POLYMER MICROGEL BEADS COMPRISING POLYMERIC MATRIX AND STERIC STABILISER WHEREIN STERIC STABILISER DOES NOT FORM PART OF THE POLYMERIC MATRIX, AND METHOD FOR SYNTHESIS
Disclosed are polymer microgel beads having a polymeric matrix that can absorb and be swollen by an aqueous liquid, the polymeric matrix having magnetic nanoparticles dispersed uniformly therethrough in an amount of at least 20 weight per cent, wherein a steric stabiliser is associated with the particles, the steric stabiliser being a polymeric material that (i) does not form part of the polymeric matrix of the beads, and (ii) comprises a steric stabilising polymeric segment and an anchoring polymeric segment, wherein the steric stabilising polymeric segment is different from the anchoring polymeric segment, and wherein the anchoring polymeric segment has an affinity toward the surface of the nanomagnetic particles and secures the stabiliser to the particles. Also disclosed is a method for the preparation of the polymer microgel beads comprising providing a dispersion comprising a continuous organic phase and a dispersed aqueous phase, the dispersed aqueous phase comprising: (i) ethylenically unsaturated monomers that are soluble in the aqueous phase and (ii) nanomagnetic particles dispersed throughout the aqueous phase, the particles being maintained in their dispersed state by a steric stabiliser, wherein the steric stabiliser is a polymeric material comprising a steric stabilising polymeric segment and an anchoring polymeric segment, wherein the steric stabilising polymeric segment is different from the anchoring polymeric segment, and wherein the anchoring polymeric segment has an affinity toward the surface of the particles and secures the stabiliser to the particles and polymerising the ethylenically unsaturated monomers to form the polymer microgel beads incorporating the nanomagnetic particles. The microgel beads are useful in hyperthermia treatments of tissue such as cancerous tissue. The beads are administered to a subject and exposed to a magnetic field, causing the beads to radiate heat at a target site.
