Facile synthesis of akermanite powder using microwave-assisted sol-gel method for biomedical applications

Akermanite (Ak) has promising prospects as an innovative bio-ceramic for bone regeneration. The most common fabrication methods to produce pure Ak powders are long-lasting synthesis routes followed by calcination at high temperatures. This study focuses on the use of microwave irradiation of a solution to provide initial Ak-based powder product that after subsequent heat treatment changes to pure Ak powder. The novel process named microwave-assisted sol-gel method actually speeds up the initial and final stages of pure Ak powder production when compared to the traditional sol-gel with later heat treatment stage. The viscous solution containing magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, and tetraethyl ortho-silicate was microwave irradiated for three minutes. X-ray diffraction showed that the microwaved products after calcination treatment at 1200 degrees C for 4 h were mostly made of Ak and a small amount of merwinite. However, by increasing the calcination treatment to 1300 degrees C, single-phase akermanite powder was achieved. By subjecting same precursor and subsequent heat treatments, the typical sol-gel method did not yield pure Ak powder. Thermal analyses and scanning electron microscopy examinations showed that the Ak crystallization temperature was lower in the case of the microwave irradiated product than in the conventional sol-gel route. The microwave irradiated product after calcination showed a porous structure formed by necking between the powder particles with a mean particle size of 2 mu m. The results of the in vitro bioactivity evaluation indicated that synthesized Ak was bioactive through proving the formation of hydroxyapatite (HAp) on the surface of pure Ak disc after 7 days of immersion in simulated body fluid (SBF). The cell adhesion findings showed that MG-63 cells adhered and spread well on the Ak disc, suggesting that Ak discs possess good biocompatibility. The results of the MTT assay demonstrated that the cell proliferation of osteoblast-like MG-63 cells was enhanced with the increase in culture time. Our in vitro bioactivity, cell morphology, and adhesion evaluations and in vitro biocompatibility assessment suggested that Ak powders were bioactive and cytocompatible and have a great potential to be selected as an ideal candidate for bone tissue engineering applications.