Gramicidin A ion channel formation in model phospholipid bilayers tethered to gold (111) electrode surfaces

Ion transport mechanism in gramicidin A channels formed in floating bilayer lipid membranes supported on gold electrodes

“…At all potentials, the resistance of the bilayer without gA is ~ 5 to 20 times larger than the resistance of the bilayer with gA. This result indicates that gA forms ion channels in the fBLM and that Na + is transported across the membrane decreasing its resistance [14]. The maximum values of Rm are observed around E = 0.1 V vs Ag/AgCl and correspond to the potential of minimum values of Qm.…”

“…Both inner and outer leaflets of the DPhPC/gA fBLM contain a mixture of DPhPC and gA in a 9:1 molar ratio transferred at the constant surface pressure of 28 mN m -1 . Previous research of gA in the DPhPC/DPTL tBLM indicated that 10% is the optimum concentration for gA to form ion channels in the DPhPC bilayer [14]. The compression isotherm of the DPhPC/gA and DPhPC monolayers on the water subphase were plotted in Figure S2.…”

“…PM-IRRAS was applied by Laredo et al [13] to study gramicidin in a phospholipid bilayer directly deposited at a gold electrode surface and discovered that gA molecules are stressed when the bilayer is directly in contact with the metal surface. To eliminate this stress, the ion channel properties of gA were also studied using a tethered bilayer lipid membrane (tBLM) where the inner leaflet consisted of a 2,3-di-O-phytanyl-sn-glycerol-1-tetraethylene glycol-DL--lipoic acid ester (DPTL) thiolipid and the outer leaflet was composed of a 1,2diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) [14]. The tetraethylene tether provided separation between the bilayer and the metal surface and indeed helped to release the stress within the film.…”

Effect of polar amino acid incorporation on Fmoc-diphenylalanine-based tetrapeptides

“…These cell-mimetic membranes have been used previously to assess the membrane disruptive activity of peptides. [40][41][42] For polar anionic and polar neutral tetrapeptides, no interaction with the tBLMs were observed at all concentrations (Fig. 4c-f).…”

Decoupling the effects of hydrophilic and hydrophobic moieties at the neuron–nanofibre interface

“…This technique has previously been used to assess the activity of various bespoke and natural peptides on lipid bilayers. [51][52][53] Upon addition of 1 and 10 mM solutions of tetrapeptide nanobres, minimal disruption of the membrane bilayer was observed. However, upon treatment of the membranes with 100 mM nanobre solutions, signicant increases in membrane conductance can be seen for Fmoc-FKKF and Fmoc-KFFK ( Fig.…”