The materials science of collagen

Area of Science:

• Biophysics
• Materials Science
• Biochemistry

Background:

• Collagen is the primary structural protein in the extracellular matrix.
• Its arrangement significantly influences the mechanical properties of connective tissues.
• Collagen's fraction and distribution are crucial for toughness and anisotropy in biomineralized materials.

Purpose of the Study:

• To review the hierarchical structure of collagen.
• To present constitutive equations describing collagen's mechanical response.
• To discuss the incorporation of viscoelasticity and hydration effects.

Main Methods:

• Classification of constitutive models into hyperelastic, macroscopic mathematical fits, and physically based models.
• Development of strain energy functions for hyperelastic models.
• Modification of linear elastic models using geometric characteristics for physically based models.

Main Results:

• Detailed review of collagen's hierarchical structure.
• Presentation of three categories of constitutive models for mechanical response.
• Discussion on incorporating viscoelasticity and hydration into models.

Conclusions:

• Collagen's structure and properties are fundamental to tissue mechanics.
• Various models can describe collagen's mechanical behavior.
• Understanding collagen is vital for applications in skin, fish scales, and bone.