CAREER: Structures and Properties of Bone at Multiple Length Scales

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Non-technical Summary: Bone is a typical mineralized biological tissue that exhibits superior mechanical properties. It is strong, tough, yet lightweight, which can be attributed to its hierarchical structures, i.e. structures at multiple length scales. However, the structures in bone at the sub-micron and nano-scales are still not well understood. In this project, the PI proposes to study the relationship between the structure and property of bone across multiple length scales, particularly in the sub-micron and nano-scales. A deeper understanding of bone can provide insights to fracture prediction and benefit the aging population and people with bone disorders. 10.2 million American people aged 50 and over have osteoporosis, which may lead to an increased risk of fracture. The new knowledge about bone will also provide inspirations for the design of more robust manmade materials, enable the advancement in biomedical materials, be extended to the research of other natural biocomposites, and significantly impact the broad range of applications in transportation, buildings, defense, biomedicine, and energy. The education and outreach activities in this project will build a pipeline to include more people from underrepresented groups, especially females, into STEM fields. Technical Summary: Fundamental understandings of bone can shed light on the challenges of developing synthetic materials that are both strong and tough through a combination of mechanisms across multiple length scales. The research objective of this proposal is to determine the composition-structure-property relationships in bone, at multiple length scales using integrated experiments and models. The central hypothesis is that the bulk properties of bone (strength, toughness, adaptation) are related to the composition, structure, and properties in its microscale structures (cement line and sub-lamellae) and nanoscale ultrastructure (mineralized collagen fibril (MCF) and extrafibrillar matrix (EFM)). The PI will first develop correlative microscopy techniques to characterize composition, structure, and properties for ultrastructure and microstructure of bone. Then in cortical bone and trabecular bone, the composition-structure-property across multiple length scales will be determined, respectively. Finally, the peri-implant bone adaptation will be investigated in terms of its extrinsic morphology and intrinsic properties. The education and outreach objective is to broaden participation from underrepresented groups, especially females, in STEM through education and outreach activities on bone. The PI is partnering with a local science museum in summer camps and after-school programs for K-12 students, especially girls, to learn about bone. Also, undergraduate and graduate students will be educated and trained on interdisciplinary (materials and medicine) bone research. The PI will also create more online video series of females in STEM workforce. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.