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WO2025121239A1 - Substrat stratifié - Google Patents

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Publication number
WO2025121239A1
WO2025121239A1 PCT/JP2024/042121 JP2024042121W WO2025121239A1 WO 2025121239 A1 WO2025121239 A1 WO 2025121239A1 JP 2024042121 W JP2024042121 W JP 2024042121W WO 2025121239 A1 WO2025121239 A1 WO 2025121239A1
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WIPO (PCT)
Prior art keywords
metal
protective layer
based particles
average
substrate
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PCT/JP2024/042121
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English (en)
Japanese (ja)
Inventor
知浩 福浦
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Sumitomo Chemical Co Ltd
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Sumitomo Chemical Co Ltd
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Priority claimed from JP2024203151A external-priority patent/JP2025092436A/ja
Application filed by Sumitomo Chemical Co Ltd filed Critical Sumitomo Chemical Co Ltd
Publication of WO2025121239A1 publication Critical patent/WO2025121239A1/fr
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence

Definitions

  • the present invention relates to a laminated substrate.
  • Patent Document 1 describes the use of a laminate including an island layer (2) composed of multiple metal particles and a spacer layer (5) that covers the island layer in a photochemical fluorescence sensor.
  • the object of the present invention is to provide a laminate substrate that has excellent fluorescence enhancement properties.
  • a plate-shaped substrate having a pair of main surfaces facing each other; a plurality of metal-based particles arranged on one main surface of the substrate and spaced apart from one another in a direction parallel to the one main surface; a protective layer covering the surface of each of the metal-based particles,
  • the plurality of metal-based particles satisfy at least one of the following (1) and (2): A laminated substrate, wherein the surface shape of the protective layer conforms to the surface shape of the metal-based particles.
  • the plurality of metal-based particles have an average particle size of 200 to 1600 nm, an average height of 55 to 500 nm, and an aspect ratio defined as the ratio of the average particle size to the average height of 1 to 8.
  • the plurality of metal-based particles are arranged on the one main surface of the substrate such that an average distance between adjacent metal-based particles is 1 to 1000 nm, and a standard deviation of the average distance is 30 nm or less.
  • [5] The metal-based particle assembly layered substrate according to any one of [1] to [4], wherein the protective layer is amorphous.
  • a laminated substrate with excellent fluorescence enhancement properties is provided.
  • FIG. 1 is a cross-sectional view that illustrates an example of a laminated substrate according to the present invention.
  • the laminated substrate according to the present disclosure includes a plate-shaped substrate having a pair of opposing main surfaces, a plurality of metal-based particles arranged on one surface of the substrate at a distance from one another in a direction parallel to the one main surface; and a protective layer covering a surface of each of the metal-based particles.
  • FIG. 1 is a cross-sectional view showing a schematic example of a laminated substrate.
  • the laminated substrate 100 shown in FIG. 1 comprises a substrate 10 having a pair of opposing principal surfaces 10a, 10b, a plurality of metal-based particles 20 arranged on the principal surface 10a of the substrate 10 at a distance from each other in a direction parallel to the principal surface 10a, and a protective layer 30 covering the surface of each metal-based particle 20.
  • the substrate 10 is plate-shaped.
  • Plate-shaped means that the substrate has a pair of opposing main surfaces 10a, 10b and side surfaces connecting the main surfaces, and the thickness, which is the distance between the main surfaces, is 1/5 or less of the maximum diameter of the main surfaces (for example, the diagonal length in the case of a rectangle).
  • the thickness may be 1/10 or less, 1/20 or less, or 1/30 of the maximum diameter of the main surfaces.
  • the area of the main surfaces is larger than the area of the other surfaces constituting the side surfaces.
  • the lower limit of the area of the main surface there is no particular limit to the lower limit of the area of the main surface, and it may be, for example, 0.25 ⁇ m 2 or more. Since the laminated substrate may be a long roll, there is no particular limit to the upper limit of the area of the main surface, and it may be, for example, 1 m 2 or less.
  • the thickness of the substrate 10 is not particularly limited, and is, for example, 10 ⁇ m to 10 mm, preferably 20 ⁇ m to 5 mm, and more preferably 30 ⁇ m to 1 mm.
  • the substrate 10 is preferably non-conductive. If the substrate 10 is conductive, electrons can be exchanged between the metal-based particles formed thereon via the substrate, which tends to reduce the plasmon resonance effect.
  • non-conductive materials constituting the substrate 10 include inorganic insulating materials such as mica, SiO 2 , ZrO 2 , and glass, and thermoplastic resins.
  • the substrate 10 may be a light-transmitting or optically transparent substrate, or may be non-light-transmitting (light-absorbing).
  • the substrate 10 may be a single-layer structure or a multi-layer structure.
  • the plurality of metal-based particles 20 are arranged on the main surface 10a of the substrate 10 at intervals from one another in a direction parallel to the main surface 10a. It is preferable that the plurality of metal-based particles 20 are not arranged at intervals from one another in a direction perpendicular to the main surface 10a. In other words, it is preferable that the metal-based particles 20 are arranged two-dimensionally along the main surface 10a.
  • the metal-based particles 20 are preferably in contact with the main surface 10a of the substrate 10.
  • the metal-based particles 20 are preferably not provided on the other main surface 10b of the substrate 10.
  • the plurality of metal-based particles 20 constitute a metal-based particle assembly layer 21.
  • the plurality of metal-based particles 20 can constitute a plasmon structure.
  • a "plasmon structure” refers to a structure that can exhibit plasmon resonance. Plasmons are compression waves of free electrons that occur due to collective vibration of free electrons in a structure.
  • the laminated substrate can be suitably used as a light emission enhancement element for various sensor elements. By applying the laminated substrate to a sensor element, the sensitivity, quantitative accuracy, and/or reproducibility (stability) of the sensor element can be improved.
  • the metal-based particles 20 are preferably made of a material capable of plasmon resonance in the ultraviolet to visible light region.
  • a material capable of plasmon resonance in the ultraviolet to visible light region means a material that, when made into nanoparticles or their assembly, exhibits a plasmon peak that appears in the ultraviolet to visible light region in absorption spectrum measurement by absorptiometry.
  • Metal-based materials capable of plasmon resonance in the ultraviolet to visible light region include, for example, precious metals such as gold, silver, copper, platinum, and palladium; metals other than precious metals such as aluminum and tantalum; alloys containing a metal selected from the precious metals and metals other than precious metals; and metal compounds (metal oxides, metal salts, etc.) containing a metal selected from the precious metals and metals other than precious metals.
  • precious metals such as gold, silver, copper, platinum, and palladium are preferred as metal-based materials capable of plasmon resonance in the ultraviolet to visible light region, and silver is more preferred from the viewpoint of being inexpensive and having small absorption (the imaginary part of the dielectric function is small at visible light wavelengths).
  • the plurality of metal-based particles 20 satisfies at least one of the following (1) and (2), and preferably satisfies both of them.
  • the plurality of metal-based particles have an average particle size D of 200 to 1600 nm, an average height H of 55 to 500 nm, and an aspect ratio AR defined as the ratio of the average particle size to the average height of 1 to 8.
  • the plurality of metal-based particles are arranged on one main surface of the substrate such that an average distance L between adjacent metal-based particles is within a range of 1 to 1000 nm, and the standard deviation LCV of the average distance is 30 nm or less.
  • the average particle size D of the multiple metal-based particles 20 that make up the metal-based particle assembly layer 21 is preferably within the range of 200 to 1200 nm, more preferably 250 to 500 nm, and even more preferably 300 to 500 nm. It is preferable that the average particle size of the metal-based particles 20 is appropriately selected depending on the type of metal-based material that makes up the metal-based particles 20.
  • the average particle diameter D of the plurality of metal-based particles 20 is the average particle diameter of the selected 10 metal-based particles when 10 metal-based particles are randomly selected in an SEM observation image taken directly above the metal-based particle assembly layer 21 composed of the plurality of metal-based particles 20, 5 tangent diameters are randomly drawn within each metal-based particle image (wherein all of the tangent diameter lines can only pass through the interior of the metal-based particle image, and one of these lines must pass only through the interior of the metal-based particle and be the longest line that can be drawn), and the average value (hereinafter, this average value is also referred to as the "average tangent diameter" is taken as the particle diameter of each metal-based particle.
  • the tangent diameter is defined as the perpendicular line connecting the distance between two parallel lines tangent to the outline (projected image) of the metal-based particle (Nikkan Kogyo Shimbun, "Particle Measurement Technology", 1994, p. 5).
  • an SEM observation image is measured using a scanning electron microscope "JSM-5500” manufactured by JEOL Ltd. or an equivalent device.
  • the obtained observation image is read in 1280 pixels horizontal x 960 pixels vertical using free image processing software "ImageJ” manufactured by the National Institutes of Health.
  • 10 random numbers are obtained from 1 to 1280 ( x1 , x2 , x3 , x4, x5 , x6 , x7 , x8, x9 , x10 ) and 10 random numbers from 1 to 960 ( y1 , y2 , y3 , y4 , y5 , y6 , y7 , y8 , y9 , y10 ).
  • 10 random number combinations are obtained: ( x1 , y1 ), ( x2 , y2), (x3, y3 ), ( x4 , y4 ) , ( x5 , y5 ), ( x6 , y6 ), ( x7 , y7 ), ( x8 , y8 ), ( x9 , y9 ) and ( x10 , y10 ).
  • Ten pairs of coordinate points (x1, y1), (x2, y2), (x3, y3), (x4, y4 ), ( x5 , y5), (x6, y6 ), ( x7 , y7 ), ( x8 , y8 ), ( x9 , y9) and ( x10 , y10 ) are obtained, with a random number generated from 1 to 1280 as the x coordinate and a random number generated from 1 to 960 as the y coordinate . Then, the above-mentioned average tangent diameter value is obtained for a total of 10 metal-based particle images including these coordinate points, and then the average particle diameter is obtained as the average of the 10 average tangent diameter values.
  • the random number combination is discarded, and random number generation is repeated until all ten coordinate points are contained within different metal-based particle images.
  • the average height H of the plurality of metal-based particles 20 is preferably within a range of 55 to 300 nm, and more preferably 70 to 150 nm.
  • the average height H of the metal-based particles 20 is the average value of 10 measurements obtained by randomly selecting 10 metal-based particles in an AFM observation image of the metal-based particle assembly layer 21 and measuring the heights of these 10 metal-based particles.
  • the aspect ratio AR of the plurality of metal-based particles 20 is preferably within a range of 2 to 8, and more preferably 2.5 to 8.
  • the aspect ratio AR of the metal-based particles 20 is defined as the ratio of the average particle diameter D to the average height H (average particle diameter D/average height H).
  • the metal-based particles 20 may be spherical, but preferably have a flat shape with an aspect ratio AR of greater than 1.
  • the multiple metal-based particles 20 are arranged so that the average distance L between adjacent metal-based particles (hereinafter also referred to as the "average interparticle distance") is 1 to 1000 nm, but is preferably arranged so that it is within the range of 1 to 150 nm.
  • adjacent metal-based particles means adjacent in a direction parallel to the main surface 10a.
  • the average interparticle distance is more preferably 1 to 100 nm, more preferably 1 to 50 nm, and even more preferably 1 to 20 nm. If the average interparticle distance is less than 1 nm, electron transfer based on the Dexter mechanism occurs between the particles, which is disadvantageous in terms of deactivation of localized plasmons.
  • the average interparticle distance is the average interparticle distance of 10 metal-based particles randomly selected in an SEM observation image taken directly above metal-based particle assembly layer 21 composed of a plurality of metal-based particles 20, and the interparticle distance between each of the selected metal-based particles and adjacent metal-based particles is calculated.
  • the interparticle distance between adjacent metal-based particles is the average value of the distances between all adjacent metal-based particles (the minimum distance between the surfaces of adjacent metal-based particles) measured.
  • the SEM observation image is measured using a scanning electron microscope "JSM-5500” manufactured by JEOL Ltd. or an equivalent device.
  • the obtained observation image is read in 1280 pixels horizontally by 960 pixels vertically using free image processing software "ImageJ” manufactured by the National Institutes of Health.
  • 10 random numbers (x 1 to x 10 ) from 1 to 1280 and 10 random numbers (y 1 to y 10 ) from 1 to 960 are obtained using the random number generation function "RANDBETWEEN" of the spreadsheet software "Excel” manufactured by Microsoft Corporation.
  • the random number combination is discarded, and random number generation is repeated until all 10 coordinate points are included within different metal-based particle images.
  • the standard deviation of the average interparticle distance is preferably 0.1 nm or more, more preferably 0.2 nm or more, and even more preferably 0.3 nm or more.
  • the standard deviation of the average interparticle distance is defined as follows. In an SEM observation image taken directly above metal-based particle assembly layer 21 composed of a plurality of metal-based particles 20, one metal-based particle is first selected at random, and the interparticle distance between that metal-based particle and adjacent metal-based particles is determined. The interparticle distance between adjacent metal-based particles is the average value obtained by measuring the distances between all adjacent metal-based particles (the minimum distance between the surfaces). In the above SEM observation image, nine metal-based particles different from the one selected at random are selected, and the interparticle distance between adjacent metal-based particles is determined for these nine metal-based particles in the same manner as above. The standard deviation of the interparticle distances between adjacent metal-based particles obtained in this way for a total of 10 metal-based particles is defined as the standard deviation of the average interparticle distance.
  • a more specific method for measuring the standard deviation of the average interparticle distance is as follows: First, the SEM observation image is measured using a scanning electron microscope "JSM-5500” manufactured by JEOL Ltd. or an equivalent device. Next, the obtained observation image is read in 1280 pixels horizontally by 960 pixels vertically using free image processing software "ImageJ” manufactured by the National Institutes of Health. Next, 10 random numbers (x 1 to x 10 ) from 1 to 1280 and 10 random numbers (y 1 to y 10 ) from 1 to 960 are obtained using the random number generation function "RANDBETWEEN" of the spreadsheet software "Excel” manufactured by Microsoft Corporation.
  • RANDBETWEEN random number generation function
  • the random number combination is discarded, and random number generation is repeated until all 10 coordinate points are included in different metal-based particle images.
  • the metal-based particles 20 preferably have a smoothly curved surface, and more preferably have a flat shape with a smoothly curved surface, but the surface may contain some minute irregularities (roughness), and in this sense the metal-based particles may be amorphous.
  • the number of metal-based particles 20 contained in metal-based particle assembly layer 21 is usually 10 or more, and preferably 30 or more. By forming a metal-based particle assembly layer containing 10 or more metal-based particles, strong plasmon resonance and an extension of the range of action of plasmon resonance are likely to occur due to the interaction between the localized plasmons of the metal-based particles.
  • the number of metal-based particles 20 contained in metal-based particle assembly layer 21 may be, for example, 50 or more, further 1000 or more, or even 10000 or more.
  • the number density of metal-based particles 20 in metal-based particle assembly layer 21 is preferably 7 particles/ ⁇ m2 or more , and more preferably 15 particles/ ⁇ m2 or more .
  • the metal-based particle assembly layer 21 is preferably one that does not exhibit electrical conductivity as a layer, and it is more preferable that the metal-based particles 20 constituting the metal-based particle assembly layer 21 are each non-conductive with their adjacent metal-based particles. If there are locations in the metal-based particle assembly layer 21 where electrons can be exchanged between the metal-based particles 20, the plasmon resonance effect tends to be reduced. Therefore, it is preferable that the metal-based particles 20 are reliably spaced apart from each other and that no conductive material is interposed between the metal-based particles 20.
  • the metal-based particles 20 themselves may be conductive.
  • the metal-based particle assembly layer 21 does not exhibit electrical conductivity as a layer can be confirmed, for example, by the fact that when a pair of tester probes of a multimeter (tester (Hewlett-Packard's "E2378A”)) is brought into contact with the metal-based particle assembly layer 21 at a distance of 10 mm to 15 mm, and the range is set to "30 M ⁇ ," the resistance value under the measurement conditions is 30 M ⁇ or more, resulting in the display of "overload.”
  • tester Hewlett-Packard's "E2378A”
  • the protective layer 30 covers the surface of each metal-based particle 20. It is preferable that the protective layer 30 is in direct contact with the surface of the metal-based particle 20.
  • the protective layer 30 may have a single-layer structure or a multilayer structure. Since a part of the surface of each metal-based particle 20 (the lower surface side in FIG. 1) is usually covered by the substrate 10, the protective layer 30 can cover at least a part of the exposed part of the surface of the metal-based particle 20 that is not covered by the substrate 10, and it is preferable that the protective layer 30 covers the entire exposed part of the surface of the metal-based particle 20 that is not covered by the substrate 10. It is preferable that the metal-based particle 20 is not covered by either the substrate 10 or the protective layer 30 and does not have a surface exposed to the outside.
  • the surface shape of the protective layer 30 follows the surface shape of the metal-based particles 20.
  • the surface shape of the protective layer 30 follows the surface shape of the metal-based particles 20 means that the surface shape of the protective layer 30 is approximately parallel to the surface shape of the metal-based particles 20 in the cross-sectional view shown in Figure 1.
  • Figure 1 is a schematic diagram of a cross section perpendicular to the main surface 10a of the substrate 10.
  • the thickness T of the protective layer 30 measured in a direction perpendicular to the main surface 10a i.e., the distance perpendicular to the main surface 10a between the interface 20a between the protective layer 30 and the metal-based particles and the surface 30a of the protective layer 30 opposite the substrate 10, is substantially uniform.
  • the protective layer thickness T being substantially uniform means that the coefficient of variation (CV value) of the protective layer thickness, i.e. (standard deviation of the protective layer thickness T/average value of the protective layer thickness T) is 30% or less.
  • the standard deviation and average value of the thickness T can be obtained as follows. Specifically, a microscope image of a cross section perpendicular to the main surface 10a of the laminated substrate is prepared using a scanning microscope or the like. The magnification of the microscope image is set so that 10 to 250 metal-based particles are included. In the microscope image, the length of the straight line of the main surface 10a is divided into 51 equal parts, and coordinates 1, 2, ..., and 50 are obtained from the left end of the cross-sectional image.
  • intersections 1-1 to 50-1 between the straight lines and the interface between the metal-based particles 20 and the protective layer 30 are obtained, and intersections (intersections 1-2 to 50-2) between the straight lines and the surface 30a of the protective layer 30 opposite the substrate 10 are obtained.
  • the distance between the intersections 1-1 and 1-2 is defined as the protective layer thickness T1
  • the distance between the intersections 2-1 and 2-2 is defined as the protective layer thickness T2
  • protective layer thicknesses T1 to T50 are obtained.
  • the average value of these 50 values is defined as the average thickness of the protective layer.
  • the standard deviation of these 50 values is defined as the standard deviation of the protective layer thickness, and (standard deviation of the protective layer thickness/average protective layer thickness) is defined as the coefficient of variation (CV value) of the protective layer thickness. It should be noted that in the microscope image, if a straight line does not intersect with a metal-based particle, the thickness is not measured for that straight line.
  • the coefficient of variation (CV value) of the thickness of the protective layer may be 20% or less, preferably 18% or less, and more preferably 15% or less.
  • the average thickness of the protective layer is not particularly limited, but may be, for example, 3 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 30 nm or more, or 40 nm or more.
  • the thickness of the protective layer may be, for example, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, 80 nm or less, or less than 50 nm.
  • the arithmetic mean roughness Ra of the surface of the protective layer may be 10 nm or more, 15 nm or more, or 20 nm or more.
  • the arithmetic mean roughness Ra may be 500 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.
  • the protective layer 30 may have a portion that contacts and covers the portion of the main surface 10a of the substrate 10 that is not covered by the metal-based particles 20, as shown in FIG. 1.
  • the material of the protective layer is preferably a non-conductive material, i.e., an insulating material.
  • insulating materials include inorganic insulating materials such as SiO2 , SiN , TiO2 , Al2O3 , and Si3N4 ; and organic insulating materials such as resin materials ( e.g., polystyrene, acrylic resin, epoxy resin, etc.).
  • the protective layer may be composed of two or more materials.
  • the protective layer may have a single-layer structure or a multi-layer structure.
  • the protective layer is preferably amorphous.
  • the fact that the protective layer 30 is amorphous can be confirmed by HAADF-STEM and electron diffraction patterns.
  • an electron diffraction pattern is obtained for the location of the protective layer in a cross-sectional STEM image of the protective layer 30, the absence of periodic contrast resulting from crystals means that the protective layer 30 can be determined to be an amorphous layer.
  • the water contact angle of the surface of the protective layer may be 40° or less, preferably 30° or less, and more preferably 20° or less.
  • the aqueous solution may be, for example, a treatment liquid containing a capture substance or a precursor thereof used when fixing the capture substance to the surface of the protective layer, or a sample that may contain the substance to be detected and that is supplied to the surface of the protective layer to which the capture substance is fixed.
  • a protective layer is advantageous in the following respects.
  • the metal-based particle is used as a luminescence enhancing element for enhancing the intensity of luminescence from a luminous body that labels a substance to be detected, if the luminous body is in direct contact with the metal-based particle, quenching due to electron tunneling from the luminous body to the metal-based particle may occur, and the enhancing effect may decrease.
  • the luminous body and the metal-based particle can be reliably separated, thereby suppressing quenching.
  • the stability (oxidation resistance, etc.) and environmental resistance (for example, light resistance, humidity resistance, heat resistance, etc.) of the metal-based particles can be improved.
  • the laminated substrate may further include another layer on top of the protective layer.
  • the laminated substrate according to this embodiment can exhibit the following features [a] and [b]. These features are believed to be manifested by interactions between localized plasmons exhibited by the plurality of metal-based particles 20.
  • [a] The range of action of plasmon resonance exhibited by metal-based particle assembly layer 21 is wide. As a result, for example, the range over which the light emission enhancing effect by plasmons reaches can be widened, and light emission from light-emitting bodies located within, for example, a range of several hundred nm (e.g., 200 nm) from the surface of metal-based particle assembly layer 21 can also be enhanced.
  • Metal-based particle assembly layer 21 exhibits strong plasmon resonance, which can provide, for example, a strong light emission enhancement effect.
  • the laminated substrate according to the present invention can enhance the emission of light from a light emitter located at a distance of, for example, 10 nm or more, even several tens of nm (e.g., 20 nm, 30 nm, or 40 nm) or more, or even 100 nm or more or 200 nm or more, from the metal-based particle assembly layer 21.
  • a light emitter located at a distance of, for example, 10 nm or more, even several tens of nm (e.g., 20 nm, 30 nm, or 40 nm) or more, or even 100 nm or more or 200 nm or more, from the metal-based particle assembly layer 21.
  • the strength of the plasmon resonance exhibited by the laminated substrate is not simply the sum of the localized plasmon resonances exhibited by the individual metal-based particles at a particular wavelength, but is even stronger.
  • the individual metal-based particles interact with each other to produce strong plasmon resonance. It is believed that such strong plasmon resonance is produced by interactions between the localized plasmons of the metal-based particles.
  • plasmon peak a plasmon resonance peak
  • the strength of the plasmon resonance of the plasmon structure can be evaluated from the magnitude of absorbance at the maximum wavelength of the plasmon peak. The greater the absorbance value, the greater the strength of the plasmon resonance tends to be.
  • the absorbance at the maximum wavelength of the plasmon peak located on the longest wavelength side in the ultraviolet to visible light region can be 1 or more, or even 1.5 or more, or even about 2.
  • the absorption spectrum of the plasmon structure can be measured by absorptiometry. Specifically, the absorption spectrum is obtained by irradiating the back side (the side opposite to the metal-based particle assembly layer) of a substrate on which a metal-based particle assembly layer is laminated with incident light in the ultraviolet to visible light region from a direction perpendicular to the substrate surface, and measuring the intensity I of the transmitted light in all directions that has passed through the metal-based particle assembly layer side, and the intensity I of the transmitted light in all directions that has passed through the opposite side to the incident surface by irradiating a substrate of the same thickness and material as the substrate of the measurement sample from a direction perpendicular to the surface of the substrate on which the metal-based particle assembly layer is not laminated with the same incident light as the substrate, and measuring the intensity I 0 of the transmitted light in all directions that has passed through the opposite side to the incident surface, using an integrating sphere spectrophotometer.
  • the absorbance which is the vertical axis of the ab
  • an objective lens and a spectrophotometer can be used to narrow the measurement field of view and perform absorption spectrum measurement.
  • the laminated substrate according to the present embodiment can increase the light emission enhancement factor, and although the reason for this is not clear, the following reasons are considered, for example. It is believed that the main factor in long-range plasmons is that the whispering gallery mode propagating on the surface of each metal particle resonates with that of adjacent particles. The whispering gallery mode that propagates on the surface of a metal particle follows the surface shape of the protective layer to that of the metal particle. In other words, it is speculated that a protective layer that covers a metal particle with a uniform thickness causes less disturbance in particle surface propagation and inter-particle propagation than a protective layer with an uneven thickness, and therefore the resonance between adjacent particles that causes long-range plasmons is more likely to occur.
  • the above-mentioned laminated substrate can be produced, for example, by the following method.
  • a plate-shaped substrate 10 is prepared.
  • the surface of the substrate can be degreased and cleaned in advance.
  • an appropriate method can be adopted depending on the material of the substrate, for example, cleaning using a liquid selected from an organic solvent and water.
  • the cleaning method include a method of immersing in the liquid, a method of ultrasonic cleaning while immersing in the liquid, and a method of wiping with a cloth (woven fabric, nonwoven fabric, etc.) soaked in the liquid.
  • the degreased cleaning may be a combination of cleaning steps using two or more liquids.
  • the degreased cleaning may include ultrasonic cleaning using alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, etc.), ultrasonic cleaning using ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), and ultrasonic cleaning using ultrapure water, in this order.
  • alcohols methyl alcohol, ethyl alcohol, isopropyl alcohol, etc.
  • ketones acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.
  • ultrasonic cleaning using ultrapure water in this order.
  • a metal-based fine particle layer is formed on the main surface of the substrate.
  • Examples of this method are the following [A] to [C].
  • [A] A bottom-up method in which a plurality of metal-based particles 20 are grown from minute seeds on a substrate 10;
  • [B] A method in which a plurality of metal-based particles 20 are coated with a protective film made of an amphiphilic material having a predetermined thickness, and then this is formed into a film on a substrate 10 by an LB (Langmuir Blodgett) film method;
  • Other methods include post-treating a thin film prepared by vapor deposition or sputtering, resist processing, etching, and a casting method using a dispersion liquid in which metal particles are dispersed.
  • the above method [A] preferably includes a step of growing metal-based particles at an extremely slow rate on a substrate 10 adjusted to a predetermined temperature (hereinafter also referred to as a "particle growth step").
  • a metal-based particle assembly layer 21 having the above-mentioned preferred average particle size, average height, aspect ratio, average interparticle distance, and standard deviation of the average interparticle distance can be obtained with good control.
  • the rate at which the metal-based particles are grown on the substrate 10 is preferably less than 1 nm/min, more preferably 0.5 nm/min or less, in terms of average height growth rate.
  • the average height growth rate here can also be called the average deposition rate or the average thickness growth rate of the metal-based particles, and is expressed by the following formula: It is defined as the average height of the metal-based particles divided by the growth time of the metal-based particles. The definition of "average height of the metal-based particles" is as described above.
  • the metal-based particle growth time refers to the time from the start to the end of the growth of the metal-based particles, specifically, the supply time of the metal-based material.
  • the metal-based particle growth time can also be rephrased as the film formation time.
  • the metal-based particle growth time is the sputtering time.
  • the temperature of the substrate 10 during the particle growth process is preferably 100°C or higher and 450°C or lower, more preferably 200°C or higher and 450°C or lower, even more preferably 250°C or higher and 350°C or lower, and even more preferably 300°C or thereabouts (approximately 300°C ⁇ 10°C).
  • the pressure (pressure in the device chamber) when growing metal particles is not particularly limited as long as the pressure allows particle growth, but is usually less than atmospheric pressure. There is no particular lower limit to the pressure, but since it is easy to adjust the average height growth rate within the above range, it is preferably 0.5 Pa or more, more preferably 6 Pa or more, and even more preferably 10 Pa or more.
  • the specific method for growing metal-based particles on the substrate 10 is not particularly limited as long as it allows particles to grow at an average height growth rate of less than 1 nm/min, but examples include sputtering and deposition methods such as vacuum deposition.
  • sputtering methods it is preferable to use direct current (DC) sputtering, since it allows a metal-based particle assembly layer to grow relatively easily and makes it easy to maintain an average height growth rate of less than 1 nm/min.
  • DC direct current
  • the sputtering method is not particularly limited, and a direct current argon ion sputtering method can be used, in which argon ions generated by an ion gun or plasma discharge are accelerated by an electric field and irradiated onto a target.
  • Other conditions in the sputtering method such as the current value, voltage value, and distance between the substrate and the target, are appropriately adjusted so that particles grow at an average height growth rate of less than 1 nm/min.
  • the average height growth rate is set to less than 1 nm/min in the particle growth step, as well as the average particle size growth rate to less than 5 nm.
  • the average particle size growth rate will usually be less than 5 nm.
  • the average particle size growth rate is more preferably 1 nm/min or less.
  • the average particle size growth rate is expressed by the following formula: It is defined as the average particle size of the metal-based particles/growth time of the metal-based particles. The definitions of "average particle size of the metal-based particles" and "growth time of the metal-based particles" are as described above.
  • metal-based particle assembly layer 21 having the above-mentioned preferred average particle size, average height, aspect ratio, average interparticle distance, and standard deviation of the average interparticle distance, it is preferable to appropriately adjust the metal-based particle growth time in the particle growth process while taking into consideration the above-mentioned preferred manufacturing conditions.
  • a protective layer is formed on the surface of the metal-based particles.
  • the method for forming the protective layer is not particularly limited, but from the viewpoint of forming a surface shape that conforms to the surface shape of the metal-based particles, dry film formation methods such as vapor deposition, sputtering, ion plating, CVD, ALD, etc., and wet film formation methods such as spray coating are preferred.
  • the sputtering method is not particularly limited, it is preferable to use a radio frequency (RF) sputtering method.
  • RF radio frequency
  • Argon gas or the like can be used as the gas.
  • SiO2 film by a sputtering method at least on the outermost surface of the protective layer.
  • the discharge output (power) is 200 W or more, preferably 500 W or more, and more preferably 1000 W or more.
  • the film can be densified while improving the ability to follow the underlying structure, and also high-speed film formation is possible.
  • RF sputtering is preferably carried out in an atmosphere of an inert gas such as argon gas, and it is preferable that oxygen not be added to the inert gas atmosphere.
  • the laminated substrate can be used as a sensor element mounted in a sensor device for detecting a target substance.
  • the laminated substrate can be washed with a piranha solution or the like, and then a capture substance that specifically binds to the target substance can be introduced into a predetermined position on the surface of the protective layer 30 (the surface opposite the substrate 10) by photolithography or the like, to form a sensor element.
  • the sensor element can detect the target substance, for example, as follows. Detection may be qualitative or quantitative, and refers to, for example, identification or quantification of the target substance.
  • Detection may be qualitative or quantitative, and refers to, for example, identification or quantification of the target substance.
  • the label which is a light-emitting body
  • the metal-based particle assembly layer of the sensor element which is preferably a plasmon structure, resonates with the excited light-emitting body, and plasmon emission enhancement occurs.
  • the target substance can be detected qualitatively or quantitatively by detecting the light emission from the excited light-emitting body using a detector.
  • the amount of the target substance present can be measured qualitatively or quantitatively by measuring the light emission intensity.
  • the laminated substrate preferably includes a metal-based particle assembly layer that is a plasmon structure, which can enhance plasmon emission, thereby improving detection sensitivity and detection accuracy.
  • the detectable substance is a substance that is the subject of qualitative or quantitative detection and specifically binds to the capture substance.
  • detectable substance There are no particular limitations on the detectable substance, and examples include nucleosides, nucleotides, nucleic acids, proteins, sugars, glycoproteins, lectins, viruses, cells, antibodies, exosomes, etc.
  • a sensor element in which the detectable substance is a biological substance or a biologically related substance is also called a biosensor element.
  • Nucleic acid refers to a polymer (nucleotide chain) of nucleoside phosphate esters in which a purine or pyrimidine base is glycosidicly linked to a sugar, and includes oligonucleotides containing probe DNA, polynucleotides, DNA (full length or fragments thereof) in which purine nucleotides and pyrimidine nucleotides are polymerized, RNA, polyamide nucleotide derivatives (PNA), etc.
  • PNA polyamide nucleotide derivatives
  • a nucleoside is a compound in which a base is glycosidicly linked to a sugar
  • a nucleotide is a compound in which a phosphate is linked to a nucleoside
  • both nucleosides and nucleotides are compounds that contain a base.
  • “Specifically bound” broadly refers to chemical bonds between substances, including non-covalent bonds, covalent bonds, and hydrogen bonds, and examples include interactions between protein molecules and electrostatic interactions between molecules.
  • the captured target substance can be detected by labeling the target substance with a luminescent label in advance and detecting the luminescence from this label.
  • the label may be a labeling substance that specifically binds to a complex obtained by specific binding between the capture substance and the target substance.
  • the luminescent substance is a substance that emits light when excitation energy is injected from excitation light.
  • the principle of luminescence in the luminescent substance is not limited, and examples include fluorescence, phosphorescence, and chemiluminescence.
  • any conventionally known substance can be used.
  • the capture substance is a substance that functions to specifically bind to and capture the substance to be detected.
  • the capture substance is, for example, fixed to the surface of the protective layer 30.
  • the capture substance is, for example, a substance that has a binding active group that can specifically bind to the substance to be detected.
  • the binding active group include a carboxyl group and a hydroxyl group that can electrostatically interact with the substance to be detected.
  • the capture substance There are no particular limitations on the capture substance, and examples include nucleosides, nucleotides, nucleic acids, proteins, sugars, glycoproteins, etc.
  • sensor devices examples include biosensor devices such as DNA sequencers, DNA microarrays, virus sensors, ion sensors, plate readers (protein chips, glycan chips, lectin chips, etc.), microspectrometers, and glucose sensors.
  • biosensor devices such as DNA sequencers, DNA microarrays, virus sensors, ion sensors, plate readers (protein chips, glycan chips, lectin chips, etc.), microspectrometers, and glucose sensors.
  • Example 1 Degreasing and Cleaning of Glass Substrate A soda glass substrate having a square shape with sides of 50 mm and a thickness of 0.7 mm was prepared. This soda glass substrate was subjected to a degreasing and cleaning treatment, which involved cleaning with isopropyl alcohol, acetone, and then ultrapure water.
  • the average particle size, based on the above definition, of the silver particles constituting the metal-based particle assembly layer was found to be 335 nm, the average interparticle distance was 16.7 nm, and the standard deviation of the average interparticle distance was 27.8 nm. From the SEM image, it can be seen that the metal-based particle assembly layer has approximately 6.25 ⁇ 10 10 silver particles (approximately 25 particles/ ⁇ m 2 ). Furthermore, based on the results of AFM imaging using a Keyence Corporation "VN-8010," the average height of the silver particles was found to be 96.2 nm. Thus, the aspect ratio (average particle size/average height) of the silver particles was calculated to be 3.48.
  • a SiO2 layer was formed as a protective layer by RF sputtering using a SiO2 target under the conditions of an argon atmosphere without oxygen introduction, a discharge output (electric power) of 1000 W, and a growth rate of the protective layer of 1.8 nm/min.
  • a substrate that is considerably larger than the target is rotated above the target to deposit the protective layer over a wide area on the substrate, and the above growth rate of the protective layer is the average rate over the entire area of the deposited protective layer.
  • the arithmetic mean roughness Ra of the surface of the protective layer of the laminated substrate was measured by AFM. Specifically, an AFM (Keyence VN-8000) was used to obtain a 5 ⁇ m ⁇ 5 ⁇ m uneven shape in contact mode on the surface of the protective layer side of the laminated substrate, and then the effective area was specified as the entire area, and the value of the arithmetic mean roughness Ra of the surface of the protective layer was output from the "3D measurement" analysis.
  • the arithmetic mean roughness Ra of the surface of the protective layer in Example 1 was 20.1 nm.
  • Example A> A metal-based particle assembly layer similar to that of Example 1 was formed on a 0.5 mm thick soda glass substrate by growing silver particles under the same conditions as in Example 1. This metal-based particle assembly layer had the same particle shape and average inter-particle distance as in Example 1.
  • a SiO2 protective layer having an average thickness of 28.0 nm was formed under the same conditions as in Example 1.
  • the surface of the protective layer was spin-coated with a rhodamine B solution at a rotation speed of 2000 rpm, and then dried to fix the rhodamine B dye, which is a light emitter, to the surface of the protective layer, thereby obtaining a photoexcited light-emitting element A.
  • the rhodamine B solution was prepared by dissolving the rhodamine B dye (Exciton Rhodamine 110) in ethanol to a concentration of 0.15 mM.
  • the standard deviation and average value of the thickness T of the protective layer were 4.0 nm and 28.0 nm, respectively.
  • the surface shape of the SiO2 protective layer followed the surface shape of the metal-based particles.
  • the coefficient of variation (CV value) of the thickness of the protective layer i.e. (standard deviation of the thickness of the protective layer/average value of the thickness of the protective layer) was 14.3%.
  • Example A' A reference optically excited light emitting element A' was obtained in the same manner as in Example A, except that no metal-based particle assembly layer was provided.
  • a comparative light-excited light-emitting element B in which a rhodamine dye was fixed was prepared in the same manner as in Example A, except that the protective layer was prepared by spin-coating an SOG solution. Specifically, an SOG solution was spin-coated on a metal-based particle assembly layer to laminate a SiO2 protective layer having an average thickness of 35.3 nm.
  • the SOG solution used was an organic SOG material "OCD T-7 5500T" manufactured by Tokyo Ohka Kogyo Co., Ltd., diluted with ethanol.
  • the surface shape of the SiO2 protective layer did not follow the surface shape of the metal-based particles and was generally smooth.
  • the standard deviation, average value, and coefficient of variation of the thickness T of the protective layer were 16.1 nm, 35.3 nm, and 45.7%, respectively.
  • the arithmetic mean roughness Ra of the surface of the protective layer was 5.2 nm, and the water contact angle of the surface of the protective layer (before the rhodamine dye was fixed) was 64.1°.
  • Comparative reference example B' A reference system comparative light-excited light-emitting element B' was obtained in the same manner as in Comparative Example B, except that the metal-based particle assembly layer was not provided.
  • an optical sensing device shown in Fig. 1 was constructed.
  • a fluorescence spectrophotometer product name: PMA-12, manufactured by Hamamatsu Photonics KK
  • a light source was used to irradiate excitation light L1 having a wavelength of 532 nm toward the laminated substrate 100.
  • Emitted light L2 was measured by a detector D through a wavelength cut filter F that cuts light having the wavelength of the excitation light L1.
  • the integral value of the emission spectrum obtained by detector D from wavelengths 550 nm to 950 nm was calculated.
  • the integral value of the emission spectrum in Example A was calculated when the integral value of the emission spectrum in Reference Example A' was set to 1, thereby obtaining the emission enhancement factor of Example A.
  • the integral value of the emission spectrum in Comparative Example B was calculated when the integral value of the emission spectrum in Comparative Reference Example B' was set to 1, thereby obtaining the emission enhancement factor of Comparative Example B.
  • the emission enhancement factors were 51.1 times and 17.1 times, respectively.

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  • Physics & Mathematics (AREA)
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  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

L'invention concerne un substrat stratifié présentant d'excellentes caractéristiques d'amplification de fluorescence.　Le substrat stratifié comprend : un substrat en forme de plaque comprenant une paire de surfaces principales qui se font face; une pluralité de particules à base de métal disposées sur une surface principale du substrat, séparées les unes des autres dans une direction parallèle à la surface principale; et une couche de protection qui recouvre les surfaces des particules à base de métal, la pluralité de particules à base de métal satisfaisant à (1) et/ou (2), et la forme de surface de la couche de protection se conformant à la forme de surface des particules à base de métal. (1) Le diamètre moyen de particule de la pluralité de particules à base de métal est compris entre 200 et 1600 nm, la hauteur moyenne de la pluralité de particules à base de métal est comprise entre 55 et 500 nm, et le rapport d'aspect défini par le rapport diamètre moyen de particule sur hauteur moyenne est compris entre 1 et 8. (2) Chaque particule à base de métal de la pluralité de particules à base de métal est disposée sur une surface principale du substrat, de telle sorte que la distance moyenne entre des particules à base de métal adjacentes soit comprise entre 1 et 1000 nm et que l'écart-type de la distance moyenne soit égal ou inférieur à 30 nm.
PCT/JP2024/042121 2023-12-07 2024-11-28 Substrat stratifié Pending WO2025121239A1 (fr)

Applications Claiming Priority (4)

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JP2023-207217 2023-12-07
JP2023207217 2023-12-07
JP2024-203151 2024-11-21
JP2024203151A JP2025092436A (ja) 2023-12-07 2024-11-21 積層基板

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08271431A (ja) * 1995-03-17 1996-10-18 Avl Medical Instr Ag 光化学蛍光センサー及びその測定方法
JP2013079442A (ja) * 2011-09-22 2013-05-02 Sumitomo Chemical Co Ltd 金属系粒子集合体の製造方法
JP2013096939A (ja) * 2011-11-04 2013-05-20 Seiko Epson Corp 光デバイス及び検出装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08271431A (ja) * 1995-03-17 1996-10-18 Avl Medical Instr Ag 光化学蛍光センサー及びその測定方法
JP2013079442A (ja) * 2011-09-22 2013-05-02 Sumitomo Chemical Co Ltd 金属系粒子集合体の製造方法
JP2013096939A (ja) * 2011-11-04 2013-05-20 Seiko Epson Corp 光デバイス及び検出装置

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