Abstract: A method of determining kinetic parameters for a reversible molecular interaction between a ligand immobilized to a solid support surface and a binding partner to the ligand in solution, comprises sequentially, without intermediate regeneration or renewal of the immobilized ligand, flowing a plurality of fluid volumes containing different known concentrations of the binding partner over the solid support surface, monitoring the momentary amount of binding partner bound to the solid support surface related to time and solution concentration of binding partner and collecting the binding data, and determining the kinetic parameters by globally fitting a predetermined kinetic model for the interaction between the binding partner and the immobilized ligand to the collected binding data, which model allows for mass transport limitation at the solid support surface.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: The invention relates to a method of determining the binding site specificity of an analyte to a ligand having at least two different binding sites, which method comprises immobilizing the ligand to a solid support, mixing the analyte with a reversibly binding reference analyte which has a dissociation behaviour that differs significantly from that of the analyte, contacting the mixture with the ligand to determine dissociation characteristics for the mixture, and determining therefrom the binding site specificity of the analyte in relation to the reference analyte. The invention also relates to an analytical system for carrying out the method, and to a computer program, computer program product and computer system for performing the method.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: A method of positioning a laminar flow of a sample fluid on a surface within a flow cell is disclosed. The method comprises providing a laminar flow of a first guiding fluid adjacent to a laminar flow of a second guiding fluid different from the first guiding fluid such that the two fluids flow together over the surface with a detectable interface to each other; detecting the interface between the two different guiding fluids; optionally adjusting the interface laterally to a desired position by adjusting the relative flow rates of the two guiding fluids; and introducing a laminar flow of the sample fluid between the laminar flows of the first and second guiding fluids such that the flow of the sample fluid is sandwiched between the guiding fluids. An analytical system for carrying out the method, a computer program, a computer program product and a computer system for performing the method are also disclosed.

Abstract: A method of determining affinity for a molecular binding interaction from measured steady state binding data comprises the steps of: a) providing a plurality of experimental binding data sets for the binding interaction between two chemical species, wherein each data set includes binding data measured at multiple time points during an association phase and a dissociation phase of the interaction, b) selecting from the plurality of experimental binding data sets a plurality of binding data measured at a defined time point at or near the end of the association phase as representing steady state binding data, c) subjecting each data set to a quality control which comprises estimating the reliability of the steady state binding data by evaluating other binding data of the same data set, d) excluding each data set which is estimated in step c) to contain unreliable steady state binding data, and e) determining the affinity from the steady state binding data of remaining data sets.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: A method of preparing an array of discrete localized binding agent-supporting regions on a solid support surface as well as an array prepared by the method are disclosed. The method comprises: providing a solid support bearing functional groups at a plurality of predefined discrete regions and being in a first surface property state; activating the functional groups to reactive groups to convert any activated surface area to a second surface property state which differs substantially from that of the first state; selectively dispensing at each predefined discrete region a predetermined volume of a liquid medium containing a binding agent to couple the binding agent to the reactive groups; and deactivating unreacted reactive groups such that the first surface property state of the solid support surface is restored. The use of the method for studying molecular interactions and for performing assays for one or more analytes are also disclosed.

Abstract: Methods and devices are provided for controlling a fluid flow over a sensing surface within a flow cell The methods employ laminar flow techniques to position a fluid flow over one or more discrete sensing areas on the sensing surface of the flow cell. Such methods permit selective sensitization of the discrete sensing areas, and provide selective contact of the discrete sensing areas with a sample fluid flow. Immobilization of a ligand upon the discrete sensing area, followed by selective contact with an analyte contained within the sample fluid flow, allows analysis by a wide variety of techniques. Sensitized sensing surfaces, and sensor devices and systems are also provided.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: Methods and devices are provided for controlling a fluid flow over a sensing surface within a flow cell. The methods employ laminar flow techniques to position a fluid flow over one or more discrete sensing areas on the sensing surface of the flow cell. Such methods permit selective sensitization of the discrete sensing areas, and provide selective contact of the discrete sensing areas with a sample fluid flow. Immobilization of a ligand upon the discrete sensing area, followed by selective contact with an analyte contained within the sample fluid flow, allows analysis by a wide variety of techniques. Sensitized sensing surfaces, and sensor devices and systems are also provided.

Abstract: A method of preparing a protein-resistant reactive solid support surface is disclosed. The method comprises the steps of providing a solid support having a hydrogel coating with a plurality of binding elements, coupling a protein resistant compound to the hydrogel via a first fraction of the binding elements, and coupling at least one binding agent to the hydrogel via a second fraction of the binding elements, whereby the protein resistant compound and the at least one binding agent are co-immobilized to the hydrogel. Also the use of the reactive surface in analysis, such as immunogenicity assays, is disclosed.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: A method of operating an analytical flow cell device comprising an elongate flow cell having a first end and a second end, at least two ports at the first end and at least one port at the second end, comprises introducing a laminar flow of a first fluid at the first end of the flow cell, and a laminar counter flow of a second fluid at the second end. Each fluid flow is discharged at the first end or the second end, and the position of the interface between the first and second fluids in the longitudinal direction of the flow cell is adjusted by controlling the relative flow rates of the first and second fluids. Also disclosed are a method of analyzing a fluid sample for an analyte, a method of sensitizing a sensing surface, and a method of contacting a sensing surface with a test fluid.

Abstract: An optical apparatus for total internal reflection spectroscopy comprises: a transparent body having an internally reflective surface; at least one source of electromagnetic radiation for providing at least one beam of collimated electromagnetic radiation; optical scanning means for directing the beam or beams to the transparent body so that the radiation is internally reflected at the reflective surface, and sequentially or continuously scanning the incident angle of the radiation over an angular range; at least one detector for detecting electromagnetic radiation exiting the transparent body, and means for counteracting variation of the irradiance in the illuminated area of the surface during the angular scan, or the effect of such variation on the reflected beam or beams. An optical apparatus for examining thin layer structures on a surface for differences in respect of optical thickness and/or refractive index, and a method for total internal reflection spectroscopy are also disclosed.

Abstract: A method of examining thin layer structures on a surface for differences in respect of optical thickness, which method comprises the steps of: irradiating the surface with light so that the light is internally or externally reflected at the surface; imaging the reflected light on a first two-dimensional detector; sequentially or continuously scanning the incident angle and/or wavelength of the light over an angular and/or wavelength range; measuring the intensities of light reflected from different parts of the surface and impinging on different parts of the detector, at at least a number of incident angles and/or wavelengths, the intensity of light reflected from each part of the surface for each angle and/or wavelength depending on the optical thickness of the thin layer structure thereon; and determining from the detected light intensities at the different light incident angles and/or wavelengths an optical thickness image of the thin layer structures on the surface.

Abstract: A method for determining interaction of an analyte with a binding agent immobilized to a solid support surface by contacting the surface with a fluid sample containing the analyte, and detecting binding events at the solid support surface, wherein the sample is based on a complex medium containing at least one species other than analyte that may interact with the solid support surface, is disclosed. The method comprises contacting the solid support surface with sample medium free from analyte prior to contacting the surface with the analyte-containing sample.

Abstract: The present invention discloses a valve integrally associated with a microfluidic transport assembly that is useful for regulating the flow of a liquid sample through an analytical instrument such as, for example, a biosensor.

Abstract: Various biomolecules can be firmly immobilized to a substrate by a method which comprises contacting a solution containing biomolecules provided with at least one tag with an immobilization substrate which has (i) binding sites for the biomolecule tag or tags, and (ii) activated reactive groups which are capable of forming covalent bonds with the biomolecules, to covalently bind the biomolecules interacting with the tag binding sites to the immobilization substrate.