Preparation and characterization of novel alkali-activated nano silica cements for biomedical application

The major goal of this study was to investigate and characterize novel Ca(OH)2‐activated nano silica (SiO2) cements for the potential application as a bone cement. Novel Ca(OH)2‐activated nano‐SiO2 powders composed of Ca(OH)2 and nano‐SiO2 were easily prepared, and the deionized water was used as the liquid phase. The initial and final setting times of Ca(OH)2‐activated nano‐SiO2 cements with liquid to powder (L/P) ratios of 1.00–1.33 mL g−1 range from 50 ± 1 to 120 ± 3 min and 96 ± 2 to 190 ± 5 min, respectively. The calorimetric curves indicate that the heat liberations of Ca(OH)2‐activated nano‐SiO2 cements (105.57–138.01 J g−1) are lower than that of C3S (about 150 J g−1). The Ca(OH)2‐activated nano‐SiO2 pastes are injectable under general extrusion force of 100 N, and their compressive strengths with suitable L/P ratios are 5–9 MPa, which is comparable with that of cancellous bone. The in vitro bioactivity of the Ca(OH)2‐activated nano‐SiO2 cement pastes were investigated by soaking in simulated body fluid for various periods. The results show amorphous apatite deposits on the paste surfaces after soaking in simulated body fluid for 2 h. With the prolonged soaking time, amorphous apatite transforms into crystalline apatite after soaking for 1 day. The Ca(OH)2‐activated nano‐SiO2 cements have short setting times, low heat liberation, injectability, suitable compressive strength, and excellent in vitro bioactivity, and may be used as bioactive bone cements for bone regeneration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.