After a PhD devoted to the mechanistic studies of non-heme iron enzymes, lipoxygenases, my post-doctoral position was in the laboratory of Professor Larry Que Jr. in the Department of Chemistry (Minneapolis, USA), working on mechanistic and spectroscopic studies of non-heme metalloproteins such as catechol dioxygenase. I obtained a full-time scientist position in Grenoble in 1994 where I started to work on binuclear manganese metalloproteins before focusing my research on metalloregulators such as the ferric uptake regulator (FUR) and NikR involved in bacterial metal homeostasis. I was in charge of the Biology of Metals Group for 12 years. Metallic cations are bound to a set of biomolecules that control their detection, transport, bioavailability and, when available, their intracellular storage. The cellular homeostasis of these metals is finely regulated at the level of gene expression and protein synthesis. My main goals are the understanding of the molecular and cellular mechanisms responsible for transport and regulatory sensing events of metal ions, which are all essential, and whose homeostasis is tightly controlled in prokaryotic and eukaryotic cells. I am also interested in understanding how metallic stresses, generated either by toxic metals (such as Cd) or by metallic nanoparticles, interfere with the homeostasis of physiological metals (Cu, Zn, and Fe). My work on metallic nanoparticles ranges from safer-by-design to mechanistic toxicology.