Biological colloids: Unique properties of membraneless organelles in the cell

Biomolecular condensates are membraneless, intracellular organelles that form via liquid-liquid phase separation (LLPS) and have the ability to concentrate a wide range of molecules in the cellular milieu. These organelles are highly dynamic and play pivotal roles in cellular organization and physiology. Many studies also link the formation and misregulation of condensates to diseases such as neurodegenerative disorders and cancer. Biomolecular condensates represent a special type of colloids that actively interact with their environment to sustain physiological functions, due to which their misregulation may upset cell signaling, resulting in pathological states. In this review, we discuss the mechanisms underlying the formation, dynamics, and evolution of these biological colloids, with a special focus on their surface properties that are critical in their interaction with other components of the cell. We also summarize experimental approaches that enable the detailed characterization of the formation, interactions, and functions of these cellular colloidal organelles.