An ideal engineered scaffold should support the regeneration of natural extracellular matrix; for bone this is principally Type I collagen and hydroxyapatite. The present work investigated the fabrication and characterisation of scaffolds comprised of (a) PCL or (b) Type I collagen +/- PDLLA produced via electrospinning and studied their influence on osteogenic regeneration. A parallel study examined the cellular response of human bone marrow stromal cells to nano-crystalline hydroxyapatite particles in a foamed PDLLA scaffold. Both the influence of particle size and chemical substitution were considered. Characterisation of materials involved scanning electron microscopy, Fourier transform infrared spectroscopy, circular dichroism, atomic force microscopy and histology. Electrospun PCL nanofibrous scaffolds potentially supported osteogenic regeneration. However, the scaffolds had to be treated post- spinning with NaOH and fetal calf serum to make them more hydrophilic to support cell attachment. With a view to producing a biomimetic material and knowing that hydrophobicity is not an issue for Type I collagen, rat-tail derived Type I collagen was selected for further studies. A number of solvents were explored to successfully electrospin the collagen. Although the wet stability of resultant scaffolds was poor, crosslinking improved scaffold stability, particularly the use of glutaraldehyde vapour. The observed denaturation. of collagen was determined to be a consequence of conformational changes rather than scission of collagen polypeptides, indicating that the electrospun collagen was not a simple analogous to gelatin. An alternative approach to stabilisation involved electrospinning collagen with a co-polymer, PDLLA, which successfully stabilised the fibrous scaffolds in the ratio ranges of 40- 60 wt% PDDLA: 60-40 wt% collagen. Future work will combine these materials with the optimised apatite filler to produce a composite material since the parallel study on cell culture of minerallPDLLA composites suggested that incorporation of mineral components did indeed enhance the alkaline phosphatase activity of human bone marrow stromal cells. Strontium substituted hydroxyapatite introduced potential benefits on alkaline phosphatase activity of bone derived cells in basal media.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:550345 |
| Date | January 2011 |
| Creators | Qiao, Xiangchen |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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