title: Enhanced interfacial adhesion and osteogenesis for rapid "bone-like" biomineralization by PECVD-based silicon oxynitride overlays.
abstract: Structurally unstable fracture sites require metal fixative devices, which have long healing times due to their lack of osteoinductivity. Bioactive glass coatings lack in interfacial bonding, delaminate, and have reduced bioactivity due to the high temperatures used for their fabrication. Here, we test the hypothesis that low-temperature PECVD amorphous silica can enhance adhesion to the underlying metal surface and that N incorporation enhances osteogenesis and rapid biomineralization. A model Ti/TiO2-SiOx interface was formed by first depositing Ti onto Si wafers, followed by surface patterning, thermal annealing to form TiO2, and depositing SiOx/Si(ON)x overlays. TEM micrographs showed conformal SiOx layers on Ti/TiO2 overlays while XPS data revealed the formation of an elemental Ti-O-Si interface. Nanoscratch testing verified strong SiOx bonding with the underlying TiO2 layers. In vitro studies showed that the surface properties changed significantly to reveal the formation of hydroxycarbonate apatite within 6 h, and Si(ON)x surface chemistry induced osteogenic gene expression of human periosteal cells and led to a rapid "bone-like" biomineral formation within 4 weeks. XANES data revealed that the incorporation of N increased the surface HA bioactivity by increasing the carbonate to phosphate ratio. In conclusion, silicon oxynitride overlays on bone-implant systems enhance osteogenesis and biomineralization via surface nitrogen incorporation.
authors.forename: Azhar
authors.initials: A
authors.lastname: Ilyas
authors.affiliation: ‡Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors.forename: Nickolay V
authors.initials: NV
authors.lastname: Lavrik
authors.affiliation: §Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, United States.|∥Center for Excellence in Hip Disorders, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, Texas 75219, United States.
authors.forename: Harry K W
authors.initials: HK
authors.lastname: Kim
authors.affiliation: ⊥Department of Materials Science and Engineering, University of Texas at Arlington, 501 West First Street, Arlington, Texas 76019, United States.
authors.forename: Pranesh B
authors.initials: PB
authors.lastname: Aswath
authors.forename: Venu G
authors.initials: VG
authors.lastname: Varanasi
mesh_terms: D002113:Calcification, Physiologic; D049109:Cell Proliferation; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis; D019736:Prostheses and Implants; D012825:Silicon / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D012825:Silicon
keywords: PECVD; gene expression; hydroxyapatite; lithography; periosteal cells; qPCR