FeCo/Graphitic Carbon-Shell Nanocrystals as MRI Contrast Agents for Cellular and Vascular Imaging

Introduction: We have recently developed and tested new FeCo/graphitic carbonshell (FeCo/GC) nanocrystals with interesting properties for MRI. The following summarizes these properties (advantages): (1) highest magnetization [1] among all magnetic materials, allowing a lower dosage for high contrast; (2) non-toxic due to encapsulating graphite carbon shell; (3) superparamagnetic up to 20 nm or higher and smallest size synthesized is down to 2–3 nm (i.e. wide size range to work with); (4) potential as highly sensitive T2 * contrast agent used for cell labeling; (5) potential as intravascular T1 contrast agent; (6) easy manipulation of the surface to modify biodistribution; (7) high optical absorbance in near-infrared (NIR) for potential optical manipulation which can provide photothermal therapy guided by MRI [2]. Below, we show experimental results demonstrating some of these properties and potential applications.