described later is higher than 0.00 for the inorganic fiber or the inorganic fiber sheet. In an electron micrograph taken of, another metal oxide is present so as to cover the surface of the silica fiber on a part or the entire surface of the silica fiber, and / or the other metal oxide is present on the silica fiber. On the surface of the fiber, fibrous, needle-like, particle-like, the intersection of the silica fibers and the presence of a form such as a web-like existing between the silica fibers can not be confirmed that the presence of the silica fiber surface It is determined that another metal oxide is present on part or the entire surface so as to cover the surface of the silica fiber.

The mass of the other metal oxide and the mass ratio of the other metal oxide present on the inside and the surface of the silica fiber can be appropriately selected, but the inorganic fiber exhibiting a function derived from the other metal oxide uniformly on the entire fiber surface. Preferably, the other metal oxide is mainly present on the surface of the silica fiber so as to provide the following.
In other words, it is preferable that the inorganic fiber has a larger mass of the other metal oxide present on the surface of the silica fiber than the mass of the other metal oxide present inside the silica fiber. It is preferably an inorganic fiber in which another metal oxide is present only on the fiber surface.
The inorganic fiber in which the other metal oxide is substantially present only on the surface of the silica fiber can be prepared, for example, by the method described in the section of “Method for producing inorganic fiber” described below.

The ESCA analysis according to the present invention is a method for irradiating the surface of an inorganic fiber or an inorganic fiber sheet with X-rays and measuring the energy of the generated photoelectrons to analyze the elements present on the surface of the inorganic fiber. It is.
Specifically, the elements present on the surface of the inorganic fiber can be analyzed by the following measurement method.
(ESCA analysis)
The inorganic fiber is supplied to an X-ray photoelectron spectroscopy analyzer (JPS-9010MK, JEOL (registered trademark)), and after performing all element scans, a narrow scan is performed for the detected elements and the elements expected to be present. , “Si: silicon atom (atomic%) existing on the surface of inorganic fiber”, and “M: metal atom derived from another metal oxide existing on the surface of inorganic fiber (in other words, metal other than silicon) Atom, atomic%) ".
Then, by calculating M / Si from the obtained measured values, the ratio of metal atoms (atomic%) derived from other metal oxides to silicon atoms (atomic%) (hereinafter, referred to as M / Si ratio) Is calculated). The M / Si ratio is a value obtained by rounding off the third decimal place of the calculation result.

The lower the M / Si ratio, the less the other metal oxide occupies the fiber surface, and the higher the M / Si ratio, the more the other metal oxide occupies the fiber surface.
The less the other metal oxide occupying the fiber surface, the better the flexibility and / or the inorganic fiber which is not brittle, but if the other metal oxide occupying the fiber surface is too small, the other metal oxide There is a possibility that the function of the inorganic fiber becomes difficult to be exhibited due to the presence of the carbon.
Therefore, the M / Si ratio is preferably 0.01 to 0.70, preferably 0.03 to 0.60, and more preferably 0.05 to 0.50.

  The inorganic fiber may be provided with another composition such as an organic compound such as a polymer or another metal, for example, inside or on the surface of the inorganic fiber, depending on its use, but further increases the stability of the structure. Can further achieve better handling properties, and as a result, it is possible to provide an inorganic fiber sheet that can be suitably used as a sensor-immobilizing carrier. And other metal oxides only.

  The fiber diameter of the inorganic fibers can be appropriately selected. As the fiber diameter of the inorganic fiber is smaller, the surface area is larger, and a carrier for immobilization with a wider detection range can be provided. Therefore, the fiber diameter of the inorganic fiber is preferably 3 μm or less, more preferably 2 μm or less, and preferably 1 μm It is preferred that: The lower limit of the fiber diameter is appropriately selected, but it is realistically 100 nm or more.

The inorganic fiber in the present invention is an inorganic fiber that is more excellent in structural stability, for example, even under severe conditions such as water at a temperature of 80 ° C., such that it is difficult for other metal oxides to fall off from the inorganic fiber. preferable. Here, the water refers to distilled water.
Specifically, “A: M / Si ratio of inorganic fiber”, “B: the inorganic fiber after immersing the inorganic fiber in water at a temperature of 80 ° C. for 30 minutes, is subjected to ESCA analysis and calculated. From the respective measured values of the “M / Si ratio”, a percentage (%, hereinafter sometimes referred to as a residual percentage) calculated by calculating 100 × B / A is high. Is preferred. The remaining percentage is a value obtained by rounding off the first decimal place of the calculation result.
By including such an inorganic fiber, an inorganic fiber sheet having more excellent structural stability, such as another metal oxide hardly falling off from the inorganic fiber even under severe conditions such as water at a temperature of 80 ° C. Therefore, it is possible to provide an even more suitable carrier for immobilizing the analyte fluorescent sensor used in the FRET method.

  The inorganic fiber having a higher residual percentage is an inorganic fiber having excellent structural stability even under severe conditions, and an inorganic fiber sheet having excellent structural stability even under severe conditions can be provided. Therefore, the residual percentage is preferably at least 10%, more preferably at least 15%, preferably at least 20%, preferably at least 25%, particularly preferably at least 30%. Preferably, it is 35% or more, preferably 40% or more, more preferably 45% or more, preferably 50% or more, preferably 55% or more, and preferably 60% or more. , Preferably at least 65%, more preferably at least 70%, preferably at least 75%, preferably at least 80%, and at least 85% It is preferred, preferably at least 90%.

The inorganic fiber sheet in the present invention is a sheet-like fiber structure made of inorganic fibers, and is preferably a sheet provided with the inorganic fibers described above.
The average fiber diameter of the inorganic fibers constituting the inorganic fiber sheet is excellent in flexibility, and is preferably 3 μm or less, preferably 2 μm or less, so that it can be suitably used as a sensor-immobilizing carrier. It is preferably 1 μm or less. The lower limit of the average fiber diameter is appropriately selected, but it is practically 100 nm or more.

The basis weight and thickness of the inorganic fiber sheet can be appropriately selected. The basis weight of the inorganic fiber sheet is determined by measuring the area and weight of the surface (principal surface) having the largest area, and converting the value into the weight per 1 m ^{2 of the} principal surface. In addition, when a load of 30 g / cm ² is applied on the main surface from the main surface of the inorganic fiber sheet to the other main surface, the length between the two main surfaces is measured with a high-precision digital measuring machine. Measure and make the length the thickness.

  Although the porosity of the inorganic fiber sheet can be appropriately selected, it is preferable that the porosity has a high porosity (bulk) of 70% or more so as to be suitably used as a carrier for fixing the sensor. The preferred porosity is 75% or more, more preferably 80% or more, further preferably 85% or more, and further preferably 90% or more. The upper limit is not particularly limited, but is preferably 99.9% or less from the viewpoint of form stability.

The inorganic fiber sheet according to the present invention can provide an inorganic fiber sheet in which other metal oxides are not present in the form of webs at intersections between the inorganic fibers.
In the present invention, it is visually determined whether or not another metal oxide is present in the form of a web by the following method.
(1) A 5000-fold electron micrograph of the inorganic fiber sheet is taken.
(2) At the portion where the inorganic fibers intersect in the photographed electron micrograph, the fiber diameter (C fiber diameter) of the larger inorganic fiber fiber diameter of the intersecting inorganic fibers. Is calculated.
(3) In a portion where the fibers intersect, a circle having a radius twice as long as the diameter of the C fiber is formed around the point where the ends in the fiber diameter direction of the fibers overlap each other. Draw on the micrograph.
(4) A circle is drawn on the electron micrograph as shown in (2) to (3) in all the portions where the fibers cross each other in the electron micrograph.
(5) The circumference of the drawn circle and its center point (the point where the ends in the fiber radial direction of each fiber overlap), and the minimum area surrounded by the ends in the fiber radial direction of each fiber are If the metal oxide is present in the entire range, it is determined that another metal oxide is present in the inorganic fiber sheet in a web-like manner.

Alternatively, it is determined whether or not another metal oxide is present in a web form by the following method.
(1) A 5000-fold electron micrograph of the inorganic fiber sheet is taken.
(2) In a portion where the inorganic fibers do not intersect and are adjacent to each other in the photographed electron micrograph, another metal oxide is present in a film-like manner between the inorganic fibers. Make sure that
When another metal oxide is present between the two inorganic fibers in a film-like manner, it is determined that the other metal oxide is present in the inorganic fiber sheet in a web-like manner.

  In other cases, it is determined that no other metal oxide is present in the inorganic fiber sheet in a web-like shape.

Next, a method for producing an inorganic fiber according to the present invention will be described.
(Method of producing inorganic fibers)
The method for producing the inorganic fiber in the present invention can be appropriately selected, for example,
(1) a step of spinning silica fibers,
(2) a step of applying a metal ion solution to the silica fiber,
(3) removing the metal ion solution from the silica fiber to which the metal ion solution has been applied;
And a method for producing an inorganic fiber.

First, the step (1) of spinning silica fibers will be described.
The method of spinning the silica fiber can be appropriately selected, and examples thereof include a melt spinning method, a dry spinning method, a wet spinning method, and a direct spinning method (melt blow method, spunbond method, electrostatic spinning method, a method of spinning using centrifugal force). A method of spinning using an associated airflow described in JP-A-2011-012372, a neutralization spinning method which is a kind of an electrostatic spinning method described in JP-A-2005-264374, and the like. It can be obtained by a known method such as a method of extracting a fiber having a small fiber diameter by removing one or more resin components.

In particular, when the silica fiber is prepared by using the electrostatic spinning method, a silica fiber or a silica fiber sheet having a small average fiber diameter and a uniform fiber diameter is preferably prepared. In particular, when a neutralization spinning method, which is a kind of electrostatic spinning method, is used, a bulky silica fiber sheet having a high porosity can be prepared, and an inorganic fiber sheet that can be suitably used as a carrier for fixing a sensor can be provided. preferable.
When the electrospinning method is employed, as a spinning solution to be used, a spinning solution containing a condensate obtained by condensation polymerization of silica alkoxide (especially, in the item of "Method of determining spinning property of spinning solution" described later) , A spinning solution determined to have spinnability) is preferable because silica fibers having a uniform and fine fiber diameter can be prepared.

The "spinnability" can be determined by actually performing the electrospinning under the following conditions and determining the following criteria.
(Method of judging spinning property of spinning solution)
A spinning solution (solid content: 20 to 50% by weight) for judging spinnability is extruded from a horizontally arranged metal nozzle (inner diameter: 0.4 mm) to the grounded aluminum plate (extrusion amount: 0.5). (1.0 to 1.0 g / hr) and a voltage is applied to the nozzle (electric field strength: 1 to 3 kV / cm, polarity: positive or negative) to cause the solution to solidify at the tip of the nozzle for 1 minute or more. Continuously spun to try to form a microfiber nonwoven fabric on an aluminum plate.
A scanning electron microscope photograph of the formed ultrafine fiber is taken and observed, and there is no droplet, and an ultrafine fiber nonwoven fabric having an average fiber diameter (arithmetic average value at 50 points) of 5 μm or less and an aspect ratio of 100 or more is produced. If there are conditions available, the solution is considered "spinnable".
In contrast, the above conditions (ie, solid content concentration, extrusion rate, electric field strength, and / or polarity) are changed, and no matter how they are combined, when there are droplets, when the fiber shape is not constant, or when the aspect ratio is changed. Is less than 100 (for example, in the form of particles), and if there is no condition that can produce the ultrafine fiber nonwoven fabric, the solution is determined to be "not spinnable".

The silica alkoxide used to prepare the spinning solution is represented by the general formula SiR2m (OR1) _4-m , wherein R1 and R2 each represent an independent alkyl group, and m represents an integer of 0 to 2, respectively. The alkyl groups R1 and R2 may be the same or different, and R1 and R2 are preferably alkyl groups having 4 or less carbon atoms. For example, methyl group CH ₃ , ethyl group C ₂ H ₅ , propyl group C ₃ H _7, isopropyl _i-C 3 _{H 7,} butyl group _C 4 _{H 9,} it can be exemplified lower alkyl groups such as isobutyl group _i-C 4 _{H 9.}
Such silica alkoxide may be organically modified with a methyl group or an epoxy group as long as it has a site where a hydrolysis reaction and a condensation polymerization reaction can occur.

  The silica alkoxide can be diluted with a solvent to stabilize. The solvent for such stabilization is not particularly limited as long as it can dissolve the silica alkoxide and can be uniformly mixed with water, but is not particularly limited. For example, methanol, ethanol, propanol, Examples thereof include aliphatic lower alcohols such as isopropanol, butanol, isobutanol, ethylene glycol and propylene glycol, dimethylformamide, and water. In addition, these mixed solvents can also be used.

  A reaction solution for forming a condensate obtained by condensation polymerization of silica alkoxide contains water for hydrolysis. In addition, since the optimal amount of water varies depending on the structure of the silica alkoxide and the mode of the desired silica fiber or silica fiber sheet, the content of water in the reaction solution is not particularly limited. For example, tetraethoxysilane may be used. When the silica fiber is used, if the amount of water exceeds 4 times (molar ratio) the alkoxide, it becomes difficult to obtain a spinning solution having spinnability. It is preferred that:

  Further, the reaction solution for forming a condensate obtained by condensation polymerization of the silica alkoxide may contain a catalyst so that the hydrolysis reaction proceeds smoothly. Although the optimum catalyst varies depending on the structure of the silica alkoxide and the mode of the desired silica fiber or silica fiber sheet, the catalyst is not particularly limited, and examples thereof include hydrochloric acid, nitric acid, sodium hydroxide, and ammonia. More specifically, it is preferable to use an acidic catalyst in order to obtain the spinning solution having spinnability.

  Further, the reaction solution may include, for example, a chelating agent for stabilizing a silica alkoxide, a silane coupling agent, a compound capable of imparting various functions such as piezoelectricity, adhesion improvement, flexibility, and an organic compound (for example, polymethyl methacrylate). ) Or additives such as dyes. In addition, these additives can be added at the time of performing the hydrolysis or after the hydrolysis.

  Further, the reaction solution may contain inorganic or organic fine particles. Examples of the inorganic fine particles include titanium oxide, manganese dioxide, copper oxide, silicon dioxide, activated carbon, and a metal (for example, platinum). Examples of the organic fine particles include a dye or a pigment. The particle size and shape of the fine particles depend on the shape and size of the target sheet, and are not particularly limited, and can be appropriately selected according to the purpose. By including such fine particles, it is possible to impart additional functions such as an optical function, porosity, and adsorption function to the finally obtained inorganic fiber or inorganic fiber sheet.

  The condensate in which the silica alkoxide is polycondensed can be obtained by heating the reaction solution as described above and allowing the hydrolysis reaction to proceed. The heating is preferably performed at a temperature equal to or lower than the boiling point of the solvent constituting the reaction solution. For example, when the solvent is water, the hydrolysis reaction can be advanced by heating at a temperature lower than 100 ° C. Note that the temperature is preferably 10 ° C. or higher because the hydrolysis reaction hardly proceeds even when the temperature is too low.

The reaction solution containing the condensate thus formed preferably has a viscosity of 0.1 poise or more, more preferably 0.5 poise or more, and more preferably 1 poise or more so as to be spun. More preferred. When spinning a fine fiber having a fiber diameter of 3 μm or less, it is preferably 100 poise or less, more preferably 20 poise or less, and preferably 10 poise or less so that the diameter can be reduced. More preferably, it is 5 poise or less.
In the case where a nozzle is used, spinning may be possible even in the case of exceeding 100 poise by setting the atmosphere at the tip of the nozzle to the same solvent gas atmosphere as the solvent of the reaction liquid.

  The silica fiber obtained by spinning as described above can be obtained, for example, in the form of a fabric (woven fabric, knitted fabric, nonwoven fabric, fiber web, etc.).

  A heat treatment may be performed on the silica fiber thus formed. By performing the heat treatment, the condensation reaction of the silanol group generally proceeds, and the strength of the silica fiber or the silica fiber sheet as a whole can be increased. For example, when the silica fiber sheet is made of a fabric, the heat treatment can provide a fabric having improved strength and excellent shape retention. The heat treatment conditions are appropriately selected so as to provide a silica fiber or a silica fiber sheet having excellent flexibility. For example, the heat treatment can be performed using an oven, a sintering furnace, or the like. Or more, and can be 300 ° C. or more. Although the upper limit is not particularly limited, if the heat treatment temperature is too high, there is a possibility that the amorphous silica contained in the silica fiber may be crystallized. Therefore, as disclosed in Non-Patent Document (Journal of the Ceramic Society of Japan 105 [5] 385-390 (1997)) and the like, if the heat treatment temperature is in the range of 600 ° C to 1200 ° C, pure water is not used. Since silica is known not to exhibit crystallization, the heating temperature of the silica fiber is 1200 ° C. or less so that the crystallization of amorphous silica can be prevented to provide a silica fiber or a silica fiber sheet having excellent flexibility. It is preferably 1000 ° C. or less.

Further, by applying a silica sol solution (adhesive) as described in JP-A-2013-194341 to the silica fiber sheet prepared as described above and subjecting it to a heat treatment, the intersection of the silica fibers is bonded. A silica fiber sheet bonded with silica derived from the agent can be prepared.
For the same heat treatment conditions as above, the temperature can be 200 ° C. or higher, 300 ° C. or higher, and preferably 1200 ° C. or lower, and preferably 1000 ° C. or lower. It is preferred that:

Next, the step (2) of applying the metal ion solution to the silica fiber will be described.
A metal ion solution is applied to the silica fiber or silica fiber sheet prepared as described above. Here, the metal ion solution is a solution containing ions of a metal that can constitute another metal oxide according to the present invention. Specifically, as a metal ion solution, a metal inorganic salt (hydrochloride, sulfate, nitrate, or the like) or a metal organic salt (acetate, citrate, or the like) or the like is soluble in water or water-based water. For example, a solution dissolved in a solvent containing alcohol can be used, and a metal cation solution is preferably used as the metal ion solution.

  The method of applying the metal ion solution to the silica fiber or the silica fiber sheet can be appropriately selected, but a method of spraying or applying the metal ion solution using a spray or the like, a method of dipping in the metal ion solution, and the like can be adopted. .

  The time during which the silica fiber or the silica fiber sheet is in contact with the metal ion solution (for example, the immersion time in the metal ion solution), and the concentration and temperature (treatment temperature) of the metal ion solution to be used are appropriately selected. If the time is too long, the concentration of the metal ion solution is too high, or the processing temperature is too high, the M / Si ratio of the inorganic fibers may be higher than 0.70. In addition, when the time is too short, the concentration of the metal ion solution is too low, or the treatment temperature is too low, the function of the inorganic fiber due to the presence of other metal oxides may not be exhibited to an intended degree. . Therefore, the processing time is preferably from 1 minute to 72 hours, preferably from 1 hour to 48 hours, and more preferably from 3 hours to 24 hours. The concentration of the metal ion solution is preferably from 0.1 mmol / L to less than 50 mmol / L, more preferably from 0.5 mmol / L to 40 mmol / L, and preferably from 1 mmol / L to 30 mmol / L. . Further, the processing temperature is preferably from 10 ° C to 50 ° C, more preferably from 15 ° C to 40 ° C, and preferably from 20 ° C to 30 ° C.

Then, (3) the step of removing the metal ion solution from the silica fiber to which the metal ion solution has been applied will be described.
Excess metal ion solution is removed from the silica fiber or the silica fiber sheet provided with the metal ion solution prepared as described above. The removal method can be selected as appropriate, but a method of washing with a solvent, a method of suction-removing a metal ion solution by suction, or the like can be employed.

  The solvent that can be used for washing can be appropriately selected, but it is preferable to use the same solvent as the solvent contained in the metal ion solution, because the excess metal ion solution can be effectively removed. The temperature of the solvent at this time is appropriately selected so that the structural stability and handleability of the inorganic fiber or the inorganic fiber sheet do not unintentionally decrease.

  Then, for example, an oven dryer, a far infrared heater, a heater such as a dry heat dryer to be heated, such as standing at room temperature atmosphere or under reduced pressure atmosphere, remaining on the inorganic fiber or inorganic fiber sheet. The solvent used for washing may be removed. The heating temperature at the time of removing the solvent is a temperature at which the solvent can be volatilized, and an upper limit temperature of the heating temperature is selected so that the structural stability and handling properties of the inorganic fibers or the inorganic fiber sheet are not unintentionally reduced.

Although inorganic fibers can be produced by a production method including the above-described steps, further, after the above-described steps,
(4) heating the inorganic fibers at least at 80 ° C. or higher;
May be served.
Due to the production method including this step, even under severe conditions such as water at a temperature of 80 ° C., inorganic metal fibers or inorganic fiber sheets that are more excellent in structural stability such that other metal oxides do not easily fall off the inorganic fibers. Can be manufactured.

The method for heating the inorganic fibers can be appropriately selected, and for example, a heater such as an oven dryer, a far-infrared heater, and a dry heat dryer can be used.
The temperature at which the inorganic fiber is heated (heating temperature) is appropriately selected depending on the configuration and physical properties of the inorganic fiber, the type of the inorganic fiber or the other metal oxide constituting the inorganic fiber sheet, and, as an example, When the other metal oxide is an oxide of aluminum, the heating temperature is preferably at least 201 ° C, more preferably at least 250 ° C, and preferably at least 300 ° C. Although the upper limit value is not particularly limited, if the heat treatment temperature is too high, there is a possibility that amorphous silica contained in the silica fibers constituting the inorganic fibers may be crystallized. Therefore, the heating temperature of the inorganic fibers is preferably 1200 ° C or lower, and more preferably 1000 ° C or lower. Further, it is preferable to appropriately select the upper limit of the heating temperature so that the crystal structure of another metal oxide does not change to an unintended one.

  By using the above-described manufacturing method, the stability of the structure can be further improved, and further, better handling can be achieved. As a result, the fluorescent substance to be detected used in the FRET method can be immobilized. Therefore, it is possible to provide an inorganic fiber or an inorganic fiber sheet that can be used more suitably, furthermore, the fiber diameter is small, the fiber surface area is wide, the detection range is wide, and the inorganic fiber or the inorganic fiber sheet is wide. Can be provided.

The binding between the carrier for sensor immobilization and the analyte fluorescence sensor can be appropriately selected according to the combination of the selected inorganic fiber sheet and the analyte fluorescence sensor, and a known binding method can be appropriately selected. After directly modifying the test substance fluorescent sensor to the immobilized carrier, or after modifying a compound having a functional group capable of chemically bonding to the test substance fluorescent sensor at the end, such as a silane coupling agent or a phosphonic acid derivative. There is a method of indirectly chemically bonding the sensor-immobilized carrier. In each bonding process, a catalyst may be used.
Further, the surface of the inorganic fiber may be modified and activated by using a plasma method, an excimer method, an ultraviolet irradiation method, or the like, and the analyte fluorescent sensor may be coupled.

  Hereinafter, the present invention will be described specifically with reference to Examples, Comparative Examples, and Test Examples, but these do not limit the scope of the present invention.

(Example 1)
Spinning step and fiber accumulation step Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst are mixed in a molar ratio of 1: 5: 2: 0.003. Then, a reflux operation was performed at a temperature of 78 ° C. for 10 hours. Then, the solvent was removed by a rotary evaporator and concentrated, and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of 2 poise. Using the obtained sol solution as a spinning solution, a gel-like silica fiber web was produced by a neutralization spinning method.
In addition, the said neutralization spinning method was implemented on the same spinning conditions as Example 8 of Unexamined-Japanese-Patent No. 2005-264374. Details are shown below.
Spinning nozzle: 0.4 mm inner diameter metal injection needle (cut at the tip)
Distance between spinning nozzle and counter electrode: 200 mm
Opposite electrode and ion generating electrode (also used as both electrodes): A 1 mm thick alumina film (dielectric substrate) is sprayed on a stainless steel plate (induction electrode), and a 30 μm diameter tungsten wire (discharge electrode) is 10 mm thick thereon. Creeping discharge elements (tungsten wire surface is opposed to the spinning nozzle and grounded, and AC high voltage of 50 Hz is applied between the stainless steel plate and tungsten wire by AC high voltage power supply)
First high-voltage power supply: -16 kV
Second high-voltage power supply: ± 5 kV (peak voltage on AC creepage: 5 kV, 50 Hz)
Airflow: 25cm / sec in horizontal direction, 15cm / sec in vertical direction
Atmosphere in spinning chamber: temperature 25 ° C, humidity 40% RH or less Continuous spinning time: 30 minutes or more

Heat treatment step of gel silica fiber web The obtained gel silica fiber web was subjected to a heat treatment at 500 ° C in an electric furnace to prepare a silica fiber web (basis weight: 8 g / m ² ).

Bonding step between fibers As an inorganic sol solution for bonding used for bonding between fibers, tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and nitric acid as a catalyst, 1: 7.2: The mixture was mixed at a molar ratio of 7: 0.0039, and reacted at a temperature of 25 ° C. (room temperature) under stirring conditions of 300 rpm for 15 hours. After the reaction, the resultant was diluted with ethanol so that the solid content of silicon oxide became 0.25% to obtain a silica sol diluted solution.
After the obtained silica fiber web was immersed in the silica sol diluted solution, excess silica sol diluted solution was removed by suction to prepare a silica sol diluted solution-containing silica fiber web.
By holding the silica fiber web containing the silica sol diluted solution in an atmosphere at 110 ° C. for 30 minutes, the solvent contained in the remaining silica sol diluted solution was dried and removed. Subsequently, the resultant was subjected to a heat treatment at 500 ° C. in an electric furnace to bond the intersections of the silica fibers with silica derived from a silica sol dilute solution to prepare a silica fiber nonwoven fabric.

Al coating step of silica fiber nonwoven fabric The silica fiber nonwoven fabric is immersed in a mixed solution of H ₂ SO ₄ : 30% H ₂ O ₂ = 3: 1 at room temperature for 30 minutes to perform piranha treatment, and then washed with pure water. did.
Subsequently, an aqueous solution (temperature: 25 ° C.) having a concentration of 1 mmol / L for both NaCl and AlCl ₃ was prepared, and the pH of the aqueous solution was adjusted to 7 by adding NaOH. Then, the silica fiber nonwoven fabric subjected to the piranha treatment was immersed in the aqueous solution at room temperature for 24 hours. Thereafter, the silica fiber nonwoven fabric is pulled up, washed with purified water, and dried at 25 ° C. to prepare a silica fiber nonwoven fabric (hereinafter, referred to as an Al-coated silica fiber nonwoven fabric) in which an oxide of aluminum covers the surface of the silica fiber. did.

Fluorescent labeling step of Al-coated silica fiber nonwoven fabric In order to introduce a carboxyl group into the fiber surface, the Al-coated silica fiber nonwoven fabric was treated with a 10 mmol / L methanol solution of 10-CDPA (10-carboxydecylphosphonic acid), a phosphonic acid derivative. And treated at room temperature overnight, followed by methanol washing, and heat treatment at 120 ° C. for 3 hours to prepare a COOH group-provided Al-coated silica fiber nonwoven fabric.

As a carboxyl group-amino group cross-linking agent (combination of a carboxylic acid activating reagent and a dehydration condensing agent), 100 mmol / L EDC (1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride): 100 mmol / L NHS ( A mixed buffer solution (pH 4.5) of N-hydroxysuccinimide = 1: 1 was applied to the COOH group-coated Al-coated silica fiber nonwoven fabric, treated at room temperature for 10 minutes, and then washed with pure water.
Subsequently, a FAM fluorescence-modified peptide (a peptide composed of 30 amino acids, which is a peptide composed of 30 amino acids, which is adjusted to a concentration of 1 mg / mL using pure water, is applied to the washed COOH group-provided Al-coated silica fiber nonwoven fabric, FAM (Fluorescein) was added, the mixture was treated at room temperature for 2 hours, and then washed with pure water to prepare a FAM fluorescence-modified peptide-added Al-coated silica fiber nonwoven fabric.
The Al / Si ratio by ESCA analysis on the fiber surface of the obtained FAM fluorescence-modified peptide-added Al-coated silica fiber nonwoven fabric was 0.14.

(Comparative Example 1)
Agarose beads (organic carrier: anti-DYKDDDDK tag antibody beads) having a diameter of 50 to 120 μm were prepared. Then, a Hanks-Hepes buffer containing 1% bovine serum albumin was applied to the prepared agarose beads, treated for 30 minutes, and then the agarose beads were washed using the same buffer.
Subsequently, the washed agarose beads were adjusted to a concentration of 1 μM using the same buffer solution to a FAM fluorescence-modified peptide (a peptide composed of 30 amino acids, and the fluorescent dye was FAM (Fluorescein)). Was added and treated at room temperature for 1 hour, followed by washing with the same buffer to prepare FAM fluorescence-modified peptide-added agarose beads.

(Test Example 1)
For the FAM fluorescence-modified peptide-added Al-coated silica fiber nonwoven fabric prepared in Example 1 and the FAM fluorescence-modified peptide-added agarose beads prepared in Comparative Example 1, a confocal laser microscope (Nikon C1 system; microscope: Nikon ECLIPSE TE2000E; lens: Plan) Apo VC × 60 oil (NA = 1.4)) is used to irradiate FAM fluorescence (excitation wavelength (Ex): 488 nm) to irradiate FAM fluorescence (fluorescence wavelength (Em). ): 500-540 nm).

The results are shown in FIG. The upper diagram in FIG. 1 is a fluorescence observation image, and the lower diagram in FIG. 1 is a transmission image in the same visual field, and one side of each image is 21.2 μm.
The degree of penetration of the fluorescent dye into the inside of the carrier was significant for the organic carrier composed of agarose beads of Comparative Example 1 with a penetration length of 5 μm, but for the inorganic carrier composed of the silica fiber nonwoven fabric of Example 1, The permeation length was less than 1 μm, which was shallower than the fiber diameter, and permeation was suppressed. When permeation into the carrier occurs, the background may increase, and it has been confirmed that the inorganic fiber sheet of the present invention is suitable for use as a carrier for fixing a test substance fluorescent sensor used for FRET analysis.

(Example 2)
According to the procedure of Example 1, except that the peptide used in Example 1 was modified with DACM fluorescence modified peptide instead of the FAM fluorescence modified peptide used in Example 1, the DACM fluorescence modified peptide-added Al was added. A coated silica fiber nonwoven fabric was prepared.
Further, in place of the FAM fluorescently modified peptide used in Example 1, a double fluorescently modified peptide obtained by simultaneously modifying the peptide used in Example 1 with FAM and DACM was used. A double-fluorescent modified peptide-added Al-coated silica fiber nonwoven fabric was prepared.

(Reference Example 1)
Also, except that the peptide used in Examples 1 and 2 (the fluorescent dye was not modified) was used in place of the FAM fluorescence-modified peptide used in Example 1 for use in the measurement described below. According to the procedure of Example 1, a non-fluorescent peptide-added Al-coated silica fiber nonwoven fabric was prepared.

(Comparative Example 2)
The same process as that performed in the preparation process of the silica fiber nonwoven fabric of Example 1 and Example 2 was performed on the main surface (area: 0.3 cm ² , circle) of the quartz glass plate, thereby performing FAM fluorescence modification. Peptide-added Al-coated quartz glass plates, DACM fluorescence-modified peptide-added Al-coated quartz glass plates, and double fluorescence-modified peptide-added Al-coated quartz glass plates were prepared.
Further, the same treatment as that performed in the preparation process of the silica fiber nonwoven fabric of Reference Example 1 was performed on the main surface (area: 0.3 cm ² , circular) of the quartz glass plate to add a non-fluorescent peptide. An Al-coated quartz glass plate was prepared.

(Test Example 2)
For the various peptide-added Al-coated silica fiber nonwoven fabrics prepared in Examples 1 and 2 and Reference Example 1, and for the various peptide-added Al-coated quartz glass plates prepared in Comparative Example 2, a fluorescent plate reader (SH, manufactured by Corona Electric Co., Ltd.) -9000), fluorescence measurement was performed at Ex / Em = 390 nm / 450 nm, 390 nm / 520 nm, and 490 nm / 520 nm. The fluorescence measurement was performed at a temperature of 37 ° C., high pressure of photomultiplier high, measurement sensitivity × 10, and a half width of 5 nm.
Then, based on the signal intensities described in (Table 1) obtained by the measurement, based on the following calculation method, in an example using an inorganic fiber sheet as a carrier and in a comparative example using a quartz glass plate as a carrier. The intensity of each FRET signal was calculated.

And No. The value obtained by subtracting (A + B + No. 2) from the signal intensity of No. 11 was defined as the FRET signal intensity.

Since the excitation wavelength (Ex) / fluorescence wavelength (Em, detection wavelength) of FAM is 490 nm / 520 nm and the excitation wavelength (Ex) / fluorescence wavelength (Em, detection wavelength) of DACM is 390 nm / 450 nm, Ex390 nm / Em520 nm Under the measurement conditions described above, fluorescence is not originally detected, but a FRET phenomenon occurs, so that FAM is excited and FAM fluorescence is detected.
In addition, this test system is a simple evaluation system for FRET measurement assuming non-competitive FRET. However, by providing two types of fluorescent substances in the fluorescent sensor part of the test substance fixed to the carrier, FRET always occurs. In addition, alternative evaluation of non-competitive FRET was also performed.

Table 2 shows the results. The results shown in Table 2 are the average of N = 5. In addition, the calculation result is compared with a result obtained by converting the carrier into a circular range of 0.3 cm ² of the main surface area as viewed from directly above.
The inorganic fiber sheet made of the silica fiber nonwoven fabric of Example 2 shows about 10 times the signal intensity as compared with the carrier made of the quartz glass plate of Comparative Example 2, and furthermore, since it is a fiber sheet, it is difficult to handle. Was also excellent. It was confirmed that the inorganic fiber sheet according to the present invention is suitable for use as a carrier for fixing a fluorescent sensor of a test substance used for FRET analysis.
In addition, there was no significant difference in FRET efficiency due to the difference in carrier.

(Example 3)
A FAM fluorescence-modified peptide-added silica fiber nonwoven fabric was prepared in the same manner as in Example 1 except that Al coating was not performed.

(Test Example 3)
The FAM fluorescence-modified peptide-added silica fiber nonwoven fabric prepared in Example 3 and the FAM fluorescence-modified peptide-added Al-coated silica fiber nonwoven fabric prepared in Example 1 were each incubated at 4 ° C. in phosphate buffered saline (PBS). After storage for 6 days, the remaining ratio of the FAM fluorescence-modified peptide on the fiber sheet surface was 47% for the former (without Al coating) and 65% for the latter (with Al coating).
From these results, the inorganic fiber sheet in which a metal oxide other than silica is present on the surface of the silica fiber, which is a preferred embodiment of the inorganic fiber sheet according to the present invention, is a carrier on which an analyte fluorescent sensor used for FRET analysis is fixed. It has been confirmed that it is more suitable for use.

(Example 4)
An aqueous solution (temperature: 25 ° C.) having a concentration of 1 mmol / L for both NaCl and AlCl ₃ was prepared, and the aqueous solution was adjusted to pH 7 by adding NaOH. Then, the silica fiber nonwoven fabric prepared in Example 1 was immersed in the aqueous solution at room temperature for 24 hours. Thereafter, the silica fiber nonwoven fabric is pulled up, washed with purified water and dried at 25 ° C., whereby an inorganic fiber nonwoven fabric (average fiber diameter: 800 nm) in which aluminum oxide is present so as to cover the surface of the silica fiber , The basis weight: 8 g / m ² , the porosity: 95%, the M / Si ratio: 0.17, and the aluminum oxide was not present in the form of webs).
A 5000-fold electron micrograph of the surface of the nonwoven fabric prepared in Example 4 was taken and shown in FIG. Further, a 100,000-fold electron micrograph of the surface of the inorganic fibers constituting the nonwoven fabric was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron micrograph of the surface of the inorganic fiber nonwoven fabric at a magnification of 5000 after being subjected to the ultrasonic treatment in this manner was taken and shown in FIG.

(Example 5)
Except for using an aqueous solution (temperature: 25 ° C.) having a concentration of 5 mmol / L for both NaCl and AlCl ₃ , aluminum oxide is present to cover the surface of the silica fiber in the same manner as in Example 4. An inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.25, and no aluminum oxide in the form of webs) were prepared.
A 5,000-fold electron micrograph of the surface of the nonwoven fabric prepared in Example 5 was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron micrograph of the surface of the inorganic fiber non-woven fabric at a magnification of 5,000 was taken after the ultrasonic treatment in this manner, and is shown in FIG.

(Example 6)
Except for using an aqueous solution (temperature: 25 ° C.) having a concentration of 10 mmol / L for both NaCl and AlCl _3, an aluminum oxide is present to cover the surface of the silica fiber in the same manner as in Example 4. An inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.27, and no aluminum oxide in a web-like form) was prepared.
An electron microscope photograph of the surface of the nonwoven fabric prepared in Example 6 at a magnification of 5000 was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron micrograph of the surface of the inorganic fiber nonwoven fabric at a magnification of 5000 after being subjected to the ultrasonic treatment in this manner was taken and shown in FIG.

(Example 7)
Except for using an aqueous solution (temperature: 25 ° C.) having a concentration of 30 mmol / L for both NaCl and AlCl ₃ , aluminum oxide is present to cover the surface of the silica fiber in the same manner as in Example 4. An inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.33, and oxides of aluminum not present in a web-like form) were prepared.
A 5000 × electron micrograph of the surface of the nonwoven fabric prepared in Example 7 was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron microscope photograph of the surface of the inorganic fiber nonwoven fabric at a magnification of 5,000 was taken after the ultrasonic treatment in this manner, and is shown in FIG.

(Example 8)
Except for using an aqueous solution (temperature: 25 ° C.) having a concentration of 40 mmol / L for both NaCl and AlCl _3, an aluminum oxide is present to cover the surface of the silica fiber in the same manner as in Example 4. An inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.45, and aluminum oxide not present in a web-like shape) were prepared.
A 5000 × electron micrograph of the surface of the nonwoven fabric prepared in Example 8 was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron microscope photograph of the surface of the inorganic fiber non-woven fabric at a magnification of 5,000 was taken after the ultrasonic treatment in this manner, and is shown in FIG.

(Comparative Example 3)
Except for using an aqueous solution (temperature: 25 ° C.) having a concentration of 50 mmol / L for both NaCl and AlCl ₃ , aluminum oxide is present to cover the surface of the silica fiber in the same manner as in Example 4. An inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 93%, M / Si ratio: 0.71, and aluminum oxide present in a web-like shape) was prepared.
An electron microscope photograph of 5000 times of the surface of the nonwoven fabric prepared in Comparative Example 3 was taken and shown in FIG.

In addition, by confirming the susceptibility of the inorganic fibers constituting the inorganic fiber nonwoven fabric to breakage, to evaluate the structural stability of the inorganic fibers and the inorganic fiber nonwoven fabric, the prepared inorganic fiber nonwoven fabric was prepared. The following sonication was performed.
The prepared inorganic fiber nonwoven fabric was immersed in distilled water, and ultrasonic waves (100 kHz) were applied to the inorganic fiber nonwoven fabric in the distilled water for 2 minutes. Then, the inorganic fiber nonwoven fabric subjected to the ultrasonic wave was pulled out of the distilled water and dried in a room temperature atmosphere.
An electron micrograph of the surface of the inorganic fiber nonwoven fabric at a magnification of 5,000 was taken after the ultrasonic treatment in this manner, and is shown in FIG.

(Example 9)
The inorganic fiber nonwoven fabric prepared in Example 4 was immersed in water at 80 ° C. for 30 minutes.
After that, the inorganic fiber nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , voids) in which aluminum oxide is present so as to cover the surface of the silica fiber by lifting from water and drying at 25 ° C. Ratio: 95%, M / Si ratio: 0.04, and aluminum oxide was not present in the form of webs).
The residual percentage was 24%.

(Example 10)
The inorganic fiber non-woven fabric prepared in Example 4 was supplied to an electric furnace set at a temperature of 200 ° C. and heat-treated for 3 hours, and an inorganic fiber in which an oxide of aluminum was present to cover the surface of the silica fiber A nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.16, and no aluminum oxide in the form of webs) was prepared.

(Example 11)
In the same manner as in Example 9, except that the inorganic fiber nonwoven fabric prepared in Example 10 was used, an inorganic fiber nonwoven fabric (average fiber diameter) in which an oxide of aluminum was present so as to cover the surface of the silica fiber was used. : 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.05, and aluminum oxide not present in the form of webs).
The residual percentage was 31%.

(Example 12)
The inorganic fiber non-woven fabric prepared in Example 4 was supplied to an electric furnace set at a temperature of 300 ° C. and heat-treated for 3 hours, and an inorganic fiber in which an aluminum oxide was present so as to cover the surface of the silica fiber. A nonwoven fabric (average fiber diameter: 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.14, and no aluminum oxide in the form of webs) was prepared.

(Example 13)
In the same manner as in Example 9, except that the inorganic fiber nonwoven fabric prepared in Example 12 was used, an inorganic fiber nonwoven fabric (average fiber diameter) in which an oxide of aluminum was present so as to cover the surface of the silica fiber was used. : 800 nm, basis weight: 8 g / m ² , porosity: 95%, M / Si ratio: 0.13, and oxides of aluminum were not present in the form of webs).
The residual percentage was 93%.

As a result of comparing Examples 4 to 13 with Comparative Example 3, the inorganic fiber nonwoven fabrics of Examples did not have aluminum oxide in the form of webs, whereas Comparative Example 3 Aluminum oxide was present in a web-like form in the inorganic fiber nonwoven fabric.
In addition, as a result of confirming an electron micrograph of the surface of each inorganic fiber nonwoven fabric at a magnification of 5000 after performing ultrasonic treatment and drying on the inorganic fiber nonwoven fabric prepared in Example and Comparative Example 3, the inorganic fiber nonwoven fabric of Example was confirmed. No exfoliation or breakage of aluminum oxide was observed in the fibers and the inorganic fiber nonwoven fabric. On the other hand, in the inorganic fiber and the inorganic fiber non-woven fabric of Comparative Example 3, a portion where aluminum oxide was peeled or damaged was observed. This proved that the inorganic nonwoven fabric composed of the inorganic fibers prepared in the examples had excellent structural stability.

  Therefore, the inorganic fiber nonwoven fabrics of Examples 4 to 13 have a problem that even if the fiber diameter is small such as a fiber diameter of 3 μm or less, the stability of the structure is poor and the handling property is poor. It was confirmed that it was improved and more suitable for use as a carrier for immobilizing a fluorescence sensor of a test substance used for FRET analysis.

In addition, the results of Example 4 and Examples 9 to 13 revealed the following.
As a result of comparison between Example 10 and Example 11, the residual percentage of the inorganic fiber nonwoven fabric prepared in Example 10 was 31%, and the inorganic fiber nonwoven fabric (inorganic fiber nonwoven fabric) was obtained even under the harsh condition of 80 ° C. in water. Other metal oxides hardly fell off from the fibers.
Furthermore, as a result of comparing Example 12 and Example 13, the residual percentage of the inorganic fiber nonwoven fabric prepared in Example 12 was as high as 93%, and the inorganic fiber nonwoven fabric was more remarkable even under severe conditions of water at a temperature of 80 ° C. (Inorganic fibers) other metal oxides were difficult to fall off.
On the other hand, as a result of comparing Example 4 with Example 9, the remaining percentage of the inorganic fiber nonwoven fabric prepared in Example 4 was 24%, and the inorganic fiber nonwoven fabric (inorganic fiber nonwoven fabric) Other metal oxides were likely to fall off from the base fiber).

  Therefore, the inorganic fibers constituting the inorganic fiber nonwoven fabric prepared in Example 10 and Example 11 are inorganic fibers having more excellent structural stability, and the inorganic fiber nonwoven fabric is a test sample used for FRET analysis. It was confirmed that it was more suitable for use as a carrier for immobilizing a substance fluorescence sensor.

  Further, the silica fibers constituting the inorganic fibers according to the examples were manufactured without being heated at a temperature exceeding 1200 ° C. in the manufacturing process. Therefore, the inorganic fibers according to the examples were considered to be more excellent in flexibility by being provided with the silica fibers containing amorphous silica.

  The inorganic fiber sheet according to the present invention can be used as a carrier for fixing a test substance fluorescent sensor used in a FRET method for analyzing a test substance using fluorescence resonance energy transfer (FRET).

Claims (5)

Using a test substance fluorescence sensor including a test substance binding portion capable of specifically binding to the test substance and a first fluorescent substance,
The test substance labeled with the second fluorescent substance is allowed to react with the test substance fluorescent sensor, or the test substance and the test substance compete with the test substance and can bind to the test substance binding portion. And reacting a competitor labeled with a second fluorescent substance with the test substance fluorescent sensor,
A FRET method for analyzing the test substance by analyzing a signal of fluorescence resonance energy transfer (FRET) generated by an interaction between the first fluorescent substance and the second fluorescent substance,
An inorganic fiber sheet used in the FRET method, for fixing the fluorescence sensor of the test substance. Inorganic fibers constituting the inorganic fiber sheet,
A silica fiber and a metal oxide other than the silica, and the metal oxide is present on the surface of the silica fiber, an inorganic fiber, the silicon on the surface of the inorganic fiber measured by ESCA analysis, The inorganic fiber sheet according to claim 1, wherein a ratio of the metal atom (atomic%) derived from the metal oxide to the atom (atomic%) is more than 0.00 and 0.70 or less.   2. The FRET method according to claim 1, wherein a fluorescence resonance energy transfer (FRET) generated by an interaction between the first fluorescent substance and the second fluorescent substance contained in the fluorescent substance to be detected immobilized on the inorganic fiber sheet. A method for analyzing a test substance by analyzing a signal of the test substance.   2. The method according to claim 1, wherein an inorganic fiber sheet is used as a carrier for fixing the analyte fluorescence sensor.   (1) a test substance fluorescent sensor including a test substance binding portion capable of specifically binding to a test substance, and a first fluorescent substance; and (2) an inorganic fiber carrying the test substance fluorescent sensor. A fluorescence resonance energy transfer (FRET) analyzer comprising a sheet.