Atomic force microscopy and indentation force measurement of bone

Area of Science:

• Biomaterials Science
• Materials Science
• Biomechanics

Background:

• Bone tissue exhibits complex anisotropic, elastic, viscoelastic, and time-dependent plastic behaviors.
• Understanding bone's mechanical properties at microstructural and molecular levels is crucial for diagnostics and therapeutics.
• Atomic force microscopy (AFM) and nanoindentation are key techniques for probing bone at the nanoscale.

Purpose of the Study:

• To review and synthesize findings from atomic force microscopy (AFM) and nanoindentation experiments on bone tissue.
• To highlight the synergistic power of combining AFM and nanoindentation for detailed bone characterization.
• To discuss challenges and advancements in nanoindentation analysis for anisotropic biological materials.

Main Methods:

• Atomic force microscopy (AFM) for ultrastructural analysis and force spectroscopy.
• Nanoindentation experiments to measure mechanical properties like elastic modulus and hardness.
• Post-hoc analysis of indentations and application of advanced analytical methods (e.g., extensions to Oliver-Pharr).

Main Results:

• AFM has elucidated bone ultrastructure and revealed a molecular self-healing effect potentially mediated by unstructured proteins.
• Nanoindentation provides insights into bone's mechanical properties, though results are protocol-dependent due to anisotropy and time-dependent behavior.
• Compiled data from human and animal bone nanoindentation studies are presented, offering a valuable literature resource.

Conclusions:

• The combined use of AFM and nanoindentation offers powerful capabilities for assessing bone's microstructural and mechanical properties.
• Advancements in nanoindentation analysis methods are improving the reliability of derived mechanical parameters.
• These techniques contribute significantly to understanding bone's complex behavior and potential self-healing mechanisms.