Anatomy

Internal medicine

Contraction (grammar)

Organic chemistry

Biomineralization

Collagen fibril

Nucleation

Biology

Ultimate tensile strength

Biophysics

Mineralization (soil science)

Engineering

Composite material

Chemistry

Materials science

Fibril

Collagen fibres

Calcium

Chemical engineering

Strontium

Nitrogen

Biochemistry

Medicine

Science

During bone formation, collagen fibrils mineralize with carbonated hydroxyapatite, leading to a hybrid material with excellent properties. Other minerals are also known to nucleate within collagen in vitro. For a series of strontium- and calcium-based minerals, we observed that their precipitation leads to a contraction of collagen fibrils, reaching stresses as large as several megapascals. The magnitude of the stress depends on the type and amount of mineral. Using in-operando synchrotron x-ray scattering, we analyzed the kinetics of mineral deposition. Whereas no contraction occurs when the mineral deposits outside fibrils only, intrafibrillar mineralization generates fibril contraction. This chemomechanical effect occurs with collagen fully immersed in water and generates a mineral-collagen composite with tensile fibers, reminiscent of the principle of reinforced concrete.

Mineralization generates megapascal contractile stresses in collagen fibrils