1. Materials World Network: Structure-response relations of advanced diagnostic toolsJudy S. Riffle, Virginia Polytechnic Institute and State University, DMR 0909065 Magnetite nanoparticles can be powerful contrast enhancement agents for T2-weighted magnetic resonance imaging (MRI). Multifunctional magnetite nanocarriers that also contain therapeutic agents are of interest because they have potential for delivering drugs and monitoring their biodistribution. There are several reports of macrophage infiltration of magnetite nanoparticles where accumulation of the phagocytic cells in an area provides sufficient local concentration to image the complexes. We have designed doubly-hydrophilic magnetic block ionomer complexes (MBICs) carrying high concentrations of antibiotics and magnetite. They have potential for targeting immune cells infected with bacteria and for simultaneous tracking of the drugs in vivo with MRI. MBICs comprised of controlled clusters of magnetite nanoparticles (each nanoparticle size = 8 nm) and cationic gentamicin encased in crosslinked poly(ethylene oxide-b-acrylate) nanogels. Diameter of the MBIC nanogels are 150-180 nm intensity ave. diameters.

2. Materials World Network: Structure-response relations of advanced diagnostic toolsJudy S. Riffle, Virginia Polytechnic Institute and State University, DMR 0909065 Combining expertise in synthesis and engineering of polymeric nanostructures from students at Virginia Tech with predictions of relaxation processes of magnetic nanoparticles carried out by our physics collaborators from the University of Western Australia has led to the understanding that clusters of superparamagnetic magnetite particles have very high transverse relaxivities (see table at the left) compared to current contrast agents. This translates into improved contrast in both high and low-field MRI. TEM image of copolymer-stabilized magnetite nanoparticle clusters with a 1:1 (w/w) ratio between the copolymer and the magnetite