New processing route to porous bioactive glass composites for bone tissue scaffolds

点击翻译按钮获取中文摘要

Bioactive glasses have been used for decades in biomedical applications where the repair and generation of new bone is required (e.g., dental implants; bone defects). A common strategy for using bioactive glasses is as composites--materials made from different materials to produce a more functional component. The most common bioactive bone tissue scaffolds are either particulate ceramics bound together with polymers, or sintered ceramics. Several methods are capable of producing porous scaffolds, however there is no generally accepted method, and the present work is focused on producing composite scaffolds through a simplified method-mixing a powder with a small volume of binding liquid. The major goal of this research is to create a particulate-based bioactive glass composite using a liquid ceramic precursor that cures in air (at room temperature and pressure) to bind bioactive glass particles together so as to form a mechanically stable bone tissue scaffold. The strategy of the proposed technology is to use clinically and commercially successful raw materials (bioactive glass) and water soluble silicate solutions (e.g., sodium silicate, "water glass"; an industrial and food safe adhesive). The innovative nature of this work is a new manufacturing route to produce porous bone tissue scaffolds to enable implementation with minimal impact on existing surgical methods. The scientific challenges to be overcome are determination of the ideal glass and silicate solution in the optimum amounts to be mixed, in an effective manner, so that carbon dioxide in the air will set the solution to bind bioactive glass particles with enough mechanical strength to permit shape retention and permit an in vitro bioactive response. The proposed research challenges traditional thinking within the field of ceramics-to avoid elevated temperature to bind ceramic particles together. The technology will be able to be used in an operating room, on demand, to allow a surgeon to directly repair a bone defect by mixing a powder with a pre-measured amount of liquid and inserting the resultant paste into the wound site whereupon the composite will harden within a few minutes. The resultant composite scaffolds will promote bone in-growth and eventually be resorbed and replaced by new bone. Experimental testing will be performed to determine: optimal glass type, particle shape, size, and distribution; type, amount, and concentrations of silicate solutions; setting time; porosity; strength; density; phases; and time to form hydroxcarbonate apatite in simulated bodily fluid immersion testing (a proxy for in vivo bioactivity). Materials characterization tools will aid in determining relationships between glass and the binder phase through visualization and quantification required for multiple regression analysis. 4 PhD, 1 MSc and 10 BSc HQP will gain highly desirable skills (e.g., communication, critical thinking, complex problem solving, and collaboration) during this grant.