Maybe an obvious question: what is the technology to see phase separation in living cells? Any technology to probe for extracellular condensates?

Phase separation in living cells is typically visualized using fluorescence microscopy techniques such as confocal, lattice light-sheet, or super-resolution (e.g., STED, SIM) imaging with fluorescently tagged proteins. These allow observation of droplet-like condensates, fusion events, and dynamic exchange.

Dynamic properties are probed by FRAP (fluorescence recovery after photobleaching) to measure molecular mobility within condensates, and FCS (fluorescence correlation spectroscopy) or XPCS (X-ray photon correlation spectroscopy) for nanoscale dynamics.

For extracellular condensates, detection is more challenging. Emerging tools include cryo-electron tomography, atomic force microscopy (AFM), and phase-sensitive light scattering or Raman imaging to detect biomolecular clustering in extracellular fluids or matrices. Extracellular vesicle–like condensates and secreted protein droplets are also being explored using label-free imaging (OCT, DIC) and microfluidic confinement assays.