Hydrolytic Expansion Induces Corrosion Propagation for Increased Fe Biodegradation

Area of Science:

• Biomaterials Engineering
• Materials Science
• Orthopedic Implants

Background:

• Iron (Fe) is a promising bone implant material due to its degradability and mechanical strength.
• However, Fe's slow degradation rate does not match bone healing rates.

Purpose of the Study:

• To accelerate the degradation rate of Fe-based bone implants.
• To investigate the effect of incorporating hydrolyzable Mg2Si into an Fe matrix.

Main Methods:

• Incorporation of Mg2Si into an Fe matrix using selective laser melting.
• Evaluation of Fe/Mg2Si composite degradation in a physiological environment.
• Assessment of cell viability and proliferation (MG-63 cells).

Main Results:

• Mg2Si hydrolysis exposed more Fe surface area and generated gases that cracked degradation product layers.
• This led to accelerated corrosion and breakdown of protective layers on the Fe matrix.
• Fe/Mg2Si composites exhibited a significantly higher degradation rate (0.33 mm/y) compared to pure Fe (0.12 mm/y).
• The composites demonstrated good cytocompatibility, supporting MG-63 cell growth and proliferation.

Conclusions:

• Hydrolytic expansion using Mg2Si is an effective strategy to accelerate Fe degradation for bone implants.
• Fe/Mg2Si composites show potential as improved bone implant materials due to enhanced degradation and cytocompatibility.