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Analytical methods with high chemical, spatial, and temporal resolution are crucial to understanding and controlling nanoparticle properties as well as translating these discoveries into society-shaping technologies. However, approaches for the characterization of solid inorganic materials and solution phase molecular species are often disparate. One powerful technique to address this gap is nuclear magnetic resonance (NMR) spectroscopy, which can facilitate routine, direct, molecular-scale analysis of nanoparticle formation and morphology in situ, in both the solution and solid phase. This dissertation describes the application of NMR to study metal nanoparticle formation, structure, and performance with unprecedented chemical detail. In Chapter 1, the dissertation is introduced by highlighting recent developments in the application of NMR spectroscopy to the study of noble metal nanoparticle growth, surface chemistry, and physical properties. In Chapter 2, the formation of bimetallic Au-Cu nanoparticles is studied by solution NMR techniques (in conjunction with mass spectrometry and X-ray absorption spectroscopy) to reveal the chemical mechanisms driving metal atom distribution in the final particle. Building on hypotheses tested in Chapter 2, Chapter 3 describes one of the first syntheses of Au-Co alloys at any length scale with fully tunable compositions. The magnetic and optical properties of the resulting Au-Co nanoparticle alloys are evaluated with NMR and photoluminescence spectroscopies, respectively, and are found to exhibit both high relaxivity and high brightness, making them ideal bimodal imaging agents. Building on these studies of nanoparticle formation, NMR spectroscopy is then used to study final particle structure and physical properties. In Chapter 4, NMR is used to probe ligand shell architectures on phosphine-terminated Au nanoparticles and allow the identification of 31P-197Au coupling for the first time in nanoparticle systems – a feature which may ultimately be used to study previously NMR-inaccessible nuclei such as 197Au. This utility is highlighted in Chapter 5 where the impact of local and global crystallographic environments in Au nanoclusters are probed using 31P NMR. In Chapter 6, solid-state NMR is used to characterize the emergence of metallic behavior in degenerately doped Cu2-xSe nanoparticles as well as to reveal the structural evolution of the particle as a function of this doping.

Penetrating peptides are unique peptides that can translocate across membranes in a non-lytic fashion. A new class of penetrating peptides that can target the mitochondria with high specificity have been developed. Targeting the mitochondria is therapeutically valuable, given the organelle’s role in energy production and apoptosis. The peptide we studied is sufficiently cationic and hydrophobic and is hypothesized to reach the mitochondrial matrix. However, the mechanism of translocation remains unknown. In our work, we use solid state NMR to gain insight into the mechanism of translocation of this mitochondria-penetrating peptide. We use static 31P NMR the membrane morphology and peptide-induced structure changes. The paramagnetic relaxation effect examined through 13C MAS NMR was used for insertion depth determination and to distinguish bilayer sidedness. We found that the peptide does not disrupt the lamellarity. Also, at low peptide concentrations the peptide binds to the outer leaflet and at high concentrations crosses the hydrophobic bilayer core and is distributed in both leaflets. Our findings support the electroporation model of translocation, but we did not observe complete translocation of the peptide. We examine the energy associated with crossing the inner mitochondrial membrane to determine the feasibility of the peptide reaching the mitochondrial matrix.