Design and Properties of Novel Substituted Borosilicate Bioactive Glasses and Their Glass-Ceramic Derivatives

 Three novel borosilicate bioactive glasses (BBGs) of general formula of 0.05Na2 O· 0.35x· 0.20B2 O3·  0.40SiO2  (molar ratio, where x  = MgO or CaO or SrO) were prepared and used to investigate the eff ect of crystallization on their properties including cytotoxicity. The three postmelt compositions were determined using X-ray fl uorescence spectroscopy, and crystallization events were studied using diff erential thermal analysis and X-ray diff raction. This information was used to determine heat treatments to prepare glass-ceramics by controlled crystallization. X-ray diff raction analysis and Fourier transform infrared spectroscopy showed that, after higher heat treatment temperatures (800− 900 ° C), borosilicate bioactive glass-ceramics (BBGCs) contained mainly borate and silicate crystalline phases. Specifically, BBGMg, BBG-Ca, and BBG-Sr glass-ceramics detected the presence of magnesium silicate-Mg2 (SiO3 )2  and magnesium borate-Mg2 B2 O5 ; wollastonite-2M-CaSiO3  and calcium borate-Ca(BO2 )2 ; and strontium silicate-SrSiO3  and strontium borate-Sr2 B2 O5 , respectively. In vitro  cytotoxicity tests were performed using the mouse fi broblast cell line (L929). Glass and glass ceramic at concentrations lower than 50 mg/mL did not exhibit any level of cytotoxicity when compared with the control. However, quantitative evaluation indicated that greater cell growth occurred in the presence of materials with crystalline phases. Control of BBGs crystallization may therefore be used to infl uence the biocompatibility of these glass-ceramic systems.