In vivo performance of a rare earth free Mg-Zn-Ca alloy manufactured using twin roll casting for potential applications in the cranial and maxillofacial fixation devices

Matthew S Dargusch; Nagasivamuni Balasubramani; Nan Yang; Sean Johnston; Yahia Ali; Gui Wang; Jeffrey Venezuela; Jiwon Carluccio; Cora Lau; Rachel Allavena; Daniel Liang; Karine Mardon; Qingsong Ye

doi:10.1016/j.bioactmat.2021.10.026

In vivo performance of a rare earth free Mg-Zn-Ca alloy manufactured using twin roll casting for potential applications in the cranial and maxillofacial fixation devices

Bioact Mater. 2021 Oct 23:12:85-96. doi: 10.1016/j.bioactmat.2021.10.026. eCollection 2022 Jun.

Authors

Affiliations

¹ Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
² The University of Queensland, Biological Resources, Brisbane, QLD, 4072, Australia.
³ School of Veterinary Science, The University of Queensland, Gatton, QLD, 4343, Australia.
⁴ Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, Melbourne, Australia.
⁵ Centre for Advanced Imaging, National Imaging Facility, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
⁶ Centre of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, Wuhan, 430060, China.
⁷ Skeletal Biology Research Centre, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Harvard School of Dental Medicine, Boston, MA, 02114, United States.

Abstract

A magnesium alloy containing essential, non-toxic, biodegradable elements such as Ca and Zn has been fabricated using a novel twin-roll casting process (TRC). Microstructure, mechanical properties, in vivo corrosion and biocompatibility have been assessed and compared to the properties of the rare earth (RE) element containing WE43 alloy. TRC Mg-0.5 wt% Zn- 0.5 wt% Ca exhibited fine grains with an average grain size ranging from 70 to 150 μm. Mechanical properties of a TRC Mg-0.5Zn-0.5Ca alloy showed an ultimate tensile strength of 220 MPa and ductility of 9.3%. The TRC Mg-0.5Zn-0.5Ca alloy showed a degradation rate of 0.51 ± 0.07 mm/y similar to that of the WE43 alloy (0.47 ± 0.09 mm/y) in the rat model after 1 week of implantation. By week 4 the biodegradation rates of both alloys studied were lowered and stabilized with fewer gas pockets around the implant. The histological analysis shows that both WE43 and TRC Mg-0.5Zn-0.5Ca alloy triggered comparable tissue healing responses at respective times of implantation. The presence of more organized scarring tissue around the TRC Mg-0.5Zn-0.5Ca alloys suggests that the biodegradation of the RE-free alloy may be more conducive to the tissue proliferation and remodelling process.

Keywords: Biocompatibility; Biodegradable implants; In vivo degradation; Mg–Zn–Ca alloy; Twin-roll strip casting.