A research group led by Professor Henrik Birkedal at the Department of Chemistry, Aarhus University, together with international collaborators, has identified a previously unknown mineralized tissue in the Mexican beaded lizard. The findings, now published in Acta Biomaterialia, provide new insights into how hard tissues can be fabricated in nature.

The so-called capping tissue covers the lizard’s scales and shows mechanical properties comparable to enamel. However, unlike enamel’s highly ordered arrangement of elongated apatite crystallites, this tissue is built from disordered nanocrystals of carbonated hydroxyapatite. This unusual microstructure results in a material that is simultaneously hard, stiff, and crack-resistant.

To characterise the material, the researchers combined high-resolution synchrotron X-ray tomography and diffraction at the DanMAX beamline at MAX IV in Lund, Sweden, with X-ray tomography at the AXIA intrastructure at Aarhus University, electron microscopy and spectroscopic techniques. These analyses revealed how nanostructural disorder can be exploited by biology to achieve mechanical performance equivalent to more ordered tissues.

The discovery broadens our chemical understanding of biomineralisation processes, showing that hardness and durability can arise from unexpected crystal architectures. Beyond the biological significance, the results open new routes for designing bioinspired materials: combining nanoscale disorder, controlled mineral composition, and organic–inorganic interfaces to achieve superior performance.

Read more at MAX IV Laboratory or access the full article in Acta Biomaterialia.

Contact
Professor Henrik Birkedal
Aarhus University
Departmen of Chemistry
Email: hbirkedal@chem.au.dk