Page 154 - IJB-9-3

International Journal of Bioprinting LPBF of AKM/PEEK biological composite

porous structures, such as triply periodic minimal surface has more advantages in stimulating cell differentiation and
scaffolds, which can meet the topological requirements of promoting vascular formation in vivo due to the release
complex bone tissue repairing [10-13] . of Mg ions [40,41] . These studies suggest that AKM has great

Poly-ether-ether-ketone (PEEK), a high-performance potential for enhancing the bioactivity of PEEK. Therefore,
engineering plastic, has been widely applied in the medical it will be of great significance if AKM/PEEK composite
industry [1,14-16] . Due to its excellent biocompatibility and material can be applied to the HT-LPBF process for the
radiolucency, PEEK has attracted much attention in manufacture of bioactive implants.
orthopedics fields [17-19] . Moreover, compared with metallic In this work, the AKM powder was compounded
materials, the lower modulus of PEEK is close to that of with PEEK in the ratios of 5 wt%, 10 wt%, and 15 wt%,
human bone, which can avoid the stress shielding effect respectively. The morphological and thermal properties
caused by the mechanical mismatch [20,21] . This makes it of composite powders were tested to evaluate the
an ideal material to be applied in fabricating customized processability of the HT-LPBF. The effects of AKM content
biological implants, such as cranial implants, interbody on the strength and modulus of fabricated composites
fusion cages, and bioinspired structures [8,22,23] . However, were investigated by tensile tests and cross-section
the high melting point of PEEK makes it difficult to be microstructure analysis. Finally, cell culture experiments
processed by the traditional LPBF strategy [24,25] . Therefore, were conducted to investigate the biocompatibility of the
several studies were performed for processing PEEK by composites. The bioactivity of the HT-LPBF-fabricated
high-temperature LPBF (HT-LPBF) [16,24,25] . Berretta et composites was evaluated by the in vitro mineralization
al. first proposed to use the energy melt ratio (EMR) to experiments. This paper presents a stable HT-LPBF process
predict the optimal processing parameters in the HT-LPBF for AKM/PEEK composite with suitable mechanical
process for PEEK . Chen et al. studied the crystallization properties and good biological activity, which has good
[26]
kinetics of PEEK during the HT-LPBF process and realized potential for clinical applications.
the fabrication of PEEK samples with tensile strength up
to 85.14 ± 4.62 MPa [8,27] . Using HT-LPBF technology to 2. Materials and methods
process PEEK makes it feasible to fabricate implants with 2.1. Preparation of AKM/PEEK powder
complex structures, which further expands the application The PEEK 450PF powder was purchased from Victrex,
of PEEK in the medical field. However, the medical UK. The AKM powder was purchased from Kunshan
applications of PEEK are still limited by its bio-inertia Chinese Technology New Material Company, China.
property, which induces weak osteogenesis and decreases Before mixing, the PEEK powder was thermally pretreated
the stability of substitutes resulting in clinical failure in at 280°C for 8 h to improve the processability because
long-term work [28,29] . the original PEEK powder has poor flowability [42,43] . This
To solve the problems induced by the bio-inertia of procedure can ensure stable powder spreading and avoid
PEEK, one of the effective strategies is incorporating powder agglomeration during the HT-LPBF process. Then,
bioactive fillers into the PEEK matrix to improve the AKM powders were ball-milled for 22 h at a rotational
the bioactivity . Previous studies have realized the speed of 300 rpm. Afterward, composite powders with
[30]
improvement of the bioactivity of PEEK by incorporating AKM ratios of 5 wt%, 10 wt%, and 15 wt% were obtained
biological fillers, such as β-tricalcium phosphate (β-TCP), by mixing the PEEK and AKM powder at a rotational
hydroxyapatite (HA), calcium silicate (CS), and bioactive speed of 400 rpm for 3 h.
glass (BG) [31-35] . These fillers help improve the bioactivity 2.2. HT-LPBF process of AKM/PEEK composites
of the PEEK matrix by releasing Ca and Si ions, which play The HK PK125 HT-LPBF system (developed by Huazhong
important roles in promoting osteogenesis . Akermanite University of Science and Technology) was utilized to
[36]
(AKM, Ca MgSi O ), as a bioceramic composed of Ca, fabricate PEEK and AKM/PEEK composites [27,44] . A wave
2
2
7
Si, and Mg, shows faster in vivo degradability and better CO laser (λ = 10.6 μm, 55 W) was equipped in the system
osteogenic ability than β-TCP [37,38] . Mohammadi et al. to carry out the fabrication process. Argon was used as a
2
synthesized nano-structured AKMs by mechanical milling protective gas to prevent the powder from being oxidized.
and conducted later sintering experiments, which verified The parameters for HT-LPBF processing of PEEK were
the apatite-forming ability of AKM by soaking it in a optimized, and the specific parameters are shown in Table 1.
simulated body fluid (SBF) solution for 7 days . Wu et al.
[36]
prepared porous AKM materials by calcining at 1300°C 2.3. Characterization methods
and proved that AKMs were beneficial for the adhesion The particle sizes and distributions were measured
and proliferation of bone marrow stromal cells (BMSCs) . by Mastersizer 3000 (British Malvern). The tensile
[39]
Furthermore, in addition to promoting osteogenesis, AKM experiments were carried out on an Electronic Universal
Volume 9 Issue 3 (2023) 146 https://doi.org/10.18063/ijb.699