WO2014084789A1

WO2014084789A1 - Method and apparatus for detection of tagged protein

Info

Publication number: WO2014084789A1
Application number: PCT/SE2013/051404
Authority: WO
Inventors: Lin Chen; Åke Danielsson; Gunnar Malmquist; Lianghua LU; Rong HOU
Original assignee: General Electric Company; Ge Healthcare Bio-Sciences Ab
Priority date: 2012-11-30
Filing date: 2013-11-28
Publication date: 2014-06-05
Also published as: CN103852465A

Abstract

A method comprises: contacting a sample solution comprising a tagged protein with a labeled binder bindable to a tag of the tagged protein; contacting the sample solution with a binding material bindable to the labeled binder which is not bound with the tag; and determining a concentration of the tagged protein in the sample solution according to a signal change before and after contacting the sample solution with the binding material. An associated apparatus is also described.

Description

METHOD AND APPARATUS FOR DETECTION OF TAGGED PROTEIN

BACKGROUND

[0001] The invention relates generally to methods and apparatuses for the detection of tagged proteins.

[0002] Tagged proteins have become very attractive in protein expression and purification. Given the continuous growth of applications of tagged proteins in structural and function studies, the availability of rapid and convenient methods for the detection of the tagged protein is desirable.

[0003] Currently used methods for the detection of tagged proteins in complex mixtures typically take two hours or more, and they are often seen as tedious. Examples of such methods are enzyme-linked immunoassays, Western blotting and methods based on specific stains. An example of the latter is In Vision™ His-tag In-gel Stain, intended for specific, sensitive staining of His-tagged fusion proteins, Catalog numbers LC6030, LC6033. According to a user guide, revision date 19 March 2012, publication part number 25-0671, and available through internet at http://tOols.imdtrogen.com/content/sfymanuals/invisi it takes at least 2 hours and 20 minutes to stain His-tagged fusion proteins for the detection.

[0004] Therefore, there is a need to develop new and/or improved methods and apparatuses for the detection of tagged proteins.

BRIEF DESCRIPTION

[0005] In one aspect, a method is provided, comprising: contacting a sample solution comprising a tagged protein with a labeled binder bindable to a tag of the tagged protein; contacting the sample solution with a binding material bindable to the labeled binder which is not bound with the tag; and determining a concentration of the tagged protein in the sample solution according to a signal change before and after contacting the sample solution with the binding material.

[0006] In another aspect, an apparatus is provided, comprising: a test strip comprising: a sample receiving portion for receiving a sample solution comprising a tagged protein; a conjugating portion comprising a labeled binder bindable to a tag of the tagged protein; and a detecting portion comprising a binding material bindable to the labeled binder which is not bound with the tag.

[0007] These and other advantages and features will be better understood from the following detailed description of preferred embodiments of the invention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic perspective view of a test strip of an apparatus provided in accordance with one embodiment of the invention;

[0009] FIG. 2 is a schematic cross-sectional view of the test strip of FIG. 1;

[0010] FIG. 3 is a photo obtained in example 5;

[0011] FIG. 4 is a diagram obtained in example 5; and

[0012] FIG. 5 is a photo obtained in example 6.

DETAILED DESCRIPTION

[0013] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value.

[0014] In the following specification and claims, the singular forms "a", "an" and "the" include plural referents, unless the context clearly dictates otherwise. Moreover, the suffix "(s)" as used herein is usually intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term. [0015] As used herein, the terms "may", "could", "could be" and "may be" indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of "may" and "may be" indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances, the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances, an event or capacity may be expected, while in other circumstances, the event or capacity may not occur. This distinction is captured by the terms "may", "could", "could be" and "may be".

[0016] The method of the present invention could be used for detecting the existence and/or quantity of a tagged protein, i.e., the concentration of the tagged protein in a sample solution.

[0017] The sample solution may be any solution comprising tagged proteins. The sample solution may be a solution prepared from the tagged proteins. In some embodiments, the sample solution may be prepared by diluting a purified tagged protein sample using such as a phosphate buffered saline (PBS) buffer.

[0018] As used herein, the term "tagged protein" refers to a protein comprising a tag.

Examples of a tag include, but are not limited to, oligo-histidine (His), glutathione-S-transferase, FLAG, streptag II, maltose binding protein, HA-tag, c-myc, T7-tag, S-tag, calmodulin binding peptide, fragment crystallizable (Fc) region of antibody, elastin like peptide, chitin-binding domain, thioredoxin, NusA, and albumin binding domain. Exemplary tagged proteins include, but are not limited to, a His-tagged protein, and a human antibody with an Fc region.

[0019] During contacting the sample solution comprising the tagged protein with the labeled binder, the tag is bound with the labeled binder. As used herein, the term "labeled binder" refers to a binder bound with a label. The labeled binder is bindable to a tag of the tagged protein. Examples of a binder include, but are not limited to, an antibody, a fragment of an antibody, and an aptamer.

[0020] In some embodiments, the binder is an antibody with a specificity directed towards the tag, e.g. an antibody directed towards His, or a non-human antibody directed towards the Fc region of a human antibody. An example of an antibody directed towards His is an anti-6X HIS epitope tag (rabbit) antibody, available, e.g., with a catalog No. of 600-401-382 from Rockland Immunochemicals Inc., Gilbertsville, PA, USA. An example of a non-human antibody directed towards the Fc region of a human antibody is an anti-human IgG F(c) (goat) antibody, available, e.g., with a catalog No. of 609-1103 from Rockland Immunochemicals Inc., Gilbertsville, PA, USA.

[0021] The label may be any physical or chemical label capable of being detected visually or using an optical instrument. The label may be enzyme-substrate combinations that produce colors upon reactions, colored particles, such as latex particles, colloidal metal labels, metal or carbon sol labels, fluorescent labels, and liposome or polymer sacs. Exemplary labels are derived from, but are not limited to, colloidal gold, latex beads, fluorescent microspheres, magnetic beads, quantum dots, and up-converting phosphors. In some embodiments, the label is derived from colloidal gold.

[0022] When contacting the sample solution with a binding material bindable to the labeled binder which is not bound with the tag, the excessive labeled binder, which is not bound with the tag, if any, binds to the binding material and causes a signal change before and after the contacting at a location where the binding material is located. The signal change is therefore inversely related to the amount of tagged protein in the sample solution.

[0023] As used herein, the term "binding material" refers to a material bindable to the labeled binder. In some embodiments, the binding material is the tagged protein. In some embodiments, the binding material is a material (such as a peptide, a protein, or a microsphere) different from the tagged protein but comprises the tag. In some embodiments, the binding material is the tag.

[0024] Because the signal is linked to the amount of the label and in turn to a concentration of the tagged protein in the sample solution, a concentration of the tagged protein may be determined according to the signal change monitored by, e.g., a visual observation or using a spectroscopy. When a spectroscopy is used, a calibration curve may be established, which could be used for the concentration quantitation of the tagged protein.

[0025] In some embodiments, after contacting with the binding material, the sample solution is contacted with a control material.

[0026] As used herein, the term "control material" refers to a material bindable to the labeled binder. In some embodiments, the control material is a binder with a specificity directed towards non-human antibodies of the species used for the binder directed towards the Fc region of a human antibody. An example of a binder with specificity directed towards non-human antibodies of the species used for the binder directed towards an Fc region of a human antibody is an anti-goat IgG F(c) (rabbit) antibody available, e.g., with a catalog No: 105-4103 from Rockland Immunochemicals Inc., Gilbertsville, PA, USA. An anti-goat antibody ensures that only the conjugating antibody from goat will be captured. Corresponding pairs of antibodies from other species than goat could also be used.

[0027] Protein A or G binds both the conjugating antibody, e.g., anti-human IgG

(GOAT), and any unconjugated Human IgG analyte and may be used as the control material. In some embodiments, the control material is at least one of: a) protein A or any IgG-binding variant thereof, b) protein G or any IgG-binding variant thereof, and c) protein L or any IgG- binding variant thereof. In some embodiments, only one material is used as the control material, which is protein A.

[0028] An example of protein A is available, e.g., with a product code of 17-0872-02 from GE Healthcare Bio-Sciences Corp., New Jersey, USA. An example of an IgG-binding variant of protein A is available, e.g. as MabSelect SuRe^™ ligand from GE Healthcare Bio- Sciences Corp., New Jersey, USA. An example of protein G is available, e.g., with a product code of 17-0619-09 from GE Healthcare Bio-Sciences Corp., New Jersey, USA.

[0029] Embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail.

[0030] Please refer to FIGS. 1 and 2, a test strip 1 of an apparatus (not labeled) provided in accordance with one embodiment of the invention comprises: a sample receiving portion 2 for receiving a sample solution comprising a tagged protein (not shown); a conjugating portion 3 comprising a labeled binder bindable to the tag of the tagged protein; and a detecting portion 4 comprising a binding material bindable to the labeled binder which is not bound with the tag.

[0031] In some embodiments, the sample solution may be contacted with the labeled binder and the binding material by diffusing the sample solution through the conjugating portion 3 and the detecting portion 4. Correspondingly, the concentration of the tagged protein may be determined according to a signal change of the detecting portion 4 before and after diffusing the sample solution comprising the tagged protein through the detecting portion 4.

[0032] The sample receiving portion 2 may be in any shape or configuration that the sample solution could be applied thereto and diffuse therethrough. The sample receiving portion 2 may be either a section of the test strip 1 or a sample pad.

[0033] In some embodiments, the sample receiving portion 2 may be a sample pad prepared by soaking a strip of glass fiber in a solution comprising, e.g., bovine serum albumin (BSA), Tween 20 and phosphate buffered saline (PBS) and drying the strip of glass fiber after being saturated.

[0034] The sample solution may be contacted with the sample receiving portion 2 by, e.g., applying the sample solution to the sample receiving portion 2 or immersing the sample receiving portion 2 into the sample solution.

[0035] The sample solution diffuses from the sample receiving portion 2 forwardly under the wi eking force. When the sample solution diffuses through the conjugating portion 3, the labeled binder is released from the conjugating portion 3 to diffuse forwardly together with sample solution. The tagged proteins bind at the tags thereof to some of the labeled binders.

[0036] The conjugating portion 3 may be in any shape or configuration that the sample solution could diffuse therethrough. The conjugating portion 3 may be either a section of the test strip 1 or a conjugating pad.

[0037] In some embodiments, the conjugating portion 3 may be a conjugating pad prepared by adsorbing a conjugation solution on a strip of glass fiber followed by drying the strip of glass fiber. The conjugation solution comprises the labeled binder.

[0038] When the sample solution diffuses through the detecting portion 4, the excess of labeled binder without any tagged protein attached binds to the binding material and is bound to the detecting portion 4.

[0039] The signals produced by the labels in the detecting portion 4 may be visible by naked eyes or detectable using optical instruments. [0040] In some embodiments, the labeled binder is colorful and the concentration of the tagged protein in the sample solution is determined according to a color change of the detecting portion 4. In some embodiments, a color of the detecting portion 4 changes with an increase or a decrease of the concentration of the tagged protein in the sample solution. Therefore, the existence and/or amount of the tagged protein may be determined by monitoring the color change.

[0041] For example, if no tagged protein in the sample solution, the color maximizes in the detecting portion 4 because the labeled binder from the conjugating portion 3 binds as many as they can in the detecting portion 4. Similarly, when the detecting portion of a first test strip is darker in color than that of a second test strip, the concentration of the tagged protein in the first sample solution tested by the first test strip may be lower than that of the tagged protein in the second sample solution tested by the second strip, and vice versa. The color change may be monitored by a visual inspection or using a spectroscopy.

[0042] In some embodiments, the intensity of the signal of the label in the detecting portion 4 may be detected by optical instruments. The intensity of the signal of the detecting portion 4 may be the output of the optical instrument. In some embodiments, the intensity of the signal is the height of a peak of the signal outputted from a strip reader.

[0043] Allowing solutions having known concentrations of the tagged protein to diffuse along test strips and detecting intensities of signals of the corresponding detecting portions may establish a formula in which the concentration of the tagged protein is a function of the intensity of the signal of the detecting portion. The concentration of the tagged protein in the sample solution to be detected may be determined by calculating using the formula and the intensity of the corresponding signal of the detecting portion 4.

[0044] In some embodiments, the test strip 1 comprises a control portion 5 comprising a control material (not shown). The sample solution diffuses forwardly from the detecting portion 4 so that the labeled binder, which is not bound to the detecting portion 4, binds to the control material of the control portion 5.

[0045] The signals produced by the labels in the control portion 5 may be visible by naked eyes or detectable using optical instruments. In some embodiments, the presence of the signal in the control portion 5 indicates the completion of the migration of the sample solution through the detecting portion 4 to the control portion 5. In some embodiments, if all the labeled binders are bound to the detecting portion 4, the labels may not be detected in the control portion 5. In some embodiments, if not all of the labeled binders are bound to the detecting portion 4, the amount of the labels detected in the control portion 5 may be used to improve the calibration quantitation of the tagged protein in the sample solution since the concentration of the tagged protein has a direct relation with the amount of the labels in the control portion 5.

[0046] The detecting portion 4 and the control portion 5 may be also called T-line and

C-line, respectively. In some embodiments, the detecting portion 4 and the control portion 5 may be formed by dispensing a T-line solution and a C-line solution respectively to two spaced areas of a membrane 7, respectively. The membrane 7 may be made of such as nitrocellulose. The T-line solution comprises the binding material. The C-line solution comprises the control material.

[0047] In some embodiments, the test strip 1 comprises an absorbing portion 6 located further from the detecting portion 4 than from the control portion 5. The absorbing portion 6 helps enhancing a wicking force directed away from the sample receiving portion 2 to draw the sample solution from the sample receiving portion 2 through the conjugating portion 3, the detecting portion 4, and the control portion 5. The absorbing portion 6 may be either a section of the test strip 1 or an absorbing pad. In some embodiments, the absorbing portion 6 may be an absorbing pad made of a bibulous material such as a cotton paper, a cellulose, a silica microfiber filter, a glass fiber, and a quartz fiber filter.

[0048] The test strip 1 may be in the form of an elongate strip including any bibulous material along which the sample solution may diffuse. The sample receiving portion 2, the conjugating portion 3, the detecting portion 4, the control portion 5 and the absorbing portion 6 of the test strip 1 may be made of same materials or different materials. The sample receiving portion 2, the conjugating portion 3, the detecting portion 4, the control portion 5 and the absorbing portion 6 of the test strip 1 may be integral with each other or may be assembled together.

[0049] In some embodiments, the sample receiving portion 2, the conjugating portion 3, the membrane 7 and the absorbing portion 6 are assembled together. In some embodiments, the conjugating portion 3 overlaps with both the sample receiving portion 2 and the membrane 7 and the membrane 7 also overlaps with the absorbing portion 6. [0050] In some embodiments, the test strip 1 comprises a backing pad 8 made of such as a plastic material like polyester (Mylar^®) or PET to support the sample receiving portion 2, the conjugating portion 3, the detecting portion 4, the control portion 5 and the absorbing portion 6 thereon.

[0051] In some embodiments, a plastic housing (not shown) may be provided to enclose the test strip 1 therein. In some embodiments, the sample receiving portion 2 may be located outside of the plastic housing.

[0052] The method of the present invention uses a relatively short time to allow the sample solution to contact the labeled binder and the binding material, and to determine the concentration of the tagged protein according to a signal change before and after contacting with the binding material. Therefore, it is simple and fast. The labeled binder and the binding material are universal to at least a series of proteins comprising a specific tag, the test strip 1 does not need to be changed when any of the series of protein comprising the specific tag needs to be tested, thereby saving cost for designing and manufacturing the test strip 1.

EXAMPLES

[0053] The following examples are included to provide additional guidance to those of ordinary skill in the art in practicing the claimed invention. These examples do not limit the invention as defined in the appended claims.

Example 1

Conjugating pad preparation

[0054] Au-Nano particle solution (1 mL, Au- P, 40 nm) (from Shanghai Qui eking Biotech Co. Ltd, Shanghai, China) was charged to a 1.5 mL micro-centrifuge tube, followed by adding 5 μΐ of 0.2 M K₂CO₃ solution (from Sinopharm Chemical Reagent Co., Ltd, Shanghai, China) and vortexing to mix well. After the further addition of 4 μΐ of mouse His-tag monoclonal antibody (Anti-His) (5 mg/ml, from Shanghai Abmart Bio-Pham Inc. Ltd, Shanghai, China), the solution was vortexed immediately and waited for 10 minutes for producing a conjugation solution.

[0055] Then, the conjugation solution was centrifuged at 11000 rpm for 10 minutes. After removal of the supernatant, 100 L of re-suspension solution comprising 1/1000 bovine serum albumin (BSA, obtained from Acros Organics, Belgium) in 0.01 M pH 7.4 phosphate buffered saline (PBS, prepared by Na₂HP0₄, NaH₂P0₄, and NaCl in water) was added into the microcentrifuge tube to re-dissolve the conjugated colloidal gold particles with Anti-His (Anti-His- Au P). A 33 glass fiber (0.8 cm-width X 4 cm-length, obtained from GE Healthcare Bio- Sciences Corp., New Jersey, USA) was placed in a micro-centrifuge tube comprising 20 L of Anti-His- AuNP solution with 180 L of conjugate dilution buffer (3% trehalose, 0.5% BSA, and 1%) Tween 20 in 0.01 M PBS) for 1-2 min until all the solution was adsorbed evenly on the

33 glass fiber. After being dried in oven at 37 C for 3 hours, the conjugating pad was ready for further strip assembling.

Example 2

Sample pad preparation

[0056] A strip of 33 glass fiber (1.5cm-width X 4cm-length) was soaked in 200 L of a sample pad solution comprising 1% BSA and 0.5% Tween20 in 0.1 M PBS till saturated. After being dried in an oven at 37 C for 3 hours, the sample pad could be used for further strip assembling.

Example 3

Membrane with T-line and C-line preparation

[0057] C-line solution was prepared by mixing 20 μΐ of 3 mg/ml Protein A (obtained from Hangzhou LongGene BioTech, Hangzhou, China) with 40 μΐ of 0.01 M PBS (pH 7.2) to afford 1 mg/ml Protein A solution.

[0058] His-tagged green florescent protein (GFP) (1 mg/ml, overexpressed in Escherichia coli (E. coli)) was used as T-line solution.

[0059] Nitrocellulose membrane 7 (FF120HP, from GE Healthcare Bio-Sciences Corp., New Jersey, USA) was stuck on a plastic adhesive backing pad 8 (DB-6, obtained from Shanghai Joey BioTech Co., Ltd, Shanghai, China).

[0060] T-line and C-line solutions were dispensed, respectively, onto the FF120HP membrane with 0.5 μΐ/cm volume using BioDot XYZ-3050 dispensing platform (BioDot Inc., Irvine, CA, USA) for respectively forming the detecting portion 4 and the control portion 5. Example 4

Strip assembling

[0061] Cotton absorbent pad 6 (470, from GE Healthcare Bio-Sciences Corp., New Jersey, USA) was attached onto the adhesive plastic backing pad 8 and covered 1-2 mm of the FF120HP membrane 7 on the backing pad 8 stuck together in example 3.

[0062] The conjugating pad 3 prepared in example 1 was assembled on the other side of the membrane 7 (1-2 mm overlapping with membrane), followed by sample pad 2 adhesion (1-2 mm overlaping to the conjugating pad 3).

[0063] The assembled strip was cut into 4 mm-wide strips by a GoldBio cutter ZQ2000 (Shanghai Goldbio Tech. Co. Ltd, Shanghai, China) as schematically illustrated in Figures 1 and 2 for the detection of the tagged protein.

Example 5

The detection of His-tagged GFP protein

[0064] Purified his-tagged protein sample (overexpressed in E. coli) was diluted to 0, 0.268, 0.536, 1.072 mg/mL in 10 mM PBS buffer (pH 7.4), respectively. To a 96-well plate, 150 of each diluted standard sample was added to a well, then a piece of test strip was inserted into each of the four wells and stood to allow the sample solution diffuses upward along the test strips. The test strips were similar with the ones prepared in example 4 but do not have C-lines on the membranes.

[0065] After 10 minutes, the strips were taken out and a photo of them is shown in FIG. 3. In FIG. 3, strip I was the strip put into a well containing no His-tagged protein in 0.01M PBS, Strip

II was the strip put into a well containing 0.268 mg/mL His-tagged protein in 0.01M PBS, Strip

III was the strip put into a well containing 0.536 mg/mL His-tagged protein in 0.01M PBS, and Strip IV was the strip put into a well containing 1.072 mg/mL His-tagged protein in 0.01M PBS. It can be seen from FIG. 3 that the color of the T-line 4 of the strip decreased with the increase of the concentration of the His-tagged protein, i.e., the color of T-line of strip I was the darkest and the color of T-line of strip IV was the lightest. [0066] The test strips were put into a GoldBio strip reader DT2030 (from Shanghai GoldBio Tech Co., Ltd, Shanghai, China) for quantitative signal reading based on T-line signal intensity. A calibration curve was established as shown in FIG. 4 based on the peak heights of T-lines of the strips.

Example 6

[0067] The experiment in example 5 was repeated but the concentrations of the sample solutions which the strips V, VI and VII diffused were different and each of the strips had a C- line.

[0068] A photo of the three strips is shown in FIG. 5, in which strip V was the strip put into a well containing no His-tagged protein in 0.01 M PBS, strip VI was the strip put into a well containing 3 g/L His-tagged protein in 0.01M PBS, and strip VII was the strip put into a well containing 5 g/L His-tagged protein in 0.01M PBS. The results in FIG. 5 indicate that the upper detection limit of His-tagged GFP protein could be more than 3 mg/mL under the testing condition.

[0069] While the disclosure has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions may be made without departing in any way from the spirit of the present disclosure. As such, further modifications and equivalents of the disclosure herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the disclosure as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method comprising: contacting a sample solution comprising a tagged protein with a labeled binder bindable to a tag of the tagged protein; contacting the sample solution with a binding material bindable to the labeled binder which is not bound with the tag; and determining a concentration of the tagged protein in the sample solution according to a signal change before and after contacting the sample solution with the binding material.

2. The method of claim 1, comprising: providing a test strip having a sample receiving portion, a conjugating portion, and a detecting portion, the conjugating portion comprising the labeled binder, the detecting portion comprising the binding material; diffusing the sample solution through the sample receiving portion, the conjugating portion, and the detecting portion; and determining the concentration of the tagged protein in the sample solution according to a signal change of the detecting portion before and after diffusing the sample solution through the detecting portion.

3. The method of claim 1 or 2, wherein determining the concentration of the tagged protein in the sample solution according to a signal change of the detecting portion is according to a color change of the detecting portion.

4. The method of claim 1 or 2, wherein the tag comprises at least one of oligo- histidine, glutathione-S-transferase, FLAG, streptag II, maltose binding protein, HA- tag, c-myc, T7-tag, S-tag, calmodulin binding peptide, Fc region of antibody, elastin like peptide, chitin-binding domain, thioredoxin, NusA, and albumin binding domain.

5. The method of claim 1 or 2, wherein the test strip comprises a control portion comprising a control material bindable to the labeled binder and wherein the control material is at least one of: a) protein A or any IgG-binding variant thereof, b) protein G or any IgG-binding variant thereof, c) protein L or any IgG-binding variant thereof, and d) a binder with specificity directed towards non-human antibodies of the species used for the binder directed towards Fc region of a human antibody.

6. The method of claim 1 or 2, wherein the test strip comprises a control portion comprising a control material bindable to the labeled binder and wherein the control material is protein A.

7. The method of one or more of claims 1-6, wherein the tag is oligo-histidine.

8. The method of claim 7, wherein the labeled binder comprises anti-oligo- histidine.

9. The method of one or more of claims 1-8, wherein the labeled binder comprises a label derived from colloidal gold.

10. The method of one or more of claims 1-9, wherein the tag is an Fc region of a human antibody and the labeled binder comprises an anti-Fc region of a human antibody.

11. The method of one or more of claims 1- 10, wherein the test strip comprises a control portion comprising a control material bindable to the labeled binder and wherein the control material is a binder directed towards the non-human antibodies of the species used for the binder directed towards an Fc region of a human antibody.

12. The method of one or more of claims 1-11, wherein the labeled binder comprises a label derived from at least one of colloidal gold, latex beads, fluorescent microsphere, magnetic beads, quantum dot, and up-converting phosphor.

13. The method of one or more of claim 1-12, wherein the labeled binder comprises a binder comprising at least one of: a) antibody, b) fragment of antibody, and c) aptamer.

14. An apparatus, comprising: a test strip comprising: a sample receiving portion for receiving a sample solution comprising a tagged protein; a conjugating portion comprising a labeled binder bindable to a tag of the tagged protein; and a detecting portion comprising a binding material bindable to the labeled binder which is not bound with the tag.

15. The apparatus of claim 14, wherein the tag comprises at least one of oligo- histidine, glutathione-S-transferase, FLAG, streptag II, maltose binding protein, HA- tag, c-myc, T7-tag, S-tag, calmodulin binding peptide, Fc region of antibody, elastin like peptide, chitin-binding domain, thioredoxin, NusA, and albumin binding domain.

16. The apparatus of claim 14 or 15, wherein the test strip comprises a control portion comprising a control material bindable to the labeled binder and wherein the control material is at least one of: a) protein A or any IgG-binding variant thereof, b) protein G or any IgG-binding variant thereof, c) protein L or any IgG-binding variant thereof, and d) a binder with specificity directed towards non-human antibodies of the species used for the binder directed towards Fc region of a human antibody.

17. The apparatus of claim 14, 15 or 16, wherein the test strip comprises a control portion comprising a control material bindable to the labeled binder, wherein the control material is protein A and wherein the tag is oligo-histidine.

18. The apparatus of one or more of claims 14-17, wherein the labeled binder comprises a label derived from colloidal gold.

19. The apparatus of one or more of claims 14-18, wherein the tag is Fc region of a human antibody region, the labeled binder comprises anti-Fc region of a human antibody, the test strip comprises a control portion comprising a control material bindable to the labeled binder, and wherein the control material is a binder directed towards the non-human antibodies of the species used for the binder directed towards an Fc region of a human antibody.

20. The apparatus of one or more of claims 14-19, wherein the labeled binder comprises a binder comprising at least one of a) antibody, b) fragment of antibody, and c) an aptamer.