Stacked bilayer helices: a new structural organization of amphiphilic molecules

Intriguing helical fibres can be created by self-assembly of simple chiral amphiphilic molecules. We study the parameters governing this spontaneous self-organization by three-dimensional (3D) electron microscopy of the helical fibres embedded in a vitreous ice-matrix. Different stable helices are generated reproducibly using specific combinations of the control parameters in our system. All fibres with diameters less than 25 nm consist of a narrow stack of compartmented bilayers twisted into a left-handed helix. Our novel helical 3D reconstruction procedures in combination with specialized cryomicroscopical specimen preparation, can rapidly elucidate the structure of such helical assemblies. This approach may complement or even replace existing diffraction-based methodologies.