In vitro bio-stability testing implantable PU-elastomers with structured surface
The initial estimate of bioperformance of the polymer-based formulations in medical devices can be realized by rapid and inexpensive in vitro investigations to simulate in vivo physiological conditions. Biostability of chondral and osteochondral implants made of polymers is strongly influenced by mechanical stress and reactive oxidative intermediates in physiologic environment of the joints. On long time scales oxidative degradation and environmental stress cracking leads to device failure and reduces life time of implants.
For predicting TPCU biostability in synovial fluids the accelerated metal ion-catalyzed method has been recommended to simulate in vivo degradation in unloaded regions with acceleration ratio of 1:15.
The aim of this study was to screen the oxidative resistance of a series of novel as well as commercially available biomedical TPCUs to predict their aging in vivo. The adequate biostability of the materials based on TPCU-PDMS-blockcopolymers was achieved varying the structure parameters. All TPCU-materials have been developed to ensure application relevant mechanical properties and to have a favorable bio performance under continuous physiological loadings. Degradation profiles have been monitored using FTIR to verify changes in molecular structure, SEM to observe surface changes, DSC and DMA to monitor changes in thermal and mechanical properties and GPC to detect changes in MW distribution. New formulations of soft TPCUs exhibit the valid bio-performance after 2 months using an accelerated testing method.
/ K. Athanasopulu, L. Kutuzova, M. Schneider, S. Sun, R. Kemkemer, G. Lorenz /