Preparation and in vitro bioactivities of calcium silicate nanophase materials

Nano-sized amorphous CaSiO3 (A-CS) and β-wollastonite (β-CS) powder were produced by chemical precipitation method and subsequent heat treatment, using Ca(NO3)2·4H2O and Na2SiO3·9H2O as the starting materials, polyethylene glycol as the dispersant. Bulk materials were produced using the two powders as precursors. Rough, porous, and elongated particles occurred in A-CS material and the grains of β-CS were smooth, dense, and spheric. The particle sizes of A-CS and β-CS were about 40 nm and 90 nm in diameter respectively. The bioactivities of A-CS and β-CS materials were investigated by soaking the two materials in SBF solution at 36.5 °C for 6 h to 15 days. Experiment results revealed that CaCO3 crystallized accompanied with HAP on the A-CS surfaces. HAP crystallized constantly on the surfaces of β-CS. The HAP layer formed on β-CS was composed of uniformly sized particles. A layer of irregular particle size was formed on the A-CS owing to the co-existence of CaCO3. The A-CS showed a faster formation of HAP due to the high release rate of Ca ion.