Bio-Resorbable Magnesium-Based Biomaterials for Neural and Orthopedic Applications

Magnesium (Mg)-based biomaterials have attracted increasing attention in biomedical applications, such as neural and orthopedic applications because of the biocompatibility, biodegradability, antibacterial properties, and excellent mechanical properties. However, rapid degradation of Mg is the major concern for many clinical applications. To address the challenge, the present dissertation developed the two approaches, including engineering proper surfaces and alloying Mg with other elements to control the degradation of Mg-based biomaterials and enhance the overall performances of Mg for neural and orthopedic applications. The first part of the dissertation developed a method to deposit a conductive polymer coating, poly(3,4-ethylenedioxythiophene) (PEDOT) onto the surface of Mg microwire for potential neural recording and stimulation applications. The optimized parameters were found for the first time. It was found that the corrosion rate of PEDOT-coated Mg microwire was much slower than the non-coated Mg microwire. The second part of the research reported the fabrication, characterization, degradation and electrical properties of biodegradable magnesium (Mg) microwires coated with two functional polymers, and the first in vivo evidence on the feasibility of Mg-based biodegradable microelectrodes for neural recording. The third part of the dissertation developed biocompatible, biodegradable Magnesium-zinc-calcium (Mg–Zn–Ca) alloys with similar mechanical properties to human bone for orthopedic applications. The objectives were to characterize Mg–2wt.% Zn–0.5 wt.% Ca (named ZC21) alloy pins microstructurally and mechanically, and determine their degradation and interactions with host cells and pathogenic bacteria in vitro and in vivo. Overall, the entire dissertation provided extensive knowledge regarding engineering proper surfaces and alloying Mg with other elements towards desired performances for neural and orthopedic applications