Authors: A. Bumb, C.A.S. Regino, M. Bernardo, P.J. Dobson, P. Choyke, M.W. Brechbiel
Affilation: National Cancer Institute, United States
Pages: 428 - 431
Keywords: diagnostics, imaging, nanoparticle, lymph node, magnetic resonance, optical
Accurate characterization of the first draining sentinel lymph nodes in primary tumors is a challenging task where current methods rely on nodal size as the primary yardstick for differentiating benign from malignant nodes. Other parameters such as the nodal shape, contour, and level of enhancement may also provide useful information. We have developed a dual reporting nanoparticle by encasing ultrasmall superparamagnetic iron oxide nanoparticles in a thin ~4nm layer of silica containing near infrared dye Cy5.5. Mice given intracutaneous injection of particle in the foot pad reveal visualization of the primary draining nodes and histology confirmed particle presence. Studies have been directed at diagnosing tumor formation where, the particle could first be used to characterize lymph node by MR, followed by fluorescence identification during surgery, and further histology using its fluorescence and iron. The particle has also been made tri-modal by conjugating radiolabeled-antibody to its surface for nuclear imaging. This silica-coated iron oxide nanoparticle (SCION) allows for verification of localization, characterization of nearby physiology, and quantification. During each stage of development, SCION was characterized for surface charge, structure, optical response, and magnetic properties. Cell viability, biodistribution, pharmacokinetics, MR, optical, and nuclear imaging studies have also been conducted.