FRG: Organoapatite-Coated Titanium Foam: A Biohybrid for Skeletal Repair

这是一个聚焦研究小组(FRG)奖，由材料研究部的聚合物、陶瓷和金属项目共同资助。有效、快速和永久的骨骼修复是生物工程和生物材料研究的重大挑战之一。承重骨修复在与衰老相关的手术、事故、疾病和创伤中是至关重要的。目前的金属种植体技术通常依赖于具有多孔涂层的固体种植体来增强细胞附着。然而，应力屏蔽和接口故障以及恢复时间延长的困难依然存在。在这里，这个重点研究小组建议通过创造一种新型的用于骨修复的生物杂交植入材料来在这一领域做出重大贡献。该生物混合体将包括一种具有生物活性有机磷灰石涂层的具有生物相容性的泡沫钛，其中将生长一种生物相，以提供一个具有更高强度、硬度和与骨架附着性的仿生系统。在第一阶段，将通过一种基于钛基质中的Ar气泡的超塑性膨胀的新工艺来制备完全多孔的钛支架。第二步，钛支架的内外表面将涂上含有少量有机分子的有机磷灰石。自组装分子和超分子簇将被用来将有机磷灰石结合到金属表面。在第三步中，通过在含有大鼠颅骨细胞的水溶液中旋转植入物来诱导骨生长。体外测试将评估将骨完全整合到涂层钛泡沫中的能力，并将仔细研究微结构对机械性能和细胞生长的影响。将详细研究每一个加工步骤，从中开发预测生物和机械最佳生物杂交的模型。将在每个步骤研究植入物的微观结构，特别强调(I)发泡材料中的气孔(气孔、大小、体积分数、形状和连通性)，(Ii)生物杂化中的涂层形态和微结构，以及(Iii)完整生物杂化中的细胞特征。还将在每个步骤中研究种植体的机械性能，重点是宏观尺度(总体强度、刚度、抗疲劳性)和微观尺度(金属/陶瓷/骨界面)。实验结果将用解析和数值力学模型进行验证。加工、微观结构和机械模型将被整合在一起，以设计出最佳的生物杂交产品。

This is a Focused Research Group(FRG) award co-funded by the Polymers, Ceramics and Metals Programs in the Division of Materials Research. Effective, rapid and permanent skeletal repair is one of the grand challenges of bioengineering and biomaterials research. Load-bearing bone repair is critical in cases of aging-related surgery, accident, disease, and trauma. Current metallic implant technology usually relies on solid implants with a porous coating to enhance cell attachment. Difficulties with stress-shielding and interface failure as well as prolonged recovery times however persist. Here, this Focused Research Group proposes to make a significant contribution in this area by creating a novel biohybrid implant material for bone repair. The biohybrid will consist of a biocompatible titanium foam with pores coated with bioactive organoapatite, in which a biological phase will be grown to provide a biomimetic system with improved strength, stiffness and attachment to the skeleton.%%%In the first stage, a fully porous titanium scaffold will be fabricated by a novel process based on the superplastic expansion of argon bubbles in a titanium matrix. In the second step, the inner and outer surfaces of the titanium scaffold will be coated with organoapatite, containing small quantities of organic molecules. Self-assembling molecules and supramolecular clusters will be used to bind the organoapatite to the metal surface. In the third step, bone growth will be induced by rotating the implant in an aqueous solution containing rat calvaria cells. In-vitro testing will assess ability to fully integrate bone into coated Ti foam and the influence of microstructure on mechanical properties and cell ingrowth will carefully studied. Each of the processing steps will be studied in detail, from which models will be developed to predict biologically and mechanically optimal biohybrids. The microstructure of the implant will be studied at each step with particular emphasis on (i) pores in the foamed materials (pore, size, volume fraction, shape and connectivity), (ii) coating morphology and microstructure in the biohybrid, and (iii) cell characteristics in the complete biohybrid. The mechanical properties of the implant will also be studied at each step, with emphasis on both the macroscopic scale (overall strength, stiffness, fatigue resistance) and the microscopic scale (metal/ceramic/bone interfaces). The experimental results will be validated using analytical and numerical mechanics models. The processing, microstructural and mechanical models will be integrate to allow for the design of an optimal biohybrid.