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Title: Modification of biomaterials using plasma polymerisation
Author: Bell, Juliet
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2013
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The peripheral nervous system has a limited ability to repair after injuries (1 mm/day). Current therapies for peripheral nerve injuries include suturing, autografting and nerve guide conduits (NGC). NGC's can be implanted into defects up to 20 mm in length. Possible improvements to the existing designs include material alterations as well as various coatings, fillers and cellular components. Plasma polymerisation is a chemical deposition technique, which can coat any surface with nano to micro-metre layers of desired chemistry. The aim of the thesis was to investigate the effect of the plasma polymers acrylic acid (AAc) and maleic anhydride on neuronal and Schwann cell metabolic rate and morphology in vitro. Evaluation of AAc and maleic anhydride surfaces was assessed using contact angle, X-ray Photoelectric Spectroscopy (XPS) and Time of Flight Secondary Mass Spectrometry (ToF-SIMS). NG108-15 neuronal cell staining protocols were optimised, then out of three maleic anhydride duty cycles (MA1, 2 and 3), MA1 supported neuronal cells with longer neurites and a higher metabolic rate. Glass and laminin/poly-L-lysine were used throughout as basal and positive controls respectively. Investigations then compared AAc with MA1 coatings under serum and serum free conditions. Whilst there were similar results under serum conditions, NG108-15 neuronal cells on MA1 under serum free conditions had significantly longer neurites compared to glass, also longer than laminin and acrylic acid. Primary rat Schwann cells were then studied, due to their integral role in peripheral nerve regeneration, on AAc and MA1. It was observed that Schwann cells had a longer, thinner phenotype and a higher total cell count on poly-L-lysine and glass compared to the plasma polymers. Primary rat dorsal root ganglion (DRG) culture was then optimised to look into the effect of both neuronal and glial types, initially using explants. DRG on AAc showed similar neurite outgrowth characteristics to those on glass, whilst DRG on MA 1 had comparatively fewer and shorter neurites. Dissociated DRG culture on MA1 and AAc surfaces were then observed to have longer neurite lengths and a higher percentage of neurons with neurites compared to glass. In conclusion, NG108-15 neuronal cells had longer and more numerous neurites on the plasma polymers compared to glass, which was corroborated using results from dissociated DRG. As the length and number of neurite outgrowths per neuron has been shown to be indicative of neuronal differentiation[100], plasma polymer coatings may support neuronal differentiation. Conversely, primary rat Schwann cells showed a longer and thinner phenotype on glass compared to the plasma polymers. DRG explants that contain both neuronal and glial cell types extended further on glass compared to the plasma polymers. Using a number of cell types was therefore a very relevant method of evaluating AAc and MA1 for neuronal applications. This work demonstrates the suitability of MA1 and AAc as coatings for nerve guide conduits, and would support further investigations into the effect of plasma polymers on neuronal/glial progenitor cells regarding differentiation and in vivo work.
Supervisor: Haycock, John W. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available