Uncommon Structures of Oppositely Charged Hyaluronan/Surfactant Assemblies under Physiological Conditions

Abstract

Self-assembled aggregates formed by semidilute polyanion hyaluronan (hyaluronic acid, HA) and an oppositely charged surfactant tetradecyltrimethylammonium bromide (TTAB) in an aqueous phosphate-buffered saline (PBS) solution have been studied via light scattering (LS), small-angle neutron scattering (SANS), and cryogenic transmission electron microscopy (cryo-TEM). The addition of 0−20 mM TTAB to a 27.7 mM (monomer, 1 wt %) HA solution (597 kDa) in PBS buffer leads to soluble complexes until phase separation occurs near charge equilibrium (>20 mM TTAB). While the viscosity remains rather constant, already small amounts of added TTAB lead to the formation of large globular superstructures, which are built in a hierarchical fashion from a locally threadlike structural arrangement of TTA micelles along the stiff HA chains, within the little changed HA network. These globular domains have radii of 60−100 nm and contain 500−700 TTA micelles, which means that they are very "fluffy" and composed of about 99% water. They do not grow in size or number upon further TTAB addition, but, instead, the additional TTA micelles form further threadlike complexes outside of the big globular domains. Such a type of polyelectrolyte−surfactant complexes (PESCs) has not been described before and has to be attributed to the particular properties of HA, which are high stiffness and relatively weak interactions with oppositely charged micelles due to having the charged carboxylic group close to the polysaccharide backbone. These findings demonstrate that the HA network structure in solution basically remains unaffected by complexation with an oppositely charged surfactant, explaining the unchanged rheological behavior and the formation of a unique PESC local "coacervate" structure within the HA hydrogel network.

Insights into Extended Structures and Their Driving Force: Influence of Salt on Polyelectrolyte/Surfactant Mixtures at the Air/Water Interface

“…The effect of chain stiffness on interfacial structures of polymer/amphiphile complexes is of high relevance for natural polymers like proteins, polysaccharides, and DNA. Usually, natural polymers are stiffer than simple synthetic ones and show a large variety in bulk and interfacial structures. , …”

“…Usually, natural polymers are stiffer than simple synthetic ones and show a large variety in bulk and interfacial structures. 59,60 ■ ASSOCIATED CONTENT * sı Supporting Information…”

Viscosity of Polyelectrolyte Surfactant Complexes—The Importance of the Choice of the Polyelectrolyte Seen for the Case of PDADMAC Versus JR 400

“…For example, mixtures of sodium hyaluronate (HA) and the cationic surfactant tetradecyl trimethylammonium bromide either lead to precipitation or have virtually no effect on the viscosity compared to the pure HA solution. 43 This indicates that in this system, the already present HA network in solution is hardly affected by the presence of the oppositely charged surfactant, a strikingly different behavior compared to that of the sodium dodecylsulfate (SDS)/JR 400 system.…”

“…However, even though the relation between the mesoscopic structure and the macroscopic behavior of individual systems is well understood, there is no general understanding why some PESCs show such a remarkable increase in viscosity, while others, which seem rather similar at first sight, do not show any comparable effects. For example, mixtures of sodium hyaluronate (HA) and the cationic surfactant tetradecyl trimethylammonium bromide either lead to precipitation or have virtually no effect on the viscosity compared to the pure HA solution . This indicates that in this system, the already present HA network in solution is hardly affected by the presence of the oppositely charged surfactant, a strikingly different behavior compared to that of the sodium dodecylsulfate (SDS)/JR 400 system.…”

Optimal Scheduling Model of WDM/OTN Network Transmission Line Based on Machine Learning

“…A routing object corresponds to a complete planned link, but it does not describe the content of the specific routing link, but only describes the basic information of the route mainly attributes such as whether the optical channel to which it belongs is a working route or a protection route. (3) Routing Link Segment [10]. It describes a segment of a link in a route, including attributes such as the route to which it belongs, the link sequence number, and the channel used.…”