Metallomics and metalloproteomics are emerging fields addressing the role, uptake, transport and storage of trace metals ions both toxic and essential for an organism. Research areas related to the understanding of the mechanisms of life processes associated to metals are covered. Similarly to the genome and proteome terms, metallome was introduced to refer to metalloproteins, metalloenzymes and other metal-containing biomolecules in a biological system. This review aims to give an overview of metal ions behaviour in organisms. The interactions of metals with biomolecules such as amino acids, peptides and protein are the main focus. Special attention is paid to the application of nanotechnology-based techniques using these interactions for medical purposes such as diagnostics, imaging and therapy.