Cosurfactant effect of a semifluorinated alkane at a fluorocarbon/water interface: Impact on the stabilization of fluorocarbon-in-water emulsions
Cosurfactant effect of a semifluorinated alkane at a fluorocarbon/water interface: Impact on the stabilization of fluorocarbon-in-water emulsions
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DOI：
10.1021/la036381m
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发表时间：
2004-05-11
期刊：
影响因子：
3.9
通讯作者：
Krafft, MP
中科院分区：
文献类型：
--
作者：
Bertilla, SM;Thomas, JL;Krafft, MP
以前的工作已经证明，半氟化烷烃CnF 2n +1CmH 2 m +1（FnHm二嵌段），当与磷脂结合使用时，强烈稳定氟碳化合物（FC）-水乳液注定要用作氧载体。虽然FnHm二嵌段在乳液的界面磷脂膜的存在下，建议占所观察到的稳定，没有直接的证据的二嵌段的位置已提供到目前为止。我们现在报告明确的实验证据的二嵌段的存在，在界面膜，两者。在宏观层面上，通过使用悬滴法研究FC/水界面，并直接在乳剂上，通过监测其对各种磷脂链长度的稳定性。我们首先确定，F8 H16与磷脂[二肉豆蔻酰磷脂酰胆碱（DMPC），二月桂酰磷脂酰胆碱（DLPC），二辛酰磷脂酰胆碱（PCL 8）]在全氟辛基溴（PFOB）/水界面具有很强的助表面活性剂的效果，证明了一个戏剧性的F8 H16浓度依赖性降低的界面张力。在FC乳液的关注，我们表明，稳定的效果，其中包括减少的FC的分子扩散速率，强烈依赖于磷脂的脂肪链的长度相比，烃段的长度，Hm，的二嵌段。当Hm长度与磷脂的脂肪链长度相似时，稳定性最大化。Hm和磷脂链长度之间的强烈不匹配实际上可以使乳液不稳定。一种不同的不稳定机制正在起作用：聚结。F8 H16在界面膜的存在进一步支持的事实，全氟癸基溴，一个重的类似物的PFOB，稳定PFOB乳液通过降低乳液的分散FC相的溶解度和扩散性，行使其稳定效果类似于所有的磷脂研究。
Previous work has demonstrated that semifluorinated alkanes CnF2n+1CmH2m+1 (FnHm diblocks), when used in conjunction with phospholipids, strongly stabilize fluorocarbon (FC)-in-water emulsions destined to be used as oxygen carriers. Although the presence of FnHm diblocks in the emulsion's interfacial phospholipid film was suggested to account for the observed stabilization, no direct proof of the diblock's location has been provided so far. We now report definite experimental evidence of the diblock's presence at the interfacial film, both. on a macroscopic level by investigating the FC/water interface using the pendant drop method and directly on emulsions by monitoring their stability for various phospholipid chain lengths. We first establish that F8H16 has a strong cosurfactant effect with phospholipids [dimyristoylphosphatidylcholine (DMPC), dilaurylphosphatidyleholine (DLPC), dioctanoylphosphatidylcholine (PCL8)] at a perfluorooctyl bromide (PFOB)/water interface, as evidenced by a dramatic F8H16-concentration-dependent decrease of the interfacial tension. Where FC emulsions are concerned, we show that the stabilization effect, which consists of a decrease of the rate of molecular diffusion of the FC, depends strongly on the length of the phospholipid's fatty chain as compared to the length of the hydrocarbon segment, Hm, of the diblock. Stabilization is maximized when the Hm length is similar to that of the phospholipid's fatty chains. A strong mismatch between Hm and the phospholipid chain length can actually destabilize the emulsion. A different destabilization mechanism is then at work: coalescence. The presence of F8H16 at the interfacial film is further supported by the fact that perfluorodecyl bromide, a heavy analogue of PFOB that stabilizes PFOB emulsions by lowering the solubility and diffusibility of the emulsion's dispersed FC phase, exercises its stabilizing effect similarly for all the phospholipids investigated.