Nanoscale Curvature Effects on the Properties of Anisotropic Nanomaterials

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With this award the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Chemistry Division is funding Professor Teri Odom at Northwestern University to study a specific type of nanoparticle -gold nanostars-that can be efficiently synthesized. Nanoparticles made from noble metals such as gold and silver are promising in a range of applications, from chemical sensors to optical imaging probes to anti-bacterial agents. However, preparing and controlling specific features (tips, edges, curves) on metal nanoparticles with non-spherical shapes are still challenging. These nanoscopic features are expected to be important as their sizes approach that of molecules. The project aims to obtain nanostars with desired features by tuning the chemistry at the nanoparticle surface. Broader impacts of these unique nanomaterials include integrating the one-pot gold nanostar synthesis with an existing lab on colloidal gold nanoparticles in freshmen general chemistry. In addition, freshman seminars focusing on nanoscience are developing projects similar to 'Ted Ed'-like videos explaining nano-concepts.This proposal seeks to determine how anisotropic nanomaterials that support unique curvature regions of positive, negative, and neutral curvature simultaneously exhibit properties distinct from symmetric (spherical) or elongated (rod-like) nanoparticles. Gold nanostars can serve as a unique model system since they can be synthesized through a seedless method resulting in distinct numbers of branches with tunable thicknesses and lengths. This work aims to resolve the mechanism of seedless growth at the single-particle level as well as determine how gold nanostar sample purity can be optimized by physical post-processing. Other goals include determining the structure-activity relationships of gold nanostars related to ligand attachment. Major outcomes of this work on nanoscale curvature include: (1) identifying functional groups in Good's buffers responsible for the formation gold nanostars with different branch numbers, branch lengths, and negative curvature degrees; (2) resolving the growth mechanism of gold nanostars at the single-particle level using in situ transmission electron microscopy; and (3) determining where biological ligands having secondary structure (double-stranded, looped, quadruplex) preferentially adsorb on the gold nanostars.