Abstract: Vesicles are formed, in part, from an amphiphilic chelating agent whereby a detectable metal marker can be complexed to the vesicle. A portion of the vesicle may also be formed from an amphiphilic compound derivatized with a ligand, whereby the vesicle may be used as a tracer in an assay. If the detectable metal marker is a fluorescent rare earth metal, the assay may be a time delay fluorescent assay. The vesicles may be dried, and reformed by addition of water for use in an assay.

Abstract: Vesicles are formed having a detectable marker and ligand conjugated to compounds forming the vesicle wall. The vesicles are dried, and reformed by addition of water for use in an assay.

Abstract: A method for separation-free solid phase immunoassay of an analyte includes contacting an anti-analyte attached to the surface of a solid support with the analyte, a light absorbing material and a fluorescent tracer for the analyte. The resulting mixture is incubated. The method includes applying excitation light to the mixture and time resolved measurement of fluorescence emission from the tracer. All excitation light and fluorescence emission are absorbed by the light absorbing material except that absorbed and emitted by the tracer bound to the anti-analyte whereby the only fluorescence emission detected is from the bound tracer. Since free tracer in the fluid phase of the assay medium does not emit fluorescence, separation of the bound and free fractions is unnecessary. The invention includes a kit of materials useful in performing an immunoassay in accordance with the method of the invention.