Antimicrobial and bioactive phosphate-free glass-ceramics for bone tissue engineering applications

Abstract

Glasses with composition 55SiO₂-10K₂O-(35-x)CaO-xMgO (x = 5, 10, 15 up to 35) were prepared via conventional melt-quench technique. The glasses were converted to glass-ceramics by controlled heat-treatment at 850 °C. Higher content of MgO instead of CaO prevents the devitrification of the glasses. The in-vitro bioactivity of the glasses/glass-ceramics was evaluated in simulated body fluid (SBF). Glasses exhibited better bioactivity than the glass-ceramics. The weight loss and ions leaching profiles (especially potassium ions) of the samples played crucial role in formation of hydroxyapatite layer and its morphology. Hydroxyapatite had Ca/P ratio close to that for natural bone. However, it could not crystallize within experimental time and exhibited amorphous nature in X-ray diffraction. Microhardness of the glasses/glass-ceramics before and after immersion in SBF is also given. Microbial tests reveal that these glasses/glass-ceramics are effective in inhibiting the growth of fungi and do not affect the normal functioning of the antimicrobial drugs.

Keywords: Bioactivity; Heat-treatment; In-vitro; Microbial test; Microhardness; SBF.