Development of a bioactive and radiopaque bismuth doped baghdadite ceramic for bone tissue engineering

Young Jung No; Tien Nguyen; Zufu Lu; Mohammad Mirkhalaf; Frank Fei; Matthew Foley; Hala Zreiqat

doi:10.1016/j.bone.2021.116147

Development of a bioactive and radiopaque bismuth doped baghdadite ceramic for bone tissue engineering

Bone. 2021 Dec:153:116147. doi: 10.1016/j.bone.2021.116147. Epub 2021 Aug 11.

Authors

Young Jung No¹, Tien Nguyen², Zufu Lu², Mohammad Mirkhalaf², Frank Fei², Matthew Foley³, Hala Zreiqat⁴

Affiliations

¹ Tissue Engineering & Biomaterials Research Unit, School of Biomedical Engineering, The University of Sydney, NSW 2006, Australia; ARC Training Centre for Innovative BioEngineering, The University of Sydney, NSW 2006, Australia. Electronic address: young.no@sydney.edu.au.
² Tissue Engineering & Biomaterials Research Unit, School of Biomedical Engineering, The University of Sydney, NSW 2006, Australia; ARC Training Centre for Innovative BioEngineering, The University of Sydney, NSW 2006, Australia.
³ Australian Centre for Microscopy & Microanalysis, The University of Sydney, NSW 2006, Australia.
⁴ Tissue Engineering & Biomaterials Research Unit, School of Biomedical Engineering, The University of Sydney, NSW 2006, Australia; ARC Training Centre for Innovative BioEngineering, The University of Sydney, NSW 2006, Australia. Electronic address: hala.zreiqat@sydney.edu.au.

PMID: 34389477
DOI: 10.1016/j.bone.2021.116147

Abstract

Baghdadite (Ca₃ZrSi₂O₉, BAG), is a Zr-doped calcium silicate that has outstanding bioactivity both in vitro and in vivo. Bioceramic scaffolds should be sufficiently radiopaque to be distinguishable in vivo from surrounding bone structures. To enhance the radiopacity of BAG, this study investigated the effect of incorporating bismuth ions into its crystalline structure (Bi_xCa_3-xZrSi₂O₉, x = 0, 0.1, 0.2, 0.5; BAG, Bi0.1-BAG, Bi0.2-BAG, Bi0.5-BAG, respectively). Monophasic baghdadite was retained after bismuth ion incorporation up to x = 0.2 at calcination temperatures of 1350 °C. When pressed and sintered, energy dispersive x-ray spectroscopy showed that BAG and Bi0.1-BAG retained crystalline homogeneity, but Bi0.2-BAG formed zirconium-rich crystalline regions. BAG, Bi0.1-BAG and Bi0.2-BAG exhibited non-degradation after 56 days of immersion in culture medium. Bi0.1-BAG exhibited the lowest change in culture medium pH (+0.0), compared to BAG (+0.7) and Bi0.2-BAG (+0.2) after 56 days of culture media immersion. Bi0.1-BAG exhibited similar strength and modulus to BAG (σ: 200-290 MPa; E: 4-5 GPa), and significantly higher compressive strength and modulus versus Bi0.2-BAG (σ: 150-200 MPa; E: 3.5-4 GPa) across 56 days of aqueous immersion. In vitro studies using primary human bone derived cells (HOBs) demonstrated a significant increase in HOBs proliferation when cultured on Bi0.1-BAG for seven days compared to BAG and Bi0.2-BAG. Importantly, Bi0.1-BAG showed increased radiopacity by ~33%, when compared to BAG, and by ~115% when compared to biphasic calcium phosphate. The properties of Bi0.1-BAG show promise for its use as a bioactive ceramic with sufficient radiopacity for treatment of bone defects.

Keywords: Bioactive ceramic; In vitro characterisation; Radiopacity; Synthetic bone grafts.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bismuth*
Ceramics
Compressive Strength
Humans
Silicates
Tissue Engineering*
Tissue Scaffolds

Substances

Ca(3)ZrSi(2)O(9)
Silicates
Bismuth