Method and apparatus for measuring binding affinity
First Claim
1. A method of determining the presence and strength of binding affinity, Kd, of a receptor, R, for a selected polymer attached at a selected region on a surface of a substrate comprising an array of polymers attached at a plurality of selected regions on the surface of the substrate, comprising the steps of:
- (a) exposing the polymers to a first concentration solution of said receptor, said receptor being labeled with a fluorescent marker;
(b) irradiating the polymers with a light source;
(c) measuring fluorescence intensity of each selected region with a confocal microscope at a time sufficient for the receptor to reach specific binding equilibrium with the selected polymer;
(d) repeating steps (a)-(c) with a second concentration solution of said receptor, said receptor being labeled with the fluorescent marker, wherein the measuring step occurs while at least one of said solutions is in contact with the substrate;
(e) calculating Kd from the fluorescence intensities and the receptor concentrations for the selected polymer by solving an equation, ##EQU7## wherein I=fluorescence intensity, [R]=receptor concentration, Imax=a saturation fluorescence intensity correction factor, to determine the presence and strength of binding of the receptor for the selected polymer.
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Abstract
A method and device for measuring the binding affinity of a receptor to a ligand. According to one aspect of the invention, arrays of polymers are synthesized or immobilized on a substrate (212). The array of polymers is exposed to a fluorescently-labelled receptor in solutions of varying concentration. The fluorescence intensity of the labelled receptor is measured by way of, e.g., a photon counter using a confocal microscope (316). Binding affinity is determined through analysis of the relationship between fluorescence intensity and the solution concentration of the receptor. On-rates are measured as a kinetic increase in surface fluorescence intensity, and the on-rate constant rate extracted from fits to the data.
515 Citations
21 Claims
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1. A method of determining the presence and strength of binding affinity, Kd, of a receptor, R, for a selected polymer attached at a selected region on a surface of a substrate comprising an array of polymers attached at a plurality of selected regions on the surface of the substrate, comprising the steps of:
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(a) exposing the polymers to a first concentration solution of said receptor, said receptor being labeled with a fluorescent marker; (b) irradiating the polymers with a light source; (c) measuring fluorescence intensity of each selected region with a confocal microscope at a time sufficient for the receptor to reach specific binding equilibrium with the selected polymer; (d) repeating steps (a)-(c) with a second concentration solution of said receptor, said receptor being labeled with the fluorescent marker, wherein the measuring step occurs while at least one of said solutions is in contact with the substrate; (e) calculating Kd from the fluorescence intensities and the receptor concentrations for the selected polymer by solving an equation, ##EQU7## wherein I=fluorescence intensity, [R]=receptor concentration, Imax=a saturation fluorescence intensity correction factor, to determine the presence and strength of binding of the receptor for the selected polymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification