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

生物活性眼镜已经在需要修复和生成新骨的生物医学应用中使用了几十年（例如，牙科植入物；骨缺损）。使用生物活性玻璃的一种常见策略是作为复合材料——由不同的材料制成的材料，以产生更多功能的成分。最常见的生物活性骨组织支架要么是颗粒陶瓷与聚合物结合在一起，要么是烧结陶瓷。制备多孔支架的方法有几种，但目前尚无公认的方法，本文主要研究采用一种简化的方法——将粉末与小体积的结合液混合制备复合支架。这项研究的主要目标是创造一种基于颗粒的生物活性玻璃复合材料，使用液体陶瓷前体，在空气中（室温和压力下）固化，将生物活性玻璃颗粒结合在一起，从而形成机械稳定的骨组织支架。拟议技术的策略是使用临床和商业上成功的原材料（生物活性玻璃）和水溶性硅酸盐溶液（例如，硅酸钠，“水玻璃”；工业和食品安全粘合剂）。这项工作的创新性质是一种新的制造途径，可以生产多孔骨组织支架，使其对现有手术方法的影响最小。需要克服的科学挑战是确定理想的玻璃和硅酸盐溶液的最佳混合量，以一种有效的方式，使空气中的二氧化碳使溶液结合具有足够机械强度的生物活性玻璃颗粒，以保持形状并允许体外生物活性反应。这项提议的研究挑战了陶瓷领域的传统思维——避免高温将陶瓷颗粒结合在一起。这项技术可以在手术室中使用，根据需要，外科医生可以通过将粉末与预先测量的液体混合，并将合成的糊状物插入伤口部位，从而在几分钟内使复合材料变硬，从而直接修复骨缺损。合成的复合支架将促进骨生长，最终被吸收并被新骨取代。将进行实验测试，以确定：最佳的玻璃类型，颗粒形状，大小和分布；硅酸盐溶液的种类、数量和浓度；设置时间;孔隙度;力量;密度;阶段;在模拟体液浸泡测试中形成羟基碳酸钙磷灰石的时间（体内生物活性的代理）。材料表征工具将有助于确定玻璃和粘合剂相之间的关系，通过可视化和定量所需的多元回归分析。4名博士，1名硕士和10名理学士HQP将获得非常理想的技能（例如，沟通，批判性思维，复杂问题解决和协作）。

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.