Figure shows the phase diagrams of the four peptides in solutions with different peptide concentrations and ionic strength values. The phase diagrams indicate that high pH values (10.5>7.4>4.8) promote coacervation, as coacervates form at low ionic strengths and even in solutions with no added salt. The net charge of all four peptides decreases as the pH values increases. The lower charge of the peptides requires lower ionic strength to form coacervates as fewer ions are needed to screen the charges in order to condense the peptides. This behavior can be observed by comparing the coverage of the phase diagrams with the net charge values of the peptides (Figures and). The coacervation capabilities (indicated by a higher coverage of the phase diagrams) are stronger when the peptides have net charges closer to zero. For example, the most favorable conditions for coacervation are found for pep2 at pH 10.5, in which it has a net charge of +0.13. On the other hand, at pH 4.8 pep2 has the highest net charge of all peptides, +2.88, and it cannot form coacervates at the experimental conditions. At pH 4.8, out of the four peptides, pep4 can form coacervates at the lowest ionic strength and peptide concentration, while pep2 does not form coacervates at all. This is in accordance with the peptides' net charge, which is lowest for pep4 (+0.88), intermediate for pep1 and pep3 (+1.88), and highest for pep2 (+2.88). At pH 7.4, pep3 is most capable of forming coacervates due to its low net charge of +0.08, while pep2 is the least capable with a high net charge of +1.07. On the other hand, pep1, which has a net charge of +0.07 is not as capable as pep3 possibly due to its zwitterionic nature (its absolute net charge is 2.07 compared to 0.08 for pep3) (Figure ). Comparing pep4 and pep2 at pH 7.4, which have similar absolute net charges (1.08 and 1.07, respectively), but opposite net charges (-0.92 and +1.07, respectively) shows that pep4 can form coacervates at lower ionic strength values. This suggests that there is some preference for coacervation of negatively charged over positively charged peptides. A possible explanation for this could be interactions formed between the larger phosphate ions from the buffer and pep2, which inhibit its condensation into coacervates. At pH 10.5, pep4, which has the most negative charge out of the four peptides (-1.00), is the least capable of forming coacervates as expected. The results of the phase diagrams at the three pH values indicate that the simple coacervation depends on the ionic nature of the peptides, nonionic peptides (pep2, pH 10.5 and pep3, pH 7.4 and 10.5) having the strongest inclination to form coacervates, followed by negatively charged (pep1, pH 10.5 and and and and and and and). The difference between the coacervation capabilities of the anionic and cationic peptides may be explained by the spread of the charges on the peptides. The negative charge of the anionic peptides is localized to the C-terminus while the positive charges of the cationic peptides are more dispersed on the peptide.