CAREER: Magnetic Imaging Guided Composite Materials Development

Case Western Reserve University, Cleveland OH

Investigators

Abstract

TECHNICAL SUMMARY: This CAREER grant supported by the Solid State and Materials Chemistry (SSMC) program aims to develop a novel class of ultra-high molecular weight polyethylene (UHMWPE)-based composites with special magnetic and mechanical properties that will facilitate the in situ study of implant-type materials in various chemical and biological fluid environments using magnetic particle imaging (MPI) technologies. Linear, branched and cross-linked UHMWPE polymer structures will be filled with specifically engineered iron oxide-based nanoparticles to prepare new functional magnetic polymer composites. The magnetic and mechanical properties of the fabricated composites will be evaluated as a function of processing conditions, compositions, and resulting microstructures in order to identify good processing approaches, and promising composite formulations that have high magnetization sensitivity for imaging, combined with good mechanical properties that are comparable to the matrix polymer. The information gathered from these studies will provide valuable knowledge on wear debris formation mechanisms of biopolymers and will contribute to the fabrication of innovative composite material systems possessing highly desired magnetic properties and good mechanical performance and reliability. This work is expected to lead ultimately to the ability to track wear and the generation of debris in real time inside the body, providing a transformational tool for improving the performance of UHMWPE prostheses. Moreover, the design and monitoring of the proposed magnetic composites will directly influence the advancement of MPI technology and possibly enable the development of bench side testing tools for polymer biomaterials that will be used for in vivo biomedical applications. NON-TECHNICAL SUMMARY: Polyethylene is widely used as a component in the fabrication of joint prostheses. A major downside of this material is that it can undergo excessive wear leading to premature loosening of the implant, which in turn can lead to failure and complicated replacement revision surgeries. Studies have shown that polyethylene wear in artificial joint replacements are not always identical and are not easily explained by exclusively mechanical factors. In cases of premature and excessive wear of polyethylene bearings, chemical degradation and oxidation of the polymer can significantly lower its mechanical resistance and result in an accelerated wear-off process. While ex vivo studies have been conducted on previously used polyethylene acetabular cups to understand the factors contributing to implant failure, the degradation mechanism is still not completely understood. An improved assessment of the structural integrity of the polyethylene material used in implants as subjected to mechanical and chemical stress will provide valuable information on the material's durability, and can help predict its wear and degradation over time. To study the real-time degradation of implant materials in various chemical and biological fluid environments, the proposed project aims to develop new polyethylene composite materials that can be investigated using an emerging imaging modality called magnetic particle imaging (MPI). The proposed research will transform the wear debris monitoring of polyethylene implant materials and impact annually one million people in the U.S. alone who undergo hip and knee replacement surgeries. The educational impact of this project will build on current initiatives to educate high school, undergraduate and graduate students through the development of cross-disciplinary courses and hands-on research programs that will incorporate the interplay between materials fabrication and imaging tools. Moreover, a modular "Traveling Magnetism Show" will be developed for K-12 students at four adaptive levels and will be showcased in local schools and science museums. In addition, a new "Women in Chemistry Workshop Series at CWRU" will be established to provide a mentoring and training platform for graduate and post-graduate female chemistry students. This program will facilitate monthly discussions and workshops to tackle important aspects of career advancement specific to women scientists.