Professor of Organic Chemistry
B.S., 1989, California Institute of Technology;
Ph. D., 1995, Harvard University; Fulbright Scholar, 1995-96,
UniversitŽ Louis Pasteur; Chateaubriand Postdoctoral Fellow, 1996-97, UniversitŽ Louis Pasteur.
Our research team blends creative organic synthesis with nanostructured materials science and self-assembly principles, to produce exotic materials with unique physical or biomimetic function. Nanomaterials with size-tunable optical or magnetic properties can be transformed into chemical sensors, nanoscale photonic and magnetic devices, or multifunctional probes or agents which interface with living systems. Chemical and physical characterization of these systems involves immersion into an exciting melting pot of interdisciplinary activities. Two areas of research are described below:
Glycochemistry. We seek a deeper understanding of carbohydrates on cell surfaces and in the extracellular matrix, particularly those which are important in cellÐcell communication or as biomaterials. Structural parameters such as chirality (D-sugars vs. L-sugars) and sulfation are often vital to biological function, but their precise roles still need to be defined. Natural and unnatural carbohydrates are synthesized to address questions of structure as well as biological function. As a complement to synthesis, we are also developing novel analytical methods such as frozen-solution NMR spectroscopy (to study molecular conformations in biologically relevant environments) and functional assays based on glycosylated nanoparticles. This multidisciplinary approach may reveal how chirality and sulfation influence carbohydrate-based cellular recognition and signaling.
Self-assembly of functional nanomaterials. Nanoparticle assemblies can exhibit collective properties which are entirely different from that of a single particle. Size, shape, spacing, and superlattice dimensions can all be tuned to produce physical phenomena of technological value. We use self-assembly techniques to create well-defined nanoparticle assemblies, so that their unique ensemble states can be correlated with structural parameters. Our control over the self-assembly process can be enhanced by coating nanoparticles with calixarenes, a versatile class of macrocyclic ligands (surfactants). Once structureÐfunction relationships in nanoparticle assemblies are established, they can be applied toward device applications. Two areas of interest in our laboratories include surface-enhanced Raman scattering (SERS) for chemical and biomolecular sensing, and chiral magnetic nanodomains for nanoscale magnetoelectronics.