Atomically Monodispersed and Fluorescent Sub-Nanometer Gold Clusters Created by Biomolecule-Assisted Etching of Nanometer-Sized Gold Particles and Rods

Atomically monodispersed gold clusters were synthesized by etching gold nanocrystals (particles and rods) with the assistance of biomolecules (amino acids, peptides, proteins, and DNA) under sonication in water. The resulting gold clusters were exclusively composed of eight atoms, as demonstrated by photoluminescence, optical absorption, electrospray ionization mass spectrometry, and transmission electron microscopy measurements. The gold clusters exhibited solvent-dependent photoluminescence properties when exposed to organic solvents, such as chloroform, tetrahydrofuran, or N,N-dimethylformamide, which was attributed to the rich surface properties of the clusters. This strategy, based on top-down etching, offers an approach to create metal clusters from nanomaterials, which show great potential applications in biological labeling/imaging and sensors that utilize photoluminescence properties as the response.