The Effects of Fe₂O₃and B₂O₃on the Glass Structural, Thermal, <i>in Vitro</i>Degradation Properties of Phosphate Based Glasses

Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composition of 48P2O5-12B2O3-(25-X)MgO-14CaO-1Na2O-(X)Fe2O3 (X = 6, 8, 10) and 45P2O5-(Y)B2O3-(32-Y)MgO-14CaO-1Na2O-8Fe2O3 (Y = 12, 15, 20), was prepared via a melting quenching process. The effect of replacing MgO with Fe2O3 and B2O3 on the structural, thermal, degradation properties of phosphate based glass was investigated. Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopy analysis confirmed the polymerisation of phosphate based glass network with addition of Fe2O3, thus the processing window was observed to increase whilst the dissolution rate was reduced, attributed to the formation of Fe-O-P cross-link. As the effect on the glass structure stability was demonstrated by both B2O3 and MgO, the nonlinear variation of thermal stability and degradation behaviour was observed for glass system with substitution of MgO by B2O3. However, due to the lower dissolution rate of glass system when compared to the biocompatible phosphate based glass in preliminary study, the expected cytocompatibility could be confirmed in the downstream activities.

Hybrid Composites of Phosphate Glass Fibre/Nano-Hydroxyapatite/Polylactide: Effects of Nano-Hydroxyapatite on Mechanical Properties and Degradation Behaviour

Hydroxyapatite/polylactide (HA/PLA) composites have been intensively investigated for their potential as biodegradable fixation devices to heal bone fractures. However, most of these composites failed to achieve a bone-mimicking level of mechanical properties, which is an essential demand of the targeted application. In this study, the nano-hydroxyapatite/polylactide composites were used as the matrix and continuous phosphate glass fibres (PGF) served as the major reinforcement to obtain the nano-HA/PGF/PLA hybrid composites. While the PGF volume fraction remained constant (25%), the nano-HA content (in weight) varied from 0% to 20%. As nano-HA loading increased, the flexural modulus of the composites increased from 8.70 ± 0.35 GPa to 14.97 ± 1.30 GPa, and the flexural strengths were enhanced from 236.31 ± 10.83 MPa to 310.55 ± 22.88 MPa. However, it is found that the degradation rates are higher with more nano-HA loaded. Enhanced water absorption ability, as well as increased voids in the composites is possible reasons for the accelerated degradation of composites with higher nano-HA loading. The hybrid composites possess mechanical properties that are superior to most of the HA/PLA composites in previous research while maintaining the biodegradability. With a proper loading of nano-HA in composites of 10 weight percent, the composites are also found with improved mechanical properties without catastrophic degradation. The composites developed in this study have great potential as biodegradable bone fixation device with enhanced load-bearing ability as confirmed and superior bioactivity as anticipated.

Modulated Degradation Rates of Bone Mineral-Like Calcium Phosphate Glass to Support the Proliferation and Osteogenic Differentiation of Bone Marrow-Derived Stem Cells

With an elemental composition similar to bone mineral,and the ability to release phosphorus and calcium that benefit bone regeneration,Calcium Phosphate Glass(CPG)serves as a promising component of bone tissue engineering scaffolds.However,the degradation of CPG composites typically results in increased acidity,and its impact on bone-forming activity is less studied.In this work,we prepared 3D-printed composite scaffolds comprising CPG,Poly-ε-caprolactone(PCL),and various Magnesium Oxide(MgO)contents.Increasing the MgO content effectively suppressed the degradation of CPG,maintaining a physiological pH of the degradation media.While the degradation of CPG/PCL scaffolds resulted in upregulated apoptosis of Rat Bone Marrow-derived Stem Cells(rBMSC),scaffolds containing MgO were free from these negative impacts,and an optimal MgO content of 1 wt%led to the most pronounced osteogenic differentiation of rBMSCs.This work demonstrated that the rapid degradation of CPG impaired the renewability of stem cells through the increased acidity of the surrounding media,and MgO effectively modulated the degradation rate of CPG,thus preventing the negative effects of rapid degradation and supporting the proliferation and osteogenic differentiation of the stem cells.