Magnetic heating of iron oxide nanoparticles and magnetic micelles for a magnetothermally-triggered drug delivery system for cancer therapy

Magnetic nanoparticles, MNPs, combined with stimuli-responsive polymers show potential to enhance the efficacy of cancer therapy in multifunctional nanoscale drug delivery systems. This project investigates the use of iron oxide nanoparticles (magnetite) to generate heat, via an applied magnetic field, to stimulate drug release of doxorubicin from an RGD-peptide targeted thermo-sensitive poly (ethylene glycol)-b-poly (caprolactone) micelle. Fe 3O4 nanoparticles custom synthesized at UA show the ability to heat to temperatures adequate for melting a semi-crystalline poly (caprolactone) micelle core. Investigations into parameters effecting magnetic heating of Fe3O4 included studying the effects of magnetic field strength, H, and frequency, f. The results showed magnetic heating of the MNPs could induce hyperthermic temperatures. Specific absorption rates (SAR) for the MNPs were in the range of previously reported magnetite SARs, and followed the relationship with magnetic field strength predicted by the Rosensweig equation. The internal energy change in magnetic micelles was larger than that observed for MNPs in hexane when heated by an AC magnetic field. Drug release studies using triamterene- and doxorubicin-loaded micelles show a temperature-dependent acceleration of drug release at temperatures above 42°C, the melting point of poly (caprolactone), as well as the possibility of magnetic induction hyperthermia-activated release