Norman Hascoe Distinguished Lecture Series

The synthesis, functionalization, and study of the physicochemical properties of gold nanoparticles protected by a capping molecular monolayer (monolayer-protected clusters, MPCs) are research areas of crucial importance in nanosciences and nanotechnologies. The final goal is to integrate nanoparticles with biomaterials, eventually making smart nano-biomachines. When the MPC core is limited to a low number of atoms and, the transition between bulk and molecule-like regimes, where electronic band energetics lead to quantum confinement effects, is observed. The monolayer not only protects the core from particle aggregation but also furnishes a way to control the electrochemical, optical, and chemical properties of the MPC itself. Research has mainly focused on simple alkanethiolate monolayers. Our contribution to the field has shown that thiolated oligopeptides based on the alpha-aminoisobutyric acid (Aib) residue allow to form 1-2 nm particles. Because of a strong interchain hydrogen-bond network, these peptide MPCs are very stable. Being very small, they display distinct physicochemical features, also related to the fact that even when short the Aib oligopeptides form a secondary structure, characterized by a strong oriented dipole moment, and display remarkable properties as electron-transfer mediators.