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

几十年来，生物活性玻璃一直被用于需要修复和生成新骨的生物医学应用中(例如，牙科植入物；骨缺陷)。使用生物活性玻璃的一个常见策略是作为复合材料--由不同材料制成的材料产生更多功能成分。最常见的生物活性骨组织支架要么是与聚合物结合在一起的颗粒陶瓷，要么是烧结陶瓷。有几种方法可以制备多孔支架，但还没有一种被普遍接受的方法，目前的工作集中在通过一种简化的方法来制备复合支架--将粉末与少量的粘结液混合。本研究的主要目标是利用液态陶瓷前驱体在空气中(在室温和压力下)固化，将生物活性玻璃颗粒结合在一起，形成机械稳定的骨组织支架，从而创建一种基于颗粒的生物活性玻璃复合材料。拟议技术的战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”；一种工业和食品安全粘合剂)。这项工作的创新本质是一条新的制造路线，可以生产多孔骨组织支架，使其能够在对现有手术方法影响最小的情况下实施。需要克服的科学挑战是以有效的方式确定理想的玻璃和硅酸盐溶液的最佳混合量，以便空气中的二氧化碳将溶液与生物活性玻璃颗粒结合在一起，使其具有足够的机械强度，以允许形状保持和允许体外生物活性反应。这项拟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粘合在一起。这项技术将能够根据需要在手术室使用，允许外科医生通过将粉末与预先测量的液体混合，并将生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。生成的复合支架将促进骨内生长，最终被吸收并被新骨取代。将进行实验测试以确定：最佳玻璃类型、颗粒形状、大小和分布；硅酸盐溶液的类型、数量和浓度；凝结时间；孔隙率；强度；密度；物相；以及在模拟体内流体浸泡测试中形成羟基碳酸盐磷灰石的时间(体内生物活性的替代指标)。材料表征工具将通过多元回归分析所需的可视化和量化，帮助确定玻璃和粘结剂相之间的关系。4名博士、1名硕士和10名理科学士HQP将在此期间获得非常理想的技能(例如，沟通、批判性思维、解决复杂问题和协作)。

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.