Assay method and apparatus

1. An apparatus for use in an assay comprising:

(a) at least one first receptacle comprising a fluid inlet and a fluid outlet;

(b) a porous membrane; and

(c) at least one analyte-specific binding agent,

characterized in that said at least one analyte-specific binding agent is immobilised on the underside of said porous membrane relative to the fluid inlet wherein the porous membrane is positioned at the fluid outlet.

2. An apparatus according to claim 1 , wherein said at least one first receptacle comprises a plurality of said first receptacles in the form of a multi-well plate.

3. An apparatus according to claim 1 , wherein a plurality of analyte-specific binding agents is immobilised on said porous membrane in the form of an array.

4. An apparatus according to claim 3 , wherein the array comprises at least one control probe.

5. An apparatus according to claim 1 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet.

6. An apparatus according to claim 1 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet and wherein the drawing means is a vacuum pump.

7. An apparatus according to claim 1 , further comprising a means for detecting binding of an analyte to the binding agent.

8. An apparatus according to claim 1 , further comprising a means for detecting binding of an analyte to the biding agent and wherein the detecting means is selected from fluorimetric, chemiluminescent, radiochemical, physical and colourimetric means.

9. An apparatus according to claim 1 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device capable of detecting and/or quantifying light emitted from porous membrane (b).

10. An apparatus according to claim 1 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device and the photometric device is a luminometer.

11. An apparatus according to claim 1 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises imaging means.

12. An apparatus according to claim 1 , wherein said at least one analyte-specific binding agent is a polynucleotide probe.

13. An apparatus according to claim 1 , wherein said at least one analyte-specific binding agent is an Expressed Sequence Tag (EST).

14. An apparatus according to claim 1 , wherein said at least one analyte-specific binding agent is a polypeptide binding agent.

15. An apparatus according to claim 1 , wherein said at least one analyte-specific binding agent is an antibody or a fragment thereof.

16. An apparatus according to claim 1 , wherein said at least one analyte-specific binding agent is immobilised directly or indirectly on said porous membrane.

17. An apparatus according to claim 1 , wherein the or each first receptacle is positioned at least in part in a second receptacle which is capable of collecting liquid from the fluid outlet of the first receptacle such its porous membrane may be submerged in said liquid.

18. A method of detecting an analyte comprising:

(a) providing an apparatus according to claim 1 ;

(b) loading a sample to be tested into the or at least one of the first receptacles; and

(c) detecting binding of the analyte to the analyte-specific binding agent.

19. A method of detecting an analyte comprising:

(a) providing an apparatus comprising at least one first receptacle having a fluid inlet and a fluid outlet and having a porous membrane;

(b) immobilising a plurality of analyte-specific binding agents in an array on the underside of said porous membrane;

(c) loading a sample to be tested into the at least one first receptacle; and

(d) detecting binding of the analyte to the analyte-specific binding agent(s).

20. A method according to claim 19 wherein the sample comprises a detectable label.

21. A method according to claim 20 wherein the detectable label is selected from an enzyme, a fluorescent label and a radiolabel.

22. A method according to claim 19 wherein step (d) comprises detecting binding of the analyte to the analyte-specific binding agent using any one of fluorimetric, chemiluminescent, radiochemical, physical and colourimetric means.

23. An apparatus for use in an assay comprising:

(a) at least one first receptacle comprising a fluid inlet and a fluid outlet;

(b) multiple porous membranes positioned between said fluid inlet and said fluid outlet, each porous membrane having a pore size; and

(c) at least one analyte-specific binding agent,

characterized in that said at least one analyte-specific binding agent is immobilised on the underside of one of said porous membranes relative to the fluid inlet, wherein the porous membranes are positioned within said at least one first receptacle so that the pore size of the porous membrane nearer the fluid inlet is greater than the pore size of the porous membrane nearer the fluid outlet.

24. An apparatus according to claim 23 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet.

25. An apparatus according to claim 23 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet and wherein the drawing means is a vacuum pump.

26. An apparatus according to claim 23 , further comprising a means for detecting binding of an analyte to the binding agent.

27. An apparatus according to claim 23 , further comprising a means for detecting binding of an analyte to the biding agent and wherein the detecting means is selected from fluorimetric, chemiluminescent, radiochemical, physical and colourimetric means.

28. An apparatus according to claim 23 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device capable of detecting and/or quantifying light emitted from porous membrane (b).

29. An apparatus according to claim 23 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device and the photometric device is a luminometer.

30. An apparatus according to claim 23 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises imaging means.

31. An apparatus according to claim 23 , wherein said at least one analyte-specific binding agent is a polynucleotide probe.

32. An apparatus according to claim 23 , wherein said at least one analyte-specific binding agent is an Expressed Sequence Tag (EST).

33. An apparatus according to claim 23 , wherein said at least one analyte-specific binding agent is a polypeptide binding agent.

34. An apparatus according to claim 23 , wherein said at least one analyte-specific binding agent is an antibody or a fragment thereof.

35. An apparatus according to claim 23 , wherein said at least one analyte-specific binding agent is immobilised directly or indirectly on said porous membrane.

36. An apparatus according to claim 23 , wherein the or each first receptacle is positioned at least in part in a second receptacle which is capable of collecting liquid from the fluid outlet of the first receptacle such its porous membrane may be submerged in said liquid.

37. An apparatus for use in an assay comprising:

(a) at least one first receptacle comprising a fluid inlet and a fluid outlet;

(b) a porous membrane; and

(c) at least one analyte-specific binding agent,

characterized in that said at least one analyte-specific binding agent is immobilised on the underside of said porous membrane relative to the fluid inlet wherein a plurality of analyte-specific binding agents is immobilised on said porous membrane in the form of an array.

38. An apparatus according to claim 37 , wherein the array comprises at least one control probe.

39. An apparatus according to claim 37 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet.

40. An apparatus according to claim 37 , further comprising a means for drawing liquid from the at least one first receptacle through the fluid outlet and wherein the drawing means is a vacuum pump.

41. An apparatus according to claim 37 , further comprising a means for detecting binding of an analyte to the binding agent.

42. An apparatus according to claim 37 , further comprising a means for detecting binding of an analyte to the biding agent and wherein the detecting means is selected from fluorimetric, chemiluminescent, radiochemical, physical and colourimetric means.

43. An apparatus according to claim 37 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device capable of detecting and/or quantifying light emitted from porous membrane (b).

44. An apparatus according to claim 37 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises a photometric device and the photometric device is a luminometer.

45. An apparatus according to claim 37 , further comprising a means for detecting binding of an analyte to the binding agent and wherein the detecting means comprises imaging means.

46. An apparatus according to claim 37 , wherein said at least one analyte-specific binding agent is a polynucleotide probe.

47. An apparatus according to claim 37 , wherein said at least one analyte-specific binding agent is an Expressed Sequence Tag (EST).

48. An apparatus according to claim 37 , wherein said at least one analyte-specific binding agent is a polypeptide binding agent.

49. An apparatus according to claim 37 , wherein said at least one analyte-specific binding agent is an antibody or a fragment thereof.

50. An apparatus according to claim 37 , wherein said at least one analyte-specific binding agent is immobilised directly or indirectly on said porous membrane.

51. An apparatus according to claim 37 , wherein the or each first receptacle is positioned at least in part in a second receptacle which is capable of collecting liquid from the fluid outlet of the first receptacle such its porous membrane may be submerged in said liquid.