In-vitro bioactivity of silicate-phosphate glasses using agriculture biomass silica

A study on mechanical and tribological properties of eco-friendly synthesized ZrO2-doped borosilicate glasses

The research article aims to investigate the mechanical and tribological characteristics of bioactive glass specimens comprising 31B2O3-20SiO2-24.5Na2O-(24.5-x) CaO and xZrO2 (mol%). This glass system was partially derived from bio-waste, with varying concentrations of Zirconia (ZrO2) represented x (x = 0, 1, 3, and 5). The specimens were fabricated using the traditional melt-quench method. Mechanical studies like hardness and compressive strength were measured using Vickers hardness tester and universal tensile machine respectively, while a pin-on-disk tribometer was used to analyze the tribological characteristics. All the specimens were soaked in SBF for a week to assess in-vitro bioactivity. The research findings indicate that Zirconia inclusion resulted in a significant reduction in the intensity of hydroxyapatite peaks of FTIR and XRD spectra, suggesting a decrease in bioactivity. However, it concurrently resulted in increased glass hardness, with the highest value (∼7.55 GPa) observed in the BSG-5 glass sample. Similarly, compressive strength results demonstrated maximum strength in BSG-5 glass specimen, with a value of approximately ∼132 MPa. Moreover, the tribological properties of the glass system were enhanced, evident from the reduced coefficient of friction and specific wear rate. Notably, the BSG-5 glass specimen exhibited the least wear coefficient of 0.018 mm3/N-m at a track radius of 40 mm and a load of 15N. These findings were further supported by SEM images of the worn-out ZrO2-Doped Borosilicate Glass surface. Overall, the results suggest that the addition of Zirconia to borosilicate glass holds promise for improving its mechanical and tribological characteristics. However, this enhancement comes at the expense of its bioactivity. Consequently, the modified glass system presents a cost effective viable option for various applications, particularly in load-bearing and dental applications.

The Effect of Heat Treatment of β-Tricalcium Phosphate-Containing Silica-Based Bioactive Aerogels on the Cellular Metabolism and Proliferation of MG63 Cells

β-Tricalcium phosphate was combined with silica aerogel in composites prepared using the sol-gel technique and supercritical drying. The materials were used in this study to check their biological activity and bone regeneration potential with MG63 cell experiments. The composites were sintered in 100 °C steps in the range of 500-1000 °C. Their mechanical properties, porosities, and solubility were determined as a function of sintering temperature. Dissolution studies revealed that the released Ca-/P molar ratios appeared to be in the optimal range to support bone tissue induction. Cell viability, ALP activity, and type I collagen gene expression results all suggested that the sintering of the compound at approximately 700-800 °C as a scaffold could be more powerful in vivo to facilitate bone formation within a bone defect, compared to that documented previously by our research team. We did not observe any detrimental effect on cell viability. Both the alkaline phosphatase enzyme activity and the type I collagen gene expression were significantly higher compared with the control and the other aerogels heat-treated at different temperatures. The mesoporous silica-based aerogel composites containing β-tricalcium phosphate particles treated at temperatures lower than 1000 °C produced a positive effect on the osteoblastic activity of MG63 cells. An in vivo 6 month-long follow-up study of the mechanically strongest 1000 °C sample in rat calvaria experiments provided proof of a complete remodeling of the bone.

A cost effective SiO2-CaO-Na2O bio-glass derived from bio-waste resources for biomedical applications

The present paper describes the in vitro bioactivity, cytocompatibility and degradation performance of SiO₂-CaO-Na₂O bio-glass synthesized using bio-waste. Egg shells and rice husk ash (RHA) bio-wastes were used as sources of calcium oxide (CaO) and silica (SiO₂), respectively. Glass samples were obtained by melt-quenching technique. Bioactivity was studied using in vitro experiments in simulated body fluid (SBF), degradation behaviour was evaluated in Tris-HCl buffer solutions recommended by ISO 10993-14 standards and cytocompatibility was estimated using MTT assay. The formation of hydroxyapatite was characterized by XRD, FTIR and SEM-EDS after soaking the glass samples in SBF solution. XRD confirmed the phase of hydroxyapatite with its standard JCPDS data. FTIR analyses revealed the occurrence of distinctive functional groups related to hydroxyapatite. Surface micrographs showed the agglomerated globular shape morphology of hydroxyapatite, while EDS analysis confirmed the existence of biological elements of apatite such as Ca, P and O. Degradation study results showed that the glass thus prepared has considerable controlled degradation rate. MTT assay revealed the cytocompatibility nature for different dosages (1000-50 μg/mL) of the prepared glass with MG-63 cells. These results perfectly established that egg shells and RHA are potentially beneficial resources for the production of bio-glasses.