Disentangling density fluctuations and membrane formation in liquid methane

Cell membranes are complex structures that are robust enough to withstand changes in temperature and pressure, yet are stable and flexible enough to cope with a vast library of cellular processes. However, the mild conditions on Earth - conditions where water is liquid and membranes can be thermally stable - are famously scarce in the vastness of space. Recent data collected by the Cassini-Huygens probe, and subsequently studied by computer modelling has shown that some nitrogen-containing “tholin” molecules may be able to spontaneously form membrane-like structures in the cold liquid methane lakes on Titan, one of the moons of Saturn. We recently obtained tantalising evidence of this self-assembly by cooling a solution of the tholin 1-aminopentane in supercritical methane to cryogenic temperatures.

Here we propose to build on this pilot work in two ways: by obtaining corresponding background measurements at each statepoint studied previously (for which an individual background is required due to density effects) and to study the “best candidate” tholin acrylonitrile, having favoured the less hazardous 1-aminopentane while refining our experimental protocol.

细胞膜是一类复杂的结构，其强度足以抵御温度与压力的变化，同时兼具稳定性与柔韧性，可适配海量细胞生理过程。然而，地球所处的温和环境——即液态水存在且细胞膜可保持热稳定的条件——在浩瀚宇宙中极为罕见。近期卡西尼-惠更斯号探测器（Cassini-Huygens probe）采集的数据经计算机建模研究后表明，部分含氮"托林（tholin）"分子或可在土星卫星土卫六（Titan）的低温液态甲烷湖中自发形成类膜结构。我们此前通过将1-氨基戊烷（1-aminopentane）的托林溶液在超临界甲烷（supercritical methane）中冷却至低温（cryogenic temperatures），已获得该自组装过程的初步佐证证据。

本研究拟在该先导性探索工作的基础上从两方面推进：其一，对此前研究的每个状态点获取对应的背景测量数据（因密度效应，每个状态点均需单独的背景数据）；其二，研究"最佳候选"托林——丙烯腈（acrylonitrile）——在优化实验方案的过程中，我们此前选用了毒性更低的1-氨基戊烷。