Schematic of the extrusion-based 3D printing fabrication of biodegradable FeMn-akermanite bone scaffolds and regrowing bone tissue after 14 and 21 days.Biodegradable iron-based metals offer a promising alternative to titanium-based bone implants for repairing damaged tissue. Despite their possibilities, there are drawbacks including limited biological activity and ferromagnetism, which can interfere with MRI. Now researchers have used 3D printing to create iron-based biodegradable bone implants that overcome many of these limitations [Putra et al., Acta Biomaterialia 162 (2023) 182-198, https://doi.org/10.1016/j.actbio.2023.03.033].
“The challenges associated with developing iron-based bone implants have been encountered by many researchers for about a decade,” explain Amir Zadpoor, Jie Zhou, and Niko E. Putra of Delft University of Technology. “We leveraged the multi-material capability of extrusion-based 3D printing [to] fabricate FeMn-akermanite composite scaffolds to solve these challenges.”
Biodegradable bone implants that dissolve gradually in the body while simultaneously promoting the growth of new tissue are attractive because they eliminate the need for secondary surgeries to remove more permanent scaffolds once the healing process is completed. Since Fe is an essential mineral in the body, it has been widely investigated as a basis for biodegradable bone implants.
“[We added] other elements, such as Mn to modify the ferromagnetic behavior of Fe and akermanite to improve the bioactive properties for bone healing,” point out Zadpoor, Zhou, and Putra.
The team from Delft and Shanghai Institute of Ceramics, Chinese Academy of Sciences, prepared an ink containing the three components with a binder that enables flow through the nozzle of a 3D printer and solidifies immediately after extrusion. The ink is built up layer by layer into complex structures, which are then debinded and sintered to remove the binder and create a robust 3D scaffold.
The porous FeMn-akermanite composite scaffolds demonstrate an accelerated biodegradation rate, losing over 30% of mass during four weeks in a blood plasma-like solution, maintain mechanical properties akin to trabecular bone, and are paramagnetic, making them MRI-compatible. The implants also encouraged the differentiation, growth, and mineralization of bone cells during in vivo tests.
“The developed porous FeMn-akermanite implants… have tremendously enlarged surface area to allow for accelerated biodegradation to match the healing process, bone-tissue ingrowth, and regeneration,” say the researchers.
Moreover, extrusion-based 3D printing is highly flexible, allowing the selection of a wide choice of materials for tailoring biofunctionalities for bone repair and other biomedical applications. Other biological agents or drugs such as antimicrobials could also be incorporated for on-demand delivery. The researchers are now assessing the performance of the implants in vivo.