Evaluation of colloidal silica suspension as efficient additive for improving physicochemical and in vitro biological properties of calcium sulfate-based nanocomposite bone cement

Abstract

In the present study new calcium sulfate-based nanocomposite bone cement with improved physicochemical and biological properties was developed. The powder component of the cement consists of 60 wt% α-calcium sulfate hemihydrate and 40 wt% biomimetically synthesized apatite, while the liquid component consists of an aqueous colloidal silica suspension (20 wt%). In this study, the above mentioned powder phase was mixed with distilled water to prepare a calcium sulfate/nanoapatite composite without any additive. Structural properties, setting time, compressive strength, in vitro bioactivity and cellular properties of the cements were investigated by appropriate techniques. From X-ray diffractometer analysis, except gypsum and apatite, no further phases were found in both silica-containing and silica-free cements. The results showed that both setting time and compressive strength of the calcium sulfate/nanoapatite cement improved by using colloidal silica suspension as cement liquid. Meanwhile, the condensed phase produced from the polymerization process of colloidal silica filled the micropores of the microstructure and covered rodlike gypsum crystals and thus controlled cement disintegration in simulated body fluid. Additionally, formation of apatite layer was favored on the surfaces of the new cement while no apatite precipitation was observed for the cement prepared by distilled water. In this study, it was also revealed that the number of viable osteosarcoma cells cultured with extracts of both cements were comparable, while silica-containing cement increased alkaline phosphatase activity of the cells. These results suggest that the developed cement may be a suitable bone filling material after well passing of the corresponding in vivo tests.

Addition of a small amount of glass to improve the degradation behavior of calcium sulfate bioceramic

“…However, previous studies demonstrated that reduction of degradation rate without sacrificing compressive strength is challenging [5]. In the present study, a sintering technique is used to reduce the degradation rate and to improve the strength of CS at the same time.…”

“…Calcium sulfate (CaSO 4 , or CS) exhibits excellent biocompatibility; its pellets were used as bone void fillers as early as 1892 [3]. However, previous studies have indicated that the biodegradation of CS pellets is much faster than the growth rate of new bone [4,5]. The CS pellets collapse within days after their implantation; they thus fail to provide sufficient support for the newly forming bone.…”

“…Nevertheless, while the degradation rate of the CS pellets decreases, the compressive strength of the pellets decreases as well. The strength decrease of CS-HAp composite could be solved through the addition of silica particles at the nanometer scale [5]. However, the risks of using nanoparticles within the human body are not yet well understood.…”

Development of a silica sol-reinforced monetite cement matrix

“…[8][9][10][11] First, the subunits of nanosilica particles in silica sol are unjoined Si(OH) 4 . Hydrogen ions (OH − ) from the surfaces of these particles tend to interact with Ca 2+ on the surface of MW-DCPA.…”

“…The concept of using silica sol in bone cement is motivated by the fact that the dissolution products of calcium and silicon from bioactive glasses lead to the up-regulation and activation of seven families of genes in osteoprogenitor cells that promote bone regeneration. 7 In the literature, silica sol has been successfully combined with bone cements including calcium hydroxide (Ca(OH) 2 ), 8,9 calcium sulphate (CaSO 4 ), 10 and HA-based CPC. 11 In our previous report, a monetite-silica sol mixture was also examined as a bioactive injectable bone cement.…”