ABSTRACT
Within the large group of nanostructured materials, metal-based nano-objects have prominent optical and structural features; their applications are attracting increasing attention in many research fields. Within metals, the noble metals like gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), rhodium (Rh), and ruthenium (Ru) have the most versatile function. Classical nanoparticles (NPs) can be produced from almost all these mentioned noble metals via different synthesis 290protocols, but there are significantly fewer publications on sub-nanometer-sized noble metal nanoclusters (MeNCs), especially for the last three metals. Metal nanoclusters (MeNCs) typically have a smaller size than ~2 nm and thus provide a bridge between metal atoms and NPs. Because of the unique physico-chemical and structural properties like ultra-small size, easy functionalization, good biocompatibility, excellent photostability, and structure-dependent unique photoluminescence (PL) features, they are extremely important nano-objects for diverse research fields. Among the noble metals, this chapter summarizes the preparation possibilities of mainly Au-, Ag-, and Cu-containing NCs, the interpretation of their structural and optical properties and their potential applications in several biomedical fields are also summarized. This chapter particularly focuses on the presentation of MeNCs as potential sensors for detection of several analytes (metal ions, anions, small (bio)molecules, peptides, proteins, and nucleic acids). Moreover, the possible use of MeNCs for bioimaging/biolabeling, drug delivery, diagnostics, and therapy is also demonstrated.
