Stretch-Induced Helical Conformations in Poly(l-lysine)/Hyaluronic Acid Multilayers

Abstract

We investigate the effect of stretching on the secondary structure of cross-linked poly(l-lysine)/hyaluronic acid (PLL/HA) multilayers. We show that stretching these films induces changes in the secondary structure of PLL chains. Our results suggest that not only α- but also 310-helices might form in the film under stretching. Such 310-helices have never been observed for PLL so far. These changes of the secondary structure of PLL are reversible, i.e., when returning to the nonstretched state one recovers the initial film structure. Using molecular dynamics simulations of chains composed of 20 l-lysine residues (PLL20), we find that these chains never adopt a helical conformation in water. In contrast, when the end-to-end distance of the chains is restrained to values smaller than the mean end-to-end distance of free chains, a distance domain rarely explored by the free chains, helical conformations become accessible. Moreover, the formation of not only α- but also 310-helices is predicted by the simulations. These results suggest that the change of the end-to-end distance of PLL chains in the stretched film is at the origin of the helix formation.

Unexpected Bactericidal Activity of Poly(arginine)/Hyaluronan Nanolayered Coatings

“…The spectra with two minima are typical of α-helix conformations. They cannot be attributed to HA chains, as it is known that in solution at pH 7.4 HA has an unordered conformation . This indicates that PAR chains should change from a coil conformation in solution to an α-helix in the film.…”

“…They cannot be attributed to HA chains, as it is known that in solution at pH 7.4 HA has an unordered conformation. 30 This indicates that PAR chains should change from a coil conformation in solution to an α-helix in the film. A similar behavior was previously observed for LbL built up with poly(lysine) and poly(glutamic acid).…”

Hyaluronan/Poly-L-lysine/Berberine Nanogels for Impaired Wound Healing

“…Indeed, the pKa of HA in solution is reported to be 3.0 and that of PL about 10 [29]. Moreover, it is reported that PL presents secondary structures that vary with pH in aqueous solution, adopting a random coil conformation under acidic and neutral conditions, and undergoing a coil-to helix transition under basic conditions [41]. Thus, we assumed that PL conformation at pH 6 is essential for maximizing PL interactions with HA.…”

Photoresponsive Nanometer-Scale Iron Alginate Hydrogels: A Study of Gel–Sol Transition Using a Quartz Crystal Microbalance

“…The design of novel functional biomaterials is nowadays focused on the employment of biobased polymers capable of responding to external stimulus, such as magnetic fields, − temperature, − pH, , light, , electrochemical potentials, and mechanical signals , in a well-controlled manner . Stimuli-responsive hydrogels are widely employed in different applications such as drug delivery, tissue engineering, sensors, actuators, and energy storage .…”