Role of storage on changes in the mechanical properties of tendon and self-assembled collagen fibers

Fibrous collagen networks are the major elements that provide mechanical in tegrity to tissues; they are composed of fiber forming collagens in combina tion with proteoglycans(PGs), Using uniaxial tensile tests we have studied the viscoelastic mechanical properties of rat tail tendon (RTT) fibers and self-assembled collagen fibers that were stored at 22 degrees C and 1 atm o f pressure. Our results indicate that storage of RTT and self-assembled typ e I collagen fibers results in increased elastic and viscous components of the stress-strain behavior consistent with the hypothesis that storage caus es the introduction of crosslinks. Analysis of the elastic and viscous mechanical data suggests that the elast ic constant of the collagen molecule in RTT is about 7.7 GPa. Measurement o f the viscous component of the stress-strain curves for RTTs and self-assem bled collagen fibers suggests that PGs may increase the viscous component a nd effectively increase the collagen fibril length.