Growing Synthetic Nacre: Simultaneous Deposition and Assembly of Interlocking Bricks

Achieving ceramics that combine stiffness, strength, and toughness in complex geometries remains a major challenge, limiting their use in applications such as bone implants. Bio-inspired architectures – composed of stiff, strong building blocks connected by deformable interfaces – offer a promising solution. However, their implementation is constrained by limited control over the arrangement and composition of blocks, especially in constructs with complex shapes at centimeter- to meter-scale. We present a light-based printing method that deposits and assembles interlocking ceramic bricks onto connecting micro-pins, inspired by nacre’s growth mechanism. A custom alumina resin was developed and printed using a tabletop LCD 3D printer, sintered, and subsequently infiltrated with polycaprolactone, a tough and biocompatible polymer that forms the deformable interfaces. The resulting nacre-like constructs, with 76-78 wt% (50-52 vol%) ceramic, showed flexural stiffness of 2.27±0.44 GPa, strength of 41.4±1.33 MPa, and energy absorption of at least 6.35±0.97 MJ/m ³ . These values match the energy absorption of cortical bone, exceed the rule-of-mixtures value by fivefold, and surpass that of monolithic ceramic by over 4,000 times. Finally, a 5 cm-long nacre-like construct replicating the geometry of the human tibia was fabricated and tested in flexion, demonstrating scalability and potential for biomedical applications.