Abstract: A method of assaying for a ligand in a sample which includes incubating, simultaneously or in any desired sequence,a) the sampleb) a reagent X andc) a reagent Y immobilised on the surface of an optical structure capable of exhibiting surface plasmon resonance,one of reagents X and Y is a specific binding partner to said ligand and the other of reagents X and Y is either a ligand analogue or a specific binding partner to said ligand, reagent X being such, that any formation of a direct or indirect complex between reagents X and Y results in an optical surface having an appreciably enhanced optical thickness as compared to the optical thickness of the optical surface which would prevail in the absence of reagent X,which method includes the step of determining whether and, if desired, the extent to which and/or rate at which the surface plasmon resonance effect exhibited by the optical structure is altered by said complex formation.

Abstract: A method of assaying for a ligand in a sample involves incubating the sample in contact with a specific binding partner for the ligand carried on one surface of an optical structure, irradiating the structure at a suitable angle or range of angles to the normal such that the resonance and/or total internal reflection of the radiation occurs within the optical structure and/or the layer of specific binding partner, and analyzing the radiation in order to determine whether, and if desired the extent to which and/or rate at which the generated radiation and/or optical characteristics of the optical structure are altered by complex formation.

Abstract: A method of assaying for a ligand in a sample involves incubating the sample in contact with a specific binding partner for the ligand carried on one surface of an optical structure, irradiating the structure at a suitable angle or range of angles to the normal such that the resonance and/or total internal reflection of the radiation occurs within the optical structure and/or the layer of specific binding partner, and analyzing the radiation in order to determine whether, and if desired the extent to which and/or rate at which the generated radiation and/or optical characteristics of the optical structure are altered by complex formation.

Abstract: The present invention relates to assay techniques for detection of ligands in solution and to means for putting such techniques into effect. In particular it relates to an improved assay technique which provides a liquid calibrator for use in standard assays in circumstances where the ligand itself is rare, expensive, or difficult to prepare in a sufficiently pure or quantifiable form.

Abstract: A method is disclosed for coating the surface of an optical structure, such as a diffraction grating, useful for the detection of a ligand, which method comprises forming on the surface of the optical structure a thin, uniform layer of a polymerizable material, particularly one which polymerizes on exposure to light or heat, and subsequently exposing said material to polymerizing conditions. A specific binding partner is subsequently absorbed on or bound to the cured polymer layer, either directly or indirectly. Complex formation between the specific binding partner and ligand present in the sample to be analyzed alters the optical properties of the device and the change forms the basis of an assay.

Abstract: The invention relates to a device for use in methods of assay, for example those involving fluorescent moieties. The device possesses a cavity or cavities into which the sample liquid may be drawn by capillary action. Each cavity is formed from two transparent solid plates (35,36): one (36) is adapted to act as a waveguide and carries a suitable immobilized reagent on its surface within the cavity; the other (35) carries on its external surface and optionally also on part only of its internal surface a layer of light-absorbing material (37). The invention also relates to a method of manufacturing devices according to the invention, and to a method of assaying for a ligand in a sample using a device according to the invention.

Abstract: The vehicle comprises a sample receiving reservoir (15), a plurality of test stations each comprising an FCFD or other capillary fill sensor cell (3), and passage (22) for providing fluid communication between the reservoir and a conduit with which end portions of said cells communicated such that in use sample from the reservoir may be fed to the plurality of cells substantially simultaneously. The vehicle makes it easier to know time zero for each assay. Passage (22) providing fluid connection may comprise at least one pore in a wall of the reservoir, the or each pore being of a size such that surface tension of the liquid normally prevents escape of ligand. Rotation of the vehicle breaks surface tension and liquid is released into the conduit.

Abstract: A method of treating the surface of an optical structure which comprises forming on the surface a thin layer of organic polymer using a solvent casting technique. Preferably the process includes the subsequent treatment of the polymer layer with a solution of a specific ligand.Complex formation between the bound ligand and its specific binding partner present in a sample to be analyzed alters the optical properties of the diffraction grating surface and the change can form the basis of an assay method.

Abstract: A specifically-reactive sample-collecting and testing device possessing a cavity or cavities each having a dimension small enough to enable sample liquid to be drawn into the cavity by capillary action, wherein a surface of the cavity carries an immobilized reagent appropriate to the test to be carried out in the device, and wherein said surface is a surface of a transparent solid plate to act as a light-transmissive waveguide and forming a wall of the cavity, said plate having an edge which is substantially optically smooth and transverse to the plane of the plate.

Abstract: A method and apparatus for analysing the spectrum of light reflected by a reflecting structure (24) in which the effect upon the analysis results of variation in the angle between the reflecting structure and the incident beam (22) is minimised. The method and apparatus may utilise a dispersive element (26) constructed and arranged so as to minimise the effect of the variations. The method and apparatus may also utilise a calibration technique in which light with a known spectrum is reflected off the reflecting structure and analysed so that compensation may be made for the effect of the variation.

Abstract: A method of optical analysis of a test sample which comprises a sample material with light-absorbing, scattering, fluorescent, phosphorescent or luminescent properties, which sample is partly in a liquid phase and partly bound to an adjacent solid surface, to discriminate the respective parts of said sample material which are located in the liquid and bound to said solid surface: comprising the steps of providing as said solid surface a surface of a transparent solid optical waveguide, and measuring light from the sample material bound to said solid surface that has passed into and through said transparent solid optical waveguide with total internal reflections and emerged from said waveguide at an angle that deviates from the optical axis of said waveguide by an angle appreciably less than .alpha., where.alpha.=arcsin.sqroot.(n.sub.2.sup.2 -n.sub.1.sup.2)where n.sub.2 is the refractive index of the material of the waveguide and n.sub.