Anomalous Diffusion in Biomolecular Condensates

Biomolecular condensates in cells can accumulate signaling molecules and reactants through molecular recognition to compartmentalize vital processes. However, it remains elusive how transport of molecules occurs in biomolecular condensates and how it is related to their viscoelastic state. Herein, building on an established model DNA-condensate system, we report an anomalous diffusion process of short oligonucleotide during their uptake by large DNA-condensates driven by specific binding interaction. In Fickian diffusion, molecules propagate with a blurry front with a square root of time dependence. In contrast, we discovered a fundamentally new type of diffusion with an ultrasharp diffusion front that propagates linearly with time. Similar sharp fronts have been observed in biological systems, but the underlying physics has remained unclear. We therefore believe that our understanding will help to better explain and tune condensate properties and biological functions.