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 (SiO 2 ) cements for the potential application as a bone cement. Novel Ca(OH) 2 ‐activated nano‐SiO 2 powders composed of Ca(OH) 2 and nano‐SiO 2 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‐SiO 2 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‐SiO 2 cements (105.57–138.01 J g −1 ) are lower than that of C 3 S (about 150 J g −1 ). The Ca(OH) 2 ‐activated nano‐SiO 2 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‐SiO 2 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‐SiO 2 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.