Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States.
Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
J Am Chem Soc. 2020 Apr 1;142(13):6139-6148. doi: 10.1021/jacs.9b13360. Epub 2020 Mar 18.
We report that incubation of aqueous dispersions of supramolecular assemblies formed by synthetic alkyl triazole-based amphiphiles against interfaces of thermotropic liquid crystals (LCs; 4-cyano-4'-pentylbiphenyl) triggers spatially localized (micrometer-scale) and transient (subsecond) flashes of light to be transmitted through the LC. Analysis of the spatiotemporal response of the LC supports our proposal that each optical "blinking" event results from collision of a single supramolecular assembly with the LC interface. Particle tracking at the LC interface confirmed that collision and subsequent spreading of amphiphiles at the interface generates a surface pressure-driven interfacial flow (Marangoni flow) that causes transient reorientation of LC and generation of a bright optical flash between crossed polarizers. We also found that dispersions of phospholipid vesicles cause "blinks". When using vesicles formed from 1,2-dilauroyl--glycero-3-phosphocholine (DLPC), we measured the frequency of blinking to decrease proportionally with the number density of vesicles in the aqueous phase, consistent with single vesicle events, with the lifetime of each blink dependent on vesicle size (800 ± 80 nm to 150 ± 30 nm). For 100 μM of DLPC, we measured vesicles with a diameter of 940 ± 290 nm to generate 47 ± 9 blinks min mm, revealing that the fraction of vesicle collisions resulting in fusion with the LC interface is ∼10. Overall, the results in this paper unmask new nonequilibrium behaviors of amphiphiles at LC interfaces, and provide fresh approaches for exploring the dynamic interactions of supramolecular assemblies of amphiphiles with fluid interfaces at the single-event level.
我们报告称，在热致液晶（LC；4-氰基-4'-戊基联苯）界面处孵育由合成烷基三唑基两亲物形成的超分子组装的水基分散体，会引发光在 LC 中通过的空间局部化（微米级）和短暂（亚秒级）闪光。对 LC 的时空响应的分析支持我们的提议，即每个光学“闪烁”事件都源于单个超分子组装体与 LC 界面的碰撞。在 LC 界面处的颗粒跟踪证实，碰撞和随后的两亲物在界面处的扩散会产生表面压力驱动的界面流（Marangoni 流），导致 LC 的瞬时重定向和在交叉偏光镜之间产生明亮的光闪光。我们还发现磷脂囊泡的分散体也会引起“闪烁”。当使用由 1,2-二肉豆蔻酰基-甘油-3-磷酸胆碱（DLPC）形成的囊泡时，我们测量到“闪烁”的频率与水相中的囊泡数密度成比例地降低，这与单个囊泡事件一致，每个闪烁的寿命取决于囊泡的大小（800±80nm 至 150±30nm）。对于 100μM 的 DLPC，我们测量到直径为 940±290nm 的囊泡会产生 47±9 次闪烁 min mm，表明导致与 LC 界面融合的囊泡碰撞分数约为 10。总体而言，本文的结果揭示了两亲物在 LC 界面处的新非平衡行为，并为在单事件水平上探索两亲物的超分子组装与流体界面的动态相互作用提供了新方法。
