Spiral organic tubes are prepared by self‐assembly of lithocholic acid in aqueous solution at pH 12.0. The tubes can transition into a straight shape as the pH of solution is reduced to 7.4. The shape transition of the tubes is reversible as the pH of solution is adjusted back to 12.0 (see image). The pH‐switchable shape transition suggests that the self‐assembled organic tubes can act as a supramolecular chemical spring.

No abstract

Self-assembled lipid tubules with crystalline bilayer walls represent useful supramolecular architectures which hold promise as vehicles for the controlled release of preloaded drugs and templates for the synthesis of one-dimensional inorganic materials. We study the local elasticity of lipid tubules of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine by radial atomic force microscope indentation, coupled with finite element analysis. A reduced stiffness is found to extend a distance of approximately 600 nm from the ends of lipid tubules. The middle section of lipid tubules is homogeneous in terms of their radial elasticity with a Young's modulus of approximately 703 MPa. The inhomogeneous radial elasticity likely arises from the variation of lipid packing density near the tubule ends.