School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK; Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
J Colloid Interface Sci. 2022 Nov;625:220-236. doi: 10.1016/j.jcis.2022.03.102. Epub 2022 Mar 31.
Self-assembly of amphipathic styrene maleic acid copolymers with phospholipids in aqueous solution results in the formation of 'nanodiscs' containing a planar segment of phospholipid bilayer encapsulated by a polymer belt. Recently, studies have reported that lipids rapidly exchange between both nanodiscs in solution and external sources of lipids. Outstanding questions remain regarding details of polymer-lipid interactions, factors influencing lipid exchange and structural effects of such exchange processes. Here, the dynamic behaviour of nanodiscs is investigated, specifically the role of membrane charge and polymer chemistry.
Two model systems are investigated: fluorescently labelled phospholipid vesicles, and Langmuir monolayers of phospholipids. Using fluorescence spectroscopy and time-resolved neutron reflectometry, the membrane potential, monolayer structure and composition are monitored with respect to time upon polymer and nanodisc interactions.
In the presence of external lipids, polymer chains embed throughout lipid membranes, the extent of which is governed by the net membrane charge. Nanodiscs stabilised by three different polymers will all exchange lipids and polymer with monolayers to differing extents, related to the properties of the stabilising polymer belt. These results demonstrate the dynamic nature of nanodiscs which interact with the local environment and are likely to deposit both lipids and polymer at all stages of use.
两亲性苯乙烯马来酸共聚物与磷脂在水溶液中自组装会形成“纳米盘”，其中包含磷脂双层的平面段，由聚合物带包裹。最近的研究报告称，脂质在溶液中的纳米盘之间以及外部脂质源之间迅速交换。关于聚合物-脂质相互作用的细节、影响脂质交换的因素以及这种交换过程的结构影响等问题仍未得到解答。本文研究了纳米盘的动态行为，特别是膜电荷和聚合物化学的作用。
研究了两种模型系统：荧光标记的磷脂囊泡和磷脂的 Langmuir 单层。通过荧光光谱和时间分辨中子反射测量，在聚合物和纳米盘相互作用时，监测膜电位、单层结构和组成随时间的变化。
在外部脂质存在的情况下，聚合物链贯穿脂质膜，其程度受净膜电荷控制。由三种不同聚合物稳定的纳米盘都将与单层交换脂质和聚合物，程度与稳定聚合物带的性质有关。这些结果表明纳米盘具有动态性质，与局部环境相互作用，并可能在使用的各个阶段沉积脂质和聚合物。
