Chair for Photonics and Optoelectronics, Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, 80539 Munich, Germany.
Faculty of Physics and CeNS, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
Langmuir. 2020 Mar 17;36(10):2629-2634. doi: 10.1021/acs.langmuir.9b02942. Epub 2020 Mar 3.
Supported lipid bilayer (SLB) membranes are key elements to mimic membrane interfaces on a planar surface. Here, we demonstrate that azobenzene photolipids (-) form fluid, homogeneous SLBs. Diffusion properties of - within SLBs were probed by fluorescence microscopy and fluorescence recovery after photobleaching. At ambient conditions, we find that the -to- isomerization causes an increase of the diffusion constant by a factor of two. Simultaneous excitation with two wavelengths and variable intensities furthermore allows to adjust the diffusion constant continuously. X-ray reflectometry and small-angle scattering measurements reveal that membrane photoisomerization results in a bilayer thickness reduction of ∼0.4 nm (or 10%). While thermally induced back-switching is not observed, we find that the bilayer fluidity is increasing with higher temperatures. This change in diffusion constant is accompanied by a red-shift in the absorption spectra. Based on these results, we suggest that the reduced diffusivity of -- is controlled by intermolecular interactions that also give rise to H-aggregate formation in bilayer membranes.
支持脂质双层（SLB）膜是模拟平面表面上膜界面的关键要素。在这里，我们证明偶氮苯光脂（-）形成流体、均匀的 SLB。通过荧光显微镜和光漂白后荧光恢复来探测 - 在 SLB 内的扩散性质。在环境条件下，我们发现 - 到 - 的异构化导致扩散常数增加了两倍。同时用两个波长和可变强度激发还可以连续调整扩散常数。X 射线反射和小角散射测量表明，膜光致异构化导致双层厚度减小约 0.4nm（或 10%）。虽然没有观察到热诱导的反向转换，但我们发现 - 的双层流动性随温度升高而增加。这种扩散常数的变化伴随着吸收光谱的红移。基于这些结果，我们认为 -- 的降低的扩散性受分子间相互作用控制，这些相互作用也导致双层膜中 H- 聚集体的形成。
