Kang Ningxi, Policova Zdenka, Bankian Gelareh, Hair Michael L, Zuo Yi Y, Neumann A Wilhelm, Acosta Edgar J
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, Canada M5S 3E5.
Biochim Biophys Acta. 2008 Jan;1778(1):291-302. doi: 10.1016/j.bbamem.2007.10.003. Epub 2007 Oct 14.
The interaction between a cationic polyelectrolyte, chitosan, and an exogenous bovine lung extract surfactant (BLES) was studied using dynamic compression/expansion cycles of dilute BLES preparations in a Constrained Sessile Drop (CSD) device equipped with an environmental chamber conditioned at 37 degrees C and 100% R.H. air. Under these conditions, dilute BLES preparations tend to produce variable and relatively high minimum surface tensions. Upon addition of "low" chitosan to BLES ratios, the minimum surface tension of BLES-chitosan preparations were consistently low (i.e. <5 mJ/m2), and the resulting surfactant monolayers (adsorbed at the air-water interface) were highly elastic and stable. However, the use of "high" chitosan to BLES ratios induced the collapse of the surfactant monolayer at high minimum surface tensions (i.e. >15 mJ/m2). The zeta potential of the lung surfactant aggregates in the subphase suggests that chitosan binds to the anionic lipids (phosphatidyl glycerols) in BLES, and that this binding is ultimately responsible for the changes in the surface activity (elasticity and stability) of these surfactant-polyelectrolyte mixtures. Furthermore the transition from "low" to "high" chitosan to BLES ratios correlates with the flocculation and de-flocculation of surfactant aggregates in the subphase. It is proposed that the aggregation/segregation of "patches" of anionic lipids in the surfactant monolayer produced at different chitosan to BLES ratios explains the enhancing/inhibitory effects of chitosan. These observations highlight the importance of electrostatic interactions in lung surfactant systems.
使用配备有环境舱（温度为37摄氏度，相对湿度为100%）的受限 sessile 滴（CSD）装置，通过稀释的牛肺提取物表面活性剂（BLES）制剂的动态压缩/膨胀循环，研究了阳离子聚电解质壳聚糖与外源性牛肺提取物表面活性剂（BLES）之间的相互作用。在这些条件下，稀释的BLES制剂往往会产生变化且相对较高的最低表面张力。当以“低”壳聚糖与BLES比例添加时，BLES - 壳聚糖制剂的最低表面张力始终较低（即<5 mJ/m2），并且由此产生的表面活性剂单分子层（吸附在气 - 水界面）具有高弹性和稳定性。然而，使用“高”壳聚糖与BLES比例会导致表面活性剂单分子层在高最低表面张力（即>15 mJ/m2）下坍塌。亚相中肺表面活性剂聚集体的zeta电位表明壳聚糖与BLES中的阴离子脂质（磷脂酰甘油）结合，并且这种结合最终导致了这些表面活性剂 - 聚电解质混合物表面活性（弹性和稳定性）的变化。此外，从“低”壳聚糖与BLES比例到“高”壳聚糖与BLES比例的转变与亚相中表面活性剂聚集体的絮凝和反絮凝相关。有人提出，在不同壳聚糖与BLES比例下产生的表面活性剂单分子层中阴离子脂质“斑块”的聚集/分离解释了壳聚糖的增强/抑制作用。这些观察结果突出了静电相互作用在肺表面活性剂系统中的重要性。
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