Nanostructured Block-copolymer Reinforced Calcium Phosphate Composites

描述(由申请人提供)：这项建议的广泛目标是开发合成方法，以开发下一代牙科修复复合材料，具有无机和有机成分的纳米结构排列，类似于牙本质和牙釉质中的结构。作为这项拟议工作的一部分，合成的自硬化复合材料将在修复因龋齿引起的龋齿方面得到应用。我们的方法是将磷酸钙矿物与两亲性(疏水/亲水)嵌段共聚物的公认能力相结合，以指导无机材料组装成介观结构杂化材料(例如，圆柱形、片状或双连续形态)。我们将从无定形的磷酸钙颗粒作为前驱物，在与嵌段共聚物形成结构后，将其结晶成以磷灰石(Ca10(PO4，CO3)6(OH)2)纳米晶为无机成分的坚固复合材料。材料的合成将有四个特定的目标：1)合成和表征稳定的无定形磷酸钙颗粒(&lt；100 nm)，能够在水和有机溶剂中形成稳定的悬浮液。2)使用两亲嵌段共聚物将ACP粒子组装成具有明确的一维、二维和三维纳米结构的材料。3)纳米复合材料的无定形无机相的控制晶化。4)将在AIMS 2和AIMS 3中制备的纳米结构复合材料的粉末与水液相混合以诱导二次结晶，从而开发出自硬化复合材料。这些用于牙科修复的新型复合材料的设计代表着一种范式的转变，即从将孤立的无机颗粒嵌入连续的聚合物基质中的传统材料转变为由聚合物渗透的连续无机相的复合材料。连续无机相的好处包括减少(甚至消除)复合材料硬化时的收缩，提高耐磨性，以及更坚固的材料。从力学上讲，两亲性嵌段共聚物作为有机成分将为复合材料提供韧性和抗断裂性能。这些自硬化复合材料对天然牙本质的粘附性应该比传统树脂更好，因为我们使用的是能够渗透到水化牙本质的水基系统。嵌段共聚体系的灵活性将使我们能够在未来定制复合材料的细观结构，以形成机械性能与正在修复的牙齿部分(例如牙本质或牙釉质)最匹配的材料。这项研究与R21的哲学是一致的，因为两亲性嵌段共聚物分相成纳米结构膜的能力从未被应用于磷酸钙矿化的结构。

DESCRIPTION (provided by applicant): The broad objective of this proposal is to develop synthetic methodologies towards next generation dental restorative composites that have a nanostructured arrangement of the inorganic and organic components, similar to the structures found in dentin and enamel. The self-hardening composites synthesized as part of this proposed work will have applications in the repair of dental cavities caused by caries. Our approach is to combine calcium phosphate minerals with the well-established ability of amphiphilic (hydrophobic/hydrophilic) block copolymers to direct the assembly of inorganic materials into mesostructured hybrids (with e.g., cylindrical, lamellar, or bicontinuous morphologies). We will start from amorphous calcium phosphate particles as a precursor phase, which, after structure formation with the block copolymers, will be crystallized to form robust composites with apatite (Ca10(PO4,CO3)6(OH)2) nanocrystals as the inorganic component. The synthesis of the materials will be completed with four specific aims: 1) Synthesis and characterization of stable amorphous calcium phosphate (ACP) particles (< 100 nm) capable of forming stable suspensions in both aqueous and organic solvents. 2) Use of amphiphilic diblock copolymers to direct the assembly of ACP particles into materials with defined 1-D, 2-D, and 3-D nanostructures. 3) Controlled crystallization of the amorphous, inorganic phase of the nanostructured composites. 4) Development of self-hardening composites by mixing powders of the nanostructured composites developed in Aims 2 and 3 with an aqueous liquid phase to induce secondary crystallization. The design of these new composites for dental restoration represents a paradigm shift away from traditional materials with isolated inorganic particles embedded within a continuous polymer matrix to composites with a continuous inorganic phase penetrated by polymer. The benefits of a continuous inorganic phase include a reduction (or even elimination) of shrinkage of the composites as they harden, improved abrasion (wear) resistance, and stronger materials. Mechanically, the amphiphilic blockcopolymer as the organic component will provide toughness and fracture resistance to the composite. The adhesion of these self-hardening composites to the natural tooth should be better than the traditional resins since we are using a water-based system that will be able to infiltrate the hydrated dentin. The flexibility of the block copolymer system will allow us in the future to tailor the mesostructure of the composites to form materials whose mechanical properties best match the part of the tooth (e.g., dentin or enamel) being repaired. This research is consistent with the R21 philosophy in that the ability of amphiphilic block copolymers to phase segregate into nanostructured films has never been applied to the structuring of calcium phosphate mineralization.