Going straight to the point, upper one-phase region was suitable area to incorporate IgG to PLL/ATP system droplets. Surprisingly, no incorporation of IgG into PLL/ATP droplets was observed in the original two-phase region, whereas in the PLL richer area, which originally showed no phase separation, IgG droplets were formed (Figure ). PLL was located according to its autofluorescence, which results from the interand intra-hydrogen bonding network of PLL molecules. IgG molecules dispersed or aggregated in almost all of original two phase (Figure ). As an exception, at an ATP final concentration of 0.14 M, IgG molecules were gathered on the droplet surface, causing PLL/ATP droplet aggregation (Figure and).