Production and characterisation of CorGlaes pure 107 degradable polymer composites

Colquhoun, Ross (2015) Production and characterisation of CorGlaes pure 107 degradable polymer composites. PhD thesis, University of Glasgow.

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Abstract

Phosphate glass fibre polymer composites have the potential to be utilised as degradable orthopaedic implant devices with modifications to the glass fibre composition allowing for materials with tailorable mechanical properties and degradation rates. Accordingly such materials could be advantageous for the development of alternative cranioplasty implant devices. In collaboration with an industrial sponsor, a promising composition of phosphate glass was characterised to assess its potential as a composite reinforcing agent along with the applicability of different composite configurations as possible cranioplasty implants. The CorGlaes® Pure 107 phosphate glass was found to demonstrate suitable dissolution rates for cell culture whilst vibrational spectroscopy and analytical chemistry techniques confirmed its structural features and suitability for fibre manufacturing. The mechanical properties of its bulk and fibre formats were determined to be in line with alternate PG compositions but initial biocompatibility screenings of glass samples using human osteosarcoma cells found this composition to be cytotoxic. This was believed to be due to localised pH changes or from the release of Zn2+ ions towards cytotoxic levels. The absence of a carbonated hydroxyapatite layer formation when immersed in simulated body fluid also indicated that this glass composition possessed no in vitro bioactivity. Composite materials based on CorGlaes® Pure 107 fibres in a polylactic acid (PLA) matrix at a 0.2 fibre volume fraction (Vf) were found to exhibit mechanical properties within the same region as those reported for cranial bones. However rapid dissolution of the reinforcing fibres (due to autocatalysis) led to premature reductions in the composite mechanical properties and resulted in a cytotoxic response during in vitro cell culture. The introduction of a secondary hydroxyapatite filler phase into the CorGlaes® Pure 107 composite to counteract the acidic pH led to changes in the samples mechanical properties and degradation media pH. However this failed to retard the fibre dissolution rate in 0.15Vf composites. At a 0.01Vf, the inclusion of HA produced biocompatible composites compared to the HA free equivalent and was attributed to the reduction of preferential Zn2+ ion release from the glass fibres due to the pH buffering at the fibre-matrix interface. However the low Vf required to achieve biocompatible composites made the CorGlaes® Pure 107 fibres unsuitable as a primary composite reinforcing agent. Consequently phosphate glass fibre composites may be suitable for cranioplasty applications with future hybrid composites allowing for the design of implant materials that are capable of eliciting an immediate in vivo response whilst retaining its long term mechanical properties.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Biomaterials, orthopaedics, bone, phosphate glass, phosphate glass fibres, bioactive glass, phosphate glass fibre composites, degradable composites, hybrid composites
Subjects: Q Science > QD Chemistry
R Medicine > RZ Other systems of medicine
T Technology > TA Engineering (General). Civil engineering (General)
Colleges/Schools: College of Science and Engineering > School of Engineering > Biomedical Engineering
Funder's Name: UNSPECIFIED
Supervisor's Name: Tanner, Professor Elizabeth
Date of Award: 2015
Depositing User: Dr Ross Colquhoun
Unique ID: glathesis:2015-6352
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 20 May 2015 07:32
Last Modified: 25 May 2015 09:02
URI: http://theses.gla.ac.uk/id/eprint/6352

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