Gel-derived bioglass as a compound of hydroxyapatite composites

Abstract

Despite the excellent biocompatibility of hydroxyapatite and bioglass, their clinical applications are limited to non-load-bearing implants and implant coatings due to their low mechanical properties. We have developed two different composites made of hydroxyapatite (HA) and gel-derived bioglasses designated S2 (80 mol% SiO(2)-16 mol% CaO-4 mol% P(2)O(5)) or A2 (40 mol% SiO(2)-54 mol% CaO-6 mol% P(2)O(5)). We show that the combination of hydroxyapatite with either bioglass results in better composite bioactivity and biocompatibility compared to HA alone. We used a commercially available hydroxyapatite that was sintered with varying additions (10%, 50%) of A2 or S2 bioglass. Scanning electron microscopy and x-ray diffraction were used to characterize the microstructure and phases of the composites. The elastic properties of bioglass/HA composites were analyzed with the use of the pulse ultrasonic technique. The bioactivity (surface activity) of the composites was assessed by determining the changes of surface morphology and composition after soaking in simulated body fluid (SBF) for 7 and 14 days. The biocompatibility of the obtained composites was then assessed in vitro using adult human bone marrow stromal cells. Cells were seeded on the material surfaces at a density of 10(4) cells cm(-2) and cultured for 7 days in non-differentiating and osteogenic conditions. The number of live cells was estimated in both standard and osteogenic cultures, followed by alkaline phosphatase (ALP) activity assay in osteogenic cultures. We determined that 10 wt% addition of A2 (E = 12.24 GPa) and 50 wt% addition of S2 (E = 16.96 GPa) to the HA base results in higher Young's modulus of the composites compared to pure hydroxyapatite (E = 9.03 GPa). The rate of Ca-P rich layer formation is higher for bioglass/HA composites containing A2 bioglass compared to the composites containing S2 bioglass. Evaluation of cell growth on the bioglass/HA composites showed that the incorporation of either 50 wt% S2 or 50 wt% A2 into the hydroxyapatite base significantly improves cell viability when compared to cells grown on pure HA. Also the cellular activity of ALP, an early marker of osteoblasts, increases with the amount of bioglass addition to the composites.

New sol‐gel bioactive glass and titania composites with enhanced physico‐chemical and biological properties

“…These data, together with cell viability results may also suggest that S2 SBG addition to TiO 2 matrix is beneficial to cell growth regardless of S2 SBG content, but if these composites are to stimulate cell differentiation the S2:TiO 2 ratio should be low (i.e., 25 wt % SBG). Previously, we showed that incorporation of gel‐derived bioactive glass into hydroxyaptite or PLGA matrix enhances osteogenic potential of human BMSCs . This work confirms our previous findings and extends the application of these gel‐derived bioglasses to TiO 2 containing biomedical devices and implants.…”

Osteoconductivity and growth factor production by MG63 osteoblastic cells on bioglass‐coated orthopedic implants

“…Encouragingly, HA/BG surpasses OsteoZip in most aspects of osteoconductivity. This is not surprising as it has been previously shown that gel-derived HA/BG composites demonstrated better bioactivity and biocompatibility compared to HA alone (Cholewa-Kowalska et al, 2009).…”

Degradation, Bioactivity, and Osteogenic Potential of Composites Made of PLGA and Two Different Sol–Gel Bioactive Glasses

“…We showed that CaO:SiO 2 ratio in these glasses influenced their physical and chemical properties and affected the growth and differentiation of bone marrow-derived cells 6,17,20. Our data further indicate that incorporation of these gel-derived glasses into a HA matrix enhanced growth and osteogenic differentiation of human mesenchymal stem cells (MSC) 5. Recently, Wu et al 41 suggested that PLGA-based composites prepared with a sol–gel derived mesoporous bioactive glass possess advantageous mechanical and biological properties compared to those containing non-mesoporous bioactive glass.…”