Figure - available from: Journal of Biomedical Materials Research Part B Applied Biomaterials
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(a) FTIR spectra and (b) mean Raman spectra (N = 5) for the glasses in the system of 40P2O5─(24 − x)MgO─(16 + x)CaO─(20 − y)Na2O─yTiO2 (where 0 ≤ x ≤ 22 and y = 0 or 1). Spectra were averaged from those collected at five different, random locations on the top surface of the glass, with minimal spectral variation indicating a high degree of homogeneity
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Varying formulations in the glass system of 40P2 O5 ─(24 - x)MgO─(16 + x)CaO─(20 - y)Na2 O─yTiO2 (where 0 ≤ x ≤ 22 and y = 0 or 1) were prepared via melt-quenching. The structure of the glasses was confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), micro Raman and solid-state nuclear magnetic resonance (NMR) spectroscopies. Th...
Citations
... It was ascribed due to the replacement of lighter element Si (density = 2.65 g/cm 3 ) by a heavier element Al (density = 3.95 g/cm 3 ). Islam et al. 2019 also reported an increase in density when the lower density element Na (0.97 g/cm 3 ) is replaced by the higher density element Ti (4.5 g/cm 3 ) [42]. ...
Bioactive glasses have been popular as coating materials on bone implants in recent years to increase their integration with the host tissue and overall biological function. Infection and toxicity are significant factors in the failure of bone-implant material. The goal of this research is to develop a sol-gel derived, Al2O3 doped nanobioactive glass-ceramics (nBGC) with non-toxic and antibacterial activity. The main crystalline phase of sodium calcium silicate was transformed to sodium calcium aluminium silicate by increasing the Al2O3 concentration, it was confirmed by X-ray diffraction (XRD) and Fourier Transform Infra-Red (FTIR) spectroscopy analysis. The density and mechanical strength were increased as 2.63–3.12 g/cm³ and 75–105 MPa, respectively for the sample x = 0 to 10 wt.%. The formation of hydroxyapatite (HAp) was proved by XRD, FTIR, and FESEM (Field Emission Scanning Electron Microscope) with EDS (Energy Dispersive X-ray Spectroscopy) analysis through variations in pH, zeta potential, and degradation behavior. Higher cell viability percentage was attained as >99% for L929 cells, outstanding antibacterial activity against E. coli and S. aureus and excellent hydrophilic nature were obtained for the sample nBGC-10Al. Altogether, a higher concentration of Al2O3 in nBGC could enhance the physical and biological properties and it can be used as an excellent candidate for orthopedic applications.
Graphical abstract
... In these glasses SiO 2 acts as a network former. [12], and platinum-rhodium crucible [52,53]) and quenched in a mould of graphite or steel or quenched in water. ...
Thermal spraying of bioglasses offers the opportunity to produce coatings for different biomedical applications. The resorption of the coatings can be adjusted by tailoring the chemical composition of the glass and the coating microstructure. This thesis describes the production of novel bioactive and bioresorbable glass coatings for biomedical applications via an emerging suspension high velocity-oxy fuel (SHVOF) thermal spray. Bioglass® (45S5) was sprayed at the flame power of 90, 75, 50 and 25 kW by varying fuel (hydrogen) and oxygen flow rates. No coating was obtained at the flame power of 90 kW, and thin coating (< 10 µm) was obtained at 25 kW. Thick (25 ± 3 µm) and uniform coatings were obtained at the flame powers of 50 and 75 kW. The 50 kW coating was 16 ± 2 % porous, while the 75 kW coating was 10 ± 1 % porous. The bioactivity tests of the coatings showed that no hydroxyapatite (HA) was deposited on the surface of 25 kW coating even after seven days of immersion in simulated body fluid (SBF). Whilst, the coatings produced at 50 and 75 kW revealed HA deposition after three days. EDX analysis of the cross-section of the coated samples showed that the 50 kW initial coating thickness reduced from 25 µm to 6 µm after immersion in SBF for 7 days, which means that this microstructure was highly reactive towards SBF and hence behaved like a resorbable coating. Coatings from two bioactive glasses, namely ICIE16 (48.0 % SiO2, 33.0 % CaO, 6.6 % Na2O, 2.4 % P2O5 and 10.0 % K2O, in wt %.) and 13-93 (53.0 % SiO2, 6.0 % Na2O, 20.0 % CaO, 12.0 % K2O, 5.0 % MgO and 4.0 % P2O5, in wt %) were successfully produced at the flame powers of 50 and 75 kW. For both formulations, thick, porous and less hard coatings were obtained at 50 kW, whilst harder, dense and less thick coatings were obtained at 75 kW. ICIE16 coatings showed more dissolution in SBF than the 13-93 coatings. Moreover, in-vitro cell tests, using MG63 cells, showed good cell attachment and proliferation on the surfaces of the coating, revealing good cytocompatibility. Resorbable phosphate based glass (PBG), P-40 (40.0 % P2O5, 16.0 % CaO, 24.0 % MgO, 20.0 % Na2O in mol %) was sprayed at 50 and 75 kW flame power. The 75 kW coating was thinner and rougher than the 50 kW coating; both coatings presented globules on the surface. The Raman analysis of the P-40 coatings suggested that the structure of the glass had changed as the concentration of Q2 (2 bridging oxygen)species has been decreased. Whilst, Q1 (1 bridging oxygen) concentration has been increased and Q0 (0 bridging oxygen) species has been formed. Due to these structural alterations, these coatings showed less ion release and mass degradation than those reported in the literature for P-40 thin films and bulk glass. Ga2O3 doped Bioglass® was manufactured for antimicrobial applications and deposited at 50 kW. Moreover, Ga2O3 and Bioglass® suspensions were co-deposited via a hybrid nozzle at 50 kW to mix them in the flame. Both coatings showed bioactivity as HA was deposited on the surfaces of these coatings after immersion in SBF for 3 days. In summary, SHVOF thermal spraying has been proven to be an effective and versatile technique to deposit different bioglasses, maintaining their amorphous tetrahedral structure and composition.
... These changes in the IR spectra can be related to a decrease in the Q 2 units and to an increase in Q 1 units as expected from the change in the O/P ratio when adding ZnO, MgO and TiO 2 . 41 In agreement with, 42 Mg, Ti and Zn are expected to cross-link the phosphate chains by creating P-O-Mg/Ti/Zn bonds at the expense of P-O-P bonds associated with a reduction in the number of Q 2 units. 41,43 Therefore, the addition of ZnO, MgO and TiO 2 is suspected to cause distortion of the glass network which is in agreement with the increase in T g seen in Table 1. ...
... 41 In agreement with, 42 Mg, Ti and Zn are expected to cross-link the phosphate chains by creating P-O-Mg/Ti/Zn bonds at the expense of P-O-P bonds associated with a reduction in the number of Q 2 units. 41,43 Therefore, the addition of ZnO, MgO and TiO 2 is suspected to cause distortion of the glass network which is in agreement with the increase in T g seen in Table 1. Similar results were reported in ref. 44. ...
The nucleation and growth behavior of glasses with the composition (75 NaPO3-25 CaF2)100−x–(TiO2/ZnO/MgO)x, with x = 0 and x = 1.5 (in mol%) is investigated. The glasses possess similar activation energy for crystallization and Johnson–Mehl–Avrami exponent, with value 2 confirming bulk crystallization of crystals with needle like shape. The Ti and Mg glasses exhibit broader nucleation curve and higher Tn max than the x = 0 and Zn glasses due to their stronger field strength. The crystal growth rates were determined and validated using SEM. Finally, we showed that the nucleation and growth of glasses can be controlled due to the large difference between onset of crystallization and maximum nucleation temperature which is crucial when preparing novel transparent glass-ceramics.
... In addition, the T c also increased with increasing Y 2 O 3 content and this was ascribed to the heat flow of the samples increasing with increasing heating rate. 62,63 Al-noaman et al investigated the effect of MgO on bioactive glasses and reported that the T c increased from 880°C to 920°C with increasing heating rates from 5°C to 20°C/min. 64 Similar results were also found by Clupper and Hench 65 and Bretcanu et al. 66 The thermal stability of the glass particles in terms of their processing window increased with the addition of yttrium oxide up to 3 mol% (see Table 3). ...
Yttrium‐doped glasses have been utilized for biomedical applications such as radiotherapy, especially for liver cancer treatment. In this paper, the crystallization behavior of phosphate‐based glasses doped with yttrium (in the system 45P2O5–(30 − x) Na2O–25CaO–xY2O3—where x = 0, 1, 3 and 5) have been investigated via Differential Scanning Calorimetry (DSC) using nonisothermal technique at different heating rates (5°C, 10°C, 15°C and 20°C/min). The glass compositions were characterized via EDX, XRD, Density and Molar volume analysis. The Moynihan and Kissinger methods were used for the determination of glass transition activation energy (Eg) which decreased from 192 to 118 kJ/mol (Moynihan) and 183 to 113 kJ/mol (Kissinger) with increasing yttrium oxide content. Incorporation of 0 to 5 mol% Y2O3 revealed an approximate decrease of 71 kJ/mol (Ozawa and Augis) for onset crystallization (Ex) and 26 kJ/mol (Kissinger) for crystallization peak activation energies (Ec). Avrami index (n) value analyzed via Matusita–Sakka equation suggested a one‐dimensional crystal growth for the glasses investigated. SEM analysis explored the crystalline morphologies and revealed one‐dimensional needle‐like crystals. Overall, it was found that these glass formulations remained amorphous with up to 5 mol% Y2O3 addition with further increases in Y2O3 content resulting in significant crystallization.
Phosphate-based glasses (PBGs) are promising materials for biomedical applications due to their biocompatible and fully resorbable characteristics in aqueous environments. These glasses can be coated onto metal substrate via the technique of suspension high-velocity oxy-fuel (SHVOF) thermal spraying to produce nanostructured coatings with improved physical and mechanical properties. PBGs coatings were produced using SHVOF thermal spray process at 50 and 75 kW flame power. The 75 kW coating was rougher (Ra = 3.6 ± 0.1 µm) than the 50 kW coating (Ra = 2.7 ± 0.1 µm), whereas the 50 kW coating was much thicker (24.6 ± 2.3 µm) than the 75 kW coating (16.0 ± 3.4 µm). Due to the rougher surface, the 75 kW coating showed high degradation and ion release rates. Moreover, structural changes were observed by Raman analysis, and the initial glass formulation contained Q1 (phosphate tetrahedra with one-bridging oxygen) and Q2 (phosphate tetrahedra with two-bridging oxygen) species. However, the coatings showed a reduction of Q2 species and higher concentrations of Q1 and Q0 (phosphate tetrahedra with no-bridging oxygen) species, which led to lower degradation rates and reduced ion release profiles in the glass coating compared to the initial glass.
This paper reports on the role of phosphate-based glass (PBG) microspheres and their physicochemical properties including in vitro biological response to human mesenchymal stem cells (hMSCs). Solid and porous microspheres were prepared via a flame spheroidisation process. The Mg content in the PBG formulations explored was reduced from 24 to 2 mol% with a subsequent increase in Ca content. A small quantity of TiO2 (1 mol%) was added to the lower Mg-content glass (2 mol%) to avoid crystallisation. Morphological and physical characterisation of porous microspheres revealed interconnected porosity (up to 76 ± 5 %), average external pore sizes of 55 ± 5 μm with surface areas ranging from 0.38 to 0.43 m² g⁻¹. Degradation and ion release studies conducted compared the solid (non-porous) and porous microspheres and revealed 1.5 to 2.5 times higher degradation rate for porous microspheres. Also, in vitro bioactivity studies using simulated body fluid (SBF) revealed Ca/P ratios for porous microspheres of all three glass formulations were between 0.75 and 0.92 which were within the range suggested for precipitated amorphous calcium phosphate. Direct cell seeding and indirect cell culture studies (via incubation with microsphere degradation products) revealed hMSCs were able to grow and undergo osteogenic differentiation in vitro, confirming cytocompatibility of the formulations tested. However, the higher Mg content (24 mol%) porous microsphere showed the most potent osteogenic response and is therefore considered as a promising candidate for bone repair applications.
Molecule like silver quantum clusters ([Ag m ] ⁿ⁺ QCs) exhibit the ultrasmall size confinement resulting in efficient broadband fluorescence. However, free [Ag m ] ⁿ⁺ QCs are also chemically active, so their stabilization is required...
