Magnetic Iron Oxide Nanoworms for Tumor Targeting and Imaging.

The application of nanotechnology to medicine is providing new approaches for the diagnosis and treatment of diseases. Ultrasensitive imaging for early detection of cancers and efficient delivery of therapeutics to malignant tumors are two primary goals in cancer bionanotechnology; however, the development of nontoxic, functional nanoparticles that can successfully home to tumors presents some significant challenges. Dextran-coated magnetic iron oxide (IO) nanoparticles are of particular interest because they show relatively low toxicity and long circulation, and dramatically enhance hydrogen T2 relaxation in magnetic resonance imaging (MRI). The clinical power of these materials may be amplified by improving MRI relaxivity, blood circulation times, and the homing of such nanoparticles to tumors. Efforts to increase MRI sensitivity have focused on development of new magnetic core materials, or on improvements in nanoparticle size or clustering. However, most efforts to improve the morphological characteristics of these nanoparticles have resulted in materials with relatively short circulation half-lives owing to incomplete additional hydrophilic coatings. An emerging theme in nanoparticle research is to control biological behavior and/or electromagnetic properties by