Solution combustion synthesis of functional diopside, akermanite, and merwinite bioceramics: Excellent biomineralization, mechanical strength, and antibacterial ability

Abstract Bioceramics based on the CaO-MgO-SiO2 system, are frequently applied to stimulate bone regeneration due to their bioactivity, controlled bioresorbability rate, biocompatibility, and improved mechanical properties. In this contribution, bioceramic materials; diopside (CaMgSi2O6), akermanite (Ca2MgSi2O7), and merwinite (Ca3MgSi2O8) were synthesized through solution combustion method using glycine as a fuel. Scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 physisorption, and energy-dispersive X-ray spectroscopy (EDX) were utilized for characterization. The proposed synthetic method produced highly-pure phases of the bioceramics after calcination at 1000 °C. The bioceramics are characterized by crystalline sizes ranged from 37 to 44 nm and specific surface areas in the range of 26 m2 g−1 to 53 m2 g−1. The in-vitro biomineralization activity and the mechanical properties of the bioceramic scaffolds were investigated by immersing them in simulated body fluid (SBF) for 3, 6, and 9 days. Interestingly, XRD, FT-IR, and SEM results demonstrated that the surface of scaffolds is covered by the hydroxyapatite (HAp) layer after immersing in SBF for 9 days. The rate of HAp deposition is extremely high for merwinite compared to akermanite and diopside, following the same trend of the CaO content. Furthermore, the mechanical properties of the fabricated scaffolds are excellent, as indicated by Young's modulus compressive strength analyses, and the mechanical strength improves with increasing the CaO content. The antibacterial activity of the bioceramics was tested against S. epidermidis, S. aureus, E.coli, and P. aeruginosa. Merwinite exhibits a superior antibacterial activity even at lower concentrations compared to diopside and akermanite. Collectively, the multifunctional properties of the synthesized bioceramics make them auspicious candidates for potential biomedical applications including bone tissue repair.