U.S. patent application number 16/570567 was filed with the patent office on 2020-01-02 for surface plasmon resonance fluorescence analysis device and surface plasmon resonance fluorescence analysis method.
The applicant listed for this patent is KONICA MINOLTA, INC.. Invention is credited to Hideyuki FUJII, Yukito NAKAMURA, Tetsuya NODA.
Application Number | 20200003688 16/570567 |
Document ID | / |
Family ID | 53777958 |
Filed Date | 2020-01-02 |
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United States Patent
Application |
20200003688 |
Kind Code |
A1 |
FUJII; Hideyuki ; et
al. |
January 2, 2020 |
Surface Plasmon Resonance Fluorescence Analysis Device And Surface
Plasmon Resonance Fluorescence Analysis Method
Abstract
A surface plasmon fluorescence analysis device that has a chip
holder, a light source, an angle adjustment unit, a light sensor, a
filter holder, an excitation light cut filter, a scattered light
transmission unit, a transmission adjustment unit, and a control
unit. As seen in plan view, the area occupied by the scattered
light transmission unit is arranged on the excitation light cut
filter or on the filter holder and is smaller than the area of a
fluorescence transmission region as seen in plan view.
Inventors: |
FUJII; Hideyuki; (Saitama,
JP) ; NODA; Tetsuya; (Tokyo, JP) ; NAKAMURA;
Yukito; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KONICA MINOLTA, INC. |
Chiyoda-ku |
|
JP |
|
|
Family ID: |
53777958 |
Appl. No.: |
16/570567 |
Filed: |
September 13, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15116631 |
Aug 4, 2016 |
10451555 |
|
|
PCT/JP2015/053102 |
Feb 4, 2015 |
|
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16570567 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 21/6428 20130101;
G01N 2021/6439 20130101; G01N 2201/0612 20130101; G01N 21/648
20130101; G01N 2201/0633 20130101; G01N 33/54373 20130101; G01N
2021/6471 20130101; G01N 21/253 20130101; G01N 21/553 20130101;
G01N 2201/068 20130101 |
International
Class: |
G01N 21/64 20060101
G01N021/64; G01N 21/552 20060101 G01N021/552; G01N 33/543 20060101
G01N033/543 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2014 |
JP |
2014-020356 |
Claims
1. A surface plasmon resonance fluorescence analysis device to
which an analysis chip including a dielectric having a metal film
on one surface of the dielectric is attached and in which the metal
film is irradiated with excitation light through the dielectric to
excite a fluorescent material for labelling a detection target
substance on the metal film, and then fluorescence emitted from the
fluorescent material is detected to thereby detect the presence or
amount of the detection target substance, the surface plasmon
resonance fluorescence analysis device comprising: a chip holder
configured to detachably hold the analysis chip; an adjustable
light source configured to emit excitation light at an incident
angle with respect to the metal film to irradiate the metal film
with the excitation light through the dielectric at an incident
angle; a light sensor configured to detect light emitted from the
vicinity of a surface of the metal film, the surface facing away
from the dielectric; an excitation-light cut filter configured to
allow fluorescence emitted from the metal film to pass through the
filter and block at least light having a certain wavelength of the
excitation light; and an adjustable stage configured to tilt the
excitation-light cut filter with respect to a normal line of a
surface of the metal film such that plasmon scattering light
emitted from the metal film is allowed to pass through; wherein the
chip holder is configured to hold the analysis chip in an
orientation to allow the light emitted from the vicinity of the
surface of the metal film to pass through the excitation-cut light
filter to reach the light sensor.
2. A surface plasmon resonance fluorescence analysis method in
which fluorescence which is emitted by a fluorescent material for
labelling a detection target substance when the fluorescent
material is excited by localized-field light on a basis of surface
plasmon resonance is detected to thereby detect the presence or
amount of the detection target substance, the surface plasmon
resonance fluorescence analysis method comprising: disposing the
detection target substance on a metal film disposed on one surface
of a dielectric; adjusting an incident angle of excitation light
with respect to the metal film; while adjusting the incident angle
of excitation light, irradiating the metal film with excitation
light through the dielectric while a scattering-light transmitting
hole is in a position where the plasmon scattering light is allowed
to pass through the scattering-light transmitting hole, wherein the
scattering-light transmitting hole is formed at a filter holder or
at an excitation light cut filter which includes a fluorescent
transmitting region that allows fluorescence to pass through the
region and blocks at least light having a certain wavelength of
excitation light, the fluorescent transmitting region being defined
by a second hole defined by the filter holder; detecting the
intensity of the plasmon scattering light that has been emitted
from the metal film and has passed through the scattering-light
transmitting hole while the metal film is irradiated with
excitation light through the dielectric at the adjusted angles;
determining an enhanced angle that is an incident angle at which
intensity of plasmon scattering light is maximized, based on the
intensity of the detected plasmon scattering light; irradiating the
metal film with excitation light through the dielectric at the
enhanced angle; disposing the excitation-light cut filter at a
position where light having a certain wavelength of the excitation
light is blocked; labelling the detection target substance disposed
on the metal film with the fluorescent material; and detecting the
intensity of the fluorescence that has been emitted from the
fluorescent material and has passed through the excitation-light
cut filter, while the metal film is irradiated with the excitation
light through the dielectric at the enhanced angle.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 15/116,631 filed Aug. 4, 2016, which is a U.S. National
Stage of International Application No. PCT/JP2015/053102 filed Feb.
4, 2015, which claims priority of Japanese application no.
2014-020356 filed Feb. 5, 2014, the entire content of all of which
are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a surface plasmon resonance
(SPR) fluorescence analysis device and a surface plasmon resonance
fluorescence analysis method in which a substance to be detected
(hereinafter, referred to as "detection target substance")
contained in a sample is detected by utilizing surface plasmon
resonance.
BACKGROUND ART
[0003] Highly-sensitive and quantitative detection of a minute
amount of a detection target substance such as protein and/or DNA
in laboratory tests or the like makes it possible to perform
treatment while quickly determining the patient's condition. For
this reason, the analysis method and analysis device which can
highly-sensitively and quantitatively detect a minute amount of a
detection target substance have been in demand.
[0004] Surface plasmon-field enhanced fluorescence spectroscopy
(hereinafter abbreviated as "SPFS") is known as a method which can
detect a detection target substance with high sensitivity (see, for
example, PTLs 1 and 2).
[0005] PTLs 1 and 2 disclose an analysis method and analysis device
that utilize SPFS. In the analysis method and analysis device, a
sensor chip is used, which includes: a prism composed of a
dielectric; a metal film formed on one surface of the prism; and a
capturing body (e.g., antibody) fixed onto the metal film. When a
sample containing a detection target substance is provided on the
metal film, the detection target substance is captured by the
capturing body (primary reaction). The captured detection target
substance is then labeled by a fluorescent material (secondary
reaction). In this state, when the metal film is irradiated with
excitation light through the prism at an angle where SPR occurs,
localized-field light can be generated on the surface of the metal
film. With this localized-field light, the fluorescent material
used for labeling the captured detection target substance on the
metal film is selectively excited, and the fluorescence emitted
from the fluorescent material is observed. In the analysis device
and analysis method, the fluorescence is detected to thereby detect
the presence or amount of the detection target substance.
[0006] In such an analysis method and analysis device utilizing
SPFS, an excitation-light cut filter that blocks excitation light
but allows fluorescence to pass through the filter is provided
before a light sensor that detects the fluorescence.
CITATION LIST
Patent Literature
PTL 1
Japanese Patent Application Laid-Open No. 10-307141
PTL 2
WO 2012/042805
SUMMARY OF INVENTION
Technical Problem
[0007] In the analysis method and analysis device utilizing SPFS,
it is necessary to set the incident angle of excitation light with
respect to the metal film such that the intensity of fluorescence
is maximized, in order to sufficiently improve the detection
sensitivity and detection accuracy.
[0008] Regarding this point, PTL 1 discloses emitting excitation
light at an incident angle at which the intensity of reflection
light from the metal film is minimized (hereinafter referred to as
"resonance angle"). However, the incident angle at which the
intensity of fluorescence is maximized and the resonance angle are
slightly different from each other, so that the analysis method and
analysis device disclosed in PTL 1 have room for improvement in
detection sensitivity and detection accuracy.
[0009] In the analysis method and analysis device disclosed in PTL
2, excitation light is emitted at an incident angle at which the
intensity of scattering light having the same wavelength as the
excitation light and generated by SPR (hereinafter referred to as
"plasmon scattering light") is maximized (hereinafter referred to
as "enhanced angle"). The enhanced angle is closer to the incident
angle at which the intensity of fluorescence is maximized than the
resonance angle is, the analysis method and analysis device
disclosed in PTL 2 are more advantageous than the analysis method
and analysis device disclosed in PTL 1 in terms of detection
sensitivity and detection accuracy. However, in the analysis method
and analysis device disclosed in PTL 2, the plasmon scattering
light is also detected using the light sensor provided for
detecting fluorescence, so that there arises a problem in that the
excitation-light cut filter has to be completely moved from the
light path of the plasmon scattering light when the enhanced angle
is determined, which causes the analysis device to grow in
size.
[0010] An object of the present invention is to provide a surface
plasmon resonance fluorescence analysis device and a surface
plasmon resonance fluorescence analysis method each capable of
determining the enhanced angle at which the plasmon scattering
light is maximized, without significantly moving the
excitation-light cut filter from the light path of the
light-reception optical system.
Solution to Problem
[0011] The inventor and et. al of this specification have found
that forming a scattering-light transmitting section that allows
plasmon scattering light to pass through the section at an
excitation-light cut filter or a filter holder and detecting, using
a light sensor, the plasmon scattering light that has passed
through the scattering-light transmitting section can solve the
problem mentioned above, and have thus added further consideration
to complete the present invention.
[0012] To solve the above-mentioned problems, a surface plasmon
resonance fluorescence analysis device according to an embodiment
of the present invention is a device to which an analysis chip
including a dielectric having a metal film on one surface of the
dielectric is attached and in which the metal film is irradiated
with excitation light through the dielectric to excite a
fluorescent material for labelling a detection target substance on
the metal film, and then fluorescence emitted from the fluorescent
material is detected to thereby detect the presence or amount of
the detection target substance, the device including: a chip holder
configured to detachably hold the analysis chip; a light source
configured to emit excitation light; an angle adjusting section
configured to adjust an incident angle of the excitation light with
respect to the metal film to irradiate the metal film with the
excitation light through the dielectric at a predetermined incident
angle; a light sensor configured to detect light emitted from the
vicinity of a surface of the metal film, the surface facing away
from the dielectric; a light-reception optical system configured to
guide the light emitted from the vicinity of the metal film to the
light sensor; an excitation-light cut filter disposed in the
light-reception optical system and including a fluorescent
transmitting region that allows fluorescence emitted from the metal
film to pass through the region but blocks at least light having a
certain wavelength of the excitation light; a filter holder
configured to hold the excitation-light cut filter; a
scattering-light transmitting section disposed at the
excitation-light cut filter or the filter holder and configured to
allow plasmon scattering light emitted from the metal film to pass
through the section; and a transmission adjusting section
configured to adjust whether to allow the plasmon scattering light
to pass through via the scattering-light transmitting section, in
which an area of the scattering-light transmitting section in a
plan view is smaller than an area of the fluorescent transmitting
region of the excitation-light cut filter in a plan view.
[0013] Moreover, to solve the above-mentioned problems, a surface
plasmon resonance fluorescence analysis device according to another
embodiment of the present invention is a device to which an
analysis chip including a dielectric having a metal film on one
surface of the dielectric is attached and in which the metal film
is irradiated with excitation light through the dielectric to
excite a fluorescent material for labelling a detection target
substance on the metal film, and then fluorescence emitted from the
fluorescent material is detected to thereby detect the presence or
amount of the detection target substance, the device including: a
chip holder configured to detachably hold the analysis chip; a
light source configured to emit excitation light; an angle
adjusting section configured to adjust an incident angle of the
excitation light with respect to the metal film to irradiate the
metal film with the excitation light through the dielectric at a
predetermined incident angle; a light sensor configured to detect
light emitted from the vicinity of a surface of the metal film, the
surface facing away from the dielectric; a light-reception optical
system configured to guide the light emitted from the vicinity of
the metal film to the light sensor; an excitation-light cut filter
disposed in the light-reception optical system and configured to
allow fluorescence emitted from the metal film to pass through the
filter but blocks at least light having a certain wavelength of the
excitation light; and a transmission adjusting section configured
to tilt the excitation-light cut filter with respect to a normal
line of a surface of the metal film such that plasmon scattering
light emitted from the metal film is allowed to pass through.
[0014] Furthermore, to solve the above-mentioned problems, a
surface plasmon resonance fluorescence analysis method according to
an embodiment of the present invention is a method in which
fluorescence that is emitted by a fluorescent material for
labelling a detection target substance when the fluorescent
material is excited by localized-field light on a basis of surface
plasmon resonance is detected to thereby detect the presence or
amount of the detection target substance, the method including:
disposing the detection target substance on a metal film disposed
on one surface of a dielectric; determining an enhanced angle that
is an incident angle at which intensity of plasmon scattering light
is maximized, by detecting the intensity of the plasmon scattering
light that has been emitted from the metal film and has passed
through a scattering-light transmitting section while the metal
film is irradiated with excitation light through the dielectric in
a state where the scattering-light transmitting section formed at
an excitation-light cut filter or a filter folder configured to
hold the excitation-light cut filter is moved to a position where
the plasmon scattering light is allowed to pass through the
section, the excitation-light cut filter including a fluorescent
transmitting region which allows fluorescence to pass through the
region but blocks at least light having a certain wavelength of
excitation light; and irradiating the metal film with the
excitation light through the dielectric such that an incident angle
with respect to the metal film becomes the enhanced angle and
detecting the intensity of the fluorescence that has been emitted
from the fluorescent material and has passed through the
fluorescent transmitting region, in a state where the fluorescent
transmitting region disposed at the excitation-light cut filter is
moved to a position where the fluorescence is allowed to pass
through the region.
[0015] Moreover, to solve the above-mentioned problems, a surface
plasmon resonance fluorescence analysis method according to another
embodiment of the present invention is a method in which
fluorescence which is emitted by a fluorescent material for
labelling a detection target substance when the fluorescent
material is excited by localized-field light on a basis of surface
plasmon resonance is detected to thereby detect the presence or
amount of the detection target substance, the method including:
disposing the detection target substance on a metal film disposed
on one surface of a dielectric; determining an enhanced angle that
is an incident angle at which intensity of plasmon scattering light
is maximized, by detecting the intensity of the plasmon scattering
light that has been emitted from the metal film and has passed
through an excitation-light cut filter while the metal film is
irradiated with excitation light through the dielectric in a state
where the excitation-light cut filter is tilted with respect to a
normal line of a surface of the metal film such that the plasmon
scattering light is allowed to pass through, the excitation-light
cut filter being configured to allow fluorescence to pass through
the filter but blocks at least light having a certain wavelength of
the excitation light; and detecting the intensity of the
fluorescence that has been emitted from the fluorescent material
and has passed through the excitation-light cut filter, while the
metal film is irradiated with the excitation light through the
dielectric such that the incident angle with respect to the metal
film becomes the enhanced angle in a state where the
excitation-light cut filter is disposed at such an angle that at
least light having a certain wavelength of the excitation light is
blocked.
Advantageous Effects of Invention
[0016] According to the present invention, during detection of a
detection target substance, using SPFS, the enhanced angle at which
the plasmon scattering light is maximized can be determined without
significantly moving the excitation-light cut filter from the light
path of the plasmon scattering light. Therefore, according to the
present invention, the presence or amount of a detection target
substance can be detected with high sensitivity, high accuracy and
high speed. Moreover, according to the present invention,
downsizing and cost reduction of the surface plasmon resonance
fluorescence analysis device can be achieved.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a schematic view illustrating a configuration of a
surface plasmon resonance fluorescence analysis device (SPFS
device) according to Embodiment 1;
[0018] FIG. 2 is a flowchart illustrating an exemplary operation
procedure of the SPFS device according to Embodiment 1;
[0019] FIGS. 3A and 3B are diagrams for describing detection of
plasmon scattering light and detection of fluorescence in the SPFS
device according to Embodiment 1;
[0020] FIGS. 4A and 4B are diagrams for describing detection of
plasmon scattering light and detection of fluorescence in an SPFS
device according to Embodiment 2;
[0021] FIG. 5 is a flowchart illustrating an exemplary operation
procedure of the SPFS device according to Embodiment 2;
[0022] FIGS. 6A and 6B are diagrams for describing detection of
plasmon scattering light and detection of fluorescence in an SPFS
device according to Embodiment 3;
[0023] FIGS. 7A and 7B are diagrams for describing detection of
plasmon scattering light and detection of fluorescence in an SPFS
device according to Embodiment 4;
[0024] FIG. 8 is a graph indicating the relationship between the
wavelength passing through an excitation-light cut filter and the
transmittance; and
[0025] FIG. 9 is a flowchart illustrating an exemplary operation
procedure of the SPFS device according to Embodiment 4.
DESCRIPTION OF EMBODIMENTS
[0026] In the following, embodiments of the present invention are
described in detail with reference to the accompanying
drawings.
Embodiment 1
(Configuration of SPFS Device)
[0027] First, a surface plasmon resonance fluorescence analysis
device (hereinafter also referred to as "SPFS device") according to
Embodiment 1 of the present invention will be described.
[0028] SPFS devices are each used in a state where an analysis chip
having a dielectric and a metal film formed on one surface of the
dielectric is attached to the device. When a sample containing a
detection target substance is provided on the metal film, the
detection target substance is captured by a capturing body. At this
time, the detection target substance may or may not be labeled by a
fluorescent material. When the captured detection target substance
is not labeled by the fluorescent material, the captured detection
target substance is then labeled by the fluorescent material. In
this state, the prism having the metal film on one surface is
irradiated with excitation light such that the excitation light is
under the total reflection condition with respect to the prism.
Thus, the interaction between the excitation light and the free
electrons in the metal film (surface plasmon resonance) occurs and
generates localized-field light. In general, this localized-field
light is called an "enhanced electric field" or "enhanced
evanescent light," and a variation in physical quantity in the
vicinity of the surface of the metal film can be measured. This
localized-field light selectively excites the fluorescent material
labeling the detection target substance captured on the metal film,
and the fluorescence emitted from the fluorescent material is
observed. The SPFS device measures the light amount of fluorescence
to detect the presence or amount of the detection target
substance.
[0029] FIG. 1 is a schematic view illustrating a configuration of
SPFS device 100 according to Embodiment 1. As illustrated in FIG.
1, SPFS device 100 includes: chip holder 12 for detachably holding
analysis chip 10; excitation optical system unit 120 for
irradiating analysis chip 10 with excitation light .alpha.;
light-reception optical system unit 140 for detecting the light
emitted from analysis chip 10 (plasmon scattering light .beta. and
fluorescence .gamma.); and control section 160 for controlling
these components. SPFS device 100 is used in a state where analysis
chip 10 is attached to chip holder 12. For this reason, analysis
chip 10 is described first, and each component of SPFS device 100
is described thereafter.
[0030] As illustrated in FIG. 1, analysis chip 10 includes:
dielectric 20 including incidence surface 21, film-formation
surface 22 and emission surface 23; metal film 30 formed on
film-formation surface 22; and channel closure 40 disposed on
film-formation surface 22 or metal film 30. Normally, analysis chip
10 is replaced for each analysis.
[0031] Dielectric 20 is a transparent member that allows excitation
light .alpha. to pass therethrough (prism). Dielectric 20 includes
incidence surface 21, film-formation surface 22 and emission
surface 23. Incidence surface 21 allows excitation light .alpha.
from excitation optical system unit 120 to enter dielectric 20.
Metal film 30 is formed on film-formation surface 22. Excitation
light .alpha. having entered dielectric 20 is reflected by metal
film 30. To be more specific, the excitation light .alpha. having
entered dielectric 20 is reflected by the interface (film-formation
surface 22) between dielectric 20 and metal film 30. Emission
surface 23 allows excitation light .alpha. reflected by metal film
30 to be emitted outside of dielectric 20. The shape of dielectric
20 is not limited to any particular shape. In the present
embodiment, the shape of dielectric 20 is a columnar shape having a
trapezoidal bottom. The surface corresponding to one bottom side of
the trapezoid is film-formation surface 22. The surface
corresponding to one leg is incidence surface 21, and the surface
corresponding to the other leg is emission surface 23. Preferably,
the trapezoid serving as the bottom surface is an isosceles
trapezoid. In such a configuration, incidence surface 21 and
emission surface 23 are symmetrical, and the S-wave component of
excitation light .alpha. does not easily remain in dielectric 20.
Incidence surface 21 is formed such that excitation light .alpha.
does not return to excitation optical system unit 120. This is
because, when excitation light .alpha. returns to the laser diode
serving as the excitation light source, the excitation state of the
laser diode is disturbed, causing the wavelength and the output of
the excitation light .alpha. to vary. Therefore, the angle of
incidence surface 21 is set within a scanning range around the
ideal enhanced angle such that excitation light .alpha. does not
perpendicularly enter incidence surface 21. For example, the angle
between incidence surface 21 and film-formation surface 22, and the
angle between film-formation surface 22 and emission surface 23 are
approximately 80 degrees. Examples of the material of dielectric 20
include a resin and glass. Preferably, the material of dielectric
20 is a resin having a refractive index of 1.4 to 1.6 and
exhibiting a small birefringence.
[0032] Metal film 30 is formed on film-formation surface 22 of
dielectric 20. When metal film 30 is provided, interaction (surface
plasmon resonance; SPR) occurs between the photons of excitation
light .alpha. which has entered film-formation surface 22 under the
total reflection condition and the free electrons in metal film 30,
and thus localized-field light can be generated on the surface of
metal film 30. The material of metal film 30 is not limited in
particular as long as the material is a metal that causes surface
plasmon resonance. Examples of the material of metal film 30
include gold, silver, copper, aluminum, and their alloys. In the
present embodiment, metal film 30 is a metal film. The formation
method for metal film 30 is not limited to any particular method.
Examples of the formation method for metal film 30 include
sputtering, vapor-deposition, and plating. Preferably, the
thickness of metal film 30 is within a range from 30 nm to 70 nm,
but is not limited in particular.
[0033] Moreover, although no illustration is given in particular, a
capturing body for capturing a detection target substance may be
fixed to a surface of metal film 30 that faces away from dielectric
20. Fixing the capturing body enables selectively detecting a
detection target substance. In this embodiment, the capturing body
is uniformly fixed in a predetermined region on metal film 30. The
capturing body is not limited to any particular type as long as the
capturing body is capable of capturing the detection target
substance. For example, the capturing body may be an antibody
specific to the detection target substance or a fragment of the
antibody.
[0034] Channel closure 40 is disposed on the surface of metal film
30 that faces away from dielectric 20 with channel 41 interposed
therebetween. When metal film 30 is only partly formed on
film-formation surface 22 of dielectric 20, channel closure 40 may
be disposed on film-formation surface 22 with channel 41 interposed
therebetween. Together with metal film 30 (and dielectric 20),
channel closure 40 forms channel 41 through which liquid such as a
sample, fluorescent labeling solution, or washing solution flows.
The capturing body is exposed to the inside of channel 41. Both
ends of flow channel 41 are respectively connected to the inlet and
outlet (both omitted in the drawing) formed on the top surface of
channel closure 40. When liquid is injected into channel 41, the
liquid makes contact with the capturing body in channel 41. Channel
closure 40 is composed of a material that allows the light emitted
from the surface of metal film 30 that faces away from dielectric
20 and emitted from the vicinity of this surface of metal film 30
(plasmon scattering light .beta. and fluorescence .gamma.) to pass
through. Examples of the material of channel closure 40 include a
resin. As long as channel closure 40 can guide the above-mentioned
light to light-reception optical system unit 140, channel closure
40 may be partly composed of an opaque material. Channel closure 40
is joined to metal film 30 or dielectric 20 by bonding using a
double-sided tape or an adhesive agent, laser welding, ultrasound
welding, or pressure fixing using a clamping member, for
example.
[0035] As illustrated in FIG. 1, excitation light .alpha. guided to
dielectric 20 enters dielectric 20 from incidence surface 21. The
excitation light .alpha. having entered dielectric 20 is incident
on the interface (film-formation surface 22) between dielectric 20
and metal film 30 at a total reflection angle (at an angle that
causes surface plasmon resonance). The reflection light from the
interface is emitted to outside of dielectric 20 from emission
surface 23 (not illustrated in the drawing). Meanwhile, when
excitation light .alpha. is incident on the interface at an angle
which causes surface plasmon resonance, plasmon scattering light
.beta. and/or fluorescence .gamma. is emitted from metal film 30
and the vicinity of metal film 30 in the direction toward
light-reception optical system unit 140.
[0036] Next, the components of SPFS device 100 are described. As
described above, SPFS device 100 includes chip holder 12,
excitation optical system unit 120, light-reception optical system
unit 140 and control section 160.
[0037] Chip holder 12 holds analysis chip 10 at a predetermined
position. Analysis chip 10 is irradiated with excitation light
.alpha. from excitation optical system unit 120 in the state where
analysis chip 10 is held by chip holder 12. At this time, plasmon
scattering light .beta. having the same wavelength as excitation
light .alpha. and/or fluorescence .gamma. output from the
fluorescent material and/or the like is emitted upward from the
surface of metal film 30 that faces away from dielectric 20 and
emitted from the vicinity of the surface. In addition, excitation
light .alpha. is reflected by the interface between dielectric 20
and metal film 30 and then emitted to the outside of dielectric 20
(illustration is omitted).
[0038] Excitation optical system unit 120 includes light source
unit 121 that emits excitation light .alpha., and angle adjusting
section 122 that adjusts the incident angle of excitation light
.alpha. with respect to the interface (film-formation surface 22)
between dielectric 20 and metal film 30.
[0039] Light source unit 121 includes a laser diode (hereinafter
abbreviated as "LD") as an excitation light source, and emits
excitation light .alpha. (single mode laser light) toward incidence
surface 21 of analysis chip 10 held by chip holder 12. To be more
specific, light source unit 121 emits only a P-wave with respect to
the interface such that the angle of excitation light .alpha. with
respect to the interface (film-formation surface 22) between
dielectric 20 and metal film 30 of analysis chip 10 is a total
reflection angle. For example, light source unit 121 includes an LD
unit, a waveform shaper and a shaping optical system (illustrations
are omitted).
[0040] The LD unit emits collimated excitation light .alpha. having
a constant wavelength and light amount such that the irradiation
spot on the interface (film-formation surface 22) between
dielectric 20 and metal film 30 forms a substantially circular
shape. The LD unit includes: an LD as an excitation light source; a
collimator that collimates excitation light .alpha. emitted from
the LD; and a temperature adjusting circuit that adjusts the light
amount of excitation light .alpha. to be constant. The excitation
light .alpha. emitted from the LD has a flat outline shape even
after the collimation. For this reason, the LD is held at a
predetermined orientation, or a slit having a predetermined shape
is inserted to a shaping optical system to be described
hereinafter, such that the irradiation spot on the interface
(film-formation surface 22) forms a substantially circular shape.
In addition, the wavelength and light amount of excitation light
.alpha. emitted from the LD vary depending on the temperature. For
this reason, the temperature adjusting circuit monitors the light
amount of the light diverged from the collimated excitation light
.alpha., using a photodiode and/or the like and adjusts the
temperature of the LD, using a heater, a Peltier device and/or the
like, such that the wavelength and light amount of the excitation
light .alpha. are adjusted to be constant.
[0041] The waveform shaper includes a bandpass filter (hereinafter
abbreviated as "BPF") and a linear polarization filter (hereinafter
abbreviated as "LP") and shapes the waveform of excitation light
.alpha. emitted from the LD unit. The excitation light .alpha. from
the LD unit has a slight wavelength distribution width, so that the
BPF changes the excitation light .alpha. from the LD unit to
narrowband light composed only of a center wavelength. In addition,
since the excitation light .alpha. from the LD unit is not complete
linear polarization, the LP changes the excitation light .alpha.
from the LD unit to complete linear polarization light. The
waveform shaper may include a half-wavelength plate that adjusts
the polarization direction of excitation light .alpha. such that
the P-wave component is incident on metal film 30.
[0042] The shaping optical system adjusts the beam diameter, the
outline shape, and/or the like of excitation light .alpha. such
that the irradiation spot on the interface (film-formation surface
22) between dielectric 20 and metal film 30 has a circular shape of
a predetermined size. The excitation light .alpha. emitted from the
shaping optical system is emitted to dielectric 20 of analysis chip
10. The shaping optical system is a slit, a zooming section, or the
like, for example.
[0043] Note that, the light source included in light source unit
121 is not limited to any particular type and may not be an LD.
Examples of the light source include a light-emitting diode, a
mercury lamp, and other laser light sources. In the case where the
light emitted from the light source is not a beam, the light
emitted from the light source is converted to a beam by a lens,
mirror, slit and/or the like. In addition, in the case where the
light emitted from the light source is not monochromatic light, the
light emitted from the light source is converted to monochromatic
light by a diffraction grating and/or the like. Moreover, when the
light emitted from the light source is not linear polarization, the
light emitted from the light source is converted to linear
polarization light by a polarizer or the like.
[0044] Angle adjusting section 122 adjusts the incident angle of
excitation light .alpha. to metal film 30 (the interface
(film-formation surface 22) between dielectric 20 and metal film
30). Angle adjusting section 122 relatively turns the optical axis
of excitation light .alpha., and chip holder 12 to emit excitation
light .alpha. to a predetermined position of metal film 30
(film-formation surface 22) through dielectric 20 at a
predetermined incident angle. In the present embodiment, angle
adjusting section 122 turns light source unit 121 about the axis
orthogonal to the optical axis of excitation light .alpha.. At this
time, the position of the turn axis is set such that the
irradiation position on metal film 30 (film-formation surface 22)
hardly moves when the incident angle is scanned. For example, when
the position of the turning center is set at a position near the
intersection of the optical axes of two rays of excitation light
.alpha. at both ends of the scanning range of the incident angle
(at a position between the irradiation position on film-formation
surface 22 and incidence surface 21), the shifting of the
irradiation position can be minimized.
[0045] Light-reception optical system unit (light-reception optical
system) 140 is disposed to face the surface of metal film 30 that
faces away from dielectric 20 in analysis chip 10 held by chip
holder 12. Light-reception optical system unit 140 detects the
light emitted from metal film 30 (plasmon scattering light .beta.
or fluorescence .gamma.). Light-reception optical system unit 140
includes first lens 141, diaphragm 142, filter holder 143,
excitation-light cut filter 144, second lens 145, light sensor 146,
and transmission adjusting section 147. First lens 141, diaphragm
142, filter holder 143, excitation-light cut filter 144, second
lens 145, and light sensor 146 are disposed opposite to the surface
of metal film 30 in this order from the side of metal film 30.
[0046] First and second lenses 141 and 145 constitute a conjugate
optical system that is not easily affected by stray light. The
light rays that travel between first and second lenses 141 and 145
become substantially parallel light. First and second lenses 141
and 145 cause fluorescence .gamma. emitted from metal film 30 to
form an image on the light reception surface of light sensor
146.
[0047] Diaphragm 142 is disposed between first lens 141 and filter
folder 143. Diaphragm 142 allows at least some of the light that
has been collimated by first lens 141 (plasmon scattering light
.beta. and/or fluorescence .gamma.) to pass through via diaphragm
hole 151. The light that has passed through diaphragm 142 reaches
fluorescent transmitting region 156 of excitation-light cut filter
144. The term "fluorescent transmitting region" used herein means a
partial region of excitation-light cut filter 144 through which
fluorescence .gamma. controlled by diaphragm 142 (or first
through-hole 152) passes during detection of fluorescence .gamma..
The plan-view shape of diaphragm hole 151 is not limited to any
particular shape. The plan-view shape of fluorescent transmitting
region 156 is the same as that of diaphragm hole 151 of diaphragm
142.
[0048] Filter holder 143 holds excitation-light cut filter 144 and
is disposed between diaphragm 142 and second lens 145. The shape of
filter holder 143 is not limited to any particular shape as long as
filter holder 143 can hold excitation-light cut filter 144. The
shape of filter holder 143 may be a shape to hold excitation-light
cut filter 144 from below or a shape to grip an outer edge portion
of excitation-light cut filter 144, for example. In this
embodiment, filter holder 143 is formed larger in size than
excitation-light cut filter 144 and holds excitation-light cut
filter 144 from below.
[0049] Filter holder 143 includes first through-hole 152 and second
through-hole 153. First through-hole 152 is disposed at a center
portion of filter holder 143. In this embodiment, first
through-hole 152 is formed larger in size than diaphragm hole 151
of diaphragm 142. First through-hole 152 allows the light that has
been focused by diaphragm 142 (plasmon scattering light .beta.
and/or fluorescence .gamma.) to pass through. The light that has
passed through first through-hole 152 reaches the rear surface of
excitation-light cut filter 144. Second through-hole 153 is formed
at filter holder 143 so as to avoid excitation-light cut filter 144
(see FIG. 1). Although details will be given hereinafter, second
through-hole 153 is formed at a position distant from an end
portion of fluorescent transmitting region 156, which is shorter
than the diameter of fluorescent transmitting region 156. Second
through-hole 153 serves as a scattering-light transmitting section
that allows plasmon scattering light .beta. to pass through and is
used for determining an enhanced angle to be described hereinafter.
The light that has passed through second through-hole
(scattering-light transmitting section) 153 reaches light sensor
146 through second lens 145. Note that, when scattering-light
transmitting section 153 allows plasmon scattering light .beta. to
pass through, scattering-light transmitting section 153 may also
allow fluorescence .gamma. to pass through. The area of
scattering-light transmitting section 153 when viewed in a plan
view is not limited to any particular area, but it is preferable
that the area of scattering-light transmitting section 153 be not
greater than 1/1000 of the area of fluorescent transmitting region
156 when viewed in a plan view. The expression "when viewed in a
plan view" used herein means a view from metal film 30.
[0050] Excitation-light cut filter 144 is disposed between
diaphragm 142 and second lens 145. Excitation-light cut filter 144
includes fluorescent transmitting region 156. Fluorescent
transmitting region 156 allows the fluorescence emitted from metal
film 30 to pass through but blocks at least light of a certain
wavelength of the excitation light. Excitation-light cut filter 144
prevents light other than the light having a wavelength of
fluorescence .gamma. from reaching light sensor 146 by reflecting
or absorbing the light having a wavelength of excitation light
.alpha. (plasmon scattering light .beta.) while allowing
fluorescence .gamma. to pass through the filter. More specifically,
excitation-light cut filter 144 removes a noise component from the
light that reaches light sensor 146, thereby making a contribution
to improving the detection accuracy and sensitivity of weak
fluorescence .gamma..
[0051] Excitation-light cut filter 144 guides only a fluorescent
component to light sensor 146 and removes an excitation light
component (plasmon scattering light .beta.) in order to detect the
fluorescent component with a high S/N ratio. Examples of
excitation-light cut filter 144 include an excitation-light
reflection filter, a short-wavelength cut filter, and a bandpass
filter. Excitation-light cut filter 144 is a filter composed of a
multilayer film for reflecting a predetermined light component for
removal, but may be a color glass filter for absorbing a
predetermined light component for removal in general.
[0052] Light sensor 146 detects fluorescence .gamma. emitted from
metal film 30 or plasmon scattering light .beta.. For example,
light sensor 146 is a photomultiplier tube having a high
sensitivity and a high S/N ratio. Light sensor 146 may be an
avalanche photodiode (APD) or the like. Note that, the size of the
irradiation spot of excitation light .alpha. on one surface of
metal film 30 (the surface facing away from dielectric 20) is
adjusted to a size smaller than the size of the measurement region
of light sensor 146 on the other surface of metal film 30 (the
surface facing away from first lens 141). This configuration makes
it possible to prevent the irradiation spot from being out of the
measurement region even when the irradiation spot is slightly
shifted in position due to an error of each parameter of dielectric
20.
[0053] Transmission adjusting section 147 moves scattering-light
transmitting section 153 on a light path in light-reception optical
system unit 140 when light sensor 146 detects plasmon scattering
light .beta.. Meanwhile, transmission adjusting section 147 moves
fluorescent transmitting region 156 within the light path of
light-reception optical system unit 140 and also moves
scattering-light transmitting section 153 to outside of the light
path within light-reception optical system unit 140 when light
sensor 146 detects fluorescence .gamma.. Transmission adjusting
section 147 includes: stage 154 that supports filter folder 143;
and motor 155 that serves as a driving source for moving filter
holder 143 (scattering-light transmitting section 153) via stage
154. Although details will be given hereinafter, transmission
adjusting section 147 is capable of determining an enhanced angle
by moving scattering-light transmitting section 153 within or
outside the light path of light-reception optical system unit 140
without significantly moving filter folder 143 and excitation-light
cut filter 144.
[0054] Control section 160 integrally controls driving sections and
makes quantification of the light reception amount of light sensor
146. In this embodiment, control section 160 includes: light-source
control section 161 that controls light source unit 121;
light-sensor control section 162 that controls light sensor 146;
motor control section 163 that controls motor 155; and control
processing section 164. Control processing section 164
comprehensively controls light-source control section 161,
light-sensor control section 162, and motor control section 163 so
as to control the entire operation of SPFS device 100. Control
section 160 is a computer for executing software, for example. As
described hereinafter, control section 160 (control processing
section 164) controls the incident angle of excitation light
.alpha. with respect to metal film 30 (film-formation surface 22)
during fluorescence measurement on the basis of the measurement
result of plasmon scattering light .beta. obtained by light sensor
146.
[0055] Next, the detection operation of SPFS device 100 will be
described. FIG. 2 is a flowchart illustrating an exemplary
operation procedure of SPFS device 100. FIGS. 3A and 3B are
diagrams for describing detection of plasmon scattering light and
detection of fluorescence. FIG. 3A is a diagram for describing
detection of plasmon scattering light and FIG. 3B is a diagram for
describing detection of fluorescence.
[0056] First, preparation for measurement is made (step S10). More
specifically, analysis chip 10 is installed at a predetermined
position of SPFS device 100. When a moisturizer is present in
channel 41 of analysis chip 10, the inside of channel 41 is washed
to remove the moisturizer so that the capturing body can
appropriately capture the detection target substance.
[0057] Next, the detection target substance in the sample and the
capturing body are made to react with each other (primary reaction,
step S20). More specifically, the sample is injected into channel
41, and the sample and the capturing body are brought into contact
with each other. When the detection target substance is present in
the sample, at least some of the detection target substance is
captured by the capturing body. Thereafter, the inside of channel
41 is washed with buffer solution or the like to remove a substance
which has not been captured by the capturing body. The sample is
not limited to a particular kind. Examples of the sample include
bodily fluids such as blood, serum, plasma, urine, nasal mucus,
saliva, and semen, and their diluted solutions.
[0058] Next, as illustrated in FIG. 3A, control processing section
164 moves filter holder 143 and places scattering-light
transmitting section 153 on the light path in light-reception
optical system unit 140 (step S30). While irradiating a
predetermined position of metal film 30 (film-formation surface 22)
with excitation light .alpha., the incident angle of excitation
light .alpha. with respect to metal film 30 (film-formation surface
22) is scanned to determine an optimum incident angle (step S40).
Control processing section 164 controls light source unit 121 and
angle adjusting section 122 to scan the incident angle of
excitation light .alpha. with respect to metal film 30
(film-formation surface 22) while irradiating a predetermined
position of metal film 30 (film-formation surface 22) with
excitation light .alpha.. In addition, control processing section
164 controls light-sensor control section 162 such that light
sensor 146 detects plasmon scattering light .beta. from metal film
30 (the surface of metal film 30 and the vicinity of the surface).
The plasmon scattering light .beta. from metal film (the surface of
metal film 30 and the vicinity of the surface) is collimated by
first lens 141 and reaches light sensor 146 via scattering-light
transmitting section 153. Thus, control processing section 164
obtains data containing the relationship between the incident angle
of excitation light .alpha. and the intensity of plasmon scattering
light .beta.. Control processing section 164 analyzes the data and
determines the incident angle (enhanced angle) at which the
intensity of plasmon scattering light .beta. is maximized. Note
that, the enhanced angle is basically determined based on the
material and the shape of dielectric 20, the thickness of metal
film 30, the refractive index of the liquid in channel 41 and/or
the like, but the enhanced angle slightly varies depending on
various factors such as the kind and the amount of fluorescent
material in channel 41, and a shaping error of dielectric 20. In
view of this, it is preferable to determine the enhanced angle each
time analysis is performed. The enhanced angle is determined in the
order of about 0.1 degrees.
[0059] Next, the incident angle of excitation light .alpha. with
respect to metal film 30 (film-formation surface 22) is set to the
enhanced angle determined at the previous step (step S50). More
specifically, control processing section 164 controls angle
adjusting section 122 to set the incident angle of excitation light
.alpha. with respect to metal film 30 (film-formation surface 22)
to the enhanced angle. In the following steps, the incident angle
of excitation light .alpha. with respect to metal film 30
(film-formation surface 22) is kept at the enhanced angle.
[0060] Next, as illustrated in FIG. 3B, control processing section
164 moves filter folder 143 and disposes fluorescent transmitting
region 156 in the light path of light-reception optical system unit
140 and also disposes scattering-light transmitting section 153
outside of the light path in light-reception optical system unit
140 (step S60). Furthermore, metal film 30 (film-formation surface
22) is irradiated with excitation light .alpha., and the intensity
of light having the same wavelength as fluorescence .gamma.
(optical blank value) is measured (step S70). More specifically,
control processing section 164 controls light-source control
section 161 to emit excitation light .alpha. to light source unit
121. Simultaneously, control processing section 164 controls first
light-sensor control section 162 such that light sensor 146 detects
the intensity of light having the same wavelength as fluorescence
.gamma.. At this time, excitation-light cut filter 144 does not
allow plasmon scattering light .beta. to pass through. Thus, light
sensor 146 can measure the intensity of light that becomes a noise
to be precise (optical blank value). The measurement value is sent
to control processing section 164 and recorded as an optical blank
value.
[0061] Next, the detection target substance that has been captured
by the capturing body is labeled by a fluorescent material
(secondary reaction, step S80). More specifically, a fluorescent
labeling solution is injected into channel 41. The fluorescence
labeling solution is, for example, a buffer solution containing an
antibody (secondary antibody) labeled by a fluorescent material.
When the fluorescent labeling solution is injected into channel 41,
the fluorescent labeling solution makes contact with the detection
target substance, and the detection target substance is labeled by
the fluorescent material. Thereafter, the inside of channel 41 is
washed with buffer solution and/or the like to remove a free
fluorescent material and/or the like.
[0062] Finally, metal film 30 (film-formation surface 22) is
irradiated with excitation light .alpha. and the intensity of
fluorescence .gamma. emitted from metal film 30 (the surface of
metal film 30 and the vicinity of the surface) is measured (step
S90). To be more specific, control processing section 164 controls
light-source control section 161 to emit excitation light .alpha.
to light source unit 121. Simultaneously, control processing
section 164 controls light-sensor control section 162 such that
light sensor 146 detects fluorescence .gamma. emitted from metal
film 30 (metal film 30 and the vicinity of metal film 30). At this
time, since excitation-light cut filter 144 does not allow plasmon
scattering light .beta. to pass therethrough, only fluorescence
.gamma. is detected by light sensor 146. Control processing section
164 subtracts the optical blank value from the measurement value to
calculate a fluorescent intensity correlated with the amount of the
detection target substance. The fluorescent intensity is converted
to the amount or the concentration of the detection target
substance and/or the like as necessary.
[0063] Through the above-mentioned procedure, since
scattering-light transmitting section 153 for detecting plasmon
scattering light .beta. is disposed at filter folder 143 in the
vicinity of the excitation-light cut filter having fluorescent
transmitting region 156 for detecting fluorescence .gamma., the
presence or amount of the detection target substance in the sample
can be detected without significantly moving excitation-light cut
filter 144.
[0064] As described above, in SPFS device 100 according to the
present embodiment, it is not necessary to significantly move
excitation-light cut filter 144 from the light path of
light-reception optical system unit 140 even when an optimum
incident angle (enhanced angle) of excitation light .alpha. with
respect to metal film 30 (film-formation surface 22) is determined.
Accordingly, SPFS device 100 according to the present embodiment
does not require complete removal of the excitation-light cut
filter from the fluorescent light path unlike the SPFS device
according to the related art (see PTL 2), thus enabling downsizing.
Moreover, SPFS device 100 according to the present embodiment can
detect the presence or amount of the detection target substance
with high sensitivity and accuracy.
Embodiment 2
[0065] As with SPFS device 100 according to Embodiment 1, an SPFS
device according to Embodiment 2 includes chip holder 12,
excitation optical system unit 120, light-reception optical system
unit 240 and control section 160. The SPFS device according to
Embodiment 2 is different from SPFS device 100 according to
Embodiment 1 only in the configuration of light-reception optical
system unit 240. Therefore, in the present embodiment, only
light-reception optical system unit 240 is described.
[0066] FIGS. 4A and 4B are diagrams for describing detection of
plasmon scattering light .beta. and detection of fluorescence
.gamma. in the SPFS device according to Embodiment 2. FIG. 4A is a
diagram for describing detection of plasmon scattering light
.beta., and FIG. 4B is a diagram for describing detection of
fluorescence .gamma..
[0067] As illustrated in FIGS. 4A and 4B, light-reception optical
system unit 240 includes first lens 141, diaphragm 142, filter
holder 143, excitation-light cut filter 144, second lens 145, light
sensor 146, and transmission adjusting section 247. First lens 141,
diaphragm 142, filter holder 143, excitation-light cut filter 144,
second lens 145, and light sensor 146 in light-reception optical
system unit 240 are identical to the respective components of
light-reception optical system unit 140 according to Embodiment
1.
[0068] Transmission adjusting section 247 blocks plasmon scattering
light .beta. heading to scattering-light transmitting section 153.
Transmission adjusting section 147 is an electromagnetic shutter or
liquid-crystal shutter. In this embodiment, transmission adjusting
section 247 is an electromagnetic shutter. Electromagnetic shutter
(transmission adjusting section) 247 includes shutter body 248 and
power supply 249 for putting shutter body 248 into a transparent
state and block state. The term "transparent state" used herein
means a state in which at least some of scattering-light
transmitting section 153 is opened and plasmon scattering light
.beta. can pass through scattering-light transmitting section 153
(see FIG. 4A). In addition, the term "block state" means a state in
which shutter body 248 covers the entirety of scattering-light
transmitting section 153, so that plasmon scattering light .beta.
cannot pass through scattering-light transmitting section 153 (see
FIG. 4B). As described above, putting scattering-light transmitting
section 153 into the transparent state or block state by
transmission adjusting section 247 makes it possible to easily
switch between detection of plasmon scattering light .beta. and
detection of fluorescence .gamma..
[0069] Next, the detection operation of the SPFS device according
to Embodiment 2 will be described. FIG. 5 is a flowchart
illustrating an exemplary operation procedure of the SPFS
device.
[0070] First, preparation for measurement is made (step S10). Next,
the detection target substance in the sample and the capturing body
are made to react with each other (primary reaction, step S20).
[0071] Next, as illustrated in FIG. 4A, control processing section
164 opens electromagnetic shutter 247 and puts plasmon scattering
light .beta. into the transparent state (step S230). While
irradiating a predetermined position of metal film 30
(film-formation surface 22) with excitation light .alpha., the
incident angle of excitation light .alpha. with respect to metal
film 30 (film-formation surface 22) is scanned to determine an
optimum incident angle (step S40).
[0072] Next, the incident angle of excitation light .alpha. with
respect to metal film 30 (film-formation surface 22) is set to the
enhanced angle determined at the previous step (step S50). In the
following steps, the incident angle of excitation light .alpha.
with respect to metal film 30 (film-formation surface 22) is kept
at the enhanced angle.
[0073] Next, as illustrated in 4B, control processing section 164
closes electromagnetic shutter 247 to set the block state with
respect to plasmon scattering light .beta. (step S260). Metal film
30 (film-formation surface 22) is irradiated with excitation light
.alpha., and the intensity of light having the same wavelength as
fluorescence .gamma. (optical blank value) is measured (step
S70).
[0074] Next, the detection target substance that has been captured
by the capturing body is labeled by a fluorescent material
(secondary reaction, step S80). Finally, metal film 30
(film-formation surface 22) is irradiated with excitation light
.alpha., and the intensity of fluorescence .gamma. emitted from
metal film 30 (the surface of metal film 30 and the vicinity of the
surface) is measured (step S90).
[0075] Through the above-mentioned procedure, it is possible to
detect the presence or amount of the detection target substance in
the sample without moving excitation-light cut filter 144.
[0076] As described above, in the SPFS device according to the
present embodiment, it is not necessary to move excitation-light
cut filter 144 from the light path of light-reception optical
system unit 240. Accordingly, the SPFS device according to the
present embodiment does not require moving of the excitation-light
cut filter in the horizontal direction unlike the SPFS device
according to the related art (see PTL 2), thus enabling downsizing.
In addition, the presence or amount of the detection target
substance can be detected with high sensitivity and accuracy.
Embodiment 3
[0077] As with SPFS device 100 according to Embodiment 1 and the
SPFS device according to Embodiment 2, an SPFS device according to
Embodiment 3 includes chip holder 12, excitation optical system
unit 120, light-reception optical system unit 340 and control
section 160. The SPFS device according to Embodiment 3 is different
from SPFS device 100 according to Embodiment 1 and the SPFS device
according to Embodiment 2 only in the configuration of
light-reception optical system unit 340. Therefore, in the present
embodiment, only light-reception optical system unit 340 is
described.
[0078] FIGS. 6A and 6B are diagrams for describing detection of
plasmon scattering light .beta. and detection of fluorescence
.gamma.. FIG. 6A is a diagram for describing detection of plasmon
scattering light .beta., and FIG. 6B is a diagram for describing
detection of fluorescence .gamma..
[0079] As illustrated in FIGS. 6A and 6B, light-reception optical
system unit 340 includes first lens 141, diaphragm 142, filter
holder 343, excitation-light cut filter 344, second lens 145, light
sensor 146, and transmission adjusting section 147. First lens 141,
diaphragm 142, second lens 145, and light sensor 146 in
light-reception optical system unit 340 according to Embodiment 3
are identical to the respective components of light-reception
optical system unit 140 according to Embodiment 1.
[0080] In Embodiment 3, filter holder 343 includes third
through-hole 352. Third through-hole 352 is disposed at a center
portion of filter holder 343. In other words, in Embodiment 3, only
one through-hole is formed in filter holder 343. Third through-hole
352 is formed larger in size than first through-hole 152 formed in
filter folder 143 according to Embodiment 1. Accordingly, filter
holder 343 according to Embodiment 3 holds excitation-light cut
filter 344 at an outer edge portion, compared with filter holder
143 according to Embodiment 1.
[0081] Excitation-light cut filter 344 includes fluorescent
transmitting region 156 which allows fluorescence .gamma. to pass
through, and scattering-light transmitting section 153 which allows
plasmon scattering light .beta. to pass through. Scattering-light
transmitting section 153 is disposed so as to avoid fluorescent
transmitting region 156. As described above, a transparent
substrate whose one or both surfaces are coated with a dielectric
multilayer film may be used for excitation-light cut filter 344,
for example. Accordingly, scattering-light transmitting section 153
can be easily formed by previously applying masking to the region
where scattering-light transmitting section 153 is to be formed,
then forming a dielectric multilayer film, and lastly peeling off
the masking. It is preferable that the area of scattering-light
transmitting section 153 be not greater than 1/1000 of the area of
fluorescent transmitting region 156 when viewed in a plan view.
[0082] Next, the detection operation of the SPFS device according
to Embodiment 3 will be described. No that, the flowchart for this
operation is the same as that of SPFS device 100 according to
Embodiment 1, so that the flowchart is omitted herein.
[0083] First, preparation for measurement is made (step S10). Next,
the detection target substance in the sample and the capturing body
are made to react with each other (primary reaction, step S20).
Next, as illustrated in FIG. 6A, control processing section 164
moves filter holder 343 and places scattering-light transmitting
section 153 on the light path in light-reception optical system
unit 340 (step S30). While irradiating a predetermined position of
metal film 30 (film-formation surface 22) with excitation light
.alpha., the incident angle of excitation light .alpha. with
respect to metal film 30 (film-formation surface 22) is scanned to
determine an optimum incident angle (step S40). Next, the incident
angle of excitation light .alpha. with respect to metal film 30
(film-formation surface 22) is set to the enhanced angle determined
at the previous step (step S50). Next, as illustrated in FIG. 6B,
control processing section 164 moves filter holder 343, disposes
fluorescent transmitting region 156 in the light path of
light-reception optical system unit 340 and also disposes
scattering-light transmitting section 153 outside of the light path
in light-reception optical system unit 340 (step S60). Furthermore,
metal film 30 (film-formation surface 22) is irradiated with
excitation light .alpha., and the intensity of light having the
same wavelength as fluorescence .gamma. (optical blank value) is
measured (step S70). Next, the detection target substance that has
been captured by the capturing body is labeled by a fluorescent
material (secondary reaction, step S80). Finally, metal film 30
(film-formation surface 22) is irradiated with excitation light
.alpha., and the intensity of fluorescence .gamma. emitted from
metal film 30 (the surface of metal film 30 and the vicinity of the
surface) is measured (step S90).
[0084] Through the above-mentioned procedure, it is possible to
detect the presence or amount of the detection target substance in
the sample without significantly moving the excitation-light cut
filter 344 as in SPFS device 100 according to Embodiment 1.
[0085] As described above, in the SPFS device according to the
present embodiment, it is not necessary to significantly move
excitation-light cut filter 144 from the light path of
light-reception optical system unit even when an optimum incident
angle (enhanced angle) of excitation light .alpha. with respect to
metal film 30 (film-formation surface 22) is determined, as
compared with SPFS device 100 according to Embodiment 1.
[0086] Note that, although not illustrated in particular,
scattering-light transmitting section 153 may be disposed within
fluorescent transmitting region 156 in excitation-light cut filter
344. In this case, it is preferable that the size of
scattering-light transmitting section 153 be not greater than
1/1000 of the size of fluorescent transmitting region 156. As
described herein, scattering-light transmitting section 153 is so
small in size compared with fluorescent transmitting region 156
that plasmon scattering light .beta. does not interfere with
detection of fluorescence .gamma.. In addition, it is not necessary
to move excitation-light cut filter 344 between detection of
plasmon scattering light .beta. and detection of fluorescence
.gamma.. Thus, the apparatus can be further downsized.
Embodiment 4
[0087] The SPFS device according to Embodiment 4 includes chip
holder 12, excitation optical system unit 120, light-reception
optical system unit 440, and control section 160 as in the SPFS
device described above. The SPFS device according to Embodiment 4
is different from the SPFS device according to Embodiment 3 only in
the configuration of light-reception optical system unit 440. Thus,
a description of only light-reception optical system unit 440 will
be given in this embodiment.
[0088] FIGS. 7A and 7B are diagrams for describing detection of
plasmon scattering light .beta. and detection of fluorescence
.gamma. in Embodiment 4. FIG. 7A is a diagram for describing
detection of plasmon scattering light .beta. and FIG. 7B is a
diagram for describing detection of fluorescence .gamma..
[0089] As illustrated in FIGS. 7A and 7B, light-reception optical
system unit 440 includes first lens 141, diaphragm 142, filter
holder 143, excitation-light cut filter 144, second lens 145, light
sensor 146, and transmission adjusting section 447. First lens 141,
diaphragm 142, filter holder 343, second lens 145 and light sensor
146 in light-reception optical system unit 440 according to
Embodiment 4 are identical to those elements in light-reception
optical system unit 140 according to Embodiment 1.
[0090] In this embodiment, filter holder 343 includes fourth
through-hole 452. Fourth through-hole 452 is formed at a center
portion of filter holder 343 in a size substantially identical to
the outer shape of excitation-light cut filter 144.
[0091] Transmission adjusting section 447 includes: .theta. stage
448 which can freely turn excitation-light cut filter 144 via
filter holder 343 around a rotation axis in a direction orthogonal
to the optical axis of fluorescence .gamma. or plasmon scattering
light .beta.; and .theta. turn mechanism 449 for turning .theta.
stage 448 by .theta..
[0092] Next, a description will be given of detection of plasmon
scattering light .beta. by turning excitation-light cut filter 144
around the turn axis by .theta.. FIG. 8 is a graph indicating the
relationship between the wave length passing through
excitation-light cut filter 144 and the transmittance of
excitation-light cut filter 144. The solid line in FIG. 8 indicates
a case where turning angle of excitation-light cut filter 144 is 0
degrees. The broken line in FIG. 8 indicates a case where the
turning angle of excitation-light cut filter 144 is 15 degrees. The
dashed-dotted line in FIG. 8 indicates a case where the turning
angle of excitation-light cut filter 144 is 20 degrees.
Excitation-light cut filter 144 having a transmission wavelength
band within a range from 652 nm to 672 nm will be described as an
example. Moreover, the wavelength of excitation light is set to 635
nm.
[0093] As illustrated in FIG. 8, it can be seen that, the
wavelength of the light passing through excitation-light cut filter
144 shifts to the short wavelength side when excitation-light cut
filter 144 having the multilayer film described above is tilted. In
other words, tilting excitation-light cut filter 144 (multilayer
film) allows plasmon scattering light .beta. to pass through
excitation-light cut filter 144. More specifically, as illustrated
by the solid line in FIG. 8, it can be seen that, when the turning
angle (incident angle) of excitation-light cut filter 144 is 0
degrees, excitation light .alpha. is sufficiently blocked.
Meanwhile, as illustrated by the dashed-dotted line in FIG. 8,
approximately 20% of the light having a wavelength of 635 nm passes
through excitation-light cut filter 144 when the turning angle of
excitation light cut filter 144 (incident angle) is 20 degrees.
Accordingly, adjustment of the tilt angle of excitation-light cut
filter 144 enables switching between detection of plasmon
scattering light .beta. and detection of fluorescence .gamma..
[0094] Next, a description will be given of a detection operation
of the SPFS device according to Embodiment 4. FIG. 9 is a flowchart
illustrating an exemplary operation procedure of the SPFS device
according to Embodiment 4.
[0095] First, preparation for measurement is made (step S10).
Subsequently, a detection target substance in a sample and a
capturing body are made to react with each other (primary reaction,
step S20).
[0096] Next, as illustrated in FIG. 7A, control processing section
164 tilts excitation-light cut filter 144 (multilayer film) at a
predetermined angle by turning filter holder 343 by .theta. (step
S430). While a predetermined position of metal film 30
(film-formation surface 22) is irradiated with excitation light
.alpha., the incident angle of excitation light .alpha. for metal
film 30 (film-formation surface 22) is scanned to determine an
optimum incident angle (step S40).
[0097] Next, the incident angle of excitation light .alpha. with
respect to metal film 30 (film-formation surface 22) is set to the
enhanced angle determined at the previous step (step S50). In the
following steps, the incident angle of excitation light .alpha.
with respect to metal film 30 (film-formation surface 22) is kept
at the enhanced angle.
[0098] Next, as illustrated in FIG. 7B, control processing section
164 puts excitation-light cut filter 144 back to the original
position before the tilting by turning filter holder 343 by .theta.
in the reverse direction (step S460). Metal film 30 (film-formation
surface 22) is irradiated with excitation light .alpha. to measure
the intensity of light (optical blank value) having the same
wavelength as fluorescence .gamma. (step S70).
[0099] Next, the detection target substance that has been captured
by the capturing body is labeled by a fluorescent material
(secondary reaction, step S80). Finally, metal film 30
(film-formation surface 22) is irradiated with excitation light
.alpha. and the intensity of fluorescence .gamma. emitted from
metal film 30 (the surface of metal film 30 and the vicinity of the
surface) is measured (step S90).
[0100] Through the above-mentioned procedure, it is possible to
detect the presence or amount of a detection target substance in a
sample without moving the excitation-light cut filter 144 in a
planner direction.
[0101] As described above, the SPFS device according to the present
embodiment brings about the effects similar to those brought about
by the SPFS device according to Embodiment 2.
INDUSTRIAL APPLICABILITY
[0102] The surface plasmon resonance fluorescence analysis device
and the surface plasmon resonance fluorescence analysis method
according to the present invention can measure a detection target
substance with high reliability, and therefore are suitable for
laboratory tests and the like, for example.
REFERENCE SIGNS LIST
[0103] 10 Analysis chip [0104] 12 Chip holder [0105] 20 Dielectric
[0106] 21 Incidence surface [0107] 22 Film-formation surface [0108]
23 Emission surface [0109] 30 Metal film [0110] 40 Channel closure
[0111] 41 Channel [0112] 100 Surface plasmon resonance fluorescence
analysis device (SPFS device) [0113] 120 Excitation optical system
unit [0114] 121 Light source unit [0115] 122 Angle adjusting
section [0116] 140, 240, 340, 440 Light-reception optical system
unit [0117] 141 First lens [0118] 142 Diaphragm [0119] 143, 343
Filter holder [0120] 144, 344 Excitation-light cut filter [0121]
145 Second lens [0122] 146 Light sensor [0123] 147, 247, 447
Transmission adjusting section [0124] 151 Throttle hole [0125] 152
First through-hole [0126] 153 Second through-hole (scattering-light
transmission section) [0127] 154, 448 Stage [0128] 155 Motor [0129]
156 Fluorescent transmitting region [0130] 160 Control section
[0131] 161 Light-source control section [0132] 162 Light-sensor
control section [0133] 163 Motor control section [0134] 164 Control
processing section [0135] 248 Shutter body [0136] 249 Power supply
[0137] 352 Third through-hole [0138] 449 Turn mechanism [0139] 452
Fourth through-hole
* * * * *