Nyssa Emerson (Yang Lab)
"Purification of Large, DNA-tagged Nanoparticle "Building Blocks" for Self-Assembly of Complex Nanostructures."
Discrete clusters of large (> 40 nm) metallic nanoparticles can act as "nanoantennas" to amplify incident light and enhance the spectroscopic signal of near-by molecules by many orders of magnitude. A major obstacle to applying this technology is the difficulty in obtaining homogeneous, well-defined nanoantennas, because reactions to produce discrete clusters of nanoparticles typically result in a mixture of products that cannot be easily separated. To overcome this obstacle, a DNA-based affinity chromatography method was developed to obtain large nanoparticles tagged with only a single DNA molecule. In contrast to untagged nanoparticles, the predictable base-pairing interaction of DNA leads these DNA-tagged "building blocks" to spontaneously assemble into a desired nanostructure simply by mixing the appropriate components together in solution. As a demonstration of this method, the synthesis of a simple nanoantenna, a dimer of two gold nanoparticles, is described. Yet, we also envision that this synthetic method can be extended to the synthesis of more complex, multi-component nanostructures as well.
Quan Wang (LSI Fellow)
"Are enzymes like rockets?"
Enzymes are essential catalysts of life. Although their biochemistry has been heavily studied, relatively little is known regarding their chemo-mechanical properties. Recently, several groups reported that enzymes diffuse (up to 30%) faster under catalytic conditions. A “rocket-like” model was proposed that attributes this accelerated diffusion to a pressure wave in solution generated by the heat released from the exothermic reaction catalyzed by the enzyme. However, this model, as well as the interpretation of the experiments are still being debated. I will describe ongoing efforts in my lab to measure and understand this phenomenon at the level of individual enzyme molecules.