Stabilized fluorescent rare earth labels and labeled physiologically reactive species

A dry analytical element useful in diagnostic or analytical methods comprising an absorbent carrier material containing a fluorescent labeled physiologically reactive species,

• said labeled species comprising a physiologically reactive species bound to a fluorescent label comprising a fluorescent rare earth chelate incorporated into a polymeric particle which is derived from a loadable latex having a discontinuous phase and an aqueous phase,
• said discontinuous phase consisting essentially of a polymer comprising:
• (a) from about 50 to about 96 weight percent of recurring units derived from a water-insoluble ethylenically unsaturated polymerizable monomer,
• (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic water-soluble or water-dispersible ethylenically unsaturated polymerizable monomer, and
• (c) from about 2 to about 20 weight percent of recurring units derived from an anionic ethylenically unsaturated polymerizable monomer containing at least one carboxy group.

A dry analytical element useful for the determination of a specific binding ligand in an immunoassay, said element comprising

• a support having thereon one or more zones, one of which is a porous spreading zone, and
• in one or more of said zones, a fluorescent labeled specific binding ligand analog of said ligand, said labeled analog comprising said ligand bound to a fluorescent label comprising a fluorescent rare earth chelate incorporated into a polymeric particle which is derived from a loadable latex having a discontinuous phase and an aqueous phase,
• said discontinuous phase consisting essentially of a polymer comprising:
• (a) from about 50 to about 96 weight percent of recurring units derived from a water-insoluble ethylenically unsaturated polymerizable monomer,
• (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic water-soluble or water-dispersible ethylenically unsaturated polymerizable monomer, and
• (c) from about 2 to about 20 weight percent of recurring units derived from an anionic ethylenically unsaturated polymerizable monomer containing at least one carboxy group.

A method for the determination of a specific binding ligand in an aqueous liquid, said method comprising the steps of;

• A. in the presence of a receptor for said ligand, contacting a sample of said liquid with a fluorescent labeled specific binding ligand analog,
• said ligand analog comprising said ligand bound to a fluorescent label comprising a fluorescent rare earth chelate incorporated into a polymeric particle which is derived from a loadable latex having a discontinuous phase and an aqueous phase, said discontinuous phase consisting essentially of a polymer comprising:
• (a) from about 50 to about 96 weight percent of recurring units derived from a water-insoluble ethylenically unsaturated polymerizable monomer,
• (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic water-soluble or water-dispersible ethylenically unsaturated polymerizable monomer, and
• (c) from about 2 to about 20 weight percent of recurring units derived from an anionic ethylenically unsaturated polymerizable monomer containing at least one carboxy group to form a complex between said receptor and said ligand analog,
• B. separating said complex from uncomplexed ligand analog, and
• C. fluorometrically detecting either said complexed or uncomplexed ligand analog.

A diagnostic test kit for the determination of a specific binding ligand, said kit comprising

• (i) a receptor for said ligand, and
• (ii) a fluorescent labeled immunologically reactive ligand analog comprising said ligand bound to a fluorescent label comprising a fluorescent rare earth chelate incorporated into a polymeric particle which is derived from a loadable latex having a discontinuous phase and an aqueous phase,
• said discontinuous phase consisting essentially of a polymer comprising:
• (a) from about 50 to about 96 weight percent of recurring units derived from a water-insoluble ethylenically unsaturated polymerizable monomer,
• (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic water-soluble or water-dispersible ethylenically unsaturated polymerizable monomer, and
• (c) from about 2 to about 20 weight percent of recurring units derived from an anionic ethylenically unsaturated polymerizable monomer containing at least one carboxy group.

A fluorescent labeled physiologically reactive species comprising a physiologically reactive species bound to a fluorescent label comprising a fluorescent rare earth chelate incorporated into a polymeric particle which is derived from a loadable latex having a discontinuous phase and an aqueous phase,

• said discontinuous phase consisting essentially of a polymer comprising:
• (a) from about 50 to about 96 weight percent of recurring units derived from one or more water-insoluble ethylenically unsaturated polymerizable monomer selected from the group consisting of styrene, .alpha.-methylstyrene, p-bromostyrene, vinyltoluene, 1-vinylnaphthalene, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl acrylate and propyl acrylate,
• (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic water-soluble or water-dispersible ethylenically unsaturated polymerizable monomer, and
• (c) from about 2 to about 20 weight percent of recurring units derived from an anionic ethylenically unsaturated polymerizable monomer containing at least one carboxy group.