Self-Emergent Protocells Generated in an Aqueous Solution with Binary Macromolecules through Liquid-Liquid Phase Separation.

Recently, regarding plausible mechanisms for the generation of microstructures inside cells, liquid-liquid phase separation (LLPS) has attracted considerable attention among researchers in the life sciences. LLPS occurs through multiple nonspecific interactions and does not always require a key-lock interaction with a binary macromolecular solution. The remarkable features of LLPS include the non-uniform localization and concentration of solutes, resulting in the ability to isolate certain chemical systems and thereby parallelize multiple chemical reactions within the limited space of a living cell. We report that in the presence of phospholipids, cell-sized liposomes are spontaneously formed in an aqueous solution, which exhibit the properties of LLPS, by using the macromolecules polyethylene glycol (PEG) and dextran. In this system, LLPS is generated through the depletion effect of macromolecules. The results showed that cell-like micro-droplets entrapping DNA wrapped by a phospholipid layer emerge in a self-organized manner.