Papers by Keyword: Substituted Apatite

Abstract: Natural bone constitutes of an inorganic phase (a biological nanoapatite) and an organic phase (mostly type I collagen). The challenge is to develop a material that can regenerate lost bone tissue with degradation and resorption kinetics compatible with the new bone formation. The aim of this study was to prepare self-organized magnesium and carbonate substituted apatite/collagen scaffolds, cross-linked with glutaraldehyde (GA). Bovine tendon was submitted to alkaline treatment resulting in a negatively charged collagen surface. The scaffolds were prepared by precipitation: simultaneous dropwise addition of solution containing calcium (Ca) and magnesium (Mg) ions and collagen into a buffered solution containing carbonate and phosphate ions in reaction vessel maintained at 37 °C, pH=8. The reaction products were cross-linked with 0.125 and 0.25% (v/v) glutaraldehyde (GA) solution and freeze-dried. The samples were characterized by Fourier-transformed infrared spectroscopy (FTIR). In vitro cytotoxicity (based on three parameters assays) and scaffolds degradation in culture medium and osteoblastic cells culture were performed in the cross-linked materials. No cytotoxic effects were observed. The cross-linked samples with the lower GA concentration showed a lower stability when placed in contact with culture medium. Human osteoblasts attached on the scaffolds surface cross-linked with 0.25% GA, forming a continuous layer after 14 days of incubation. These results showed potential application of the designed scaffolds for bone tissue engineering.

Abstract: The success or failure of a bioactive ceramic implant material in the body depends on a complex interaction between a synthetic foreign body and the host. These interactions occur at many levels from the nano-structural level, where subtle changes in surface physio-chemistry substantially alters the nature of the biomaterial-host tissue interface, to the meso- or macrostructural level where dependence on porosity mediates bioactivity through its effect on nutrient transfer and scaffold mechanics. Thus the factors that control the biological response to implant materials are a complex combination of mechanical, physical and chemical attributes which when combined favorably lead to ‘bioactivity’ in a material, or more correctly a ‘bioactive’ response to the material. This is illustrated in the successful use of porous bioactive ceramic scaffolds as synthetic bone graft substitute materials, where micro and meso-porosity, bulk and surface chemistry are manipulated to provide a framework that is highly conducive to the process of bone regeneration, balancing bone apposition and remodeling. Moreover, we now have the opportunity to developing an understanding of the complex balance of forces at play during bone grafting through investigation of these biological responses.