Vitamin E-stabilised UHMWPE for orthopaedic implants:quantitative determination of vitamin E and characterisation of its transformation products


The fate of vitamin E and the formation and identification of its transformation products were investigated at different stages of the manufacturing process of commercially produced cross-linked (by γ-irradiation) UHMWPE stabilised with vitamin E (vitamin E infused-post irradiation) used for tibia-components (as articulating surfaces) in total knee arthroplasty (total knee replacement). Vitamin E (α-tocopherol) and its transformation products were extracted from microtomed Tibia films and the different products were separated, isolated, purified using high performance liquid chromatography (HPLC), and characterised by spectroscopic methods and LC-MS. The amount of vitamin E and that of the products formed in the different Tibia samples and in their extracts were also quantified using FTIR and HPLC analysis and calibration curves. Thorough analysis of the Tibia extracts has shown that a number of vitamin E transformation products were formed at different concentrations at two selected stages of the implant manufacturing process that is before and after sterilisation by γ-irradiation. The identified products were found to correspond mainly to different stereoisomeric forms of a small number of vitamin E transformation products. Most of the observed products were of dimeric and trimeric nature with their identity confirmed through a detailed study of their spectral and chromatographic characteristics. It was found that the products of vitamin E, prior to the sterilisation step but after the crosslinking and doping of vitamin E, were mainly the dihydroxydimers and trimers (Tibia samples at this stage are referred to as “Tibia-VEPE”). After sterilisation and completion of the manufacturing process, additional dimers of vitamin E were also formed (Tibia samples at this stage are referred to as ‘Tibia-VEPE-Sterile’), Furthermore, two tocopherol-derived aldehydes (aldehyde 5-formyl-γ-tocopherol and aldehyde 7-formyl-γ-tocopherol) were also formed but at very low concentrations especially in the Tibia-VEPE-Sterile samples. The question of whether vitamin E becomes chemically reacted (grafted) onto the polymer matrix during the manufacturing process of the Tibia is also addressed.

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Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
Additional Information: © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Uncontrolled Keywords: vitamin E,orthopaedic implants,UHMWPE,antioxidant,Condensed Matter Physics,Mechanics of Materials,Polymers and Plastics,Materials Chemistry
Publication ISSN: 1873-2321
Last Modified: 18 Jun 2024 07:13
Date Deposited: 19 Aug 2019 10:07
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2016-03
Published Online Date: 2015-12-12
Accepted Date: 2015-11-30
Submitted Date: 2015-08-13
Authors: Al-Malaika, Sahar (ORCID Profile 0000-0002-1378-0603)
Doudin, Khalid (ORCID Profile 0000-0003-3604-9861)

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