Tiny droplets inside your cells have these 'ghost walls' that decide exactly which molecules can get in and which stay out.
March 27, 2026
Original Paper
Interfacial Permeability, Reflectivity and Preferential Internal Mixing of Phase-Separated Condensates
arXiv · 2603.25447
The Takeaway
Cells organize their internal chemistry using 'condensates'—liquid blobs that lack a physical membrane. This study shows these droplets possess a 'biased reflectivity' at their surface, allowing them to selectively bounce certain molecules away while locking others inside, acting like a physical container without actually being one.
From the abstract
Biomolecular condensates organize biochemical processes by spatially concentrating molecules while allowing for dynamic exchange with their surroundings. However, transport across their interface can be strongly attenuated, leading to enhanced retention and preferential internal mixing. Two key mechanisms have been proposed to describe this behavior: biased interfacial reflectivity, which compares how strongly particles are reflected at the interface when attempting to enter or leave the condens