Additively manufactured functionally graded biodegradable porous iron

Area of Science:

• Biomaterials Engineering
• Additive Manufacturing
• Materials Science

Background:

• Biodegradable metals are crucial for bone regeneration and preventing long-term implant infections.
• Existing additively manufactured porous structures lack functional gradients and biodegradability.
• Ideal bone substitutes require tailored properties for tissue integration and eventual resorption.

Purpose of the Study:

• To report the first fabrication of additively manufactured (AM) functionally graded biodegradable porous metallic biomaterials.
• To investigate the impact of topological design, specifically functional gradients, on material properties.
• To evaluate the potential of these novel biomaterials as bone substitutes.

Main Methods:

• Utilized a diamond unit cell for topological design of four porous structures (two functionally graded, two uniform).
• Fabricated specimens from pure iron powder using selective laser melting (SLM).
• Conducted experimental and computational analyses of permeability, biodegradation, mechanical properties, and cytocompatibility.

Main Results:

• Topological design with functional gradients controlled fluid flow, mass transport, and biodegradation rates (up to 4-fold variation in permeability, 3-fold in biodegradation).
• Scaffolds exhibited desired biodegradation rates (5-16% weight loss after 4 weeks) and bone-mimicking mechanical properties (E = 0.5-2.1 GPa, σy = 8-48 MPa).
• Demonstrated excellent cytocompatibility with no significant difference from controls.

Conclusions:

• Additively manufactured functionally graded porous iron shows great potential as a bone-substituting material.
• Topological design, particularly functional gradients, effectively controls mechanical properties and degradation behavior.
• This approach offers a promising strategy for developing advanced biodegradable metallic biomaterials for bone regeneration.