Nanoparticle Architecture Preserves Magnetic Properties during Coating to Enable Robust Multi-Modal Functionality
Lauren E. Woodard, Cindi L. Dennis, Julie A. Borchers, Anilchandra Attaluri, Esteban Velarde, Charlene Dawidczyk, Peter C. Searson, Martin G. Pomper, Robert Ivkov
Mixed metal/metal oxide nanoparticles offer potential as multifunctional platforms for disease diagnosis and therapy, or 'theranostics' [1-9]. We describe the synthesis and characterization of gold/silica/iron oxide core-shell nanoparticles, for which the magnetic properties of the iron oxide core are preserved, while adding functionality for multimodal imaging and heating. Physical characterization indicates that a silica layer surrounds the individual magnetic grains of the polycrystalline iron oxide core, while preserving the magnetic properties. Gold was reduced from solution to encapsulate the silica/iron oxide cores. Contrast with x-rays and magnetic resonance (MR) across a range of concentrations was quantitatively assessed to determine potential utility as a dual-modality contrast agent. Heating with alternating magnetic fields (AMFs) revealed little impact of coating on magnetic cores, and laser heating indicates improved energy conversion with gold coating. In vivo imagining and heating is demonstrated in an experimental model of prostrate cancer. These results encourage further development of gold/silica/iron oxide core-shell nanoparticles for biomedical applications.