Synthesis, characterization and antimicrobial activity of nano-crystalline tricalcium silicate bio-cement

Tricalcium silicate phases were synthesized in nano-size particles by two different methods that are; the solid state reaction and the sol gel method. The solid state method is based on direct firing mixture of molar ratios from ultra pure calcium carbonate and silicon dioxide at about 1500°C, while the sol-gel process is depended on a reaction between calcium nitrate tetra hydrate and tetraethyl orthosilicate at pH = 4.5 the formed C3S gel is calcined at 1500°C. A comparative study was carried out between the two synthesized powders in terms of setting times, micro-hardness test, pH values, calcium ion concentration, X-ray diffraction analysis, infrared spectroscopy and scanning electron microscopy (SEM). The evaluation of antibacterial activity of free released Ca2+ ions is performed using agar diffusion method. The data showed that C3S powder synthesized by sol-gel method has more chemical reactivity with an increasing rate of hydration reaction than sample prepared by solid state reaction. The sol gel sample has shorter setting time, better hardness values, more alkaline hydration medium with higher pH and calcium ion concentration values. The test sol gel sample showed much better antimicrobial activity due to the superior influence of released Ca ions during the hydration process.