Self-Winding Gelatin-Amyloid Wires for Soft Actuators and Sensors.

The origin of self-winding mechanisms in plants' tendrils has fascinated scientists for centuries and continues to inspire developments in material science and nanotechnology. Here, bioinspired water-responsive wires that replicate these mechanisms, including the formation of coils and chiral perversions, are presented. A right-handed gelatin matrix is loaded with rigid left-handed amyloid fibrils and roll-dry-spun into wires in which self-winding activation emerges from simultaneous bending and twisting deformations. Wire bending is a consequence of amyloid fibrils' concentration and distribution within the wire, whereas twisting is controlled by amyloid fibrils' orientation. The resultant wires can be functionalized by organic molecules and inorganic nanoparticles, and potential applications in magnetic actuators and sensors are demonstrated. The simple fabrication method and the remarkable spontaneous self-winding response of these gelatin-amyloid wires exemplify how biomaterials based on mixed proteins have striking potential to develop advanced and tunable properties that can serve robotics, soft machines, and engineering systems.