Evaluation of shrinkage temperature of bovine pericardium tissue for bioprosthetic heart valve application by differential scanning calorimetry and freeze-drying microscopy

Abstract

Bovine pericardium bioprosthesis has become a commonly accepted device for heart valve replacement. Present practice relies on the measurement of shrinkage temperature, observed as a dramatic shortening of tissue length. Several reports in the last decade have utilized differential scanning calorimetry (DSC) as an alternative method to determine the shrinkage temperature, which is accompanied by the absorption of heat, giving rise to an endothermic peak over the shrinkage temperature range of biological tissues. Usually, freeze-drying microscope is used to determine collapse temperature during the lyophilization of solutions. On this experiment we used this technique to study the shrinkage event. The aim of this work was to compare the results of shrinkage temperature obtained by DSC with the results obtained by freeze-drying microscopy. The results showed that both techniques provided excellent sensitivity and reproducibility, and gave information on the thermal shrinkage transition via the thermodynamical parameters inherent of each method

Ordered Collagen Membranes: Production and Characterization

“…In spite of this, shrinkage temperature (T s ) is widely used to characterize the replacement tissues [29], giving equivalent information to differential scanning calorimetry (DSC) experiments [30]. Therefore, we have measured T s to characterize the thermal stability of the membranes under study.…”

Prospects in Lyophilization of Bovine Pericardium

“…The equipment has the capacity to heat the sample up to 100°C but it has never been used to study the denaturation event. In order to verify the efficiency of freeze‐drying microscopy in measuring the denaturation temperature, Tattini and coworkers (35) performed DSC and freeze‐drying microscopy measurements on each of two sample materials: one natural (fresh bovine pericardium) and the other one of interest for cardiovascular devices (bovine pericardium cross‐linked with GA). The measurements were performed to compare the results of shrinkage temperature obtained by DSC with the results obtained by freeze‐drying microscopy.…”

Freeze-drying microscopy in mathematical modeling of a biomaterial freeze-drying

“…Freeze-drying microscopy has been a technique usually used in the determination of critical temperatures of liquid formulations (Tattini Jr et al, 2007;Tattini Jr, Parra, Pitombo, 2009). It consists of a microscope coupled to a freeze-drying chamber that permits visual observations of the product during the freeze-drying process.…”