Department of Chemistry, Hankuk University of Foreign Studies, Yongin 17035, Korea.
Int J Mol Sci. 2020 Oct 28;21(21):8030. doi: 10.3390/ijms21218030.
In this work, we study a chemical method to transfer water molecules from a nanoscale compartment to another initially empty compartment through a nanochannel. Without any external force, water molecules do not spontaneously move to the empty compartment because of the energy barrier for breaking water hydrogen bonds in the transport process and the attraction between water molecules and the compartment walls. To overcome the energy barrier, we put osmolytes into the empty compartment, and to remove the attraction, we weaken the compartment-water interaction. This allows water molecules to spontaneously move to the empty compartment. We find that the initiation and time-transient behavior of water transport depend on the properties of the osmolytes specified by their number and the strength of their interaction with water. Interestingly, when osmolytes strongly interact with water molecules, transport immediately starts and continues until all water molecules are transferred to the initially empty compartment. However, when the osmolyte interaction strength is intermediate, transport initiates stochastically, depending on the number of osmolytes. Surprisingly, because of strong water-water interactions, osmosis-driven water transport through a nanochannel is similar to pulling a string at a constant speed. Our study helps us understand what minimal conditions are needed for complete transfer of water molecules to another compartment through a nanochannel, which may be of general concern in many fields involving molecular transfer.
在这项工作中，我们研究了一种通过纳米通道将水分子从纳米级隔室转移到另一个初始为空的隔室的化学方法。由于在传输过程中断开水分子氢键的能量障碍以及水分子与隔室壁之间的吸引力，水分子不会自发地移动到空隔室。为了克服能量障碍，我们将渗透物放入空隔室中，为了消除吸引力，我们减弱隔室与水的相互作用。这使得水分子可以自发地移动到空隔室。我们发现水传输的启动和时间瞬态行为取决于渗透物的特性，由其数量和与水的相互作用强度指定。有趣的是，当渗透物与水分子强烈相互作用时，传输立即开始并持续进行，直到所有水分子都转移到初始为空的隔室。然而，当渗透物相互作用强度处于中间时，传输会随机启动，这取决于渗透物的数量。令人惊讶的是，由于强烈的水分子间相互作用，纳米通道中渗透物驱动的水传输类似于以恒定速度拉动一根绳子。我们的研究有助于我们了解通过纳米通道将水分子完全转移到另一个隔室所需的最小条件，这可能在涉及分子转移的许多领域都受到关注。
