Mechanical Properties of Mineralized Biological Tissues

Mineralized biological tissues such as bone, dentin and enamel combine an organic matrix of collagen and non-collagenous proteins with an inorganic phase of hydroxyapatite crystals in a hierarchically organised structure. At the nanoscale, collagen molecules assemble into fibrils that are reinforced by plate-like mineral crystals. These mineralised collagen fibrils form lamellae and higher-order architectures whose orientation, density and interfaces govern macroscopic stiffness, strength and toughness. Mechanical behaviour emerges from a balance of elastic deformation, plastic yielding and energy-dissipation mechanisms such as molecular uncoiling, fibril-matrix sliding and crack deflection. Water bound at ultrastructural interfaces further modulates load transmission and fracture resistance. Multiscale experimental techniques—ranging from atomic-force microscopy and synchrotron diffraction to microtensile testing—and advanced computational models are now revealing how local ultrastructure transmits deformation across length scales. This integrated understanding underpins improved diagnosis of skeletal fragility, informs the design of bio-inspired composites and suggests new targets for therapeutic intervention.

Research from Nature Portfolio

Recent studies have uncovered the biomolecular regulation of bone mineral ultrastructure by non-collagenous proteins, demonstrating that osteocalcin and osteopontin jointly determine crystal size and organisation while independently shaping crystal morphology. These findings clarify how protein–mineral interactions control tissue quality. In parallel, a three-dimensional Monte Carlo model of a mineralised collagen fibril has quantified the effects of tortuosity and constrictivity on water diffusivity, revealing pronounced anisotropy in transport properties and highlighting the dominant role of tortuous pathways in nanoscale fluid movement.

Mechanical Properties of Mineralized Biological Tissues publication trend

The graph below shows the total number of articles in mechanical properties of mineralized biological tissues across all publications each year (not limited to Nature Index journals).

Technical terms

Mineralized collagen fibril: Composite nanoscale structure of collagen molecules interspersed with hydroxyapatite crystals forming the fundamental load-bearing unit in bone and dentin.

Non-collagenous proteins: Extracellular matrix proteins (e.g. osteocalcin, osteopontin) that regulate mineral nucleation, crystal growth and organisation in mineralised tissues.

Tortuosity: Ratio of the actual convoluted path length available for fluid or ion transport to the straight-line distance, reflecting complexity of pathways.

Elastic modulus: Measure of material stiffness defined as the ratio of stress to reversible strain in the linear elastic regime.

Yield stress: Stress level at which a material transitions from elastic deformation to permanent, plastic deformation.

Lamella: Thin sheet-like layer within cortical bone, composed of aligned mineralised collagen fibrils, forming a key level of hierarchical organisation.

References

1. Integrating computational and experimental advances in bone multiscale mechanics. Progress in Materials Science (2025).
2. The Ultrastructure of Bone and Its Relevance to Mechanical Properties. Frontiers in Physics (2017).
3. Biomolecular regulation, composition and nanoarchitecture of bone mineral. Scientific Reports (2018).
4. A 3D Model of the Effect of Tortuosity and Constrictivity on the Diffusion in Mineralized Collagen Fibril. Scientific Reports (2019).
5. The elasto-plastic nano- and microscale compressive behaviour of rehydrated mineralised collagen fibres. Acta Biomaterialia (2023).
6. Microtensile properties and failure mechanisms of cortical bone at the lamellar level. Acta Biomaterialia (2020).