Pore strain behaviour of collagen-glycosaminoglycan analogues of extracellular matrix

Mechanical properties of a highly porous collagen-glycosaminoglycan (CG) analogue of extracellular matrix were investigated. The stress-strain behaviour of the matrices displayed the typical concave-up shape characteristic of porous materials and soft tissues. Deformation behaviour of the material was further investigated using novel methodology to determine material strains at the micrometre level. Central to the methodology was the use of scanning electron microscopy (SEM) in conjunction with a digital image analyser. The method for strain determination at the micrometre level was verified by comparison with measurement of surface strain using an optical method. An unexpected finding in these materials is that Poissonʹs ratio varies with engineering strain. A geometrical/ mathematical model was developed to explain this behaviour. These results encourage further investigation of the mechanical properties of these materials, in order to provide important insights into the physical microenvironment in which cells reside.