JP2013061179A - Sensor chip for surface plasmon field-enhanced fluorescence spectroscopy and measuring method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor chip for SPFS dispensing with previous fractionation of analytes by a column treatment, namely, capable of quickly performing a measurement, preventing loss of the analytes caused by the column treatment, and highly accurately determining the quantity of specific analytes, and to provide a measuring method using the same.SOLUTION: The sensor chip for a channel type SPFS includes ligands that are fixed on the channel bottom face. The ligand has different binding abilities for each of analytes having two or more types with different sugar chain shapes, and the ligands form a density gradient in the flow direction of the channel.

Description

  The present invention relates to a sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy [SPFS] and a measurement method using the sensor chip. More particularly, the present invention relates to a flow path type SPFS sensor chip and an SPFS measurement method using the sensor chip.

  Conventionally, proteins in blood, urine, and tissues have been widely used in disease diagnosis. Many of proteins in a living body exist in a state where the surface of a protein composed of amino acids is modified with a sugar chain. Even for proteins with the same amino acid sequence (proteins with the same name), there are a wide variety of modified sugar chains, and it is known that the sugar chain structure differs depending on the state of the cell producing the protein.

  Detection of molecules that are present in the blood of cancer patients but not in the blood of healthy individuals is useful for the diagnosis of cancer and has been developed as many clinical diagnostic agents. Such a molecule is called a biomarker [BM] and is often a glycoprotein.

  As a technique for detecting a biomarker (here, glycoprotein is used as an example) present in a trace amount in the blood, as shown in FIG. 3, the primary antibody that is an antigen-capturing carrier is uniformly held on the bottom of the flow path. In general, a reaction such as an immune sandwich reaction is performed to measure the target amount of analyte. Widely used SPR devices (such as Biacore's affinity measurement device) flow the antigen-capturing carrier solution through the flow path to cause physical adsorption, and then (1) react the solution containing the antigen (such as a sugar chain protein) The change in refractive index is detected. Further, surface plasmon excitation enhanced fluorescence spectroscopy [SPFS] is also known (Patent Document 1). In the SPFS apparatus, after the same step as (1) of SPR, (2) a solution of a fluorescence detection reagent is sequentially added. The fluorescence enhanced by the surface plasmon is detected.

  In the analysis using such a conventional flow path type SPR or SPFS device, the primary antibody is generally held almost uniformly on the bottom surface of the flow path, and a certain section ( Quantification of the captured glycoprotein in the measurement area) is performed. When a specific type of glycoprotein is selectively quantified among glycoproteins in which multiple types of sugar chains are mixed, a lectin that selectively binds to the specific type of glycoprotein in advance. A sample containing substantially only the specific type of glycoprotein and no other types of glycoprotein is prepared by affinity chromatography using a column packed with It was necessary to perform SPFS.

  On the other hand, Patent Document 2 describes a sugar chain analysis method for detecting fluorescence by an evanescent excitation method (microarray scanner device), which is a microarray analysis using the interaction between a lectin and a sugar chain. Evanescent light (localized field light) is weak light that oozes out from the interface to a height of 200 to 300 nm (about half the excitation wavelength) when the excitation light is totally reflected inside the glass. The probe captured within the above range by the interaction between the lectin and the sugar chain, with almost no excitation of the fluorescent substance that labels the brown-moving (not captured) probe etc. The fluorescent substance to be labeled can be selectively observed. As a more specific embodiment for that purpose, as shown in A and B of FIG. 4 (FIG. 9 of Patent Document 2), a lectin is immobilized on a slide glass, and a fluorescently labeled sugar chain probe or a fluorescently labeled glycoprotein is attached thereto. A mode of binding, a mode of immobilizing an antibody on a slide glass, binding a glycoprotein to this, and binding a fluorescently labeled lectin (sandwich assay) are described, as shown in E of FIG. It is also described that profiling of glycoproteins contained in a sample can be performed by using a plurality of lectins having different sugar recognition capabilities on one microarray.

  However, the amount of fluorescence that can be excited by evanescent waves (local field light) is weak, and if a large amount of labeled sugar chains do not bind to the lectin on the substrate, it will not be recognized as a fluorescent signal, and a glycoprotein having a specific sugar chain will not be recognized. Although it may be possible to qualitatively analyze whether or not it is contained in a sample, there is a problem that it is difficult to perform the quantification.

JP 2010-169518 A International Publication No. 2005/064333

  In the present invention, it is not necessary to fractionate a sample by column processing in advance, that is, it is possible to measure quickly, prevent loss of the analyte accompanying column processing, and SPFS that can quantify a specific analyte with high accuracy. An object of the present invention is to provide a sensor chip for use and a measuring method using the same.

  The inventors of the present invention provide a lectin having a high binding ability to a glycoprotein having a sugar chain of a specific shape (hereinafter sometimes referred to as “specific analyte”), and a glycoprotein having a sugar chain of a shape different from that of the lectin. (It may be referred to as “non-specific analyte” hereinafter.), It was noted that it has some binding ability although it is weak. Then, when such a lectin is immobilized by forming a density gradient on a flow path type SPFS sensor chip and a sample in which the specific analyte and the non-specific analyte are mixed is allowed to flow down, Depending on the difference in the ability of the light and non-specific analyte to bind to the lectin, it is possible to accumulate each in a separate part of the flow path, or to accumulate only the former in the flow path (the latter is allowed to flow down without being accumulated). In addition, since SPFS was used, it was found that the accumulated analyte could be detected and quantified with high accuracy, and the present invention was completed.

  That is, the SPFS sensor chip of the present invention is a flow path type SPFS sensor chip in which a ligand is immobilized on the bottom surface of the flow path, and there are two or more types of ligands having different sugar chain shapes. It has a different binding ability from each of the analytes, and is characterized in that the ligand forms a density gradient in the flow direction of the flow path.

The ligand is preferably a lectin.
The density gradient is preferably formed by two or more step densities.
The ligand is preferably composed of two or more kinds of ligands, and each ligand is fixed to the bottom surface of the flow path by forming a density gradient in the flow direction of the flow path.

Moreover, the measuring method of the present invention comprises:
Step (i): A step of disposing the SPFS sensor chip of the present invention in such a manner that the direction of the density gradient of the ligand, which is the first ligand, matches the flow direction of the flow path;
Step (ii): A step of bringing a specimen that may contain an analyte having two or more types having different sugar chain shapes into contact with the SPFS sensor chip;
Step (iii): After the step (ii), a step of bringing a second ligand labeled with a fluorescent substance that can bind to the analyte into contact with the SPFS sensor chip;
Step (iv): After the step (iii), in the predetermined area of the SPFS sensor chip, the fluorescence generated from the fluorescent material is measured based on SPFS, and the analyte captured in the predetermined area is detected. Or a step of quantifying.

  In the step (iv), measurement based on SPFS is performed in a plurality of areas of the sensor chip for SPFS, and sugar chains having a specific shape with respect to the total amount of the analyte captured in the plurality of areas based on the measurement values Preferably, determining the proportion of the analyte having

  According to the present invention, an SPFS sensor chip capable of performing accurate quantification without impairing the credibility of the quantification result due to loss or alteration caused by the separation operation, and capable of high sensitivity measurement by the electric field enhancement effect by plasmon excitation, and The measurement method used can be provided.

  Therefore, for example, even when the quantitative ratio of the specific analyte and the non-specific analyte contained in the sample is 1: 10,000, the specific analyte can be quantified with high accuracy. Furthermore, when both the specific analyte and the non-specific analyte are quantified, an accurate quantitative ratio can be presented from a highly accurate quantitative value for each. This number of 1: 10,000 is overwhelmingly higher than the quantity ratio allowed in some literature. Therefore, the present invention is extremely useful as a tool for finding new clinical significance. For example, by using it for detection of a glycoprotein (AFP-L3) having a sugar chain of a specific shape, it can be applied to disease diagnosis of liver cancer from the initial stage where the amount is still small.

  As described above, the present invention can quantify a specific analyte from a specimen containing two or more kinds of analytes with high sensitivity (wide dynamic range) and high accuracy without loss due to a prior separation operation.

  In addition, when each of two or more types of analytes is quantified, the quantification results of a plurality of analytes can be used. For example, detection of sugar chain proteins having different sugar chain structures and correlation between two or more detection amounts are useful for diagnosis of a disease state.

FIG. 1 is a diagram schematically showing one aspect of the SPFS sensor chip of the present invention. The SPFS sensor chip is equally divided into five areas to immobilize lens bean lectin [LCA]. In this case, a mode in which five step densities are formed in the flow direction of the flow path is shown. (b) In Example 1, it is the figure which showed typically a mode that the sensor chip for SPFS of (a) was fixed to the flow path, and SPFS measurement was performed. FIG. 2 shows a sample containing glycoproteins (that is, BM-a and BM-a ′) in which one embodiment of the SPFS sensor chip of the present invention is fixed to a flow channel and two types having different sugar chain shapes are present. It is the figure which showed a mode that this was made to contact typically. FIG. 3 is a diagram schematically showing 1) a primary antibody immobilized on a conventional sensor chip, and BM-a and BM-a ′, which are glycoproteins bound to the primary antibody. 2) It is also a diagram schematically showing a fluorescently labeled secondary antibody bound to the glycoprotein. Usually, SPR measurement is performed in 1) and SPFS measurement is performed in 2). FIG. 4 shows A to E of FIG. FIG. 5 is a diagram schematically showing the first to fourth embodiments of the density gradient according to the present invention. The triangle representing the ligand of the SPFS sensor chip has a height proportional to the immobilization density. ing. For example, in the first embodiment, the ligand forms a density gradient such that the upstream side has a low density and the downstream side has a high density. Also in the second to fourth aspects, the left hand of the SPFS sensor chip is upstream of the flow path, and the right hand is downstream thereof.

Hereinafter, the SPFS sensor chip of the present invention and the SPFS measurement method using the sensor chip will be described in detail.
<Sensor chip for SPFS>
The SPFS sensor chip of the present invention is a flow path type SPFS sensor chip in which a ligand is immobilized. For example, as shown in FIGS. 1 (a) and (b), the ligand flows in the flow direction of the flow path. A density gradient is formed.

  The sensor chip used in the present invention can have the same configuration as a known sensor chip that can be used for SPFS measurement, except for the aspect of ligand immobilization, and the aspect is not particularly limited. Moreover, the flow path used by this invention can also take the structure similar to the well-known flow path which can be used for SPFS measurement, The aspect is not specifically limited.

(Ligand)
In the present invention, two kinds of ligands are used.
The first ligand is a bio-related molecule immobilized on the bottom surface of the channel, which binds to the analyte contained in the sample and can be held for a predetermined time (at least during the measurement of SPFS). Two or more types having different shapes have different binding ability from each of the existing analytes. That is, the first ligand binds with high affinity to an analyte having a sugar chain of a specific shape (specific analyte), but is low with some other analytes (non-specific analyte). It may be capable of binding with affinity, or may specifically bind only to a specific analyte and not substantially bind to a non-specific analyte (excluding non-specific binding). Good.

  Biologically relevant substances that can be used as a first ligand that can bind to an analyte via a sugar chain include lectins, enzyme proteins having a sugar binding domain, cytokines having affinity for sugar chains, and variants thereof. , And antibodies that interact with sugar chains, and the like, with lectins being particularly preferred.

Examples of biologically relevant substances that are candidates for the first ligand include the following.
Examples of the lectin include lectins belonging to various molecular families obtained from animals, plants, fungi, bacteria, viruses, etc., that is, “R-type lectin” related to ricin B chain found in all living worlds including bacteria, true `` Calnexin calreticulin '', which exists in all nuclei and is involved in glycoprotein folding, is widely present in multicellular animals, and is a calcium-requiring `` required calcium '' that contains many representative lectins such as `` selectin '' and `` collectin ''. "C-type lectin", "galectin" that is widely distributed in the animal kingdom and shows specificity to galactose, "legume lectin" that forms a large family in the plant legume family, and has structural similarities to this and is involved in animal intracellular transport "L-type lectin", mannose 6-phosphate-binding "P-type lectin" involved in intracellular transport of lysosomal enzymes, glycosaminoglyce Binding to acidic sugar chain, including emissions "annexin", and "I-type lectin" are mentioned belong to the immunoglobulin super family, including "Siglec".

  Examples of other lectins include ACA [Sennin Kolectin], BPL [Murasakikiwanju lectin], ConA [Tachinama bean lectin], DBA [Horsegram lectin], DSA [Datura saga lectin], ECA [Deigo bean lectin] , EEL [Spindle Tree lectin], GNA [Yukinohana lectin], GSL-I [Glyphonia bean lectin], GSL-II [Glyphonia bean lectin], HHL [Amaryllis lectin], Jacalin [Jack fruit lectin], LBA [ Lima lectin], LCA [Lentil lectin], LEL [Tomato lectin], LTL [Lotus bean lectin], MPA [American crisp lectin], NPA [Rappa daffodil lectin], PHA-E [Inge Bean lectin], PHA-L [kidney bean lectin], PNA [peanut lectin], PSA [pea lectin], PTL-I [deer pea lectin], PTL-II [deer lectin lectin], PWM [Yoshima pokeweed lectin], RCA120 [castor Bean lectin], SBA [soybean lectin], SJA [endurectin], SNA [chicken lectin], SSA [Japanese chick lectin], STL [potato lectin], TJA-I [kikarasu lectin], TJA-II [ki] Crow Uri lectin], UDA [Common Stinging Nettle lectin], UEA-I [Harienida lectin], VFA [Fabama lectin], VVA [Hairy Vetch lectin], WFA [Fuji lectin], WGA [Bread wheat lectin] Down], and the like.

Examples of the enzyme protein having the sugar binding domain include various glycosidases (xylanase, glucanase), glycosyltransferase (UDP-GalNAc: polypeptide GalNAc transferase), and the like. In addition, cytokines having affinity for sugar chains include interleukin-2 (IL-2), interleukin-12 (IL-12), tumor necrosis factor α (TNF-α), fibroblast growth factor (FGF). And the like. Examples of antibodies that interact with sugar chains include sugar chain-related tumor markers (CA19-9, Forssman antigen, T antigen, Tn antigen, sialyl T antigen), blood group-related sugar chains (A, B, H, Examples include antibodies against Le ^a , Le ^x antigen) and differentiation-related antigens (Ii, SSEA-1-4).

  On the other hand, the second ligand is a ligand for fluorescently labeling the analyte captured by the first ligand. For the accuracy of measurement, this second ligand is different from the above-mentioned first ligand and has the same binding ability as each of two or more types of analytes having different sugar chain shapes, that is, between analytes. Therefore, it is necessary to be able to recognize and combine portions that are substantially unchanged. The second ligand may be selected appropriately depending on the analyte. For example, when the analyte is a glycoprotein, an antibody that interacts with the protein portion of the glycoprotein is appropriate as the second ligand. is there.

(Analyte)
The analyte that can be analyzed in the present invention is a biological molecule or a fragment thereof having a sugar chain and having the first and second ligands as described above. Examples of such biological molecules include nucleic acids having sugar chains (DNA, RNA, polynucleotides, oligonucleotides, PNA (peptide nucleic acids), which may be single-stranded or double-stranded, or the like, or Nucleosides, nucleotides and modified molecules thereof); proteins having sugar chains (polypeptides, oligopeptides, etc.), so-called glycoproteins or glycopeptides; amino acids having sugar chains (including modified amino acids); carbohydrates (oligosaccharides, oligosaccharides) Polysaccharides, sugar chains, etc.); lipids having sugar chains, so-called glycolipids; or their modified molecules, complexes and the like. Specifically, tumor markers used as biomarkers, signaling substances, hormones and the like are included.

  Specific examples of tumor markers that are typical analytes in the present invention include α-fetoprotein [AFP]. This AFP is an oncofetal glycoprotein that is expressed in fetal liver or malignant tumors such as hepatocellular carcinoma and Yorksack tumors. Human AFP has one asparagine-linked sugar chain per molecule, and the sugar chain structure has already been clarified. In addition, it is known that the sugar chain structure changes with canceration of cells, and with hepatocellular carcinoma, fucose is linked to N-acetylglucosamine at the non-reducing end of the asparagine-linked sugar chain by α1,6 linkage. AFP with added sugar chains increases.

  Such a cancerous change of a sugar chain can be detected using various lectins having different affinities depending on the structure of the sugar chain as the first ligand. For example, lentil lectin [LCA] has high affinity for AFP having a sugar chain to which fucose is added (LCA affinity AFP, also referred to as AFP-L3), but has an AFP having a sugar chain to which fucose is not added. It does not mean that there is no affinity for (also referred to as LCA non-affinity AFP, AFP-L1). It has some affinity and can be captured. Therefore, analysis using AFP as an analyte (AFP having a sugar chain to which fucose is added is referred to as “specific analyte”, and AFP having a sugar chain to which fucose is not added is referred to as “non-specific analyte”). When done, it is preferred to use LCA as the first ligand.

(Density gradient)
In the SPFS sensor chip of the present invention, the density of the immobilized ligand (first ligand) forms a gradient along the flow direction of the flow path.

  The density gradient may be formed so that the density continuously changes, but may be formed by two or more step densities. For example, as shown in FIGS. 1 (a) and 1 (b), when the SPFS sensor chip is equally divided into five areas and a ligand (lectin) is immobilized, there are five steps in the flow direction of the flow path. The aspect etc. which form a typical density are mentioned. In order to form such a stepwise density, for example, solutions having different concentrations of ligands are prepared stepwise, and each solution is applied to a predetermined section on the bottom surface of the channel to immobilize the ligands. do it.

  The density of the first ligand in each area, the number and size of the areas, the spacing between the areas, etc. are within the range where the specific analyte can be selectively accumulated. Performance, contact time with each analyte (liquid feeding time or liquid feeding speed), and measurement conditions such as the number of each analyte can be appropriately adjusted. As shown in the Examples, if the contact time between the surface of the SPFS sensor chip on which the first ligand is immobilized and the specimen containing the specific analyte and the non-specific analyte is sufficient, the non-specific analyte Such non-specific analytes will gradually move downstream, while specific analytes will continue to be captured upstream, so eventually the specific and non-specific analytes will be captured. Can be separated and accumulated in different areas, but if the contact time is insufficient, they may accumulate in the same area without being sufficiently separated, and the respective amounts may not be determined.

  Furthermore, two or more kinds of the first ligands immobilized on the SPFS sensor chip of the present invention can be used in combination. For example, the case of using two types of ligands (for example, lectins) that can bind to the respective sugar chains of two types of glycoproteins having different sugar chain shapes is exemplified. In addition, the two types of ligands can form a density gradient in the same direction, or can form a density gradient in opposite directions. In addition, a density gradient is formed only on one of the two ligands, and the other ligand is formed at a uniform density without a density gradient, or a part of the region where one ligand is formed. Further, it can be formed with a density gradient or with a uniform density.

  The method of forming the density gradient is not particularly limited as long as the specific analyte can be selectively accumulated and quantified, but more specifically, the following four modes are typical. As an example. When two or more types of ligands are immobilized on the SPFS sensor chip, other types of ligands can be uniformly provided that the ligands capable of binding to a specific analyte are formed so as to have at least a density gradient. It may be formed with a certain density or partially.

First aspect
As shown in FIG. 5, the first aspect of the density gradient is an aspect in which the specific analyte is preferentially captured on the upstream side and the non-specific analyte is preferentially captured on the downstream side. For example, when LCA is used as the first ligand and a density gradient is formed such that the upstream side has a low density and the downstream side has a high density, the LCA affinity AFP (specific analyte) has an LCA having a low density on the upstream side. However, LCA non-affinity AFP (non-specific analyte) is difficult to capture on the upstream side of the low density, or even if it is captured, the binding force is weak and the binding force is weak. Since it gradually flows to the downstream side, many LCAs eventually accumulate on the downstream side with high density. Therefore, among the AFPs accumulated on the upstream side, the LCA affinity AFP (specific analyte) is dominant, while the LCA non-affinity AFP (non-specific AFP) is accumulated on the downstream AFP. Analyst) becomes dominant. As the first ligand in such a first embodiment, it is necessary to select a ligand that binds to a specific analyte with high affinity, but can bind to a non-specific analyte with low affinity. . In such an embodiment, contrary to the above, forming a density gradient of LCA so that the upstream side has a high density and the downstream side has a low density means that LCA affinity AFP (specific analyte) and LCA non-affinity Both AFPs (non-specific analytes) are unsuitable because they are captured upstream and cannot be separated and quantified.

<< Second aspect >>
As shown in FIG. 5, the second embodiment of the density gradient is a mode in which specific analytes are captured at any density from upstream to downstream, while non-specific analytes flow down (pass) without being captured. is there. For example, as in the first embodiment described above, LCA is used as the first ligand, and this forms a density gradient such that the upstream side has a low density and the downstream side has a high density. Do not accumulate. When the first ligand in such a second embodiment binds to a specific analyte with high affinity, but is selected to be able to bind to a non-specific analyte with low affinity, The downstream density needs to be adjusted appropriately (below the predetermined value), but the one that specifically binds only to the specific analyte and does not substantially bind to the non-specific analyte is selected. In this case, it is not necessary to adjust the density on the downstream side.

  In addition, as shown in FIG. 2, the lectin immobilized on the SPFS sensor chip forms a density gradient, and the sugar chain portion of BM-a ′ (the chain-like portion in which small circles are connected in the figure) ; Corresponding to “non-specific analyte” in FIG. 5, without binding to the sugar chain part of BM-a (in the figure, a chain-like part having a series of small circles and having branches; Typically, BM-a ′ is passed through to bind to the “special analyte”.), And BM-a is captured in areas with high lectin density.

《Third embodiment》
As a third embodiment of the density gradient, as shown in FIG. 5, one of the first ligands (A) is immobilized so as to become dense from the upstream to the downstream of the flow path, and the other first ligand Similarly, (B) may be fixed in such a manner that it becomes dense from sparse to dense from the upstream to the downstream of the flow path.

  In such a third aspect, by using two kinds of first ligands (A) and (B), two kinds of specific analytes (A) and (B) are separately accumulated in different areas. It is possible. That is, the specific analyte (A) is accumulated in an area where the first ligand (A) is immobilized at a specific density or more, and the first ligand (B) is immobilized at a specific density or more. The specific analyte (B) is accumulated in the area, but the density of the immobilized ligands is adjusted appropriately so that the former area and the latter area do not overlap, for example, the former area becomes more upstream. Thus, the latter area can be made more downstream. In addition, non-specific analytes may be allowed to flow down without being captured in any area, or an area different from the area where two types of specific analytes (A) and (B) are accumulated (for example, most It is also possible to accumulate on the downstream side.

  In this case, the specific analyte (B) and the non-specific analyte are not captured by the first ligand (A), and the specific analyte (A) and the non-specific analyte are not captured by the first ligand (B). It is necessary to keep in mind. That is, in the third aspect, the first ligand (A) binds to the specific analyte (A) with high affinity, but the specific analyte (B) and the non-specific analyte are low but somewhat low. When a substance that can bind with affinity is selected, the first ligand (B) and the non-specific analyte are not substantially captured in the area where the specific analyte (A) is preferentially captured. It is necessary to appropriately adjust the density of A) (a density equal to or lower than a predetermined value), and the specific analyte (B) and the non-specific analyte are specifically bound only to the specific analyte (A). If a material that does not substantially bind is selected, the density need not be adjusted. On the other hand, the first ligand (B) also binds to the specific analyte (B) with high affinity, but can bind to the specific analyte (A) and the non-specific analyte with low affinity. If selected, the density of the first ligand (B) is set so that the specific analyte (A) and the non-specific analyte are not substantially captured in the area where the specific analyte (B) is preferentially captured. It is necessary to adjust appropriately (the density is equal to or lower than a predetermined value), and specifically binds only to the specific analyte (B) and does not substantially bind to the specific analyte (A) and the non-specific analyte. If one is selected, there is no need to adjust its density.

《Fourth aspect》
As a fourth embodiment of the density gradient, as shown in FIG. 5, one of the first ligands (A) is immobilized so as to become dense from the upstream to the downstream of the flow path, and the other first ligand On the contrary, (B) may be fixed in such a manner that it becomes denser and sparse from upstream to downstream of the flow path.

  In such a fourth embodiment, two kinds of specific analytes (A) and (B) can be separated separately on the upstream side and the downstream side by using two kinds of first ligands (A) and (B). Can be captured. That is, the specific analyte (A) is accumulated on the downstream side where the first ligand (A) is immobilized at a specific density or higher, and the first ligand (B) is immobilized at a specific density or higher. The specific analyte (B) is accumulated on the upstream side. In addition, non-specific analytes may be allowed to flow down without being captured in any area, or an area different from the area where two types of specific analytes (A) and (B) are accumulated (for example, most It is also possible to accumulate on the downstream side.

  Also in this case, the specific analyte (A) and the non-specific analyte are not captured in the area where the specific analyte (B) on the upstream side is accumulated, and the specific analyte (A) on the downstream side is accumulated. Therefore, it is necessary to take care so that the specific analyte (B) and the non-specific analyte are not captured. That is, in the fourth embodiment, the first ligand (A) binds with the specific analyte (A) with high affinity, but the specific analyte (B) and the non-specific analyte are both low but somewhat. When a substance that can bind with affinity is selected, the specific analyte (B) and the non-specific analyte are not substantially captured in the area where the specific analyte (A) on the downstream side is preferentially captured. It is necessary to appropriately adjust the density of one ligand (A) (below a predetermined value), specifically bind only to the specific analyte (A), and to the specific analyte (B) and non-specific If a substance that does not substantially bind to the analyte is selected, the downstream density need not be adjusted. On the other hand, the first ligand (B) also binds to the specific analyte (B) with high affinity, but can bind to the specific analyte (A) and the non-specific analyte with low affinity. In the case where the specific analyte (B) is preferentially captured, the first ligand (B) is selected so that the specific analyte (A) and the non-specific analyte are not substantially captured in the area that preferentially captures the specific analyte (B) on the upstream side. ) Is appropriately adjusted (the density is equal to or lower than a predetermined value), and the specific analyte (A) and the non-specific analyte are substantially bound by specifically binding only to the specific analyte (B). When the non-bonded one is selected, the upstream density need not be adjusted.

<Measurement method using sensor chip for SPFS>
The measurement method of the present invention includes the following steps (i) to (iv).
Step (i): A step of disposing the SPFS sensor chip of the present invention in such a manner that the direction of the density gradient of the ligand, which is the first ligand, coincides with the flow direction of the flow path.

Step (ii): A step of bringing a specimen that may contain an analyte having two or more types having different sugar chain shapes into contact with the SPFS sensor chip.
Step (iii): A step of bringing the second ligand labeled with a fluorescent substance that can bind to the analyte into contact with the SPFS sensor chip after the step (ii).

  Step (iv): After the step (iii), in the predetermined area of the SPFS sensor chip, the fluorescence generated from the fluorescent material is measured based on SPFS, and the analyte captured in the predetermined area is detected. Or the process of quantifying.

  In the step (iv), measurement based on SPFS is performed in a plurality of areas of the sensor chip for SPFS, and sugar chains having a specific shape with respect to the total amount of the analyte captured in the plurality of areas based on the measurement values Preferably, determining the proportion of the analyte having

(Sample)
Examples of specimens include blood (serum / plasma), urine, nasal fluid, saliva, stool, body cavity fluid (spinal fluid, ascites, pleural effusion, etc.), etc. It may be used. Of these specimens, blood, serum, plasma, urine, nasal fluid and saliva that may contain tumor markers are preferred.

(contact)
In the contact, the specimen is fed into the flow path, and the surface on which the first ligand of the SPFS sensor chip is immobilized is immersed in the liquid feeding, and the first ligand and the analyte in the specimen are An embodiment in which the SPFS sensor chip and the specimen are brought into contact with each other is preferable.

  The liquid feeding speed may be adjusted so that the contact time between the SPFS sensor chip on which the first ligand is immobilized and the analyte in the sample is sufficient. It may be a thing. Further, in order to bring the first ligand and the analyte into contact with each other slowly (increase the contact time), for example, a gel may be used to increase the viscosity of the liquid feeding medium.

(Second ligand labeled with fluorescent substance)
The fluorescent substance is not particularly limited as long as it is a known fluorescent substance capable of SPFS measurement, and a conventional method can be used for labeling the fluorescent substance on the second ligand.

(Detection and quantification)
By measuring the fluorescence emitted from the second ligand formed into a complex with the analyte by SPFS, the analyte can be detected or quantified. The fluorescence intensity measured in each area of the flow path reflects the amount of analyte captured in each area, and the analyte can be quantified by using a separately created calibration curve. Is possible.

  For example, in the first aspect described above, each of the specific analyte and the non-specific analyte can be quantified from the fluorescence intensity of the area where the specific analyte and the non-specific analyte are assumed to be captured. When specific and non-specific analytes are captured across multiple areas, the total amount of each specific and non-specific analyte can be determined from the total of those areas. If the quantitative values of all the areas are summed, the total amount of the analyte including the specific analyte and the non-specific analyte can be obtained. In addition, as in the second and fourth aspects described above, when the non-specific analyte is not quantified, and therefore the total amount of the analyte does not need to be quantified, only the detection or quantification of the specific analyte is performed. You just have to do it.

Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these.
[Example 1]
(1-1) Immobilization of antigen capture carrier:
A glass transparent support (“BK7” manufactured by SCHOTT AG) having a refractive index [nd] of 1.52 and a thickness of 1 mm and an outer shape of 20 mm × 100 mm is plasma-cleaned, and a chromium thin film is formed on one side of the support by a sputtering method. After the formation, a thin gold film was formed on the surface by sputtering. The thickness of the chromium thin film was 1 nm, and the thickness of the gold thin film was 50 nm.

  On the obtained support, an area is formed by packing so as to divide into 5 equal parts in the longitudinal direction, and lentil lectin [LCA] having different concentrations (0.1, 0.5, 2.0, 5.0 and 12.0 mg / mL) in each of the 5 areas. A solution containing was added and immobilized by physical adsorption.

  Thereafter, the SPFS sensor chip having a five-step density gradient was manufactured by performing non-specific adsorption prevention treatment by allowing to stand for 2 hours in a PBS solution containing 1% by weight bovine serum albumin [BSA]. .

(1-2) Production of flow path:
After removing / cleaning the BSA solution, polydimethyldioxide having a 2 mm x 10 mm hole on the surface of the SPFS sensor chip with the packing removed, an outer shape of 20 mm x 20 mm, and a thickness of 0.5 mm corresponding to the channel height Five siloxane [PDMS] sheets are provided, and a 4 mm thick PDMS spacer (as a gasket, seals the gap between the flow path and the SPFS sensor chip so as to cover the SPFS sensor chip from the outside of the flow path. The polymethylmethacrylate plate having the same outer shape as that of the product) was put on and pressure-bonded (however, this silicon rubber spacer was not in contact with the liquid feed), and the channel and the polymethylmethacrylate plate were fixed with screws.

(1-3) Antigen delivery:
As an antigen, “Control L for Mutus Wako AFP-L3” manufactured by Wako Pure Chemical Industries, Ltd. (AFP-L3 accounted for about 32% of the total AFP, and the total AFP concentration was about 49 ng / mL). 0.5 mL was slowly fed over 10 minutes, and then the PBS solution was slowly fed for 20 minutes, and then the shift of the resonance angle was measured over time with surface plasmons to confirm that the antigen was bound.

  Here, after fixing the LD light source so that the angle of incidence of the laser beam on the gold thin film of the SPFS sensor chip becomes the optimum angle, the SPFS sensor chip is irradiated with excitation light from the LD light source, and a cut filter (Japan Vacuum) Fluorescence by surface plasmon excitation enhanced fluorescence spectroscopy through a 10x objective lens (manufactured by Nikon Corporation) as a condensing lens and a CCD image sensor (manufactured by Texas Instruments Japan) And detected as “blank fluorescence signal”.

(1-4) Preparation of fluorescently labeled antibodies:
A fluorescently labeled antibody was prepared as follows using a fluorescent substance labeling kit.
That is, anti-α-fetoprotein [AFP] monoclonal antibody (1D5; 2.5 mg / mL; manufactured by Japan Medical Laboratory), 0.1 M sodium bicarbonate and Alexa Fluor (registered trademark) 647 reactive dye mixed And allowed to react at room temperature for 1 hour. After the reaction, gel filtration chromatography and ultrafiltration were performed to remove Alexa Fluor 647 reactive dye that was not used for labeling.

(1-5) Reaction by detection antibody delivery:
1.5 mL of PBS containing 1,000 ng / mL of fluorescently labeled anti-AFP monoclonal antibody was added, and the solution was slowly fed over 10 minutes.
Thereafter, the solution was slowly fed and washed with PBS containing 0.01% by weight of Tween 20 over 30 minutes.

(1-6) SPFS fluorescence measurement:
30 minutes after the start of cleaning, fluorescence of five areas on the SPFS sensor chip was sequentially detected by the CCD image sensor, and “SPFS signal” was measured respectively.

(1-7) Optimization of liquid feeding time:
In (1-3), the antigen is fed for 10 minutes, then PBS is sent for 20 minutes, and then the antigen is sent for 10 minutes, followed by PBS each. 5 minutes on each of the SPFS sensor chips (total flow for 10 minutes (antigen only), 20 minutes, 40 minutes and 50 minutes) The SPFS signal was measured. The results are shown in Table 1.

  In Table 1, when the liquid was fed for 30 minutes, particularly large peaks appeared in the second and fourth areas from the left, and it was observed that AFP was accumulated in each area. It is estimated that AFP-L3 is separately accumulated in the former area and other AFPs are separately accumulated in the latter area, similarly to the estimation in the preparation of the calibration curve described later (1-8). Even when the liquid feeding time is 20 minutes, 40 minutes, and 50 minutes, AFP-L3 and other AFPs can be accumulated in different areas.

  On the other hand, when the liquid feeding time is 10 minutes, it seems that AFP-L3 and other AFPs are accumulated in the first and second areas from the left without being sufficiently separated. Even in the 1st and 2nd areas where the ligand density is relatively small, the fluorescence intensity is larger than that in the other areas. The 1st and 2nd areas are sufficient for the number of AFP-L3 and other AFPs. This is because a large number of ligands are immobilized.

(1-8) Creating a calibration curve:
After performing (1-1) and (1-2), 0.5 mL of “Control L for Mutus Wako AFP-L3” prepared as a calibration curve sample (described later) was slowly fed over 30 minutes. Then, 1.5 mL of PBS containing 1,000 ng / mL of the fluorescently labeled anti-AFP monoclonal antibody obtained in (1-4) was added, and the solution was slowly fed over 10 minutes. Thereafter, the solution was slowly fed and washed with PBS containing 0.01% by weight of Tween 20 over 30 minutes. Thirty minutes after the start of washing, five areas were sequentially observed from one CCD, and each SPFS signal was measured.

  For the calibration curve sample, PBS alone (AFP concentration 0 ng / mL) and “Control L for Mutus Wako AFP-L3” were diluted with PBS so that the total AFP concentrations were 2.0, 5.0, 15 and 40 ng / mL, respectively. Is. “Control L for Mutus Wako AFP-L3” is that AFP-L3 accounts for about 32% of the total AFP, so the AFP-L3 concentrations of these calibration curve samples are 0, 0.64, 1.60, 4.8 and 12.8 ng / mL.

  These results are shown in Table 2.

From Table 2, the second and fourth largest peaks from the left appeared as in the previous results, and it was observed that AFP was accumulated. When [(1 + 2nd SPFS signal) / (1 + 2 + 3 + 4 + 5th SPFS signal)] × 100 was calculated, the ratio was about 32% which was the same as the content of AFP-L3. It is presumed that (AFP-L3) accumulates upstream (first and second from the left), and other sugar chain structure AFP accumulates downstream (fourth and fifth) from the left. This is considered to correspond to the first embodiment of FIG. 5, and the AFP-L3, which is a specific analyte, is located on the downstream side of the SPFS sensor chip (the first and second areas). AFP other than L3, which is a non-specific analyte, is accumulated in the fifth area). From the conditions such as the ligand density, the affinity between the ligand and the analyte, and the liquid feeding time, it is considered that there was little AFP accumulated near the middle of the SPFS sensor chip (third area).

  Table 3 shows the calibration curve created for each total value.

(1-9) Measurement of AFP sample:
Mixing “Control L for Mutus Wako AFP-L3” containing AFP-L3 and “recombinant-AFP” (Abnova) not containing AFP-L3 so that the AFP-L3 content is 3.2%. The SPFS signal was measured. From the total value of the SPFS signal and the respective calibration curves, AFP containing L3 sugar chain was calculated to be 1.72 ng / mL, and AFP not containing L3 sugar chain was calculated to be 47.0 ng / mL. It agreed well with each of 47.7 ng / mL.

  Further, a calibration curve was similarly prepared in the low concentration range of AFP (0, 20, 100, 500 and 2000 pg / mL) to confirm linearity. Thereafter, using this calibration curve, the solution prepared so that the content of AFP-L3 was 3.2% was diluted 10-fold and 100-fold, and the SPFS signal was measured. The total value of the SPFS signal and the concentration obtained from each calibration curve were in good agreement with the calculated feed concentration.

[Example 2]
(2-1) The antigen capture carrier was immobilized in the same manner as in Example 1 (1-1) to produce a SPFS sensor chip.

  (2-2) In manufacturing the flow channel, the height of the flow channel is lowered to increase the probability that the flowing sample contacts the surface of the sensor chip for SPFS. Example 1 (1-2) was performed except that the sheet was changed to a PDMS sheet.

(2-3) Antigen feeding was performed in the same manner as in Example 1 (1-3).
(2-4) It was found that in the reaction by feeding the detection antibody, accumulation in the second area and the fourth area was achieved by setting the feeding time of (1-5) to 2 hours.

(2-5) Creating a calibration curve:
In (1-8), the SPFS signal was measured in the same manner as in (1-8) except that the feeding time was 2 hours. The results are shown in Table 4.

A calibration curve was created only from the second and fourth areas.

(2-6) Measurement of AFP sample:
The SPFS signal was measured in the same manner as in Example 1 (1-9). Results equivalent to those in Example 1 were obtained.

[Example 3]
(3-1) Immobilization of the antigen capture carrier is carried out by using an anti-AFP antibody (anion (sulfated tyrosine pentamer) prepared according to JP-A-8-134100 (Unitika) instead of lentil lectin [LCA]. An SPFS sensor chip was produced in the same manner as in Example 1 (1-1) except that the conjugated anti-AFP monoclonal antibody (mouse) was used.

(3-2) The flow path was produced in the same manner as in Example 1 (1-2).
(3-3) Antigen feeding was performed in the same manner as in Example 1 (1-3).
(3-4) The reaction by feeding the detection antibody was carried out in the same manner as in Example 1 (1-5).

  As a result, separation was possible in the same manner as in Table 4 of Example 2. It was found that even the same high ceiling channel as in Example 1 was accumulated in the second area and the fourth area. This indicates that the antibody used in the solid phase is easier to accumulate without using the lectin than the lectin, and is consistent with the general knowledge that the antibody has a higher affinity than the lectin. ing.

<Discussion>
Since the measurement method using the sensor chip for SPFS of the present invention has a wide dynamic range, when analyzing an AFP with an unknown sugar chain structure ratio, one is about 1 pg / mL and the other is about 10,000 pg. Even at / mL, simultaneous measurement is possible.

Claims (6)

  A flow-path type surface plasmon excitation enhanced fluorescence spectroscopy sensor chip in which a ligand is immobilized on the bottom of the flow path, wherein the ligand includes two or more types of analytes having different sugar chain shapes. A sensor chip for surface plasmon excitation-enhanced fluorescence spectroscopy, which has different binding capacities and the ligand forms a density gradient in the flow direction of the flow path.   The sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy according to claim 1, wherein the ligand is a lectin.   The sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy according to claim 1 or 2, wherein the density gradient is formed by two or more stepwise densities.   The surface according to any one of claims 1 to 3, wherein the ligand is composed of two or more kinds of ligands, and each ligand is formed on the bottom surface of the flow path by forming a density gradient in the flow direction of the flow path. Sensor chip for plasmon excitation enhanced fluorescence spectroscopy. Step (i): A sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy according to any one of claims 1 to 4, wherein the density gradient direction of the ligand as the first ligand and the flow direction of the flow path are Arranging in a consistent manner;
Step (ii): a step of contacting a specimen that may contain an analyte having two or more types having different sugar chain shapes with the sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy;
Step (iii): After the step (ii), a step of bringing a second ligand labeled with a fluorescent substance that can bind to the analyte into contact with the sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy;
Step (iv): After the step (iii), in the predetermined area of the surface plasmon excitation enhanced fluorescence spectroscopy sensor chip, the fluorescence generated from the fluorescent material is measured based on the surface plasmon excitation enhanced fluorescence spectroscopy, A measurement method comprising a step of detecting or quantifying the analyte captured in the predetermined area.   In the step (iv), measurement is performed based on surface plasmon excitation enhanced fluorescence spectroscopy in a plurality of areas of the sensor chip for surface plasmon excitation enhanced fluorescence spectroscopy, and captured on the plurality of areas based on the measured values. The measurement method according to claim 5, comprising determining a ratio of an analyte having a sugar chain having a specific shape relative to the total amount of the analyte.