Asymmetric collapse in biomimetic complex coacervates revealed by local polymer and water dynamics.

TitleAsymmetric collapse in biomimetic complex coacervates revealed by local polymer and water dynamics.
Publication TypeJournal Article
Year of Publication2013
AuthorsOrtony, JH, Hwang, DSoo, Franck, JM, Waite, JH, Han, S
Date Published2013 May 13
KeywordsAmino Acid Sequence, Animals, Biomimetic Materials, Electron Spin Resonance Spectroscopy, Hyaluronic Acid, Hydrogen-Ion Concentration, Magnetic Resonance Spectroscopy, Molecular Sequence Data, Mytilus edulis, Recombinant Proteins, Rheology, Spin Labels, Static Electricity, Water

Complex coacervation is a phenomenon characterized by the association of oppositely charged polyelectrolytes into micrometer-scale liquid condensates. This process is the purported first step in the formation of underwater adhesives by sessile marine organisms, as well as the process harnessed for the formation of new synthetic and protein-based contemporary materials. Efforts to understand the physical nature of complex coacervates are important for developing robust adhesives, injectable materials, or novel drug delivery vehicles for biomedical applications; however, their internal fluidity necessitates the use of in situ characterization strategies of their local dynamic properties, capabilities not offered by conventional techniques such as X-ray scattering, microscopy, or bulk rheological measurements. Herein, we employ the novel magnetic resonance technique Overhauser dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP), together with electron paramagnetic resonance (EPR) line shape analysis, to concurrently quantify local molecular and hydration dynamics, with species- and site-specificity. We observe striking differences in the structure and dynamics of the protein-based biomimetic complex coacervates from their synthetic analogues, which is an asymmetric collapse of the polyelectrolyte constituents. From this study we suggest charge heterogeneity within a given polyelectrolyte chain to be an important parameter by which the internal structure of complex coacervates may be tuned. Acquiring molecular-level insight to the internal structure and dynamics of dynamic polymer complexes in water through the in situ characterization of site- and species-specific local polymer and hydration dynamics should be a promising general approach that has not been widely employed for materials characterization.

Alternate JournalBiomacromolecules
PubMed ID23540713
PubMed Central IDPMC4090114
Grant ListR01 DE018468 / DE / NIDCR NIH HHS / United States
R01 DE018468 / DE / NIDCR NIH HHS / United States