spherically shaped polyvinyl alcohol polymer particles are prepared encapsulating a magnetic colloid that provides the particles with magnetic properties for use in binding biomolecules . the particles have a size of 1 - 10 μm that makes them particularly suitable for use in cell separation / sorting , cleaning biosubstances in suspension and diagnostic assays . the particles are prepared by dispersing a magnetic colloid containing a magnetic material such as a ferromagnetic or superparamagnetic substance in an aqueous solution of polyvinyl alcohol containing reactive hydroxyl groups , adding the resultant mixture to an organic phase containing a mixture of at least two emulsifiers , and adding a water - soluble cross - linking agent such as a dialdehyde that reacts with the hydroxyl groups of polyvinyl alcohol to form the polymer particles . the emulsifiers are miscible in the polyvinyl alcohol solution , and at least one emulsifier is semi - hydrophilic and at least one emulsifier is lipophilic . the cross - linking agent may be used in combination with a water - soluble diamine . the polymer particles contain reactive hydroxyl groups and can be provided with spacer molecules to which biomolecules such as antibodies , peptides , proteins , enzymes , streptavidin , avidin , oligonucleotides , oligosaccharides or dna can be coupled . vinyl monomers having one or more functional groups such as carboxyl , hydroxyl , amino , aldehyde or oxirane may be grafted to the polymer particles by radical polymerization under the catalytic effect of cerium .