Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction

Abstract

Melt quenched silicate glasses containing calcium, phosphorus and alkali metals have the ability to promote bone regeneration and to fuse to living bone. Of these glasses 45S5 Bioglass s is the most widely used being sold in over 35 countries as a bone graft product for medical and dental applications; particulate 45S5 is also incorporated into toothpastes to help remineralize the surface of teeth. Recently it has been suggested that adding titanium dioxide can increase the bioactivity of these materials. This work investigates the structural consequences of incorporating 4 mol% TiO 2 into Bioglass s using isotopic substitution (of the Ti) applied to neutron diffraction and X-ray Absorption Near Edge Structure (XANES). We present the first isotopic substitution data applied to melt quench derived Bioglass or its derivatives. Results show that titanium is on average surrounded by 5.2(1) nearest neighbor oxygen atoms. This implies an upper limit of 40% four-fold coordinated titanium and shows that the network connectivity is reduced from 2.11 to 1.97 for small quantities of titanium. Titanium XANES micro-fluorescence confirms the titanium environment is homogenous on the micron length scale within these glasses. Solid state magic angle spinning (MAS) NMR confirms the network connectivity model proposed. Furthermore, the results show the intermediate range order containing Na-O, Ca-O, O-P-O and O-Si-O correlations are unaffected by the addition of small quantities of TiO 2 into these systems.

Atomic structure of chlorine containing calcium silicate glasses by neutron diffraction and 29Si solid‐state NMR

“…The position of the O-(Si)-O correlation is reasonably well-defined by the geometry of the SiO 4 tetrahedra given by ffiffiffiffiffiffiffi ffi 8=3 p r Si-O , being~2.65 A. The O-(Si)-O coordination number can also be modeled using connectivity models and confirmed using 29 Si NMR. For a silicate glass the network connectivity (NC) is given by,…”

“…Solid-state NMR spectra were obtained at the EPSRC UK National Solid-state NMR service at Durham on a 4.0 mm pencil Varian VNMRS 400 MHz spectrometer. The observed 29 Si spectra were acquired with a frequency of 79.438 MHz, spectral width of 40322.6 Hz, acquisition time of 12.7 ms, and repetitions in the range 56-800 with a recycling time of 120 seconds at ambient temperature. Direct excitation had a pulse duration of 4.6 ls with a two pulse phase modulated decoupling 20 spin rate of 6000 Hz with reference to tetramethylsilane (0 ppm).…”

Mechanical characteristic and biological behaviour of implanted and restorative bioglasses used in medicine and dentistry: A systematic review

“…-Ag and Sr substituted bioactive glass for the investigation of antibacterial effects [19,20]; -Focused on cells growth, proliferation and protein interactions [21][22][23][24][25][26][27]; -Studies evaluating only the bioactivity and hydroxyl apatite (HA) formation [28][29][30][31][32][33][34]; -General characterization and synthesis of bioglass powders [35,36]; -Mechanical properties of a bioactive ceramic ␤-TCP [37].…”

NXFit: a program for simultaneously fitting X-ray and neutron diffraction pair-distribution functions to provide optimized structural parameters

“…Examples of such materials include bioactive glasses (Martin et al, 2012;Smith, Martin et al, 2013), Ca-Mg-Cu metallic glasses (Barney et al, 2011) and amorphous iron phosphate (Al-Hasni et al, 2013).…”