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Uncommon Structures of Oppositely Charged Hyaluronan/Surfactant Assemblies under Physiological Conditions.
Biomacromolecules ( IF 6.2 ) Pub Date : 2020-07-27 , DOI: 10.1021/acs.biomac.0c00221
Philipp Buchold 1, 2 , Maor Ram-On 3 , Yeshayahu Talmon 3 , Ingo Hoffmann 2 , Ralf Schweins 2 , Michael Gradzielski 1
Affiliation  

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.

中文翻译:

在生理条件下带相反电荷的透明质酸/表面活性剂组合的不常见结构。

通过光散射(LS),小角度中子研究了由半稀释聚阴离子透明质酸(透明质酸,HA)和带相反电荷的表面活性剂十四烷基三甲基溴化铵(TTAB)在磷酸盐缓冲盐水(PBS)溶液中形成的自组装聚集体。散射(SANS)和低温透射电子显微镜(cryo-TEM)。在PBS缓冲液中的27.7 mM(单体,1 wt%)HA溶液(597 kDa)中添加0–20 mM TTAB会形成可溶性复合物,直到在电荷平衡附近(> 20 mM TTAB)发生相分离为止。虽然粘度保持相当恒定,但已经加入少量的TTAB会导致形成较大的球状上部结构,这些结构是由TTA胶束沿刚性HA链的局部线状结构排列以分层方式构建的,在变化不大的HA网络中。这些球状区域的半径为60–100 nm,并包含500–700 TTA胶束,这意味着它们非常“蓬松”,由约99%的水组成。在进一步添加TTAB时,它们的大小或数量不会增加,但是,其他TTA胶束会在大球状结构域之外形成其他线状复合物。这种类型的聚电解质-表面活性剂复合物(PESCs)之前未曾描述过,并且必须归因于HA的特殊性质,即HA具有高刚度和与带相反电荷的胶束的相对较弱的相互作用,这是由于带电的羧基接近于多糖主链。这些发现表明,溶液中的HA网络结构基本上不受与带相反电荷的表面活性剂络合的影响,
更新日期:2020-09-14
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