Quantcast

Electrostatic Effects on the Conformation and Elasticity of Hyaluronic Acid, a Moderately Flexible Polyelectrolyte

Research paper by John P. Berezney, Omar A. Saleh

Indexed on: 25 Jan '17Published on: 24 Jan '17Published in: Macromolecules



Abstract

Hyaluronic acid (HA) is a charged polysaccharide with an intrinsic stiffness intermediate between flexible and semiflexible polymers. To investigate the interplay of that stiffness with solution electrostatic interactions, we perform single-molecule stretching measurements on HA over 4 decades of monovalent ionic strength. We observe a low-force (<1 pN), salt-sensitive swollen (Pincus) elasticity regime and use a rescaling analysis to show that the data are inconsistent with a quadratic, “OSF” dependence of the chain’s persistence length on the solution Debye length. Instead, the persistence length varies nearly linearly with Debye length. The chain’s high-force (1–10 pN) elastic response deviates from exact worm-like chain models, even after accounting for electrostatic effects; the failure of these models emphasizes the utility of both low-force data and a robust scaling-based analysis scheme. Our results give insight into electrostatic effects in an intermediately stiff polymer as well as demonstrating elastic phenomena that could impact understanding of HA’s mechanobiological roles.

Figure 10.1021/acs.macromol.6b02166.1.jpg
Figure 10.1021/acs.macromol.6b02166.2.jpg
Figure 10.1021/acs.macromol.6b02166.3.jpg
Figure 10.1021/acs.macromol.6b02166.4.jpg