The Physical Chemistry of Biological Systems (CPSysBio) group is dedicated to understanding the physico-chemical mechanisms that govern the architecture and functioning of biological systems, ranging from isolated molecules to cells and tissues. Thanks to our expertise in chemistry, physics, biochemistry, and molecular and cellular biology, we develop analytical strategies and instruments to study mechanisms related to living systems. Our research covers a range of objects from isolated macromolecules (proteins and protein complexes, membrane proteins, biomimetic systems) to cells and tissues. We employ and develop advanced experimental techniques such as absorption and fluorescence spectroscopies (steady-state or time-resolved), fluorescence optical microscopy (video microscopy, FLIM, FRET), and flow cytometry on the SpICy platform or IR nano-spectroscopy coupled with AFM on the MUSIICS platform. Our primarily fundamental research allows us, for example, to elucidate various phenomena such as cell signaling in phagocytes and the assembly of NADPH oxidase, the effect of nanoparticles on cellular response, the role of neuroglobins in carcinogenesis, or tissue biomineralization. These studies pave the way for a better understanding of host-pathogen interactions and the development of new therapies for infectious diseases or the control of oxidative stress. Our research also focuses on the therapeutic applications of nanoparticles in oncology and the analysis of biological samples, aiming at various applications in fields such as analytical chemistry, medicine, radiobiology, and radiochemistry.