Page 562 - IJB-9-6

International Journal of Bioprinting Osteogenic, antibacterial CpTi-MgOCu implants

ensuring the implant’s long-term stability and preventing and ceramic powers used were spherical. The fabrication
the need for revision procedures due to their aseptic used two AM processes: directed energy deposition
loosening. This study aims to fabricate CpTi, CpTi + 1 (DED) and selective laser melting (SLM). Samples for
wt.% MgO (CpTi-MgO), and CpTi + 1 wt.% MgO + 3 in vitro study were printed on a 5-axis DED-based AM
wt.% Cu (CpTi-MgO-Cu) compositions using metal AM. system (FormAlloy, Spring Valley, CA). Although coarser
These compositions were characterized in terms of their powder particles (45–150 µm) are preferred for DED-
microstructure and microhardness. In vivo rat studies were based AM systems, we optimized the printing parameters
conducted to evaluate the biological performance of these to accommodate finer particle size of <63 µm for the
compositions. Structures utilized for the in vivo studies printing operation. The printing operation was conducted
were ~40 vol.% porous with an approximate pore size of in an argon-purged environment with O < 20 ppm in the
2
600–700 µm since pore sizes in this range are optimum printing chamber. A cold rolled CpTi substrate was used
for enhanced tissue integration and osseointegration [35,36] . as a build plate. Discs of 8 mm diameter and 4 mm height
Additionally, in vitro bacterial culture was studied using were printed on the DED system. The printing parameters
the commonly occurring Staphylococcus aureus strain to used for the compositions are presented in Table 1.
evaluate the antibacterial efficacy of CpTi-MgO-Cu. We Samples used for in vivo study were printed on an SLM-
hypothesize that the CpTi-MgO-Cu composition will based powder bed fusion system (3D Systems ProX DMP
®
demonstrate better osseointegration performance than 200, Rock Hill, SC, USA) with a 300 W fiber laser and a
CpTi in vivo with no cytotoxicity due to the presence of wavelength of λ = 1070 nm. Porous structures of 2.4 mm
Cu, as schematically shown in Figure 1. diameter and 4 mm height with ~40 vol.% porosity were

2. Materials and methods designed in 3DXpert CAD Software (3D Systems, Rock
Hill, SC, USA). Premixed powders were poured into the
2.1. Processing of samples using metal additive supply chamber and compacted using a compaction plate. A
manufacturing thick CpTi plate of ~2.5 cm thickness was used as the build
CpTi, CpTi-MgO, and CpTi-MgO-Cu compositions platform and secured on the melting stage. A roller system
were processed using metal additive manufacturing. A carried powders from the supply to the build stage, with 30
metal matrix composition of CpTi-MgO was prepared by µm set as the layer thickness. The laser power and scanning
premixing CpTi powders (GKN Hoeganaes, Cinnaminson, speed for all the compositions are reported in Table 1. 3D
NJ, USA) with 1 wt.% of MgO (Inframat® Advanced Systems provide printing parameters used for CpTi and
Materials™, Manchester, CT, USA) powders. Similarly, CpTi-MgO as the standard Ti printing parameters. Laser
CpTi-MgO-Cu composition was prepared by premixing power was increased by 10%, and scan speed reduced by
CpTi powders with 1 and 3 wt.% of MgO and Cu (GKN 10% to increase the print energy input for CpTi-MgO-Cu
Hoeganaes, Cinnaminson, NJ, USA) powders, respectively. since Cu displays poor laser absorption and needs more
All metal and ceramic powders used for fabrication were energy for additive manufacturing operation [37,38] . Post-
sieved to obtain a powder particle size of <63 µm. All metal printing porous cylinders were cut from the build plate and

Figure 1. Schematic of MgO-induced osteogenic activity toward early-stage osseointegration and bactericidal effect of Cu in CpTi. The CpTi-MgO-Cu
was processed via metal additive manufacturing, enabling the incorporation of designed porosity. This further expedites the bone remodeling and tissue
attachment on the implant’s surface, contributing to its long-term stability in vivo.

Volume 9 Issue 6 (2023) 554 https://doi.org/10.36922/ijb.1167