Center for Functional Nanomaterials Seminar

Center for Functional Nanomaterials Seminar

Wednesday, January 30, 2008, 1:45 pm
CFN Building 735 – Second Floor Seminar Room

NANOCRYSTALS PREPARED BY MODERN MATERIALS CHEMISTRY METHODS

STEPHEN O’BRIEN, DEPT. APPLIED PHYSICS AND MATERIALS RESEARCH SCIENCE AND ENGINEERING CENTER, COLUMBIA UNIVERSITY, NEW YORK NY 10027, USA

Nanocrystals prepared by modern materials chemistry methods are discrete units with a crystalline inorganic core and an organic ligand coating for a shell. They are best thought of as an inorganic-organic hybrid when considering their applications, functionality and properties. Here I describe two examples of their use as building blocks. (i) Monodisperse Magnetic Nanoparticles for Specific Antibody Targeted MRI Contrast Imaging. Non-invasive imaging of specific proteins or cells in the body has the potential to improve the diagnosis and treatment of numerous diseases. We report here the development of a long-lived immunotargeted iron oxide nanoparticle contrast agent composed of monodispersed, monocrystalline γ-Fe2O3 iron oxide nanoparticles coated with a monolayer of phospholipids and conjugated to modified IgG antibodies. Proof of specificity is demonstrated using MHC Class II antibodies. MR images were taken of Lewis rats injected with 4 mg/kg unconjugated iron oxide nanoparticles using T1 weighted, T2 weighted Fast Spin Echo and T2* weighted scan sequences. (ii) Nanocrystal superlattices of II-VI semiconductors. Nanocrystals can be used as building blocks to form simple ordered arrays, called superlattices, which resemble the close-packed structures of atoms in crystals or hard spheres. The procedure can be described as a co-crystallization of nanocrystal dispersions following appropriate choice of solvents, substrates and conditions for self-assembly. The superlattices that result exhibit remarkable structural and compositional diversity, representing a variety of close packed structures reminiscent of binary alloy phase