Fig. 2: Formation and characterization of coacervate microdroplet through liquid-liquid phase separation of polyP and simple molecules.

a Diagrams of polyP-Mn coacervate microdroplet formation through LLPS of polyanionic polyP with cation ligand Mn²⁺; b Bright field image of polyP-Mn coacervates. 0.5 mM polyP (P100) was incubated with equal volume of 50 mM MnCl₂. Scale bar, 2 μm; c Phase distribution of the polyP-Mn with respect to polyP concentration and the molar ratio of polyP to Mn²⁺. Green spheres indicate that spherical polyP-Mn droplets were observed, while gray circles represent no coacervate droplets were observed; d Diagrams of polyP-RER coacervate microdroplet formation through LLPS of polyP with cation ligand tripeptide (RER); e Bright field image of polyP-RER coacervates. 0.2 mM polyP (P100) was incubated with equal volume of 20 mM RER. Scale bar, 2 μm; Representative images (b, e) from n = 3 independent experiments; f Phase distribution of the polyP-RER with respect to polyP concentration and the molar ratio of polyP to RER. Green spheres indicate that spherical polyP-RER droplets were observed, while gray circles represent no coacervate droplets were observed; g The distribution of hydrodynamic diameter of polyP-Mn and polyP-RER coacervate microdroplets measured by DLS at 25 °C, pH 7.0. Data are presented as mean ± SD (n = 3 independent experiments); h SEM-EDS images of polyP-based coacervate microdroplets. Upper panel: polyP-Mn coacervate microdroplets. Elemental mapping showed that phosphorus (P), oxygen (O) and manganese (Mn) colocalized inside the coacervate microdroplets. Scale bar, 2.5 μm; Bottom panel: polyP-RER coacervate microdroplets. Elemental mapping showed that phosphorus (P), oxygen (O) and nitrogen (N) colocalized inside the coacervate microdroplets. Scale bar, 1 μm. Representative images (h) from n = 3 independent experiments; i Raman spectra of polyP solution, polyP-Mn and polyP-RER coacervate microdroplets. Source data are provided as a Source Data file.