Enzyme-induced mineralization of calcium carbonate in 3D printable granular hydrogels.

Many biological materials, such as bone, are organic-inorganic composites, made from a polymeric matrix that supports biomineralization under mild conditions. These materials are usually composed of a small set of abundant components like polysaccharides, proteins, and minerals, and exhibit a remarkable combination of density normalized stiffness, toughness, and functionality. Producing bio-inspired synthetic porous composites with a similar combination of properties through energy-efficient processes still presents an unmet challenge. Some aspects of this challenge can be addressed using living bacteria that induce biomineralization. However, living bacteria limit biomedical applications, especially in vivo, require careful handling, and are costly. To address these limitations, we introduce enzyme-containing granular precursors exclusively made from naturally sourced polymers. These precursors can be cast or direct ink written into cm-sized structures before they are mineralized under benign conditions to reach CaCO Supplementary Information: The online version contains supplementary material available at 10.1007/s42114-026-01662-5.