Fabrication of Plga/Hap and Plga/Phb/Hap Fibrous Nanocomposite Materials for Osseous Tissue Regeneration

The study presents the manufacturing of nanofibrous structures as osteoconductive, osteoinductive materials for osseous tissue regeneration. The fibrous structures were obtained by electrospinning of poly(l-lactide-coglicolide) (PLGA) with addition of hydroxyapatite (HAp) and of a blend of PLGA with polyhydroxybutyrate with HAp added. The polymers used in the experiment were synthesised by an innovative method with a zirconium catalyst. First, the optimal electrospinning process parameters were selected. For the characterisation of the obtained osseous tissue reconstruction materials, the physical, macroscopic, functional, mechanical and thermal properties as well as crystallinity index were studied. The study of the radiation sterilisation influence on average molar mass, thermal and mechanical properties was made in order to analyse the degradation effect.

Exploring the Osteoinductivity of Calcium Phosphate Ceramics/PLA or Collagen Composites

The purpose of this study is to explore the osteoinductivity of the composite materials (calcium phosphate ceramics/PLA or collagen composites) with similar physical character of osteoinductive calcium phosphate ceramics and the influence of the chemical composition of the composite materials on osteoinductivity, and also to provide an experimental evidence for optimizing the design of the composite materials. Two kinds of composite materials were prepared. One (BCP/PLA) is fabricated with different ratio of BCP (biphasic calcium phosphate) ceramics powder and PDLLA powder through the particulateleaching technique. The other (BCP/collagen) is that BCP ceramics sintered at 1250oC and modified with collagen. The porous materials cylinders with Φ 5×8 mm were prepared. SEM was used to observe the microstructure and physical morphology of the composite materials. The two groups of composite materials cylinders were implanted in the dorsal muscles of four dogs. Six samples of each group were implanted in each dog respectively. The specimens were harvested at 2, 4, 12 and 24 weeks post operation, and thin decalcified sections were prepared for light microscopy (LM) analysis to evaluate their osteoinductivity and compare the capability of osteoinduction. The fibro-tissue and bone-like tissue were observed in the two composites, but no obvious bone formation was found in the tested periods. The results indicated that the composite materials could modify the mechanical property of ceramics. However, if the composite materials were biodegraded soon, new bone could not form into the scaffold, and the calcium phosphate should be the major component of osteoinductive materials.