Abstract: A method and apparatus for measuring binding between a plurality of molecules of a first type and a plurality of molecules of a second type is presented. Apparatus utilizes a sensor possessing a waveguide to which have been attached in close proximity to its surface, features resembling molecules of said first type. Light is injected into said waveguide so as to produce an evanescent field at its surface. Molecules of said second type are tagged with a tag belonging to that class of chemicals which alters a characteristic of light, when said light passes through said chemical tag. Apparatus utilizes a rapid means of monitoring the change in optical signal coming from said waveguide as binding proceeds between tagged molecules of type 2 and the feature resembling molecules of type 1 on said waveguide. This allows direct measurement of binding and dissociation rates between the two types of molecules.

Abstract: A method for performing a rapid, homogenous assays for monitoring the reactions of a binding target, by immobilizing a fluorescent-capable chelate complex that is derivatized so as to posses recognition binding ligands, labeling the complex with a labeled second chelator that is added to the assay thereby forming a fluorescent mixed chelate, and measuring the fluorescent mixed chelate, whereby the measurement of the label enable monitoring of the reaction of the binding target. A rapid assay for performing the above method including a first chelating molecule, a fluorescent-capable ion complexed with the first chelating molecule, a second chelating molecule for reacting with the fluorescent-capable ion complexed with the first chelating molecule, and a measuring device for measuring fluorescent resulting from the second chelating molecule reacting with the fluorescent-capable ion complexed with the first chelating molecule.