Complex coacervation of hyaluronic acid and chitosan: effects of pH, ionic strength, charge density, chain length and the charge ratio
Complex coacervation of hyaluronic acid and chitosan: effects of pH, ionic strength, charge density, chain length and the charge ratio
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DOI：
10.1039/c5sm01829c
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发表时间：
2015-01-01
期刊：
影响因子：
3.4
通讯作者：
Iyilik, E. Kilic
中科院分区：
文献类型：
--
作者：
Kayitmazer, A. B.;Koksal, A. F.;Iyilik, E. Kilic
透明质酸(HA)和壳聚糖(CH)可以形成纳米粒子、水凝胶、微球、海绵和薄膜，所有这些都具有广泛的生物医学应用。这种不同的物相反映了HA/CH复合体的多种途径。在这里，我们使用浊度法，动态光散射，光学显微镜和Zeta电位测量表明，密相的状态取决于HA羧基和CH胺的摩尔比，并强烈依赖于它们各自的电离度，α和β。由于HA和CH之间的电荷互补性很强，静电自组装在很酸性的pH下发生，但在离子强度(I)&Gt；=1.5M氯化钠时几乎看不到。所有体系在浊度的i依赖关系上都表现出不连续性，对应于从凝聚物到絮凝物的转变。聚合物链长或电荷密度的增加都会增强相分离。值得注意的是，非化学计量比的凝聚悬浮液形成的Zeta电位远离零。这一结果归因于链的半柔性的熵效应以及两个生物聚合物之间的电荷不匹配。
Hyaluronic acid (HA) and chitosan (CH) can form nanoparticles, hydrogels, microspheres, sponges, and films, all with a wide range of biomedical applications. This variety of phases reflects the multiple pathways available to HA/CH complexes. Here, we use turbidimetry, dynamic light scattering, light microscopy and zeta potential measurements to show that the state of the dense phase depends on the molar ratio of HA carboxyl to CH amines, and is strongly dependent on their respective degrees of ionization, alpha and beta. Due to the strong charge complementarity between HA and CH, electrostatic self-assembly takes place at very acidic pH, but is almost unobservable at ionic strength (I) >= 1.5 M NaCl. All systems display discontinuity in the I-dependence of the turbidity, corresponding to a transition from coacervates to flocculates. An increase in either polymer chain length or charge density enhances phase separation. Remarkably, non-stoichiometric coacervate suspensions form at zeta potentials far away from zero. This result is attributed to the entropic effects of chain semi-flexibility as well as to the charge mismatch between the two biopolymers.