Porous strontium-doped apatite-wollastonite scaffolds were evaluated as potential substitutes for enhanced bone regeneration and the prevention of peri-prosthetic infections. Parent glasses of composition 35.5SiO2-7.1MgO-0.4CaF2-7.1P2O5-(49.9-x)CaO-xSrO mol%, where x = 0, 6.2, 12.5, 18.7, 24.9 or 37.4, were produced via the melt-quench route, ground and sieved < 45 μm. Porous scaffolds were obtained following the foam-replication method and heat-treated at 1050 °C for 2 h for controlled nucleation and growth of the crystal phases. All six glasses produced were amorphous. Differential scanning calorimetry showed that the formation of the calcium silicate phase strongly depended on the amount of strontium contained in the parent glass, linearly moving to higher temperatures with increasing strontium. Morphological evaluation (scanning electron microscopy and micro-computed tomography) proved that the obtained scaffold porosity, about 55 vol%, did not depend on the strontium content. X-ray diffraction showed that strontium preferentially substituted in apatite, while only higher strontium compositions formed a strontium magnesium calcium silicate phase. Compressive and biaxial flexural strength were both comparable to cancellous bone. Compositions containing 0 %, 6.2 % and 12.5 % strontium showed excellent apatite forming ability when submerged in simulated body fluid, which then decreased with increasing strontium for the three higher-strontium compositions. Microbiological tests carried out on strontium-containing salts showed no effective antibacterial properties for strontium as a free element. Amongst the six strontium-containing glasses, only the 37.4 % strontium oxide glass showed antimicrobial effects against Pseudomonas aeruginosa in broth dilution tests. Proliferation and osteogenic differentiation of porous scaffolds were tested on human bone cells. No conclusive results were obtained for the G292 cell line. When scaffolds were tested with human primary mesenchymal stromal cells, an increase in DNA content was observed with increasing strontium, while enhanced alkaline phosphatase activity and increased collagen production were found for low strontium compositions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:758304 |
| Date | January 2018 |
| Creators | Pontiroli, Lucia |
| Contributors | Wood, David J. ; Do, Thuy ; Yang, Xuebin |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/21944/ |
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