Al Mesfer, Mohammad, authorKipper, Matthew, advisorSnow, Christopher, committee memberWilson, Jesse, committee member2025-09-012027-08-252025https://hdl.handle.net/10217/241744https://doi.org/10.25675/3.02064Lanthanide ions (Ln3+), such as Tb3+ and Eu3+, possess unique luminescent properties valuable for biological imaging. However, limitations including inefficient direct excitation and challenges in cellular delivery and sensitization hinder their application. Peptide-based complexes offer a promising platform for Ln3+ sensitization, providing biocompatibility and potential genetic encodability. This thesis investigates antenna-modified lanthanide-binding peptides (LBPs) designed to improve Ln3+ sensitization. A known LBP was engineered by replacing its native tryptophan sensitizer with cysteine, enabling site-specific conjugation of aromatic antennas (phenanthroline, pyrene, coumarin) via maleimide chemistry. This strategy aimed to optimize excitation wavelengths (shifting from ~280 nm). Successful bioconjugation was confirmed by MALDI-TOF MS. Spectroscopic analysis revealed distinct antenna-dependent effects on Ln3+ emission. Notably, the phenanthroline conjugate selectively sensitized Eu3+ (~615 nm) but not Tb3+ under identical conditions. Conversely, both pyrene and coumarin conjugates quenched Ln3+ luminescence. Attempts at cellular imaging following intracellular expression of the parent LBP were hindered by limitations in available microscopy instrumentation. Nevertheless, this research validates site-specific antenna conjugation as a strategy for modulating Ln3+ sensitization pathways. The findings provide insights into peptide-lanthanide energy transfer, inform the design of future LBP-based probes, and establish a foundation for subsequent development towards cellular applications.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.TextEmbargo expires: 08/25/2027.