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Biodegradable Si3N4 bioceramic sintered with Sr, Mg and Si for spinal fusion: Surface characterization and biological evaluation
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Material in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
Swedish University of Agricultural Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
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2018 (English)In: Applied Materials Today, ISSN 2352-9407, Vol. 12, p. 260-275Article in journal (Refereed) Published
Abstract [en]

Silicon nitride (Si3N4) is an industrial ceramic used in spinal fusion and maxillofacial reconstructionbecause of its excellent mechanical properties and good biocompatibility. This study compares the sur-face properties, apatite formation ability, bacterial infection, cell-biomaterial interactions, and in vivotoxicity (zebrafish) of newly developed Si3N4 bioceramics (sintered with bioactive sintering additivesSrO, MgO and SiO2) with two standard biomaterials; titanium (Ti) and traditional Si3N4 bioceramics (sin-tered with standard sintering additives Al2O3 and Y2O3). In general, Si3N4 bioceramics (both the newlydeveloped and the traditional) displayed less in vitro bacterial affinity than Ti, which may arise fromdifferences in the surface properties between these two types of material. The newly developed Si3N4bioceramics developed lower biofilm coverage and thinner biofilm, compared to traditional Si3N4 bioce-ramics. The effects of ionic dissolution products (leach) on proliferation and differentiation of MC3T3-E1cell were also investigated. Ionic dissolution products containing moderate amount of Sr, Mg and Siions (approximately 4.72 mg/L, 3.26 mg/L and 3.67 mg/L, respectively) stimulated osteoblast prolifera-tion during the first 2 days in culture. Interestingly, ionic dissolution products from the traditional Si3N4bioceramics that contained small amount of Si and Y ions achieved the greatest stimulatory effect foralkaline phosphatase activity after 7 days culture. The toxicity of ionic dissolution products was investi-gated in a putative developmental biology model: zebrafish (Danio rerio). No toxicity, or developmentalabnormalities, was observed in zebrafish embryos exposed to ionic dissolution products, for up to 144 hpost fertilization. These newly developed Si3N4 bioceramics with bioactive sintering additives show greatpotential as orthopedic implants, for applications such as spinal fusion cages. Future work will focus onevaluation of the newly developed Si3N4 bioceramics using a large animal model.

Place, publisher, year, edition, pages
2018. Vol. 12, p. 260-275
Keywords [en]
Si3N4 bioceramic, Spinal fusion, Biocompatibility, Bioactive ions, Zebrafish
National Category
Medical Materials
Identifiers
URN: urn:nbn:se:uu:diva-356522DOI: 10.1016/j.apmt.2018.06.002ISI: 000443213700023OAI: oai:DiVA.org:uu-356522DiVA, id: diva2:1236019
Funder
Carl Tryggers foundation Available from: 2018-07-30 Created: 2018-07-30 Last updated: 2019-06-26Bibliographically approved
In thesis
1. Spark plasma sintered ZrO2-SiO2 glass ceramics and Si3N4 bioceramics
Open this publication in new window or tab >>Spark plasma sintered ZrO2-SiO2 glass ceramics and Si3N4 bioceramics
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on elaboration and characterization of two types of bioceramics: one is ZrO2-SiO2 nanocrystalline glass ceramic (NCGC) for dental application. The goal is to develop new ZrO2-SiO2 NCGCs with a combination of high strength and high translucency; the other is biodegradable Si3N4 ceramics for spinal fusion. This project aims to improve the osteointergration property of Si3N4 ceramics. Translucent glass ceramics typically suffer from impaired mechanical properties, compared to full-ceramics. We presented a method of obtaining ZrO2-SiO2 NCGCs, with a microstructure of monocrystalline ZrO2 nanoparticles (NPs), embedded in an amorphous SiO2 matrix. Raw powders containing different ZrO2 contents were prepared by the sol-gel method, followed by the spark plasma sintering (SPS). The NCGC with a composition of 35%ZrO2-65%SiO2 (molar ratio, 35Zr) was transparent. Tetragonal ZrO2 NPs were spherical with a diameter of 20–40 nm. The average flexural strength of 35Zr NCGC was 234 MPa. To improve the flexural strength, NCGCs with compositions of 45%ZrO2-55%SiO2 (45Zr), 55%ZrO2-45%SiO2 (55Zr), 65%ZrO2-35%SiO2 (65Zr) were also elaborated. All NCGCs showed high translucency. The flexural strength of the NCGCs significantly increased with the increase of ZrO2 content, achieving as high as 1014 MPa for 65Zr NCGC.  ZrO2 NPs in 65Zr NCGC were ellipsoidal and had a core-shell structure with a thin Zr/Si interfacial layer as the shell. Some of the ZrO2 NPs were connected and formed ZrOnanofibers. Moreover, the ZrOnanofibers were orderly stacked in short-range to form the 3D nano-architecture. The high flexural strength of the 65Zr NCGC mainly originates from synergistic strengthening effects of the thin Zr/Si interfacial layer and 3D stacked nano-architecture. Regarding biodegradable Si3N4 bioceramics, we used a ternary sintering additive of SrO, MgO and SiO2.   The mechanical properties of the developed Si3N4 bioceramics were comparable to those of traditional Si3N4 ceramics. Sr2+, Mg2+, and Si4+ ions released from the intergranular glass phase after immersion in solution, indicating that the developed Si3N4 bioceramics showed certain biodegradable ability. These ions enhanced the proliferation and differentiation of preosteoblasts. Meanwhile, the ionic dissolution products did not show any toxic effects to the development or physiology of zebrafish embryos.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 70
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1710
Keywords
ZrO2-SiO2 glass ceramic, high-strength, translucency, 3D nano-architecture, Si3N4 bioceramic, biodegradable, spark plasma sintering
National Category
Ceramics
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-357128 (URN)978-91-513-0419-9 (ISBN)
Public defence
2018-10-10, Häggsalen, 10132, Ångström, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Funder
Carl Tryggers foundation
Available from: 2018-09-18 Created: 2018-08-12 Last updated: 2018-10-02

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Fu, LePalmer, MichaelEngqvist, HåkanXia, Wei

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