Quantum-sized metallic clusters protected by
biological ligands represent a new class of luminescent materials;
yet the understanding of structural information and photoluminescence origin of these ultrasmall clusters remains a
challenge. Herein we systematically study the surface ligand
dynamics and ligand−metal core interactions of peptide-protected
gold nanoclusters (AuNCs) with combined experimental
characterizations and theoretical molecular simulations. We
show that the peptide sequence plays an important role in
determining the surface peptide structuring, interfacial water
dynamics and ligand−Au core interaction, which can be tailored
by controlling peptide acetylation, constituent amino acid electron donating/withdrawing capacity, aromaticity/hydrophobicity
and by adjusting environmental pH. Specifically, emission enhancement is achieved through increasing the electron density of
surface ligands in proximity to the Au core, discouraging photoinduced quenching, and by reducing the amount of surfacebound water molecules. These findings provide key design principles for understanding the surface dynamics of peptideprotected nanoparticles and maximizing the photoluminescence of metallic clusters through the exploitation of biologically
relevant ligand properties