Highly Viscous Coatings from Archaea-Inspired Lipids Improve Single Protein Characterization with Nanopores

Despite the importance of proteins, nanopore sensing has so far been mostly focused on single molecule DNA and RNA characterization. One factor that limited experiments with proteins were nonspecific interactions of proteins with the walls of synthetic nanopores. We showed recently, that nanopores with fluid coatings of phospholipid bilayers circumvented this problem. In addition, anchoring proteins to lipid anchors slowed down protein translocation through nanopores and enabled determination of parameters such as the shape, volume, and dipole moment of individual non-spherical proteins. To slow down the translocation time of lipid-anchored proteins further, we have recently formed highly viscous coatings from archaea-inspired lipids. These synthetic lipids are composed of two hydrophilic head groups connected by a long hydrophobic chain; each head group is also attached to an acyl chain that spans half of the membrane thickness. As these lipids contain -in one molecule- the components of a typical lipid bilayer, a single layer is sufficient to form a stable membrane. Monolayers of these new lipids have a two to twenty-fold increased viscosity than typical phospholipid bilayers. The Archaea-inspired lipids discussed here show promise in terms of slowing translocation times and the resulting data made it possible to characterize individual proteins with increased accuracy than coatings from standard phospholipid bilayers.