Dual scale biomechanics of extracellular matrix proteins probed by Brillouin scattering and quasistatic tensile testing

The biomechanics of living tissues are critical to normal tissue function and disturbances in these properties are widely implicated in aging and disease. Protein fibres of the extracellular matrix (collagen and elastin) are the fundamental mechanical structures in connective tissues such as bone, cartilage and vasculature. We applied Brillouin light scattering (BLS) spectroscopy and quasistatic stress-strain testing to the study of the mechanics and structure of collagen and elastin fibres purified from connective tissues. BLS probes mechanical properties on a microscopic scale in biological tissues and thereby providing insights into structure-function relationships under normal and pathological conditions. The sensitivity of BLS measurements to fibre structure and hydration was investigated using samples mounted onto reflective substrates. We obtained a complete characterization of the mechanical tensor and elastic moduli which could be compared with complementary data from quasistatic stress-strain measurements at different hydration levels, hence giving the full description of fibre viscoelasticity.