Award Abstract # 2323499
Collaborative Research: Predicting the Mechanical Properties of Biomimetic Apatite Crystals Due to Co and Cr Ion Substitutions

NSF Org: DMR
Division Of Materials Research
Recipient: UNIVERSITY OF ARKANSAS
Initial Amendment Date: July 27, 2023
Latest Amendment Date: May 17, 2024
Award Number: 2323499
Award Instrument: Standard Grant
Program Manager: Nitsa Rosenzweig
nirosenz@nsf.gov
 (703)292-7256
DMR
 Division Of Materials Research
MPS
 Directorate for Mathematical and Physical Sciences
Start Date: September 1, 2023
End Date: December 31, 2023 (Estimated)
Total Intended Award Amount: $254,925.00
Total Awarded Amount to Date: $0.00
Funds Obligated to Date: FY 2023 = $0.00
History of Investigator:
  • Arun Nair (Principal Investigator)
    Arun.Nair@afit.edu
Recipient Sponsored Research Office: University of Arkansas
1125 W MAPLE ST STE 316
FAYETTEVILLE
AR  US  72701-3124
(479)575-3845
Sponsor Congressional District: 03
Primary Place of Performance: University of Arkansas
863 W. Dickson St.
FAYETTEVILLE
AR  US  72701-1201
Primary Place of Performance
Congressional District:
03
Unique Entity Identifier (UEI): MECEHTM8DB17
Parent UEI:
NSF Program(s): BIOMATERIALS PROGRAM
Primary Program Source: 01002324DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 094Z, 7237, 7573, 8614
Program Element Code(s): 762300
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.049

ABSTRACT

Non-technical Abstract:
When implants, like hip implants made of cobalt and chrome degrade, they can release atoms of those heavy metals into the surrounding bone. Some of those atoms can make their way into the bone itself; more specifically they can get inside the hard part of your bones which is made up of a mineral called apatite. The movement of these atoms into the apatite can change the way your bones work, making them more likely to break. However, because the apatite minerals in your bones are extremely small, it has been very difficult to study where these heavy metal ions go and how they affect bone strength. The goal of this project is therefore to use a combination of computer modelling and experiments using very powerful X-rays to figure out where the metal atoms go in the apatite mineral and determine whether or not they make the bone more breakable. By combining computer models and experiments, techniques will be developed that allow researchers to understand how metal atoms interact with bone apatite and predict how those atoms affect bone strength in the millions of people with cobalt and chromium containing bone implants. Integrated with this research, the principal investigators will strive to create environments that make students more confident about their scientific abilities. This will be done by providing opportunities for students to work in the lab, by teaching inclusive classes that reach broad audiences, and by acting as role models for students who do not often see people like them (women and racial minorities) in scientific roles.

Technical Abstract:
Degradation of cobalt (Co) and chromium (Cr) containing implants are associated with release of heavy metal ions and an increase in bone fracture risk. Since bone is primarily composed of apatite mineral which exhibits a high propensity for cationic substitutions, it is likely that the bone matrix is absorbing these ions resulting in significant changes in crystal structure and mechanics. The principal investigators hypothesize that the incorporation of cobalt (Co) and chromium (Cr) in the near-implant bone plays a significant role in promoting fracture. However, due to the difficulty in studying nano-sized apatites, there remain several unanswered questions relative to this process including how Co and Cr substitute into apatite, how the ions affect the apatite mechanical properties, and what Co and Cr concentrations are needed to affect bone fracture. To answer these questions, an ab initio-based model of apatite crystals with Co and Cr substitutions will be developed to predict the change in crystallographic and mechanical properties of apatite crystals at the nanoscale. These predictions will be validated by experimental approaches using biomimetic apatite systems and high-energy synchrotron X-ray diffraction techniques. These data will be combined to create multiscale models of apatite crystals to study fracture initiation processes due to Co and Cr substitutions. The results from this study can benefit millions of North Americans with cobalt-chrome implants by creating a new avenue for treatment developments to minimize fracture in this already at-risk population. In addition, they will facilitate the tunability of apatite biomaterials for future bone graft and scaffolding applications. Integrated with the research, is an educational plan which seeks to increase self-efficacy in the realm of science for a variety of students. This will be accomplished by providing lab access to undergraduate and graduate students, developing culturally relevant inclusive scientific courses, and acting as role models for under-represented students.

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.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

Millions of people use cobalt and chromium containing bone implants, these implants can release atoms of those heavy metals into the surrounding bone as they degrade. Some of those atoms can be absorbed by parts of bones which is made up of a mineral called apatite. The movement of these atoms into the apatite can change the way bone work, making them more prone to fracture. However, because the apatite minerals in the bones are extremely small, it is very difficult to study where these heavy metal ions go and how they affect bone strength. The project therefore uses computational modeling methods to find out where the metal atoms go in the apatite mineral and determine whether they make the bone more prone to fracture. How metal atoms interact with bone apatite and predict how those atoms affect bone strength is the prime focus of this project. 

We performed preliminary studies during the project time frame (September 2023-December 2023) to understand the effect of Co and Cr ion substitutions in apatite crystals by developing several computational models. Our preliminary data suggests that Co and Cr ion substitutions affects the lattice properties of the apatite crystals and requires further studies to quantify the mechanical properties.  

 


Last Modified: 07/12/2024
Modified by: Arun K Nair

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