Fig. 1: Evaporation-triggered segregative LLPS inside the all-aqueous sessile droplet.
a Schematic drawing of early genetic molecule compartmentalization inside the evaporating aqueous droplets. According to timeline of the early history of life, the Pre-RNA world and RNA world may have occurred at 3.8–4.0 Gya77, with the first RNA polymers formed in warm little ponds78. Silica-rich surface could serve as the reactor that supports various prebiotic reactions such as the polymerization of the polynucleotides;42,79 b, d Phase diagrams of PEG and dextran mixtures. The red solid line is the binodal curve that distinguishes the single-phase region and the two-phase coexistence region. The arrowed line represents the tie line of ATPS, along which a mixture undergoes liquid-liquid phase separation (LLPS) and forms a PEG-rich phase and a dextran-rich phase. The star represents the composition of the sessile droplet, with 5 wt% PEG–10 wt% dextran in (b) and 9 wt% PEG–4 wt% dextran in (d); c Phase-separated pattern evolution inside an evaporating droplet of regime 1, shown in both bright-field image sequence and fluorescence image sequence, respectively; The dextran-rich phase is labeled by fluorescein isothiocyanate-dextran (FITC-dextran, green) and PEG-rich phase is labeled by Rhodamine B (red). e Phase-separated pattern evolution inside an evaporating droplet of regime 2, shown in bright-field image sequence and fluorescence image sequence, respectively; The fluorescence labeling is the same with that in (c). For c and e, images are obtained over analysis of seven independent trials with relative humidity ranging from 55 to 65%. The scale bar is 500 μm.
