A Novel Silicone Magnetic Microsphere for Ligand-Targeted Drug Delivery

Abstract

In ligand-targeted drug delivery, a carrier particle is conjugated with a ligand designed to bind specifically to a receptor expressed on the membrane of a chosen cell type. A therapeutic agent is adsorbed onto or absorbed within the carrier, and its release is often triggered by magnetic stimulation or other means. In this work, we present a novel silicone-magnetite microsphere as the drug carrier for ligand-targeted drug delivery. Each carrier contains up to 50% wt. magnetite nanoparticles (10nm diameter) each coated with a monolayer of an amine-functionalized silicone polymer for a total microsphere diameter scalable between 0.5-2.0 microns. The silicon matrix of this carrier facilitates compatibility with lipophilic drugs, the high magnetic content allows the potential for magnetically-stimulated drug release, and an abundance of primary amines within the matrix enables surface functionalization with a variety of ligands. We demonstrate the utility of these new microspheres for ligand-targeted drug delivery by binding folic acid to the microsphere surface, and explore targeting of malignant cells which overexpress folate binding protein. Binding in this study is verified via fluorescence microscopy of a tagged immunoassay.