(359a) 3D Printing-Guided Chiral Nanostructures in Bio-Hybrid Nanocomposites

The chiral or helical structures inherent to biomolecules contribute to the exceptional fracture resistance observed in the "smasher-type" mantis shrimp's dactyl club and the vibrant metallic colors in beetles. Drawing inspiration from these natural helical structures, this study integrates "bottom-up" molecular self-assembly with "top-down" 3D printing to design intricate geometries with a guided, radially twisted chiral hierarchy using inks derived from cellulose nanocrystals (CNC). We utilize the processing parameters of direct ink-writing (DIW) 3D printing to manipulate the chiral nematic liquid crystalline phase in cellulose-based inks before deposition. This approach allows us to steer structural development from a specific initial condition. Through comprehensive rheological analyses, we have found that printing the chiral inks at a shear rate that induces a pseudonematic state in cellulose molecules leads to uniform chiral recovery after the cessation of flow. The subsequent biomineralization of these printed structures with a chiral arrangement of CNC particles has revealed significant enhancement in their mechanical properties, demonstrating a synergistic interaction between biomineralization and chiral assembly that induces nanoscale ordering. This biomimetic strategy offers a pathway to develop materials with superior mechanical properties derived from 3D nano/microstructures, which can be translated into larger scale 3D printed designs.