Dissolution kinetics of a Si‐rich nanocomposite and its effect on osteoblast gene expression

Abstract

Silica-calcium phosphate nanocomposite (SCPC) has recently been proposed as a novel resorbable, bioactive, and mechanically compatible template for bone reconstruction. The effect of the physicochemical properties on the surface reactivity and dissolution kinetics of SCPC immersed in simulated body fluid (SBF) was investigated and compared to that of bioactive glass (BG). Moreover, the stimulatory effect on osteoblast gene expression of SCPC was determined using quantitative real-time polymerase chain reaction (qRT-PCR), and compared to that of hydroxyapatite (HA-200). Mercury porosimetry revealed that surface areas of SCPC particles containing 10 (SCPC10), 30 (SCPC30), and 50 (SCPC50) wt % Si-content were 14-, 18-, and 32-times higher than that of BG. Inductively coupled plasma analysis showed that after 192 h of immersion, Si-rich SCPC50 exhibited controlled bulk-dissolution and released 43.1 ppm Si, which was sixfold higher than that released from BG (7.7 ppm). Moreover, SCPC50 showed a rapid Ca-uptake from SBF and developed a surface apatite layer after only 2 h, whereas a similar layer was detected on BG after 8 days of immersion under the same experimental conditions. qRT-PCR revealed that osteopontin and osteocalcin mRNA expression by osteoblast-like cells attached to Si-rich SCPC50 was significantly higher than that on HA-200 or polystyrene after 2 days in culture. This suggested a role of dissolved Si in stimulating the differentiation and mineralization of osteoblast precursor cells. The favorable physiochemical and bioactivity properties of Si-rich SCPC nanocomposite indicate that SCPC can have wide applications as a synthetic bone graft for cell delivery applications in tissue engineering.

Acceleration of Alveolar Ridge Augmentation Using a Low Dose of Recombinant Human Bone Morphogenetic Protein-2 Loaded on a Resorbable Bioactive Ceramic

“…In conjunction with the absorption of high Ca concentration, the attached stem cells produced calcified nodules and mineralized extracellular matrix (27,28) . On the mRNA level, qRT-PCR revealed that osteopontin and osteocalcin mRNA expression by osteoblast-like cells attached to SCPC50 was significantly higher than that on SCPC10, HA-200 or polystyrene after 2 days in culture (30)(31)(32)(33) .…”

Hydroxyapatite/SiO2 Composites via Freeze Casting for Bone Tissue Engineering

“…The significance of Si as essential trace element for the formation of healthy bone [42,43] due to its enhancement of collagen synthesis has been demonstrated. [7,44,45] Chemically precipitated Si-HA has been shown to promote the formation of organized collagen fibrils in sheep at an earlier time point than HA alone, [46] and bone in-growth and bone/implant coverage has been reported also to be significant higher with Si-HA than pure HA [47] in vivo. The ECM with collagen as main component is not only a S. Blindow et al/Hydroxyapatite/SiO 2 Composites via Freeze Casting .…”

“…Consistent with these findings increased collagen I synthesis as well as the expression of other osteoblastic marker genes like osteocalcin and osteopontin caused by Si have been reported. [7] Hitherto Si-substituted CaPs are prepared by co-precipitation from soluble precursors. Si-HA was reported to increase bone cell proliferation [8] and to enhance the in-growth of cells and bone apposition after implantation.…”

Wollastonite nanofiber–doped self-setting calcium phosphate bioactive cement for bone tissue regeneration

“…Furthermore, solution of high Si concentration showed the potential capacity to activate bone-related gene expression, stimulate osteoblast proliferation, and promote new bone formation. 10 A study by Cortés et al 11 showed that wollastonite exhibited excellent in vitro bioactivity, and the formation rate of apatite on its surface was faster than other biocompatible glasses and glass ceramics in simulated body fluid solution. In addition, wollastonite composites as plasma-sprayed coating on titanium alloy substrates and wollastonite-titanium dioxide or wollastonite-polymer composites showed good bioactivity and biocompatibility.…”