Synthesis and Characterization of Novel Anchorlipids for Tethered Bilayer Lipid Membranes

Abstract

Tethered bilayer lipid membranes are versatile solid-supported model membrane systems. Core to these systems is an anchorlipid that covalently links a lipid bilayer to a support. The molecular structure of these lipids can have a significant impact on the properties of the resulting bilayer. Here, the synthesis of anchorlipids containing ester groups in the tethering part is described. The lipids are used to form bilayer membranes, and the resulting structures are compared with membranes formed using conventional anchorlipids or sparsely tethered membranes. All membranes showed good electrical sealing properties; the disulphide-terminated anchorlipids could be used in a sparsely tethered system without significantly reducing the sealing properties of the lipid bilayers. The sparsely tethered systems also allowed for higher ion transport across the membrane, which is in good correlation with higher hydration of the spacer region as seen by neutron scattering.

Tethered Membrane Architectures—Design and Applications

“…Neutron scattering showed that the change in spacer segment composition did not increase the hydration of the sub-membrane space which remained low at around 5 volume-% (Andersson et al, 2017). This suggests that the packing density of the inner leaflet also plays a significant role in determining the hydration of the sub-membrane compartment.…”

“…The high packing density of fully tethered lipid would likely limit the amount of water in the sub-membrane space even if the hydrophobic conformation of the spacer segment was not a significant factor. Experiments were conducted using a different anchorlipid chemistry (DPhyAL), in which the ethylene glycol spacer was replaced with an ester-based segment that is unable to adopt the same helical conformation as a PEG-based spacer and is also more polar than an ethylene glycol chain (Andersson et al, 2017).…”

“…Reducing the tethering density of the inner leaflet to create an stBLM results in significantly increased sub-membrane hydration (Junghans and Koper, 2010;Andersson et al, 2017). However, when using a mixture of anchorlipid and a spacer molecule such as mercaptoethanol, the sealing properties of the resulting lipid membrane are reduced.…”

“…In an stBLM comprised of DPhySL or DPhyTL mixed with 40-60% mercaptoethanol as a spacer, membrane resistance was reduced by up to four orders of magnitude when valinomycin was incorporated in the presence of KCl, compared to a reduction of only one or two orders of magnitude in fully tethered membrane systems (Andersson et al, 2017). While the dilution of the inner leaflet with mercaptoethanol reduced the membrane resistance from 5-10 M cm 2 to around 1-2 M cm 2 , this was not the case when DPhySL was diluted with mercaptoethanol, possibly because this spacer chemistry allows for better packing density when diluted than the other spacer architectures.…”

“…n = 2)(Andersson et al, 2017) DPhyGL (n = 3)(Andersson et al, 2017) DPhyAL (n = 4)(Andersson et al, 2017) DPhyTT (n = 4)(Junghans and Koper, 2010) DPhyHT (n = 6)(Junghans and Koper, 2010) DPhyOT (n = 8)(Junghans and Koper, 2010) DPhyHDL(Junghans and Koper, 2010) DPhySDL(Andersson, 2013) HC 18(Budvytyte et al, 2013) FC16(Budvytyte et al, 2013) (Continued) Frontiers in Materials | www.frontiersin.org…”