Cossairt, Brandi MLowe, Christopher2026-04-202026-04-202026-04-202026Lowe_washington_0250E_29256.pdfhttps://hdl.handle.net/1773/55456Thesis (Ph.D.)--University of Washington, 2026Chiral CdE (E=S, Se, Te) nanocrystals (NCs) are an emerging class of materials with potential applications in optoelectronics, bioimaging, and sensing. Among the strategies for generating chiral CdE NCs, which include 1) chiral molecule templated nucleation and growth, 2) assembly of CdE NCs into chiral arrangements, and 3) chiral ligand exchange on the surface of the NCs, the latter is most attractive for biological applications because it enables direct interfacing between high-quality NCs and chiral biomolecules. Although ligand exchange with cysteine has been shown to induce chirality in CdE NCs, no prior studies have demonstrated the use of intrinsically chiral biomolecules, like peptides and proteins, to generate chiroptical responses in these materials. Chapter 1 reviews the synthetic tunability of CdE NCs and current approaches of synthesizing chiral nanostructures. It then introduces the structural complexity of biomolecules and highlights existing strategies for assembling hybrid biomolecule:CdE systems. The relevant chiral length scales of proteins and NCs are compared, motivating an interfacing strategy that couples biomolecular chirality with the surface-sensitive electronic structure of CdE NCs. Chapter 2 establishes an aqueous ligand exchange process in which glycine (the only achiral amino acid) serves as a versatile intermediate for displacement by cysteine (Cys)-containing elastin-like polypeptides. This exchange results in clear chirality transfer, evidenced by circular dichroism (CD) signals at the QD electronic transitions. The resulting polypeptide-bound QDs also exhibit thermally reversible coacervation, characterized by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Chapter 3 extends this glycine-mediated exchange strategy to CdS nanorods (NRs) and examines how Cys concentration and local coordination environment influence NR optical properties, including UV-Vis absorbance, CD, and photoluminescence. These studies reveal that Cys derivatives can be detected at µM concentrations and suggest that both internal and n-terminal Cys residues are capable of inducing strong chiroptical responses. Chapter 4 applies these insights to protein-induced chirality in glycine-capped CdS NRs of two lengths. Incubation with a designed helical repeat protein containing four internal Cys residues (DHR-4Cys) rapidly displaces glycine and produces CD signals corresponding to the NR electronic transitions. NR length is found to have minimal influence on the resulting g-factors. TEM analysis reveals a substantial protein-derived ligand shell, and secondary structure analysis confirms that the protein remains folded upon binding. Remarkably, induced chirality is observed at nM protein loadings, corresponding to roughly two proteins per NR. This work represents the first demonstration of chirality induction in CdE NCs using an ordered protein scaffold.application/pdfen-USnonebiomoleculeschiralityhybrid materialsnanocrystalsInorganic chemistryChemistryThesis