High Strength Bioresorbable PLA/CaP Composites

描述(申请人提供)：由可降解聚合物和生物活性磷酸钙制成的生物可吸收复合材料是临床上理想的骨固定和修复材料，因为它们不需要在骨愈合后二次手术移除。然而，目前生物可吸收聚乳酸/磷酸钙复合材料(PLA/CAP)用于骨固定的一个关键障碍是其较弱的力学性能。本项目的目标是开发一种新的技术来提高聚乳酸/CAP复合材料的机械强度，使其与天然骨相媲美，从而使其在承重部位得到更广泛的应用。由于复合材料中聚乳酸基质和盖子填料之间的界面粘合至关重要，因此我们的战略是开发一种技术，将核-壳有机-无机杂化结构与特殊的膦螯合剂和表面引发聚合有效地结合在一起，以在聚乳酸基质和盖子填料之间建立直接的化学键。在改进界面的基础上，我们的目标是将生物可吸收复合材料的机械强度提高到自然骨的平均值(例如，拉伸强度的目标值为100 Mpa)。此外，通过进一步优化一些关键变量(如帽相、颗粒大小、聚乳酸分子量(MW)和帽/聚乳酸质量比)，我们寻求将聚乳酸/聚乳酸复合材料的机械强度调整到较宽的范围(例如，拉伸强度50-100兆帕)，使其与不同位置的自然骨的机械强度最匹配。该研究将研究复合材料的初始机械强度和降解相关机械强度以及生物相互作用。这项研究的成功将产生生物可吸收复合材料，具有更好的生物相容性和高且可调的机械强度，能够很好地匹配新骨生长。这将使这种可吸收材料在骨愈合过程中保持足够的强度，消除应力屏蔽，避免临床上的不良炎症影响，从而更广泛和成功地应用于骨固定和修复，特别是承重区。在临床上，使用这种生物可吸收材料代替目前不可吸收的金属装置将对患者有很大的好处，因为它避免了对诊断工具(如计算机断层扫描)的干扰，避免了在骨折愈合后再次手术取出装置的可能性，并降低了总的治疗成本。

DESCRIPTION (provided by applicant): Bioresorbable composites made from degradable polymers and bioactive calcium phosphates are clinically desirable for bone fixation and repair, because they do not have to be removed by second surgery after bone heals. However, a critical barrier to wider and more successful use of current bioresorbable polylactide/calcium phosphate (PLA/CaP) composites to bone fixation is their weak mechanical properties. The goal of this project is to develop a new technology to improve the mechanical strength of PLA/CaP composites to match that of natural bone, so that they can have wider application in load-bearing locations. Due to the critical importance of the interfacial adhesion between the PLA matrix and CaP filler within the composites, the strategy is to develop a technology that effectively combines a core-shell organic-inorganic hybrid structure with a special phosphonic chelating agent and surface initiated polymerization to establish direct chemical bonds between the PLA matrix and CaP filler. Based on the improved interface, we target to improve the mechanical strengths of the bioresorbable composites to the average value of natural bone (e.g. 100 MPa as the target value of the tensile strength). Moreover, by additional optimizing a number of critical variables (e.g. CaP phase, particle size, PLA molecular weight (MW) and CaP/PLA mass ratio), we seek to adjust the mechanical strength of PLA/CaP composites into a wide range (e.g. tensile strength 50 - 100 MPa), so that they can best match those of natural bones from varied locations. Both of the initial mechanical strength and the degradation dependent mechanical strength as well as biological interaction of the composites will be studied in the proposed research. Success of the proposed research will produce bioresorbable composites with improved biocompatibility and high and adjustable mechanical strength which can well match new bone growth. This will allow such bioresorbable materials to be more widely and successfully applied to bone fixation and repair, particularly for the load-bearing areas, by maintaining sufficient strength during bone healing, eliminating stress-shielding, and avoiding the clinical adverse inflammatory effects. Clinically, using such bioresorbable materials instead of current non-resorbable metallic devices would be of great benefit to patients, by avoiding the interference with diagnostic instruments (e.g. computed tomography (CT)), eliminating the possible second surgery to remove the device after bone heals, and reducing the total treatment cost.