Process for the preparation of magnetizable microspheres based on polysiloxane and their biological application

Claim 1

Magnetizable microspheres, comprising a matrix based on at least one organopolysiloxane of the formula (I) R"R'RSiO(SiR.sub.2 O).sub.n (SiRR"O).sub.m SiRR'R" (I) wherein: the R radicals may be identical or different, and are selected from a C 1 -C 3 alkyl radical and a phenyl radical; the R' radicals may be identical or different and are selected from an OH group, a C 1 -C 3 alkyl radical and a phenyl radical; the R" radicals may be identical or different and are selected from a C 1 -C 4 alkyl radical, a phenyl radical, 3,3,3-trifluoropropyl, a vinyl radical and a radical --R" --'X wherein R"' is a divalent organic radical and X is selected from an epoxy, hydroxy, carboxy, aldehyde, ester, aceto-ester, mercapto, mercapto ester, mercaptoalkoxy, amino, alkylamino, dialkylamino, trialkylamino, quaternary ammonium, amino alcohol, amido, hydrazide, hydrazino, C1-C3 haloalkyl, cyano, cyanato, ##STR11## sulfate, sulfonyl and halobenzyl group, at least 50% of the R radical are methyl radicals; n and m are whole or fractional numbers having a value sufficient to provide a matrix having a viscosity ranging from 400,000 to 10,000,000 mPas at 25° C., and, if at least one R" is selected from a vinyl radical or said --R" --'X radical, n and m have values sufficient to provide a ratio of the number of R" units selected from a vinyl radical or said --R" '--X radical per organopolysiloxane molecule ranging from 1:1 to 1,000:1; and, encapsulated in said matrix, magnetizable particles having a diameter less than 300 angstroms.