Supercritical fluids: a novel route to polymeric allografts?
PhD Supervisor(s): Steve Howdle, Prof Kevin Shakesheff
Contact Email: matthewspurcell@gmail.com
Undergraduate Degree: Chemical Engineering (Loughborough University)
PhD Summary
My Ph.D. research is focused on addressing the need for a synthetic alternative to the current 'gold standard' for impaction bone grafting (IBG) procedures - morsellised bone. Expense, availability, risk of disease transmission, and rejection are all drivers for an alternative. Supercritical carbon dioxide foaming of polymers to create porous scaffolds using amorphous or semi-crystalline polymers is a technique that has seen development and publications in literature over the last sixteen years. The solvent free process can use low temperatures, ideal for tissue engineering scaffolds.
My work has focused on using supercritical carbon dioxide to create different porous polymeric scaffolds and identifying and progressing the most promising an application a replacement to allograft for IBG. To this end poly (D, L-lactide) (PDLLA) and poly (D, L-lactide-co-glycolide) (PDLLGA) porous scaffolds, foamed using supercritical carbon dioxide; seeded with mesenchymal stem cells (MSCs); and impacted, in a process that replicates impaction bone grafting, have been investigated in vitro and in vivo (murine and ovine). This work has been performed in collaboration with University of Southampton, where the in vitro work and the murine model were based. The ovine model was based at the Royal Veterinary College, Hatfield.
Incorporation of hydroxyapatite (HA), as micro and nano particles, into the scaffolds at the supercritical foaming stage has also been investigated and the scaffolds have been characterised using a combination of micro x-ray computed tomography, scanning electron microscopy, elemental analysis, dynamic mechanical analysis and compression testing.
Results so far indicate high molecular weight PDLLA with 10% HA is one of the most promising formulations. Bony like matrix formation has been observed in vivo on scaffolds implanted with and without the presence of MSCs.
I am also carrying out collaborative work with exciting new polymers developed at Imperial College London. I have investigated the behaviour of these biocompatible polymers in supercritical carbon dioxide which has led to the creation and characterisation of porous scaffolds using these polymers.
Publications, Presentations and Awards
Publications
