Recent technological developments have expanded and intensified the use of metals in domains as diverse as renewable energy, computing, and medicine. Among those metals, technology-critical elements (TCEs, including lanthanides) are essential, but scarcer or produced by only a handful of countries. On the other end of their lifecycle, recycling and disposal of technological waste also raise the question of the impact of these metals on environment and human health. Understanding the mechanisms of interaction of TCEs with life could inform the development of bio-inspired technologies and innovative strategies for their extraction, recycling, and remediation. Nevertheless, identifying protein-metal interactions remains challenging due to the transient character of this interaction. Here, we propose a modular approach for the labelling of proteins interacting with lanthanides. We will synthesize molecular probes composed of a detection module for the metal, a tag module to label the interacting protein, and an activatable linker that will enable the labelling of the protein only if interacting with a metal. We will then assess the efficacy of those probes in vitro on isolated proteins. Finally, once a proof-of-concept is established, we will apply these chemical tools to investigate the metal interactome in mammalian cells. We will thus decipher what are the key biological interactors of TCEs, their roles in living systems and the features that enable efficient binding to metals. We expect that our findings will give insights into the toxicology of those elements and inform environmental and occupational safety policies. On the longer term, new bio-inspired strategies for their extraction, recycling, decorporation and remediation will arise from the molecular understanding of metal-life interactions, enabling a well thought-out usage of these elements to support the environmental and numerical transitions.