Application of novel iron core/iron oxide shell nanoparticles to sentinel lymph node identification

Current ‘gold standard’ staging of breast cancer and melanoma relies on accurate in vivo identification of the sentinel lymph node. By replacing conventional tracers (dyes and radiocolloids) with magnetic nanoparticles and using a handheld magnetometer probe for in vivo identification, it is believed the accuracy of sentinel node identification in nonsuperficial cancers can be improved due to increased spatial resolution of magnetometer probes and additional anatomical information afforded by MRI road-mapping. By using novel iron core/iron oxide shell nanoparticles, the sensitivity of sentinel node mapping via MRI can be increased due to an increased magnetic saturation compared to traditional iron oxide nanoparticles. A series of in vitro magnetic phantoms (iron core vs. iron oxide nanoparticles) were prepared to simulate magnetic particle accumulation in the sentinel lymph node. A novel handheld magnetometer probe was used to measure the relative signals of each phantom, and determine if clinical application of iron core particles can improve in vivo detection of the sentinel node compared to traditional iron oxide nanoparticles. The findings indicate that novel iron core nanoparticles above a certain size possess high magnetic saturation, but can also be produced with low coercivity and high susceptibility. While some modification to the design of handheld magnetometer probes may be required for particles with large coercivity, use of iron core particles could improve MRI and magnetometer probe detection sensitivity by up to 330 %.