Magnetically induced release of fluorescein isothiocyanate (FITC) from polymer nanoparticle composites (PNCs)

Magnetically induced drug release can be used as a site-specific, minimally invasive pharmaceutical treatment. Its purpose is to increase the efficacy of drug therapies to diseased or damaged tissue and to decrease the amount of unnecessary damage to healthy, surrounding tissue. To prove the concept of drug release by a magnetic field, this study focused on the release of a fluorescent molecule from magnetic polymeric nanoparticle composites (PNCs) via induction of an alternating current (AC) magnetic field. Fluorescent magnetic PNCs used were 250 ?m or less in size, and were made of poly(methyl methacrylate) (PMMA) containing either the magnetic material magnetite nanoparticles or cobalt nanoparticles, and the fluorescent dye fluorescein isothiocyanate (FITC). Characterization of the composites included transmission electron microscopy (TEM) and scanning electron microscopy (SEM) for size and morphology, fluorescent microscopy for fluorescent images, elemental analysis for iron and cobalt content, and superconducting quantum interference device (SQUID) magnetometer readings for saturation magnetization measurements and field profiles of each particle type. Magnetic release of FITC from the composites was induced by applying an AC magnetic field to the PNCs in phosphate buffered saline (PBS) at various frequencies in the range of 44-430 Hz at the corresponding voltage of 15-123 V, magnetic field strength of approximately 465 G and current of 11 A. The PNCs were exposed to the magnetic field for various amounts of time ranging from 5 minutes to 3 hours and at temperatures of 4°C, 22°C, and 43°C. For each experiment, a control sample that was not exposed to the magnetic field was also tested for release. Fluorescence released was measured using a fluorospectrometer following filtration and sample dilution. The investigations demonstrated that the release of FITC was not significantly dependent on the frequency of the magnetic field, the experimental duration, nor the presence of the AC magnetic field. The study demonstrated, however, that greater release of FITC was dependent on higher temperatures and that magnetite-PNCs released more FITC than cobalt-PNCs. This research potentially leads the way to the biological applications of in-vitro and in-vivo studies of magnetically induced, controlled drug release from magnetic polymeric structures