Abstract: The invention concerns the field of medical devices, more particularly devices for joint extraction, within an organism, of at least one metal cation and at least one target molecule. In order to do this, the device comprises: a) at least one ligand exhibiting specific affinity for the target molecule; b) at least one means for extraction of the metal cation, said means being a perfusion fluid comprising at least one chelating agent, the perfusion fluid being contained in a dialysis or microdialysis system. The use of these devices makes it possible, for example, to prevent and/or treat pathologies linked to dysregulation of the homeostasis of metals and/or target molecules in the organism, for example neurological diseases and/or proteinopathies.