Process for detecting evanescently excited luminescence

• US 5,959,292 A
• Filed: 11/25/1996
• Issued: 09/28/1999
• Est. Priority Date: 05/27/1994
• Status: Expired due to Term

• Current Assignee: Novartis Corporation (Novartis Ag)
• Original Assignee: Novartis Corporation (Novartis Ag)
• Inventors: Ehrat, Markus, Neuschafer, Dieter, Duveneck, Gert L.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Lee, John R
• Application Number:
  US08/737,845
• Time in Patent Office: 1,037 Days
• Field of Search: 250/227.11, 250/237 G, 250/458.1, 250/459.1, 250/461.1, 250/461.2, 385/12, 385/13, 385/129, 385/130, 385/131, 385/147, 385/37, 356/128, 356/135, 356/136, 356/137, 422/82.05, 422/82.06, 422/82.07, 422/82.08, 422/82.09, 422/82.11, 436/518, 436/519, 436/527
• US Class Current: 250/227.11
• CPC Class Codes: G01N 21/648 using evanescent coupling or surface plasmon coupling for the excitation of fluorescence
• CPC Class Codes: G01N 21/7703 using reagent-clad optical fibres or optical waveguides using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B
• CPC Class Codes: G01N 21/7743 the reagent-coated grating coupling light in or out of the waveguide

Abstract

The invention relates to a process for detecting luminescence with a planar dielectric optical sensor platform consisting of a transparent substrate (a) to which a thin transparent waveguiding layer (b) is applied, which sensor platform is provided with a grating for the input-coupling of the excitation light and the refractive index of said substrate (a) is lower than the refractive index of the waveguiding layer (b), by bringing a liquid sample into contact with the layer (b), and measuring the luminescence produced by substances having luminescence properties in the sample, or by substances having luminescence properties immobilized on the layer (b), optoelectronically. The invention also relates to the use of the process in quantitative affinity sensing and to the use thereof for the quantitative determination of luminescent constituents in optically turbid solutions.

Claims

1. A process for detecting luminescence with a planar dielectric optical sensor platform comprising a transparent substrate (a) to which a thin transparent waveguiding layer (b) is applied, which sensor platform is provided with a grating for the input-coupling of the excitation light and the refractive index of said substrate (a) is lower than the refractive index of the waveguiding layer (b), by bringing a liquid sample into contact with the layer (b), and measuring the luminescence produced by substances having luminescence properties in the sample, or by substances having luminescence properties immobilised on the layer (b), optoelectronically, wherein

(A) the excitation light is coupled into the planar waveguide and traverses the waveguiding layer, whereby the substances having luminescence properties are excited to luminescence in the evanescent field of the waveguiding layer,

(B) the grating has a depth modulation of 3 to 60 nm,

(C) the thickness of the layer (b) is 40 to 160 nm, and

(D) the ratio of depth modulation to the thickness of the layer (b) is smaller than 0.5.

2. A process according to claim 1, wherein essentially parallel light is used for exciting luminescence.

3. A process according to claim 1, wherein laser light of wavelength 300 to 1100 nm is used for exciting luminescence.

4. A process according to claim 1, wherein laser light of wavelength 450 to 850 nm is used for exciting luminescence.

5. A process according to claim 1, wherein laser light of wavelength 480 to 700 nm is used for exciting luminescence.

6. A process according to claim 1, wherein the substances capable of luminescence used for detecting the analyte are immobilised direct on the surface of the waveguiding layer.

7. A process according to claim 1, which comprises immobilising a specific binding partner as chemical or biochemical detector substance for the analyte itself or for one of the binding partners on the surface of the sensor platform in a multi-step assay in the course of which the analyte becomes bound in one of the partial steps.

8. A process according to claim 1, which comprises detecting the isotropically emitted, evanescently excited luminescence.

9. A process according to claim 1, which comprises detecting at the edges of the sensor platform the evanescently excited luminescence coupled back into said sensor platform.

10. A process according to claim 1, which comprises detecting the isotropically emitted luminescence as well as the evanescently excited light which is coupled back, independently of each other but simultaneously.

11. A process according to claim 1, which comprises determining simultaneously the absorption of the excitation light coupled into the waveguide.

12. A process according to claim 1, wherein the excitation light is coupled into the waveguide in continuous wave (cw) mode.

13. A process according to claim 1, which comprises input-coupling the excitation light in the form of a timed pulse and detecting the luminescence time-resolved.

14. A process according to claim 13, wherein the pulse length is adjusted from one picosecond up to 100 seconds.

15. A process according to claim 1, which comprises input-coupling the excitation light with modulated intensity at one or more than one frequency, and detecting the resultant phase shift and modulation of the sample luminescence.

16. A process according to claim 1, wherein the sample to be detected is egg yolk, blood, serum, plasma or urine.

17. A process according to claim 1, wherein the sample to be detected is a surface water, a soil or plant extract, a bioprocess broth or synthesis broth.

18. A process according to claim 1, wherein a biochemical substance is quantitatively determined by the detection of luminescence.

19. A process according to claim 1, wherein antibodies or antigens are quantitatively determined by the detection of luminescence.

20. A process according to claim 1, wherein receptors, oligonucleotides, DNA strands, RNA strands, DNA analogs, RNA analogs, enzymes, enzyme substrates, enzyme cofactors, enzyme inhibitors, lectins or carbohydrates are quantitatively determined by the detection of luminescence.

21. A process according to claim 1, wherein in luminescent components present in optically turbid fluids are quantitatively determined by the detection of luminescence.

22. An optical sensor platform comprising a transparent substrate (a) to which a thin transparent waveguiding layer (b) is applied, which sensor platform is provided with a grating for the input-coupling of the excitation light and the refractive index of said substrate (a) is lower than the refractive index of the waveguiding layer (b), wherein

(A) the grating has a depth modulation of 3 to 60 nm,

(B) the thickness of the layer (b) is 40 to 160 nm, and

(C) the ratio of depth modulation to the thickness of the layer (b) is smaller than 0.5.

23. An optical sensor platform according to claim 22, wherein the substrate comprises quartz, an inorganic glass or a plastics material.

24. An optical sensor platform according to claim 22, wherein the substrate comprises an inorganic glass.

25. An optical sensor platform according to claim 22, wherein the substrate comprises polycarbonate or polymethylmethacrylate.

26. An optical sensor platform according to claim 22, wherein an interlayer comprising SiO₂, a thermoplastic, thermosetting or structurally crosslinked plastic is provided between the substrate and the waveguiding layer, which interlayer has a refractive index lower than, or identical to, that of the substrate.

27. An optical sensor platform according to claim 22, wherein the interlayer has a thickness of, or less than, 10 μ

m.

28. An optical sensor platform according to claim 22, wherein the planar transparent waveguiding layer is a material having a refractive index greater than 2.

29. An optical sensor platform according to claim 22, wherein the planar transparent waveguiding layer comprises Ta₂ O₅ or TiO₂.

30. An optical sensor platform according to claim 22, wherein the planar transparent waveguiding layer has a thickness of 80 nm to 160 nm.

31. An optical sensor platform according to claim 22, wherein the grating for the input-coupling of excitation light is an optical diffraction grating.

32. An optical sensor platform according to claim 31, wherein the optical diffraction grating is a relief grating.

33. An optical sensor platform according to claim 31, wherein the grating has the form of a sinusoidal, sawtooth or rectangular curve.

34. An optical sensor platform according to claim 31, wherein the grating has a grating period of 200 to 1000 nm.

35. An optical sensor platform according to claim 31, wherein the grating has a depth modulation of 5 to 30 nm.

36. An optical sensor platform according to claim 31, wherein the grating has a line to space ratio of 0.5 to 2.

37. An optical sensor platform according to claim 22, wherein an adhesion promoting layer is present between the waveguiding layer and the sample.

38. An optical sensor platform according to claim 37, wherein the adhesion promoting layer has a thickness of or less than 50 nm.

39. An optical sensor platform according to claim 22, wherein the sensor platform is regenerable and can be used repeatedly.

40. An optical sensor platform according to claim 22, wherein a substance having luminescence properties or a binding partner for an analyte is immobilised on the surface of the waveguding layer.

41. An apparatus for the detection of luminescence comprising a sensor platform according to claim 22, a coherent light source;

and a detector unit for the measurment of evanescently exited luminescence.