Iron-rich diet enhances the damage resistance of bamboo rat tooth enamel

Despite constraints in bioavailable elements, organisms maximize the use of limited resources to create biological materials with exceptional performance. However, little is known about how trace elements and their resulting structures specifically influence macroscopic properties. Herein, by feeding high-iron foods, we raised bamboo rats with iron-rich incisors and systematically studied the mechanical effects of iron in enamel. We demonstrate that additional iron in the pigmented enamel of Rhizomys pruinosus simultaneously enhance hardness, abrasive tolerance, and damage resistance. These benefits result from the aggregation of iron compound in the intercrystalline domains (ICDs) around hydroxyapatite nanowires, which leads to a nanoscale radial modulus gradient in nanowire-ICD structural units, thereby enhancing their bending resistance and interfacial strength. Our findings highlight that compositional tuning, combined with the advantages of hierarchical architectures, enables a synergistic enhancement of strength and toughness. This strategy offers insight into the design of advanced structural materials.