title: Osteoblastic differentiation under controlled bioactive ion release by silica and titania doped sodium-free calcium phosphate-based glass.
abstract: Sodium-free phosphate-based glasses (PGs) doped with both SiO2 and TiO2 (50P2O5-40CaO-xSiO2-(10-x)TiO2, where x=10, 7, 5, 3, and 0mol%) were developed and characterised for controlled ion release applications in bone tissue engineering. Substituting SiO2 with TiO2 directly increased PG density and glass transition temperature, indicating a cross-linking effect of Ti on the glass network which was reflected by significantly reduced degradation rates in an aqueous environment. X-ray diffraction confirmed the presence of Ti(P2O7) in crystallised TiO2-containing PGs, and nuclear magnetic resonance showed an increase in Q(1) phosphate species with increasing TiO2 content. Substitution of SiO2 with TiO2 also reduced hydrophilicity and surface energy. In biological assays, MC3T3-E1 pre-osteoblasts effectively adhered to the surface of PG discs and the incorporation of TiO2, and hence higher stability of the PG network, significantly increased cell viability and metabolic activity indicating the biocompatibility of the PGs. Addition of SiO2 increased ionic release from the PG, which stimulated alkaline phosphatase (ALP) activity in MC3T3-E1 cells upon ion exposure. The incorporation of 3mol% TiO2 was required to stabilise the PG network against unfavourable rapid degradation in aqueous environments. However, ALP activity was greatest in PGs doped with 5-7mol% SiO2 due to up-regulation of ionic concentrations. Thus, the properties of PGs can be readily controlled by modifying the extent of Si and Ti doping in order to optimise ion release and osteoblastic differentiation for bone tissue engineering applications.
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada.
authors.forename: Maziar
authors.initials: M
authors.lastname: Shah Mohammadi
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada.
authors.forename: Florencia
authors.initials: F
authors.lastname: Chicatun
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada.
authors.forename: Christoph
authors.initials: C
authors.lastname: Stähli
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada.
authors.forename: Naser
authors.initials: N
authors.lastname: Muja
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada; National Research Council Canada, QC J4B 6Y4, Canada.
authors.forename: Martin N
authors.initials: MN
authors.lastname: Bureau
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2, Canada. Electronic address: showan.nazhat@mcgill.ca.
authors.forename: Showan N
authors.initials: SN
authors.lastname: Nazhat
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002130:Calcium Phosphates / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004055:Differential Thermal Analysis; D005898:Glass / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D012822:Silicon Dioxide / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology*; D013499:Surface Properties; D014025:Titanium / Q000494:pharmacology*; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D007477:Ions; C009495:titanium dioxide; D012822:Silicon Dioxide; C020243:calcium phosphate; D012964:Sodium; D014025:Titanium; D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase; Bone repair; Calcium phosphate-based glass; Cell–material interaction; Osteoinduction; Silica