The Effects of Biodegradation on the Cytocompatibility of Bioresorbable Fe-Based Scaffolds: A Review

The effects of process parameters on the mechanical properties and degradation behavior of Fe/HA biodegradable materials

HA/Fe composites were prepared by powder metallurgy. The effects of ball milling time, pressing pressure, and sintering temperature on the porosity and hardness of the composites were investigated, and their mechanical properties and biocompatibility were evaluated. The results show that as the ball milling time increases (30∼60min), the average particle size initially decreases and then increases (82.91∼53.49∼77.98 μm). Additionally, an appropriate increase in pressing pressure and sintering temperature can decrease the composite's porosity and increase its hardness. When the pressing pressure is 27 KN and the sintering temperature is 1000°C, the composite material has excellent mechanical properties (hardness 268.5 Hv, compressive strength 106.736 MPa) and good in vitro biocompatibility. The hemolysis rate of the sample was 1.719518 %. When the concentration of the extract was 50 %, the cell proliferation rate could reach 136.26 %. Furthermore, the degradation properties of the composites were studied. At 12 months the corrosion rate of HA/Fe composites reached 0.3173 mm/a. It was also observed varying degradation mechanisms was different in different soaking cycles, and the dominant degradation mechanism was gradually changed from HA in the early stage to Fe in the later stage, which played a positive guiding role in the development of iron matrix composites with different degradation rates.

Modifications on porous absorbable Fe-based scaffolds for bone applications: A review from corrosion and biocompatibility viewpoints

Iron (Fe) and Fe-based scaffolds have become a research frontier in absorbable materials which is inherent to their promising mechanical properties including fatigue strength and ductility. Nevertheless, their slow corrosion rate and low biocompatibility have been their major obstacles to be applied in clinical applications. Over the last decade, various modifications on porous Fe-based scaffolds have been performed to ameliorate both properties encompassing surface coating, microstructural alteration via alloying, and advanced topologically order structural design produced by additive manufacturing (AM) techniques. The recent advent of AM produces topologically ordered porous Fe-based structures with an optimized architecture having controllable pore size and strut thickness, intricate internal design, and larger exposed surface area. This undoubtedly opens up new options for controlling Fe corrosion and its structural strengths. However, the in vitro biocompatibility of the AM porous Fe still needs to be addressed considering its higher corrosion rate due to the larger exposed surface area. This review summarizes the latest progress of the modifications on porous Fe-based scaffolds with a specific focus on their responses on the corrosion behavior and biocompatibility.