Figure 3

Properties of functionalized USPIOs. TEM of (A) as-made oleic acid-stabilized USPIO cores, (B) cPEG-PPS-USPIO micelles, (C) C1-USPIOs, (D) C2-USPIOs, and (E) clusters formed by hybridization of C1-USPIOs and C2-USPIOs. All scale bars are in 100 nm. In the first four cases, nanoparticles appear to be generally well-dispersed, but were also capable of forming short-ranged packing structures. (F) DLS size-volume distributions of C1-USPIOs (blue), C2-USPIOs (red), and clusters formed by hybridization of C1- and C2-USPIOs (green) suggest that the individual ssDNA-displaying USPIO micelles exhibit a hydrodynamic diameter of approximately 70 nm, while clusters formed by mixing the two populations are generally greater than of 1 μm in diameter. (G) TGA weight loss curves of oleic acid (blue), cPEG-PPS (red), OA-USPIOs (yellow), and cPEG-PPS-USPIOs (green) suggest that oleic acid is not displaced in the micellization process, and instead is encapsulated into the interior of the micelles along with the iron oxide core.