Super-swelled lyotropic single crystals

Significance Lipids self-assemble in water into diverse polycrystalline mesophases. The swelling capacity of these superstructures is finite, specific, and traditionally dictated by lipid composition. Bicontinuous cubic phases have tremendous potential in drug delivery and protein crystallization. However, limited swelling caps unit cells at dimensions too small to encapsulate many drugs and most proteins. In this work, we discovered that bicontinuous cubic phase swelling is not solely determined by lipid composition. Self-assembly conditions yield stable unit cell sizes fourfold larger than usual. Unexpectedly, these conditions also dictate mesophase ordering resulting in X-ray and electron microscopy diffraction patterns that do not conform to polycrystallinity. Instead, macroscale super-swelled single crystals are encountered. This discovery highlights insights in understanding swelling and ordering of self-assembled materials.