DNA-Polylysine Complex Coacervates

The mechanisms underlying coacervation have been studied by adjusting solution conditions, macromolecular length and weight, and polymer mixing ratios. However, there is a lack of understanding of how the internal flexibility of macromolecules affects coacervation. Nucleic acids provide many advantages for studying this effect because of their ability to form different secondary structures based on their sequences. Within biology, there exists a wide range of secondary structures with varying flexibility, from highly-flexible single-strands to rigid quadruplexes. By using these structures, we can control flexibility, charge density, and sequence heterogeneity. However, despite changing the sequence and structure, we can maintain constant charge and the relevant chemistry for coacervation to occur. Here, we test the ability of a variety of nucleic acid structures to form coacervates by complexing with poly-l-lysine, and we show that more flexible nucleic acid structures are less prone to coacervation at higher salt conditions.