Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Langmuir. 2021 Apr 6;37(13):3970-3981. doi: 10.1021/acs.langmuir.1c00214. Epub 2021 Mar 24.
Interfaces between molecular organic architectures and oxidic substrates are a central feature of biosensors and applications of biomimetics in science and technology. For phospholipid bilayers, the large range of pH- and ionic strength-dependent surface charge densities adopted by titanium dioxide and other oxidic surfaces leads to a rich landscape of phenomena that provides exquisite control of membrane interactions with such substrates. Using neutron reflectometry measurements, we report sharp, reversible transitions that occur between closely surface-associated and weakly coupled states. We show that these states arise from a complex interplay of the tunable length scale of electrostatic interactions with the length scale arising from other forces that are independent of solution conditions. A generalized free energy potential, with its inputs only derived from established measurements of surface and bilayer properties, quantitatively describes these and previously reported observations concerning the unbinding of bilayers from supporting substrates.
分子有机结构与氧化基底之间的界面是生物传感器的一个核心特征，也是仿生学在科学和技术中应用的一个核心特征。对于磷脂双层膜而言，二氧化钛和其他氧化基底所采用的大范围的 pH 值和离子强度依赖的表面电荷密度，导致了丰富的现象景观，为膜与这些基底的相互作用提供了精细的控制。利用中子反射测量，我们报告了在紧密相关的表面关联和弱耦合状态之间发生的尖锐、可逆的转变。我们表明，这些状态源自于静电相互作用的可调长度尺度与独立于溶液条件的其他力的长度尺度之间的复杂相互作用。一个广义的自由能势，其输入仅源自于对表面和双层膜性质的已建立的测量，定量地描述了这些状态以及之前关于双层膜从支撑基底上解吸的观察结果。
