FLUORESCENCE IMMUNO-CHROMATOGRAPHY, KIT AND TEST STRIP FOR THE SAME

• US 20140273271A1
• Filed: 03/14/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Furukawa Electric Company Limited
• Original Assignee: Furukawa Electric Company Limited
• Inventors: AIZAWA, Hideki, OHKUBO, Michio
• Granted Patent: US 9,726,605 B2
• Time in Patent Office: Days
• US Class Current: 436/501
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: G01N 33/54388 based on lateral flow
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387

Abstract

An immunochromatography carried out by illuminating a fluorescent substance in a membrane with excitation light and detecting fluorescence emitted from the fluorescent substance, the immunochromatography comprising the steps of:

• • preparing a membrane having a transparent film, the transparent film being closely attached to the surface of the membrane, the transparent film satisfying a specific property related to a refractive index with respect to analyte liquid;
  • illuminating a fluorescent substance in the membrane with excitation light through the transparent film; and
  • detecting another fluorescence components not exceeding the critical angle, the another fluorescence components being included in the fluorescence emitted from the fluorescent substance, the detection being made by virtue of the fluorescence components passing through the film.

Claims

1. A fluorescence immunochromatography carried out by illuminating a fluorescent substance in a membrane with excitation light and detecting fluorescence emitted from the fluorescent substance, the fluorescence immunochromatography comprising the steps of:

preparing a membrane having a transparent film, the transparent film being closely attached to the surface of the membrane, the transparent film satisfying following Formula (1) related to a refractive index with respect to analyte liquid;

illuminating a fluorescent substance in the membrane with excitation light through the transparent film, thereby bringing fluorescence components into a guided wave of the transparent film, the fluorescence components being included in the fluorescence incident to the transparent film, the fluorescence components having an incident angle exceeding a critical angle, the fluorescence being wave guided by virtue of the fluorescence components totally reflected on the interface between the transparent film and the air and on the surface of the membrane, the membrane being closely attached to the surface of the transparent film; and

detecting another fluorescence components not exceeding the critical angle, the another fluorescence components being included in the fluorescence emitted from the fluorescent substance, the detection being made by virtue of the fluorescence components passing through the film.

n_Ff>

n_Wf 

 

Formula (1)

(n_Ff′

;

refractive index of transparent film at wavelength λ

^f of the fluorescence)

(n_Wf′

;

refractive index of analyte liquid at wavelength λ

^f of the fluorescence)

2. The fluorescence immunochromatography according to claim 1, wherein, as for the transparent film, a film satisfying following Formula (2) related to a refractive index with respect to analyte liquid is applied

n_Ff>

n_Wf+0.1 

 

Formula (2)

(n_Ff and n_Wf have the same meanings as defined in Formula (1)).

3. The fluorescence immunochromatography according to claim 1, wherein both the light transmittance (T_Fe) for wavelength λ

^e of the excitation light and the light transmittance (T_Ff) for wavelength λ

^f of the fluorescence of the transparent film are 80% or higher.

4. A fluorescence immunochromatography according to claim 1, wherein the contact angle of water on the transparent film is 50°

or more.

5. The fluorescence immunochromatography according to claim 1, wherein fluorescent silica particles containing the fluorescent substance introduced to silica are used.

6. The fluorescence immunochromatography according to claim 1, wherein the wavelength λ

^e of the excitation light is between 300 nm and 700 nm, and wherein the wavelength λ

^f of the fluorescence is between 350 nm and 800 nm.

7. The fluorescence immunochromatography according to claim 1, wherein the wavelength λ

^e of the excitation light is between 500 nm and 550 nm, and wherein the wavelength λ

^f of the fluorescence is between 530 nm and 580 nm.

8. The fluorescence immunochromatography according to claim 1, wherein the fluorescence incident to the transparent film and diffused therein is totally reflected on the interface between the transparent film and the air and on the interface between the transparent film and the membrane so that the transparent film becomes a waveguide, which suppresses the fluorescence from being diffused in the membrane and increases detectability of the fluorescence near the fluorescent substance.

9. The fluorescence immunochromatography according to claim 1, wherein the excitation light is illuminated from a laser diode or a light emitting diode while a device for detecting only the fluorescence by removing the excitation light using an optical filter is used.

10. The fluorescence immunochromatography according to claim 1, wherein the detection determination is made within 5 minutes.

11. A kit used for immunochromatography to be carried out by illuminating a fluorescent substance with excitation light and detecting fluorescence emitted from the fluorescent substance, the kit comprising a test strip and a fluorescent substance,

the test strip having a transparent film and a membrane main body for the transparent film being applied,

the fluorescent substance for being added onto the membrane main body,

the transparent film having a refractive index satisfying following Formula (1) with respect to analyte liquid, thereby bringing the fluorescence incident to the transparent film into a guided wave of the transparent film, the fluorescence being wave guided by virtue of the fluorescence components totally reflected on the interface between the transparent film and the air and on the surface of the membrane, the membrane being closely attached to the surface of the transparent film.

n_Ff>

n_Wf 

 

Formula (1)

(n_Ff;

refractive index of transparent film at wavelength λ

^f of the fluorescence)

(n_Wf;

refractive index of analyte liquid at wavelength λ

^f of the fluorescence)

12. The kit according to claim 11, further comprising labeled a silica particle as a labeling reagent, the labeled silica particles being formed from a silica particle containing a fluorescent substance therein.

13. The kit according to claim 11, wherein the transparent film has a thickness of between 20 μ

m and 1 mm.

14. The kit according to claim 11, wherein the material of the transparent film is at least one selected from polyvinylidene fluoride, cellulose acetate, polymethyl methacrylate, polypropylene, nylon, polyethylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, and polyethylene terephthalate to satisfy Formula (1) in correspondence with a refractive index of analyte liquid.

15. A test strip used for immunochromatography to be carried out by illuminating a fluorescent substance with excitation light and detecting fluorescence emitted from the fluorescent substance, the test strip comprising a transparent film and a membrane main body for the transparent film being applied,

the transparent film having a refractive index satisfying following Formula (1) with respect to analyte liquid, thereby bringing the fluorescence incident to the transparent film into a guided wave of the transparent film, the fluorescence being wave guided by virtue of the fluorescence components totally reflected on the interface between the transparent film and the air and on the surface of the membrane, the membrane being closely attached to the surface of the transparent film.

n_Ff>

n_Wf 

 

Formula (1)

(n_Ff;

refractive index of transparent film at wavelength λ

^f of the fluorescence)

(n_Wf;

refractive index of analyte liquid at wavelength λ

^f of the fluorescence)

16. The test strip according to claim 15, wherein the fluorescent substance is introduced to the silica particles.

17. The test strip according to claim 15, wherein the transparent film has a thickness of between 20 μ

m and 1 mm.

18. The test strip according to claim 15, wherein the material of the transparent film is at least one selected from polyvinylidene fluoride, cellulose acetate, polymethyl methacrylate, polypropylene, nylon, polyethylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, and polyethylene terephthalate.