Poster M13 - 3D-printed magnesium isotropic porous scaffolds via multi-material additive manufacturing for bone tissue engineering

Introduction: Magnesium implants offer immense potential as the new generation of bone implants due to their degradability, biocompatibility, and exceptional mechanical properties matching those of native bone. However, due to their high reactivity, manufacturing of magnesium implants prove challenging, with high complexity structures even more difficult. Furthermore, their rapid degradation and hydrogen bubbles generated during degradation causing separation of tissue layers has prevented widespread adoption from the traditional implant materials such as titanium or stainless steel. Blended multiple material processes multi-material additive manufacturing presents as an attractive solution to addressing inherent material characteristics of magnesium, specifically with thermoplastics due to their versatility, and low cost allowing for ease of adoption. However, thermoplastics faces the opposite drawback to magnesium with their slow degradation rate and being too soft to be applied to high load bearing areas. By utilizing 3D-printing and polycaprolactone fused filament fabrication, we are able to overcome the constraints of requiring inert environments and other safety concerns and print magnesium at room temperature and normal conditions, as well as address degradation issues due to inherent material properties of the respective materials.

Materials and

Methods: This study investigates possibility of printing Mg at room temperature and conditions as well as the influence of additively manufacturing magnesium to a FDA-approved, biodegradable thermoplastic on material properties including mechanical and degradation behavior. Isotropic scaffolds of 1.2mm pores were 3D-printing using an off-the-shelf 3D printing with no major modifications at low nozzle temperatures with room conditions. Scaffolds of various concentration ranging up to 45 w% were subject to a comprehensive range of characterization techniques, including SEM, SEM-EDX, micro-CT, tensile, compression and viscometry were employed to analyze the material properties. To verify the degradation, we utilized ICP-MS to quantify Mg elution from the scaffolds.

Results, Conclusions, and Discussions: The findings unveiled that addition of magnesium to scaffolds is capped at 45 w% due to the increase in viscosity as Mg percentage in the material increases. We observed increased crystallization temperature, decreased melting temperature, and enhanced shear thickening behavior. Furthermore, the presence of Mg in scaffolds correlates with superior compressive and tensile strength, though not reaching that of pure Mg at 45%. SEM-EDX results shows successful incorporation of magnesium in scaffolds, however the lack of Mg presentation on the surface of the scaffolds correlates with the delayed release of Mg. This comprehensive investigation verifies the possibility of printing magnesium as well as provides valuable insights into Mg additive manufacturing, paving the way for superior biodegradable implant materials for 3D printed scaffolds

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