Dendrimer based nanocomposites (DNC-s) are recently developed materials that are composed of small clusters of guest domains dispersed in nanoscopic size polymer hosts with no covalent bonds between host and guest. These inorganic-organic hybrid materials are uniform, and can be made in controlled sizes and surfsces. They often display unique physical and chemical properties because of the atomic/molecular level dispersion of their components. The concept itself will be demonstrated on nanocomposites of poly(amidoamine) (PAMAM) dendrimers, which have been employed for creating novel, soluble inorganic nanocomposites including stable zero valence metals at room temperature, using post-complexation chemistry. As an example, we report on the fabrication and utility of gold nanocomposite devices (NCDs) to selectively deliver radiation to tumors by exploiting differences between normal and tumor vasculature. We focus on {Au-198} nanocomposites to deliver beta-radiation to tumors in a B16 melanoma bearing mice model. Au(0) atoms in the NCDs are made radioactive by direct irradiation in a neutron beam making both imaging and radiotherapy possible. This technique enables us to first synthesize the nanomaterials, then fabricate and characterize the complex device, and finally activate the NCDs. This approach will shorten the development of new active NCD systems allowing the use of other short halflife radionuclides. This general approach of organic/inorganic hybrids provides a simple and economic way to design and prepare unique nanosized devices for the imaging and treatment of cancer. Utility and properties of these novel materials will be illustrated on various examples, such as biodistribution of single dendrimer devices with or without cell-specific targeting. The role of compositional and methodological differences in the resulting nanocomposite structure will also be discussed.
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