| abstract |
Improved fluorescent labels comprise a fluorescent rare earth chelate incorporated into a polymeric particle derived from a loadable latex. The polymer comprises: (a) from about 50 to about 96 weight percent of recurring units derived from a hydrophobic ethylenically unsaturated polymerizable monomer, (b) from about 2 to about 30 weight percent of recurring units derived from a nonionic hydrophilic 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 solubilizing group. The labels of this invention have greatly improved stability in aqueous solutions and do not prematurely agglomerate during storage. They can be attached to any of a variety of physiologically reactive species to provide labeled species, and are particularly useful in specific binding assays. |