Ligand impact on reactive oxygen species generation of Au10 and Au25 nanoclusters upon one- and two-photon excitation
Hussein Fakhouri, Martina Perić Bakulić, Issan Zhang, Hao Yuan, Dipankar Bain, Fabien Rondepierre, Pierre‐François Brevet, Željka Sanader Maršić, Rodolphe Antoine, Vlasta Bonačić‐Koutecký, Dušica Maysinger
Abstract
Abstract In photodynamic therapy (PDT), light-sensitive photosensitizers produce reactive oxygen species (ROS) after irradiation in the presence of oxygen. Atomically-precise thiolate-protected gold nanoclusters are molecule-like nanostructures with discrete energy levels presenting long lifetimes, surface biofunctionality, and strong near-infrared excitation ideal for ROS generation in PDT. We directly compare thiolate-gold macromolecular complexes (Au 10 ) and atomically-precise gold nanoclusters (Au 25 ), and investigate the influence of ligands on their photoexcitation. With the ability of atomically-precise nanochemistry, we produce Au 10 SG 10 , Au 10 AcCys 10 , Au 25 SG 18 , and Au 25 AcCys 18 (SG: glutathione; AcCys: N-acetyl-cysteine) fully characterized by high-resolution mass spectrometry. Our theoretical investigation reveals key factors (energetics of excited states and structural influence of surface ligands) and their relative importance in singlet oxygen formation upon one- and two-photon excitation. Finally, we explore ROS generation by gold nanoclusters in living cells with one- and two-photon excitation. Our study presents in-depth analyses of events within gold nanoclusters when photo-excited both in the linear and nonlinear optical regimes, and possible biological consequences in cells.