Though creation and characterization of water soluble luminescent silver nanodots were achieved only in the past decade, a large variety of emitters in diverse scaffolds have been reported. Photophysical properties approach those of semiconductor quantum dots, but relatively small sizes are retained. Because of these properties, silver nanodots are finding ever-expanding roles as probes and biolabels. In this critical review we revisit the studies on silver nanodots in inert environments and in aqueous solutions. The recent advances detailing their chemical and physical properties of silver nanodots are highlighted with an effort to decipher the relations between their chemical/photophysical properties and their structures. The primary results about their biological applications are discussed here as well, especially relating to their chemical and photophysical behaviours in biological environments (216 references).

Emissive f-block coordination complexes constitute an important class of optical probes, with applications ranging from sensing of bioactive species, high throughput assays and screening protocols in vitro, to time-resolved imaging studies in cellulo or in vivo. The key chemistry issues to be addressed in complex design and characterisation are defined, with an emphasis on the use of emissive europium and terbium complexes and their conjugates in molecular imaging. Both luminescent ‘tags’ useful in energy transfer studies and ‘responsive’ systems for sensing are discussed.

DNA‐encapsulated silver clusters are readily conjugated to proteins and serve as alternatives to organic dyes and semiconductor quantum dots. Stable and bright on the bulk and single molecule levels, Ag nanocluster fluorescence is readily observed when staining live cell surfaces. Being significantly brighter and more photostable than organics and much smaller than quantum dots with a single point of attachment, these nanomaterials offer promising new approaches for bulk and single molecule biolabeling.