Development of Novel High Strength Biodegradable Metals for Temporary Biomedical Implants

Michigan State University, East Lansing MI

Investigators

Abstract

Non-Technical Abstract: A dream of the biomedical devices industry is to replace permanent endovascular stents with stents that can perform their function in the first few months and then dissolve in the host body, eliminating harmful long-term effects experienced with current permanent stents. This work seeks to overcome one of the most challenging aspects of biodegradable implant materials, controlling the microstructure, through processing, for enhancing the mechanical behavior and controlling the lifetime in physiological environments. The broader impacts of this work include use of the advanced thermomechanical processing methods to improve the mechanical properties of zinc-based biodegradable metals. This approach has the potential to change how biodegradable implants are processed and can initiate a revolution in the biomedical industry by implementing new processes for manufacturing biodegradable implants materials. Other broader impacts of the proposed work include producing modules on processing-microstructure-property relationships of zinc alloys, expanding an established K-12 hands-on SEM-based outreach program at Michigan State University (MSU), and providing research opportunities for graduate and undergraduate students. The modules and outreach program are intended to help promote K-12 students to enter Science, Technology, Engineering and Math (STEM) disciplines. Overall, this work is intended to make a lasting effect by understanding processing-microstructure-property relationships of zinc alloys. Technical Abstract: Because they exhibit near-ideal biocorrosion and biocompatibility behavior, zinc (Zn) and its alloys show promise for biomedical applications such as biodegradable stents. However, a primary drawback of pure Zn as an absorbable stent material is the lack of mechanical strength. The strengths of Zn alloys can be significantly improved through severe plastic deformation (SPD) techniques such as high-pressure torsion and equal channel angular pressing, both of which result in a significantly refined microstructure. The application of SPD techniques, such as these, is especially promising for metal matrix nanocomposites (MMNCs). Although MMNCs containing Zn as a matrix is in its infancy, they have the potential to result in biodegradable materials with enhanced strengths, while maintaining biocorrosion behavior and biocompatibility attractive for biodegradable implants. Overall, this program will evaluate the viability of Zn-matrix MMNCs as biodegradable implants and will test the novel SPD approach for grain refinement. A focus of this work will be to understand processing-microstructure-property relations of these materials. In addition, an understanding of the corrosion behavior and mechanisms and the nature of the biocompatibility of these materials in comparison to standard biodegradable Zn alloys will be obtained.