Multiphase Water-in-Oil Emulsion Droplets for Cell-Free Transcription–Translation

The construction of genetically encoded cellular mimics in compartments containing organized synthetic cytosols is desirable for the development of artificial cells. Phase separated aqueous domains were placed within water-in-oil emulsion droplets in a manner compatible with transcription and translation machinery. Aqueous two-phase and three-phase systems (ATPS and A3PS) were assembled with dextran, poly(ethylene glycol), and Ficoll. Aqueous two-phase systems were capable of supporting the cell-free expression of protein within water droplets, whereas the aqueous three-phase-based system did not give rise to detectable protein synthesis. The expressed protein preferentially partitioned to the dextran-enriched phase. The system could serve as a foundation for building cellular mimics with liquid organelles.