Abstract: Hydrophilic latex particles consisting of a homo- or co-polymer of monomers which are sparingly soluble in water, which hydrophilic latex particles can be prepared by emulsion polymerization in the presence of a water-soluble, radical-forming initiator but without an addition of an emulsifier, stabilizer or wetting agent. A process for the preparation of these hydrophilic latex particles, wherein a monomer which is sparingly soluble in water or several monomers which are sparingly soluble in water are dispersed in water and, with the exclusion of oxygen, for example in an inert atmosphere, are homo- or co-polymerized by emulsion polymerization in the presence of a water-soluble, radical-forming initiator but without any addition of an emulsifier, stabilizer or wetting agent.A diagnostic agent containing these hydrophilic latex particles as carrier and biologically and/or immunologically active substances covalently bound to this carrier either directly or via a coupling agent as a bridge.

Abstract: Three-dimensional polymeric material in the form of spherical particles of diameter .ltoreq.3 mm and containing up to 40% of free aldehyde groups which exhibits a measurable specific surface area is prepared by copolymerization of an aldehyde monomer R.sub.1 CH.dbd.C(CH.dbd.O)R.sub.2, where R.sub.1 is H, C.sub.1-5 alkyl, aryl or furyl and R.sub.2 is H, C.sub.1-5 alkyl, halogen, CN, phenyl or furyl, with a crosslinking agent in the aqueous dispersion phase. The dispersion contains 1 - 25% of a component reducing the monomer solubility in water, which is either an inorganic salt of alkali metal or alkaline earth metal or a water-soluble alcohol. The crosslinking agent used as comonomer is divinylbenzene, diester CH.sub.2 .dbd.C(R.sub.1)COOR.sub.2 OCOC(R.sub.1).dbd.CH.sub.2 (R.sub.1 .dbd. H, C.sub.1-10 alkyl or halogen; R.sub.2 .dbd. C.sub.1-10 alkylene or hydroxyalkylene), or diamide CH.sub.2 .dbd.C(R.sub.1)CONHR.sub.2 NHCOC(R.sub.1).dbd.CH.sub.2 (R.sub.1 .dbd. H, C.sub.1-10 alkyl or halogen; R.sub.2 .dbd. C.