Water-insoluble reagent elements containing same and methods of use

A reagent consisting essentially of:

• a surfactant-free, water-insoluble polymeric latex particle composed of a vinyl addition polymer, said particle having covalently attached thereto an immunological species which is capable of participating in an immunological reaction with a corresponding receptor, said polymer being represented by the formula:
• --A).sub.x (B).sub.y (D).sub.z
• wherein A represents recurring units derived from one or more hydrophobic ethylenically unsaturated monomers,
• B represents recurring units derived from one or more ethylenically unsaturated monomers represented by the formula:
• ##STR4## wherein R is hydrogen or substituted or unsubstituted alkyl having 1 to 6 carbon atoms,
• R.sup.1 is --CH.dbd.CHR.sup.2 or --CH.sub.2 CH.sub.2 X wherein X is a leaving group which is displaced by a nucleophile or is eliminated in the form of HX by treatment with a base, and R.sup.2 is hydrogen, substituted or unsubstituted alkyl having 1 to 6 carbon atoms, or substituted or unsubstituted aryl having 6 to 12 nuclear carbon atoms, and
• L is a linking group selected from the group consisting of substituted or unsubstituted alkylene having 1 to 20 carbon and hetero atoms, substituted or unsubstituted arylene having 6 to 12 nuclear carbon atoms, and a combination of one or more of each of said alkylene and arylene groups,
• D represents recurring units derived from one or more ethylenically unsaturated monomers other than those represented by A or B,
• x is from 0 to about 99.9 mole percent, y is from about 0.1 to 100 mole percent, and z is from 0 to about 20 mole percent,
• the interior of said particle being substantially free of detectable tracer material,
• the reagent being provided by:
• (1) preparing said surfactant-free polymeric particle by emulsion polymerization of monomers A, B and C in the absence of a surfactant or emulsifier, and
• (2) covalently attaching said surfactant-free polymeric particle through the reactive ##STR5## of the B recurring units to said immunological species.