RT Journal Article
SR Electronic
T1 Connecting the stimuli-responsive rheology of biopolymer hydrogels to underlying hydrogen-bonding interactions
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.07.27.222802
DO 10.1101/2020.07.27.222802
A1 Giulia Giubertoni
A1 Federica Burla
A1 Huib J. Bakker
A1 Gijsje H. Koenderink
YR 2020
UL http://biorxiv.org/content/early/2020/07/27/2020.07.27.222802.abstract
AB Many biopolymer hydrogels are environmentally responsive because they are held together by physical associations that depend on pH and temperature. Here we investigate how the pH and temperature response of the rheology of hyaluronan hydrogels is connected to the underlying molecular interactions. Hyaluronan is an essential structural biopolymer in the human body with many applications in biomedicine. Using two-dimensional infrared (2DIR) spectroscopy, we show that hyaluronan chains become connected by hydrogen bonds when the pH is changed from 7.0 to 2.5, and that the bond density at pH 2.5 is independent of temperature. Temperature-dependent rheology measurements show that due to this hydrogen bonding the stress relaxation at pH 2.5 is strongly slowed down in comparison to pH 7.0, consistent with the sticky reptation model of associative polymers. From the flow activation energy we conclude that each polymer is crosslinked by multiple (5-15) hydrogen bonds to others, causing slow macroscopic stress relaxation, despite the short time scale of breaking and reformation of each individual hydrogen bond. Our findings can aid the design of stimuli-responsive hydrogels with tailored viscoelastic properties for biomedical applications.Competing Interest StatementThe authors have declared no competing interest.