Genetically Engineered Supercharged Polypeptide Fluids: Fast and Persistent Self-Ordering Induced by Touch

Mechanically induced disorder–order transitions have been studied in fluid surfactant solutions or polymer thermotropic liquid crystals. However, isothermally induced ordered phases do not persist after cessation of shear, which limits their technological applicability. Moreover, no such stimuli-responsive materials involving biomacromolecules have been reported although biopolymer liquids are gaining a lot of attention. A biological fluid system is introduced in which anionic polypeptides are complexed with cationic surfactants. The resulting fluids exhibited very sensitive isotropic–nematic transition triggered by shear. The formed liquid crystal was preserved after cessation of mechanical stimulus. Self-ordering behavior of the material was achieved through water flow and finger pressing. The latter mechanical induction resulted in the formation of complex pattern that can be read out by birefringence, allowing the recording of fingerprint information.