MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Biomacromolecules. 2011 Apr 11;12(4):1322-31. doi: 10.1021/bm200070k. Epub 2011 Mar 25.
In this study, we investigate the growth and internal properties of polyelectrolyte multilayer films made of poly(l-lysine) and hyaluronan (PLL/HA) under pH-amplified conditions, that is, by alternate deposition of PLL at high pH and HA at low pH. We focus especially on the influence of the molecular weight of HA in this process as well as on its concentration in solution. Film growth was followed by quartz crystal microbalance and by infrared spectroscopy to quantify the deposited mass and to characterize the internal properties of the films, including the presence of hydrogen bonds and the ionization degree of HA in the films. Film growth was significantly faster for HA of high molecular weight (1300 kDa) as compared with 400 and 200 kDa. PLL was found to exhibit a random structure once deposited in the films. Furthermore, we found that PLL-ending films are more stable when they are placed in PBS than their HA counterparts. This was explained on the basis of more cohesive interactions in the films for PLL-ending films. Finally, we quantified PLL(FITC) diffusion into the films and observed that PLL diffusion is enhanced when PLL is paired with the HA of high MW. All together, these results suggest that besides purely physicochemical parameters such as variation in pH, the molecular weight of HA, its concentration in solution, and the possibility to form intermolecular HA association play important roles in film growth, internal cohesion, and stability.
在这项研究中，我们研究了在 pH 放大条件下由聚赖氨酸（PLL）和透明质酸（HA）制成的聚电解质多层膜的生长和内部特性，即在高 pH 下交替沉积 PLL 和在低 pH 下交替沉积 HA。我们特别关注在此过程中 HA 的分子量以及其在溶液中的浓度的影响。通过石英晶体微天平和红外光谱法来跟踪薄膜的生长，以定量沉积的质量并表征薄膜的内部特性，包括氢键的存在以及薄膜中 HA 的离解度。与分子量为 400 和 200 kDa 的 HA 相比，高分子量（1300 kDa）的 HA 的薄膜生长速度明显更快。一旦沉积在薄膜中，PLL 就会呈现出无规结构。此外，我们发现将 PLL 末端的薄膜置于 PBS 中比 HA 末端的薄膜更稳定。这是基于 PLL 末端的薄膜具有更具内聚性的相互作用来解释的。最后，我们定量了 PLL（FITC）扩散到薄膜中的情况，并观察到当 PLL 与高分子量的 HA 配对时，PLL 扩散会增强。总之，这些结果表明，除了 pH 变化等纯物理化学参数外，HA 的分子量、其在溶液中的浓度以及形成分子间 HA 缔合的可能性在薄膜生长、内部内聚性和稳定性方面也起着重要作用。
