In developing bioresorbable metallic implants for bone applications, what do you think are the biggest challenges?

One of the foremost challenges in developing bioresorbable metallic implants lies in precisely controlling the degradation kinetics to match the rate of bone regeneration. For instance, while magnesium-based alloys degrade rapidly and can induce local alkalinity and hydrogen gas evolution, zinc and iron exhibit slower degradation profiles that may not be conducive to timely bioresorption. Achieving a predictable, uniform corrosion behavior within physiological environments,especially given inter-patient variability in pH, local inflammation, and mechanical load is non-trivial.

Moreover, the mechanical performance of these metals during the degradation process must be maintained long enough to provide adequate support for healing bone tissue, without leading to premature mechanical failure. This is particularly critical in load-bearing applications where early loss of structural integrity can compromise clinical outcomes.

Another central issue is the biocompatibility of the degradation products. While magnesium ions are generally well-tolerated, the accumulation of iron or zinc degradation products in situ could lead to localized cytotoxicity or interfere with cellular signaling pathways involved in osteogenesis and angiogenesis.

Alloy strategies to modulate corrosion rates often introduce elements whose long-term biological interactions are insufficiently characterized. The interplay between corrosion behavior, microstructure, mechanical performance, and host response introduces a complex multi-parametric design space that still lacks robust in vivo validation across large patient cohorts.

Translational hurdles also persist, including reproducibility in manufacturing, regulatory uncertainty, and the absence of standardized testing protocols tailored to resorbable metals, all of which delay clinical implementation despite promising preclinical data.