Fig. 1.

Schematic of gramicidin channels as molecular force probes for sensing changes in bulk lipid bilayer properties. Two non-conducting gramicidin monomers (green cylindrical structures) can dimerize to form a conducting dimer. The thickness of the bilayer (d₀) is larger than the length of the conducting dimer (l), therefore a bilayer deformation energy is required to enable this dimerization. Amphiphiles – compounds with both hydrophilic and lipophilic properties – can lead to changes in bulk bilayer properties that can be sensed by gramicidin channels.