The interior of a cell is dense and crowded with polydisperse molecules, and subjected to biochemical activity that fluidizes it. Crowding and activity endow the intracellular milieu with specific properties. In particular, using single-particle tracking of genetically-encoded nanoparticles, we found that particle diffusion is not Brownian in vivo. Many reasons can explain this non-Brownian diffusion, such as particle interactions, the type of biochemical noise, or local heterogeneities due to the ultrastructure of the cytoplasm. The purpose of this internship is to study and model, using in vitro systems, how nanoparticles can diffuse in a cytoplasmic extract, as a controllable surrogate for a real cell.