Accelerated biodegradation of iron-based implants via tantalum-implanted surface nanostructures

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Surface Engineering

Background:

• Pure iron (Fe) is a potential biodegradable orthopedic implant material with good mechanical and biological properties.
• Current limitations include slow, irregular degradation in physiological conditions, hindering clinical application.
• Developing methods for controlled and accelerated degradation is crucial for Fe-based implants.

Purpose of the Study:

• To develop a novel surface modification strategy for pure iron (Fe) implants to achieve uniform and accelerated degradation.
• To investigate the effects of surface nanostructuring and galvanic coupling on Fe degradation rates and mechanical stability.
• To evaluate the biocompatibility and osteoblast response of the modified Fe surface.

Main Methods:

• Target-ion induced plasma sputtering (TIPS) was used to introduce tantalum (Ta) nanostructures onto the Fe surface, creating nano-galvanic couples.
• Electrochemical tests were performed to assess degradation rates and uniformity.
• Long-term in vitro immersion tests (~40 weeks) evaluated mechanical property changes.
• In vitro osteoblast assays and an in vivo rabbit femur implantation model assessed biocompatibility.

Main Results:

• TIPS treatment resulted in uniformly distributed nano-galvanic corrosion cells (nano Ta-Fe), leading to accelerated and uniform surface degradation compared to bare Fe.
• The mechanical properties of the nano Ta-Fe surface remained stable throughout the 40-week immersion test.
• Nano Ta-Fe enhanced osteoblast adhesion and spreading, showing no signs of cellular or tissue toxicity in vitro and in vivo.

Conclusions:

• Surface nanostructuring with tantalum (Ta) via TIPS effectively creates nano-galvanic couples for controlled Fe degradation.
• The Ta-implanted nanostructured Fe surface demonstrates improved degradation kinetics, stable mechanical integrity, and excellent biocompatibility.
• This approach holds significant potential for advancing Fe-based biodegradable orthopedic implants for clinical use.