title: Effects of silica on the bioactivity of calcium phosphate composites in vitro.
abstract: In the present study, silica-calcium phosphate composites (SiO(2)-CaP composites) were developed by mixing the starting materials (SiO(2) and CaHPO(4)) in different ratios with the addition of 0.1% w/v NaOH solution. The phase composition of the SiO(2)-CaP composites was determined by XRD and FTIR. After thermal treatment at 350 degrees C/1 h and at 1000 degrees C/3.5 h; all SiO(2)-CaP composites composed of beta-quartz, alpha-cristobalite and beta-Ca2P2O7. The presence of calcium phosphate enhanced the transformation of beta-quartz into alpha-cristobalite at 1000 degrees C. SEM observation indicated favorable attachment and spreading of neonatal rat calvaria osteoblasts onto the surface of silica-rich SiO(2)-CaP composites. After attachment, these cells produced significantly higher amount of protein and expressed higher AP activity than cells attached to silica-poor samples. Results of the study suggested that the silica-based composites are more bioactive than calcium phosphate-based composites. Silica promoted the expression of osteoblast phenotype by both solution-mediated effect and direct interaction with the surface of the substrate.
authors.affiliation: Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: C Q
authors.initials: CQ
authors.lastname: Ning
authors.forename: J
authors.initials: J
authors.lastname: Mehta
authors.forename: A
authors.initials: A
authors.lastname: El-Ghannam
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001672:Biocompatible Materials / Q000737:chemistry; D018786:Bone Substitutes / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry* / Q000494:pharmacology*; D002460:Cell Line; D005786:Gene Expression Regulation; D010006:Osteoblasts / Q000187:drug effects / Q000502:physiology; D051381:Rats; D012822:Silicon Dioxide / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D012822:Silicon Dioxide; C020243:calcium phosphate; D000469:Alkaline Phosphatase