Comparison of two antioxidants for poly(etherurethane urea) in an acceleratedin vitro biodegradation system

Abstract

Vitamin E (+/-alpha-tocopherol) was recently investigated as an antioxidant for implanted poly(etherurethane urea) (PEUU) elastomers. In that work, vitamin E prevented chemical degradation of biaxially strained PEUU up to 5 weeks implantation, and prevented pitting and cracking of the PEUU surface for the duration of the 10-week cage implant study. The promising results of the in vivo studies motivated a detailed comparison of vitamin E with Santowhite, the standard antioxidant used in PEUU elastomers. To evaluate vitamin E and Santowhite as antioxidants in PEUU, an accelerated in vitro treatment system was used that mimics the in vivo degradation of PEUUs. Vitamin E was even more effective than Santowhite in preventing pitting and cracking to the biaxially strained PEUU elastomers. The inhibition of ether oxidation was greater with vitamin E than with Santowhite when compared by equivalent concentrations and molar concentrations, respectively. It is hypothesized that the increased effectiveness of vitamin E in this system, compared to Santowhite, is due to differences in antioxidant mechanism(s). Vitamin E is more efficient in preventing PEUU oxidation than Santowhite because its phenoxy radical is more stable and it can terminate more than one chain per vitamin E molecule.

Correlating macrophage morphology and cytokine production resulting from biomaterial contact

“…These results further confirmed expression of the GFP‐actin protein. As the generation of ROS by monocyte derived macrophages has been shown by our group and others to contribute to the biodegradation of polyurethane elastomers, experiments were performed to ascertain if ROS production was affected by GFP‐actin transfection 40, 42. To that end, ROS levels were determined by monitoring the fluorescence of rhodamine generated by the oxidation of DHR‐123.…”

The biocompatibility and antibacterial properties of waterborne polyurethane-silver nanocomposites

“…10% H 2 O 2 and 0.05 M CoCl 2 was used as the accelerated environment for oxidation degradation in vitro [13,14]. Samples (7.5 mm in diameter, 0.2 mm in thickness) were immersed at 37 C for 7 days.…”

“…Surface bubbles were removed in an ultrasonic cleaner every 12 h. After the treatment, the specimens were rinsed thoroughly in distilled water and dried. The surface was examined under a field emission scanning electron microscope (FESEM) (JEOL JSM-6700F) operated at 3 kV for signs of surface ruffling, cracking or pitting [13].…”

Biocompatibility of poly(ether)urethane‐gold nanocomposites

“…Highly reactive oxygen species such as H 2 O 2 and À ÀOH, produced by the macrophages and other phagocytes during inflammation, may initiate the oxidation by free radical reactions. Efforts have been made to improve the biostability of the solvent-borne PU by modification of the chemical structure, [7][8][9] or by addition of antioxidants such as vitamin E. 10 Particle additives are one way to alter and enhance the properties of polymers. A classical example is the addition of carbon black to rubbers that is responsible for increased strength and durability.…”