In this talk, I will review the physics of the depletion interaction, demonstrating how it can profoundly  influence  the properties of several systems at the interface between bio- and soft-matter physics. This mechanism of “attraction through repulsion”, quite general in multi-component systems where different species intermingle and mutually exclude their volumes, will be  proved to be the key determinant of the complex phase behaviour of colloid-polymer mixtures [1] as well as the responsible for a dramatic change in the conformational and self-entanglement properties of a macromolecule in a crowded environment [2]. To this end, I will also present and discuss some efficient and rigorous coarse-graining methodologies [3] which, retaining  only the relevant degrees of freedom,  allow to explore the large-scale behaviour of these systems while reducing their complexity from a computational  perspective.

[1]G. D’Adamo, A. Pelissetto and C. Pierleoni, J. Chem. Phys. 141, 024902 (2014).
[2]G. D’Adamo and C. Micheletti, Macromolecules 48, 6337 (2015)
[3]G. D’Adamo, A. Pelissetto and C. Pierleoni, Soft Matter, 8, 5151 (2011).