Physico-chemical and biological studies on three-dimensional porous silk/spray-dried mesoporous bioactive glass scaffolds

The incorporation of a bioactive inorganic phase in polymeric scaffolds is a good strategy for the improvement of the bioactivity and the mechanical properties, which represent crucial features in the field of bone tissue engineering. In this study,spray-dried mesoporous bioactive glassparticles (SD-MBG), belonging to the binary system of SiO2-CaO (80:20mol%), were used to prepare composite scaffolds by freeze-drying technique,using a silk fibroin matrix.The physico-chemical and biological properties of the scaffolds were extensively studied.The scaffolds showed a highly interconnected porosity with a mean pore size in the range of 150 mm for both pure silk and silk/SD-MBG scaffolds. The elastic moduli of the silk and silk /SD-MBG scaffolds were 1.1 MPa and 6.9 MPa and compressive strength were 0.5 MPa and 0.9 MPa, respectively, showing a noticeable increase of the mechanical properties of the composite scaffolds compared to the silk ones.The contact angle value decreased from 105.3° to 71.2° with the incorporation of SD-MBG particles.Moreover, the SD-MBG incorporation countered the lack of bioactivity of the silk scaffolds inducing the precipitation of hydroxyapatite layer on their surface already after 1 day of incubation in simulated body fluid. The composite scaffolds showed good biocompatibility and a good alkaline phosphatase activity toward human mesenchymal stromal cells, showing the ability for their use as three-dimensional constructs for bone tissue engineering.