Silicone-Based Magnetic Microspheres for Magnetic Hyperthermia Therapeutics

Abstract

Magnetic microspheres are used in a wide variety of applications within the scientific community - from cell-sorting to microscale force experiments. Recently, they have shown promise in magnetic hyperthermia therapeutics, which may be an effective substitute for more traditional chemotherapy and radiation treatments of malignant tumors. An ideal magnetic microsphere for magnetic hyperthermia must have a high magnetic content and a biocompatible matrix. We present here the first instance of a silicone-based magnetic elastomer with the nanoscale homogeneity required for the fabrication of uniform magnetic microspheres. We fabricate microspheres (0.5 - 1 μm diameter) of this material with magnetic content approaching 50% wt. and demonstrate heating with an external high frequency magnetic field. High magnetic content and the absence of aggregation of the constituent magnetic nanoparticles in our material leads to a high specific absorption rate (SAR, or the power absorbed per gram of material) upon magnetic stimulation, and therefore effective heating. Furthermore, hyperthermia studies with magnetite nanoparticles have shown that SAR depends very heavily on diameter; therefore, in this work we produce magnetic microspheres containing monodisperse nanoparticles across a range of applicable diameters and explore the effects of particles size on SAR.