Biomimetic Mineralization by Combining Block Copolymer Self-Assembly and One Dimensional Crystal Nucleation

非技术：该奖项由德雷塞尔大学材料研究部的生物材料项目颁发，旨在使用“自下而上”的定向组装方法来模拟天然骨骼结构，并了解天然骨骼特性的起源。骨是第二常见的移植组织；全世界每年进行的骨移植手术超过220万例。从这项研究中获得的知识不仅有助于开发用于组织工程的新一代骨模拟材料，还将为设计更强、更轻的新型混合材料纳米复合材料提供线索。该提案的教育部分包括：1)开发两个关于天然材料特性的课程模块；2)指导研究生和本科生；3)让高中学生和教师，特别是来自代表性不足的少数群体的学生和教师参与拟议的研究活动。这些教育活动包括以下广泛的影响：1)建议的计划将通过让高中学生和教师参与研究活动，帮助弥合现有教育发展水平之间的差距；2)提议的外展计划将专门针对鼓励费城地区未被充分代表的少数群体的参与。技术方面：尽管宏观结构各不相同，但在形态上不同的骨骼具有相似的由胶原原纤维组成的纳米结构，其中有组织的羟基磷灰石纳米晶体沿原纤维嵌入67 nm的周期，这些纳米晶体平行于原纤维轴排列。合成软质材料已成功地用于控制矿物晶体的取向。然而，合成支架中矿物质的空间分布尚未以仿生方式复制。提出的设计旨在在分子水平上模仿天然骨的分层结构。研究人员将结合一维成核和嵌段共聚物（BCP）自组装来实现这一目标。通过控制精心选择的BCP在一维聚合物纳米纤维上的结晶，由于耗尽诱导的浓度梯度，晶体生长遵循一个周期模式，周期从几个周期到数百纳米不等。BCP晶体附近的化学环境可以被调整以允许纳米限制的生物矿化。通过这种方法，首次可以精确控制矿物纳米晶体的取向和空间分布。BCP分子量的变化也允许对生物矿化过程进行详细的形态和结构控制。这些研究人员预计，前所未有的结构控制将为混合材料的仿生设计提供新的途径，特别是骨模拟。更广泛的影响活动包括指导高中学生和教师，重点关注费城地区代表性不足的群体。

Non-technical: This award by the Biomaterials program in the Division of Materials Research to Drexel University aims to use a "bottom-up", directed assembly method to mimic the natural bone structure, and to understand the origin of the properties of natural bone. Bone is the second most commonly transplanted tissue; over 2.2 million bone graft procedures are performed annually worldwide. Knowledge gained from the study will not only help to develop new generation bone mimics for tissue engineering, it will also shed light on novel hybrid materials design towards stronger and lighter nanocomposites. The educational component of the proposal includes: 1) developing two class modules addressing natural materials properties; 2) mentoring graduate and undergraduate students; and 3) involving high school students and teachers, particularly from underrepresented minority groups, in the proposed research activities. These educational activities encompass the following broad impacts: 1) the proposed plans will help bridge the existing gap between levels of educational developments by involving high school students and teachers in research activities; and 2) the proposed outreach program will be specifically geared towards encouraging the participation of underrepresented minority groups in the Philadelphia region.Technical: Despite various macro-structures, morphogenically different bones share similar nanostructures consisting of collagen fibrils within which organized hydroxyapatite nanocrystals are embedded with a period of 67 nm along the fibrils, and these nanocrystals are aligned parallel to the fibril axis. Synthetic soft materials have been used to successfully to control the orientation of mineral crystals. The spatial distribution of minerals in a synthetic scaffold, however, has yet to be reproduced in a biomimetic manner. The proposed design aims to mimic the hierarchical structure of natural bone on the molecular level. The investigators will combine one-dimensional nucleation and block copolymer (BCP) self-assembly to achieve this goal. By controlling crystallization of carefully selected BCP on 1D polymer nanofibers, because of depletion-induced concentration gradients, the crystal growth follows a periodic pattern with the period ranging from a few terns to hundreds of nanometers. The chemical environment in the vicinity of the BCP crystals can be tuned to allow nanoconfined biomineralization. Through this approach, for the first time, both the orientation and spatial distribution of the mineral nanocrystals can be precisely controlled. Changing BCP molecular weight also allows detailed morphological and structural control of the biomineralization process. These researchers anticipate that the unprecedented structural control will provide a new route for biomimetic design of hybrid materials in general and bone mimics in particular. The broader impact activities include mentoring high school students and teachers with a focus on underrepresented groups from the Philadelphia region.