Dynamic mechanical characteristics of intact and structurally modified bovine pericardial tissues.

Bovine pericardium (BP) is a source of natural biomaterials with a wide range of clinical applications. In the present work we studied the dynamic mechanical behavior of BP in native form and under specific enzymatic degradation with chondroitinase ABC extracted a 17% of the total glycosaminoglycans (GAGs). The GAGs content of native BP was composed mainly from hyaluronan, chondroitine sulfate and dermatan sulfate. Dynamic tensile mechanical testing of BP in the frequency range 0.1-20 Hz demonstrated its viscoelastic nature. The storage modulus was equal to 6.5 (native) and 5.5 (degraded) MPa initially, increased in the region nearby 1 Hz by about 15%. This was related with physical resonance mechanisms activated in this frequency region. The high modulus (modulus of the high linear phase of stress-strain) was equal to 14 (native) and 10 (degraded) MPa, dropped at high frequencies to 7 and 5 Mpa, respectively. The damping, expressed by the hysteresis, was equal to 20% of the loading energy, changed exponentially with the frequency to 30% at 20 Hz. It seemed that of the elastic mechanical parameters, the storage modulus and the high modulus were even slightly dropped as a result of degradation. As a final conclusion, there was evident that GAGs may play a non-negligible role in the dynamic mechanical behavior of BP and, probably in other soft tissue biomechanics. It is suggested that the GAGs content may be considered during the design and chemical modification of biomaterials based on BP and other soft tissues.