Mixing of oppositely-charged polyelectrolytes in aqueous solution results in phase separation into liquid coacervates or solid precipitates. If one or both polyelectrolytes is grafted to a neutral block, phase separation instead occurs at the microscale, producing micelles, gels, and other structures. Despite many years of investigation, we are not currently able to predict the properties of polyelectrolyte complexes from those of the constituent polymers. I will present results from polyelectrolyte complexation studies of oligonucleotides and cationic peptides. These systems offer the ability to probe the physics of complexation with defined sequence, low polydispersity polymers, and also can provide key insights into intracellular phase separations and delivery of therapeutic nucleic acids. We find that the phase (coacervate vs precipitate) of oligonucleotide-containing complexes is controlled by the hybridization state (single- vs double-stranded) of the nucleic acid, apparently as a result of double-stranded nucleic acids' higher charge density. I will discuss how this, as well as properties such as polymer length, mixing ratio, and salt concentration, influence the properties of both the bulk and micro-phase separated assemblies.

Nucleic acid - peptide complexes and micelles: Phase control and characterization

254th National Meeting (2017)

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