Effect of squalene absorption on oxidative stability of highly crosslinked UHMWPE stabilized with natural polyphenols

摘要

The uptake of synovial lipids into ultra high molecular weight polyethylene (UHMWPE) has been recently related with the in vivo and ex vivo oxidation of irradiated and remelted UHMWPE. Natural polyphenols have been demonstrated effective in protecting highly crosslinked UHMWPE from oxidation. This manuscript aims to investigate how squalene as a model unsaturated lipid affects the oxidative stability of polyphenol-stabilized highly crosslinked UHMWPE. The irradiated UHMWPE showed less squalene uptake and diffusion in comparison to the unirradiated UHMWPE due to the crosslinked structures in the former. Upon accelerated aging at 70 ℃ and 5 atm O_2 for different durations, the presence of squalene significantly accelerated the initiation, development and propagation of oxidation for the virgin and irradiated UHMWPE. The presence of antioxidants including natural polyphenols effectively prosponded and reduced oxidation of the squalene-doped irradiated UHMWPEs. The oxidation levels and depth of irradiated antioxidant/UHMWPE blends were much less than those for the irradiated UHMWPE. It is concluded that the natural polyphenols are effective in prohibiting oxidation related to the presence of squalene. This finding may be of clinical relevance in terms of stabilization of irradiated UHMWPE against synovial lipids-related oxidation.