Preparation and characterization of a silk fibroin/calcium sulfate bone cement

This study aimed to prepare and characterize a silk fibroin/calcium sulfate (SF/CS) bone cement. SF solutions of the following concentrations 3, 4.5, 6, 7.5, and 9 g/L were used to prepare bone cement samples with SF-to-CS ratios of 0.35, 0.40, 0.45, 0.50, and 0.55 mL of SF solutions (or water as control) per g of CS. Compressive strength, setting time, degradation when immersed in phosphate-buffered saline, X-ray diffraction, Fourier infrared spectroscopy, and scanning electron microscopy were used to characterize the SF/CS bone cement. Biocompatibility was determined using rat bone mesenchymal stem cells (rBMSCs) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The optimal bone cement was obtained with 0.4 mL of 6 g/L SF solution per g of α-hemihydrate CS powder. Compared with CS bone cement, compressive strength of SF/CS bone cement was 19.7% higher (p = 0.003). Samples prepared with SF had less degradation in phosphate-buffered saline than the ones prepared with deionized water. Using SF solution as the solidifying liquid increases the initial setting and final setting time of CS compared with deionized water. Using extracts from SF/CS bone cement, all cell relative proliferation rates were >100%, showing no cytotoxicity for any sample. In conclusion, using the 6 g/L SF solution at 0.40 mL/g of CS increased the cement compressive strength. SF solution added to CS achieved a bone cement with increased durability compared with CS bone cement. The SF/CS cement had no cytotoxicity on rBMSCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 512-519, 2018.