Fluorescence measurement probe, fluorescence measurement probe unit, and fluorescence measuring device

Abstract

Provided is a fluorescence measuring device capable of measuring biopolymers such as proteins in real time at lower concentrations than in conventional devices. This fluorescence measurement probe is used by being connected by an optical fiber to a light source for irradiating a liquid being measured with excitation light and a detector for detecting fluorescence derived from the liquid being measured that is excited by the excitation light from the light source, the fluorescence measurement probe being provided with: a port for introducing the excitation light from the optical fiber and for guiding out fluorescence and scattered light from the liquid being measured to the optical fiber; a condensing optical system for collimating and / or condensing the excitation light, the fluorescence, and the scattered light; a polarizing plate transparent to the excitation light, the fluorescence, and the scattered light; and a housing for internally accommodating the condensing optical system and the polarizing plate and having an opening portion for injecting the excitation light into the liquid being measured and taking in the fluorescence and the scattered light from the liquid being measured.

Description

Fluorescence measurement probe, fluorescence measurement probe unit, fluorescence measurement device

[0001] The present invention relates to a fluorescence measurement probe used in a fluorescence measurement device or a fluorescence measurement method for calculating characteristic values ​​of biopolymers, for example.

[0002] For example, in the manufacturing process of biopharmaceuticals, etc., accurate real-time quantification of low concentrations (e.g., about 0.1 g / L) of biopolymers contained in culture media at the initial stage of culture is required to appropriately control the production status of biologically derived polymeric compounds (biopolymers) such as antibodies.

[0003] A conventional measurement method is based on polarization-fluorescence matrix measurement, which has been reported to have a protein detection limit of 0.18 g / L, as shown in Non-Patent Document 1.

[0004] However, the measurement device used in the above-mentioned measurement method is equipped with two polarizing plates on each of the light source side and the detector side in order to sufficiently increase the polarization extinction ratio and improve measurement accuracy. This not only increases manufacturing costs, but also requires the provision of driving means for operating the two polarizing plates, making it difficult to make the device small, resulting in a problem of a relatively large, stationary device.

[0005] Furthermore, because the measuring device is a stationary type, it is difficult to measure the liquid to be measured immediately after it is collected; the collected liquid must be carried to a laboratory where the measuring device is installed for measurement, which makes it difficult to measure in real time.

[0006] “Development of rapid polarized total synchronous fluorescence spectroscopy (pTSFS) method for protein quantification in a model bioreactor brother”, Bernard O. Boateng et al. , Biotechnology and Bioengineering, 118, 1805-1817 (2021)

[0007] The present invention has been made in consideration of these problems, and its main object is to provide a measuring device that is capable of measuring biopolymers such as proteins at low concentrations in real time, while being less expensive than conventional devices.

[0008] That is, the fluorescence measuring device according to the present invention is a fluorescence measuring device comprising a light source and a detector for detecting fluorescence excited by excitation light emitted from the light source, wherein a polarizing plate that transmits the excitation light and the fluorescence is provided between the light source and the detector, and the excitation light and the fluorescence are transmitted through the same polarizing plate.

[0009] With a fluorescence measuring device configured in this manner, since the excitation light and the fluorescence pass through the same polarizing plate, it is possible for the excitation light and the fluorescence to pass through a common polarizing plate made of a single polarizer, which not only reduces manufacturing costs but also makes it possible to omit a polarizing plate drive mechanism, etc. As a result, it is possible to create a rod-type sensor with an outer diameter of 15 mm or less that can be directly attached to a general-purpose attachment port formed on a container or the like containing the liquid to be measured, something that was previously impossible to achieve, and it is possible to measure fluorescence derived from low concentrations of biopolymers, etc., as accurately as possible in real time.

[0010] Furthermore, by using a common polarizing plate for transmitting excitation light and fluorescence, it is possible to align the direction of the excitation light incident on the measurement object with the direction of the fluorescence emitted from the measurement object, thereby making it possible to appropriately limit the amount of information used in polarization-fluorescence matrix analysis and avoid overly complicated information processing.

[0011] By controlling the polarization of both the excitation light incident on the measurement liquid and the fluorescence excited by the excitation light and incident on the detector from the measurement liquid using a polarizing plate, the difference between the direction of the excitation light and the direction of the detected fluorescence can be determined, and this information can be used to observe the molecular weight, association state, etc. of biopolymers in the measurement liquid. However, since the polarizers constituting the polarizing plate vary slightly in their polarizing properties even when they are from the same manufacturer and have the same model number, it has been difficult to measure the molecular weight, association state, etc. of biopolymers in the measurement liquid with sufficient accuracy using conventional device configurations. On the other hand, the fluorescence measuring device of the present invention, which can transmit the excitation light and fluorescence at the same position through a single polarizer, can minimize the number of polarizers and consistently obtain highly accurate data regardless of individual differences in the polarizers, thereby enabling accurate measurements of the molecular weight, association state, etc. of biopolymers in the measurement liquid.

[0012] The detector may also detect scattered light generated by irradiating the measurement target liquid with the excitation light, and the excitation light, the fluorescence, and the scattered light may all pass through the same polarizing plate. In conventional fluorescence measuring devices, scattered light has been treated as noise, but by detecting both fluorescence and scattered light, it is possible to obtain information about the measurement target liquid that could not be obtained from fluorescence alone.

[0013] When measuring fluorescence and scattered light in this way, there is a risk that the amount of information obtained by the detector will be too great; however, by making it so that the excitation light, fluorescence, and scattered light all pass through the same polarizing plate, it is possible to simplify the measurement conditions and, if necessary, to control the amount of information so that it does not become too great.

[0014] If the fluorescence measuring device comprises a measuring device main body equipped with the light source and the detector, and a fluorescence measuring probe connected to the light source and the detector by optical fibers, measurements can be performed with the fluorescence measuring probe immersed in the liquid to be measured. This eliminates the need to take a portion of the liquid to be measured and set it in the measuring device, and allows measurement of characteristic values ​​such as the concentration of biopolymers in the liquid to be measured in real time.

[0015] If the polarizing plate is provided inside the probe, the main body of the measuring device can be further reduced in size, which is preferable.

[0016] The present invention also includes a fluorescence measurement probe connected by an optical fiber to a light source that irradiates a measurement target liquid with excitation light and a detector that detects fluorescence derived from the measurement target liquid excited by the excitation light from the light source, the fluorescence measurement probe including a polarizing plate that transmits the excitation light and the fluorescence. The polarizing plate preferably transmits not only the excitation light and the fluorescence but also scattered light from the measurement target liquid.

[0017] A specific embodiment of the fluorescence measurement probe includes a housing that houses the polarizing plate and has an opening that emits the excitation light to the liquid to be measured and takes in the fluorescence and scattered light from the liquid to be measured; an inlet port that introduces the excitation light from the optical fiber into the housing; and an outlet port that introduces the fluorescence and scattered light from the liquid to be measured from the inside of the housing to the optical fiber.

[0018] The fluorescence measurement probe is preferably further provided with a focusing optical system that collimates and / or focuses the excitation light, the fluorescence, and the scattered light, because this makes it possible to focus the excitation light at a predetermined location in the liquid to be measured, and to collimate the fluorescence and the scattered light so that they can be easily guided into the optical fiber.

[0019] In a specific embodiment of the present invention, the light-collecting optical system includes a collimator, a mirror, and / or a lens.

[0020] The focusing optical system preferably collimates or focuses the excitation light and then guides it to the polarizing plate, and the focusing optical system preferably collimates or focuses the fluorescence and the scattered light and then guides them to the polarizing plate.

[0021] It is preferable that the inlet port and the outlet port are the same port, since this allows the size of the housing to be made as small as possible.

[0022] A fluorescence measurement probe unit comprising the above-described fluorescence measurement probe and an optical fiber is also part of the present invention.

[0023] A specific embodiment of the above-mentioned probe unit for measuring fluorescence is one in which the optical fiber is a two-branched optical fiber bundle.

[0024] In order to prevent the polarizing plate and other components housed in the probe unit from coming into contact with the liquid to be measured and becoming soiled, it is preferable that the fluorescence measurement probe unit further includes a spacer member that separates the fluorescence measurement probe from the liquid to be measured.

[0025] The present invention also includes a fluorescence measuring device comprising a light source that emits the excitation light, the above-mentioned fluorescence measurement probe unit, a detector that detects the fluorescence and the scattered light, and an information processing unit (also referred to as a calculation unit) that calculates characteristic values ​​of the liquid to be measured based on the fluorescence and the scattered light detected by the detector.

[0026] To enable use in polarization-fluorescence matrix measurement, it is preferable that the light source emits excitation light of multiple wavelengths, specifically wavelengths of 250 nm or more and 450 nm or less, and it is more preferable that the polarizing plate is compatible with all of the multiple wavelengths.

[0027] According to the present invention, it is possible to provide a fluorescence measuring device that is capable of measuring biopolymers at lower concentrations than conventional devices in real time.

[0028] The present invention relates to a fluorescence measuring device and a fluorescence measuring probe, and more particularly to a fluorescence measuring device according to an embodiment of the present invention.

[0029] An embodiment of the present invention will be described below with reference to the drawings.

[0030] The fluorescence measuring device 100 according to this embodiment is used to measure the characteristic values ​​of biologically derived polymeric compounds (biopolymers), such as antibodies, contained in a measurement target liquid S, such as a culture medium supernatant, an antibody purified solution, an antibody pharmaceutical drug substance, or an antibody pharmaceutical formulation, using a polarization-fluorescence matrix measurement method.

[0031] The biopolymers are biologically derived polymer compounds, such as peptides, hormones, antibodies, and other proteins, viral vectors, and exosomes and other extracellular vesicles. The characteristic values ​​are values ​​that represent, for example, the concentration, molecular weight, and association state of the biopolymers. As shown in FIG. 1 , the fluorescence measuring device 100 includes a measuring device main body 1 equipped with a light source, a detector, and an information processing unit, and a fluorescence measuring probe unit 2 equipped with a fluorescence measuring probe that is connected to the measuring device main body 1 and used by immersing its tip in the measurement target liquid S.

[0032] The light source 11 is not particularly limited as long as it can emit excitation light that can be used for fluorescence measurement, but it is preferable that it be capable of dispersing and emitting excitation light of multiple wavelengths from 250 nm to 450 nm. Specific examples include a light source equipped with a Xe lamp and a spectroscopic unit, or a light source combining LEDs with different center wavelengths. The spectroscopic unit may be, for example, a monochromator, a filter wheel equipped with multiple bandpass filters, or a linear variable filter. A method for combining multiple types of LEDs may be, for example, a fiber bundle or a fiber multiplexer.

[0033] The detector 12 detects the fluorescence and scattered light from the measurement target liquid S excited by the excitation light from the light source, and any detector that is used in the polarization-fluorescence matrix measurement method can be used without any problems. In order to perform spectrum measurement in a short time, it is desirable to use a one-dimensional or two-dimensional image sensor as the light-receiving element provided in each detector.

[0034] The information processing unit 13, for example, calculates the characteristic values ​​of the liquid S to be measured based on information regarding the fluorescence and scattered light output from the detector 12, and is configured to function as the information processing unit 13 by, for example, a so-called general-purpose computer equipped with a CPU, memory, input / output interface, etc., through cooperation of the CPU and its peripheral devices based on various application software (hereinafter referred to as programs) stored in the memory.

[0035] The probe unit 2 includes the above-mentioned fluorescence measuring probe 21 and an optical fiber 22 that connects the fluorescence measuring probe 21 to the measuring device main body 1 .

[0036] As shown in FIG. 1, the fluorescence measurement probe 21 is used by being connected to the light source 11 and the detector 12 provided in the measurement device main body 1, and, for example, as shown in FIG. 2, is provided with: a port 211 for introducing excitation light from the optical fiber 22 and guiding fluorescence and scattered light from the measurement target liquid S to the optical fiber 22; a focusing optical system 212 for collimating and / or focusing the excitation light, the fluorescence, and the scattered light; a polarizing plate 213 for transmitting the excitation light, the fluorescence, and the scattered light; and a housing 214 for accommodating the focusing optical system 212 and the polarizing plate 213 therein, the housing 214 having an opening 215 for emitting the excitation light to the measurement target liquid S and taking in the fluorescence and scattered light from the measurement target liquid.

[0037] The housing 214 is, for example, a rectangular parallelepiped made of a metal or resin that does not transmit light, and one end of the housing 214 is formed with a port 211 (which functions as an introduction port in this case) for taking in the excitation light emitted from the light source 11 and guided by the optical fiber 22. Although the case where the housing 214 is rectangular parallelepiped is described here, other shapes such as a cylindrical shape may also be used.

[0038] In addition, the housing 214 has an opening 215 formed at the end opposite to the end where the port 211 is formed, for example, for emitting excitation light from inside the housing toward the liquid S to be measured.

[0039] The opening 215 also serves to introduce into the housing 214 the fluorescence and scattered light excited by the excitation light and emitted from the measurement target liquid S. The port 211 also functions as an outlet port that outputs the fluorescence and scattered light introduced into the housing 214 from the opening 215 toward the optical fiber 22. In this manner, in this embodiment, the optical path (introduction optical path L1) through which light from the light source is introduced into the housing from the introduction port and passes through the opening 215 to irradiate the measurement target liquid is the same as the optical path (exit optical path L2) through which fluorescence and scattered light from the measurement target liquid enter the housing from the opening 215 and proceed toward the second port. As a result, the introduction optical path L1 and the exit optical path L2 are both configured to pass through the same polarizing plate 213 at the same position inside the housing.

[0040] In this embodiment, the focusing optical system 212 includes a collimator that collimates the excitation light and a lens that focuses the fluorescence and scattered light. For example, an aluminum reflective collimator can be used as the collimator. A wide variety of lenses can be used as the lens, including plano-convex lenses, aspherical lenses, and achromatic doublet lenses. In preparation for using ultraviolet light as the excitation light, it is preferable to use fused silica or calcium fluoride as the material for the lens, which has a relatively high transmittance and is relatively stable even against UV light.

[0041] The polarizing plate 213 is not particularly limited as long as it is compatible with the wavelengths of the excitation light, the fluorescence, and the scattered light. However, for example, UV light can be used without any problems. Furthermore, a wire grid polarizing plate is preferred because it can control the polarization of light regardless of the direction of incidence of the light onto the polarizing plate. The polarizing plate 213 is preferably compatible with all wavelengths of light contained in the excitation light emitted from the light source 11. The polarizing plate is preferably composed of a single polarizer, but may also include multiple polarizers. Specifically, the polarizing plate may be composed of multiple plate-shaped polarizers stacked together with their face plates in contact with each other, or may be arranged side by side on the same surface with their sides butted against each other. When the polarizing plate 213 as a single component includes multiple polarizers as described above, the direction of light split by each polarizer may or may not be uniform, as long as light can pass through the polarizing plate 213.

[0042] The optical fiber 22 may be any fiber that can guide the excitation light emitted from the light source 11 to the fluorescence measurement probe 21 and guide the fluorescence and scattered light emitted from the measurement target liquid S to the detector 12. However, in order to simplify the structure of the fluorescence measurement probe 21 as much as possible, it is preferable to use a two-branch optical fiber bundle in which the ends connected to the light source 11 and the detector 12 are bifurcated.

[0043] The fluorescence measuring probe unit 2 according to this embodiment further includes a spacer member 23 for separating the fluorescence measuring probe 21 from the liquid S to be measured.

[0044] The spacer member 23 is, for example, as shown in FIG. 2, cylindrical and made of a material such as resin that does not transmit light, and can be attached to the housing 214 by inserting one end of the spacer member 23 into an opening 215 of the housing 214, and can be removed from the housing 214 after use and can be disposed of.

[0045] 2, a lens or a glass plate is fitted into the end of the spacer member 23 opposite to the end that contacts the housing 214, thereby preventing the measurement target liquid S from entering the housing 214. The focal point of this lens is preferably set as close to the lens as possible to minimize attenuation of the excitation light, fluorescence, and scattered light in the measurement target liquid.

[0046] A method for measuring biopolymers using the fluorescence measurement probe 21 and fluorescence measurement device 100 according to this embodiment is, for example, as follows: The spacer member 23 is attached to the tip of the fluorescence measurement probe 21. With the fluorescence measurement probe 21 fixed so that the tip of the attached spacer member 23 comes into contact with the measurement target liquid S, excitation light in a predetermined wavelength range (e.g., 250 nm or more and 450 nm or less) is emitted from the light source 11. The light source 11 sequentially emits light within a predetermined wavelength range, changing the wavelength by one wavelength at a time.

[0047] The excitation light introduced into the housing 214 via the optical fiber 22 and the port 211 is collimated by the collimator provided in the fluorescence measurement probe 21, passes through a polarizing plate 213, and is emitted from an opening 215 toward the measurement target liquid S. The fluorescence and scattered light emitted from the measurement target liquid S in response to the excitation light are collected by a plano-convex lens provided in the opening 215, and then transmitted through the polarizing plate 213, and introduced from the port 211 to the detector 12 via the optical fiber 22.

[0048] Information such as the wavelength and intensity of the fluorescence and scattered light for each excitation wavelength detected by the detector 12 is sent from the detector 12 to the information processing unit 13, and the information processing unit 13 receives this information and performs polarization-fluorescence matrix analysis based on the wavelength of the excitation light and the intensity of the fluorescence.

[0049] Furthermore, the information processing unit 13 estimates the size of the biopolymer based on information such as the wavelength and intensity of the scattered light, and the amount of change in intensity over time.

[0050] Thereafter, the information processing unit 13 may combine information about the concentration of biopolymers calculated using the polarization-fluorescence matrix described above with information about the size of the biopolymers estimated based on the scattered light, and output the combined information to a display unit (not shown).

[0051] When the measurement for one sample liquid S is completed, the spacer member 23 is removed from the housing 214 of the fluorescence measurement probe 21 .

[0052] When measuring the next liquid S to be measured, the same procedure is repeated from the beginning using a new spacer member 23 .

[0053] <Effects of this embodiment> According to the fluorescence measurement probe 21 and fluorescence measurement device 100 configured in this manner, the fluorescence measurement probe 21 is provided with the polarizing plate 213, and this polarizing plate 213 transmits the excitation light from the light source 11 and the fluorescence and scattered light from the measurement target liquid S. Therefore, a common polarizing plate 213 can be used on both the light source 11 side and the detector 12 side, which not only keeps manufacturing costs low but also makes the main body 1 of the fluorescence measurement device 100 as compact as possible, allowing the fluorescence measurement device 100 to be, for example, a tabletop type that can be carried to a room where it is used and placed on a table for use.

[0054] Furthermore, not only can the measurement device main body 1 be made smaller, but measurements can also be performed while the fluorescence measurement probe 21, which is connected to the light source 11 and detector 12 by an optical fiber 22, is immersed in the measurement target liquid S contained in a container. Therefore, the fluorescence measurement device 100 equipped with the fluorescence measurement probe 21 of this embodiment can measure characteristic values ​​such as the concentration of biopolymers contained in the measurement target liquid S in real time, eliminating the need to collect a portion of the measurement target liquid S and set it in the measurement device.

[0055] Furthermore, the fluorescence measuring device 100 according to the embodiment actively utilizes scattered light, which is removed or corrected as noise in conventional fluorescence measurement methods, and therefore can obtain not only the concentration of biopolymers but also more detailed information such as the molecular size and the presence or absence of association.

[0056] Since the light source 11 emits light with a wavelength of 250 nm or more and 450 nm or less as excitation light, this measurement method is particularly suitable for measuring the concentration of peptides, proteins, and the like.

[0057] Since a two-branch optical fiber bundle is used as the optical fiber 22, the number of components in the fluorescence measurement probe 21 can be reduced as much as possible, making the fluorescence measurement probe 21 more compact than when two optical fibers are connected to the fluorescence measurement probe 21.

[0058] Since the fluorescence measurement probe unit 2 is provided with a spacer member 23, the fluorescence measurement probe 21 itself does not come into direct contact with the measurement target liquid S, and it is possible to prevent parts such as an expensive polarizing plate 213 from being soiled.

[0059] The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, only one polarizing plate 213 is provided, but another polarizing plate may be provided at another location on the inlet light path and / or outlet light path. The polarizing plate may be provided at any location on the inlet light path and / or outlet light path. However, in a configuration including a probe unit equipped with an optical fiber, it is preferable that the polarizing plate be provided between the optical fiber and the liquid to be measured.

[0060] The focusing optical system may include a mirror instead of the lens as shown in Fig. 3. As the mirror, for example, an off-axis parabolic mirror or the like can be preferably used. In this case, since the excitation light after passing through the polarizing plate is focused laterally by the mirror, it is preferable to change the position of the opening provided in the housing of the fluorescence measurement probe, for example, to provide it on the side surface of the housing, as shown in Fig. 3.

[0061] The fluorescence measurement probe may include components other than those described above. For example, two or more of a collimator, a lens, and a mirror may be used in combination upstream of the polarizing plate (on the light source and detector side), or two or more of a collimator, a lens, and a mirror may be used in combination downstream of the polarizing plate (on the measurement target liquid side). A focusing optical system may be provided only upstream or only downstream of the polarizing plate. Furthermore, each component may also function as another component, thereby further miniaturizing the probe. For example, the collimator, which is a component of the focusing optical system, may function as the introduction port described above. If necessary, the focusing optical system may include optical components other than those described above.

[0062] The introduction port and the exit port provided in the fluorescence measurement probe may be a single port as in the above-described embodiment, or two or more separate ports may be provided so that the introduction light path L1 and the exit light path L2 are separate light paths. Even when a single port is provided, the optical path of the excitation light passing through the introduction light path L1 and the optical path of the fluorescence and / or scattered light passing through the exit light path L2 do not need to completely coincide with each other, and it is sufficient that the excitation light and the fluorescence (and scattered light, if necessary) pass through the same polarizing plate, for example, by at least partially overlapping them.

[0063] The optical fiber is not limited to a two-branch optical fiber bundle, and two or more unbranched optical fibers may be used.

[0064] A polarizing plate that transmits all of the excitation light, fluorescence, and scattered light may be disposed inside the measurement device body, rather than inside the probe.

[0065] The fluorescence measuring device does not necessarily have to be equipped with a probe unit, and may be one that samples a sample liquid into a measurement cell disposed inside the measuring device main body and performs measurement.

[0066] In the above-described embodiment, only one detector is provided, and both fluorescence and scattered light are detected by the single detector, but it is also possible to provide one fluorescence detector that detects fluorescence and one scattered light detector that detects scattered light. In the above-described embodiment, the scattered light is also measured, but it is not necessarily required to measure the scattered light.

[0067] It goes without saying that the above-described embodiments and modified embodiments may be combined in part or in whole as appropriate, and various modifications are possible within the scope of the invention.

[0068] According to the present invention, it is possible to provide a fluorescence measuring device that is capable of measuring biopolymers such as proteins at lower concentrations than conventional devices in real time.

[0069] REFERENCE SIGNS LIST 100 Fluorescence measuring device 1 Measuring device main body 11 Light source 12 Detector 13 Information processing unit 2 Fluorescence measuring probe unit 21 Fluorescence measuring probe 211 Port 212 Light collecting optical system 213 Polarizing plate 214 Housing 215 Opening 22 Optical fiber 23 Spacer member S Measurement target liquid

Claims

1. A fluorescence measurement device including a light source and a detector for detecting fluorescence excited by excitation light emitted from the light source, wherein a polarizing plate that transmits the excitation light and the fluorescence is provided between the light source and the detector, and the excitation light and the fluorescence pass through the same polarizing plate.

2. The fluorescence measurement device according to claim 1, wherein the detector also detects scattered light generated by irradiating a measurement target liquid with the excitation light, and all of the excitation light, the fluorescence, and the scattered light pass through the same polarizing plate.

3. The fluorescence measurement device according to claim 1 or 2, wherein the detector is a one-dimensional or two-dimensional image sensor.

4. The fluorescence measurement device according to any one of claims 1 to 3, including a measurement device main body including the light source and the detector, and a fluorescence measurement probe connected to and used with the light source and the detector by an optical fiber.

5. The fluorescence measurement device according to claim 4, wherein the polarizing plate is provided inside the probe.

6. A fluorescence measurement probe connected to and used with a light source that irradiates a measurement target liquid with excitation light and a detector that detects fluorescence derived from the measurement target liquid excited by the excitation light from the light source, the fluorescence measurement probe including a polarizing plate that transmits the excitation light and the fluorescence.

7. The fluorescence measurement probe according to claim 6, wherein the polarizing plate transmits not only the excitation light and the fluorescence but also scattered light from the measurement target liquid.

8. A housing that houses the polarizing plate therein and has an opening that emits the excitation light to the measurement target liquid and captures the fluorescence and the scattered light from the measurement target liquid, an introduction port that introduces the excitation light from the optical fiber into the housing, and a derivation port that derives the fluorescence and the scattered light from the measurement target liquid from the housing to the optical fiber, the fluorescence measurement probe according to claim 6 or 7.

9. The fluorescence measurement probe according to any one of claims 6 to 8, further including a condensing optical system that collimates and / or condenses the excitation light, the fluorescence, and the scattered light.

10. The fluorescence measurement probe according to claim 9, wherein the condensing optical system includes a collimator, a mirror, and / or a lens.

11. The fluorescence measurement probe according to claim 9 or 10, wherein the light condensing optical system guides the excitation light to the polarizing plate after parallelizing or condensing the excitation light.

12. The fluorescence measurement probe according to any one of claims 9 to 11, wherein the light condensing optical system guides the fluorescence and the scattered light to the polarizing plate after parallelizing or condensing the fluorescence and the scattered light.

13. The fluorescence measurement probe according to claim 8, wherein the introduction port and the export port are the same one port.

14. A fluorescence measurement probe unit comprising the fluorescence measurement probe according to any one of claims 6 to 13 and an optical fiber.

15. The fluorescence measurement probe unit according to claim 14, wherein the optical fiber is a bifurcated optical fiber bundle.

16. The fluorescence measurement probe unit according to claim 14 or 15, further comprising a spacer member that separates the fluorescence measurement probe from the liquid to be measured.

17. A fluorescence measurement device comprising: a light source that emits the excitation light; the fluorescence measurement probe unit according to any one of claims 14 to 16; a detector that detects the fluorescence and the scattered light; and a calculation unit that calculates a characteristic value of the liquid to be measured based on the fluorescence and the scattered light detected by the detector.

18. The fluorescence measurement device according to claim 17, wherein the light source emits excitation light having a plurality of wavelengths.

19. The fluorescence measurement device according to claim 17 or 18, wherein the light source emits excitation light having a wavelength of 250 nm or more and 450 nm or less.

20. The fluorescence measurement device according to any one of claims 17 to 19, wherein the polarizing plate is capable of corresponding to all of the plurality of wavelengths.

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