This is a copy of the slides presented at the meeting but not formally written up for the volume.

Semiconductor, metal and ceramic nanocrystals have optical, magnetic and chemical properties that can be radically different from molecular or bulk systems. These unique and tunable features can be leveraged in biomedical applications. As an introduction we will give several examples in which such systems have been used to improve the diagnosis, imaging, and treatment of disease. Then we will discuss both the synthetic and analytical challenges with forming these materials for problems in medicine. We will first present general techniques for imparting water solubility to nanocrystals using amphilphilic co-polymers. Our strategy uses as a starting point high quality nanocrystals that are best formed in organic solvents. We then transfer the materials to water using copolymers generated using a maleic anhydride coupling scheme that permits the coupling of a wide variety of PEG polymers, both unfunctionalized and functionalized, to hydrophobic tails. The hydrodynamic size and concentration of the nanoparticle-polymer complexes requires new techniques, including size-exclusion chromatography, cryogenic transmission electron microscopy and mass spectroscopy. Ultimately, many of the key features of the nanoparticles are defined by their specific and non-specific interactions with biomolecules in complex biological fluids. Characterization of this full 'nanocrystal-polymer-biomolecule' complex requires additional methods drawn from both biochemistry and cell biology. In particular, we find analytical ultracentrifugation to be ideally suited for quantitative evaluation of these systems.