The present invention relates to magnetizable "core-shell" particles based on crosslinked organopolysiloxane, useful alone or in an aqueous dispersion. The present invention also relates to a process for the preparation of magnetizable "core-shell" particles and their application to biology.
In French Patent Application No. 2,624,873, the assignee of the present invention described magnetizable composite particles based on crosslinked organopolysiloxane, said particles consisting of a matrix originating from the hydrosilylation of an organopolysiloxane and an organohydrogenpolysiloxane and, encapsulated in said matrix, magnetizable fillers coated with a dispersing agent insoluble in water. The presence of this dispersing agent can be a drawback for use in biology because the agent can migrate towards the surface of the particles and give rise to side reactions.
The Applicant has now found composite microspheres of which the core comprises a magnetizable filler not coated with a hydrophobic surfactant.