Ionic Liquid-Assisted Synthesis of Mesoporous Silk Fibroin/Silica Hybrids for Biomedical Applications
New mesoporous silk fibroin (SF)/silica hybrids were processed via a one-pot soft and energy-efficient sol-gel chemistry and self-assembly from a silica precursor, an acidic or basic catalyst, and the ionic liquid 1-butyl-3-methylimidazolium chloride, acting as both solvent and mesoporosity-inducer. The as-prepared materials were obtained as slightly transparent-opaque, amorphous monoliths, easily transformed into powders, and stable up to ca. 300 °C. Structural data suggest the formation of a hexagonal mesostructure with low range order and apparent surface areas, pore volumes, and pore radii of 205-263 m 2 g -1 , 0.16-0.19 cm 3 g -1 , and 1.2-1.6 nm, respectively. In all samples, the dominating conformation of the SF chains is the ß-sheet. Cytotoxicity/bioactivity resazurin assays and fluorescence microscopy demonstrate the high viability of MC3T3 pre-osteoblasts to indirect (=99 ± 9%) and direct (78 ± 2 to 99 ± 13%) contact with the SF/silica materials. Considering their properties and further improvements, these systems are promising candidates to be explored in bone tissue engineering. They also offer excellent prospects as electrolytes for solid-state electrochemical devices, in particular for fuel cells. ; This work was supported by Fundacão para a Ciência e a Tecnologia (FCT)/Deutscher Akademischer Austauschdienst (DAAD) Transnational Cooperation Project no. 6818 "Ionic liquid-and ionic liquid crystal-assisted formation of hybrid biomaterials scaffolds". We further wish to thank the European Union, QREN, FEDER through "Programa Operacional Factores de Competitividade" (COMPETE), and CICE-COAveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. This work was also funded by project UniRCell (POCI-01-0145-FEDER-016422 and SAICTPAC/0032/ 2015) financed by the European Regional Development Fund (ERDF) through COMPETE 2020, POCI and FCT. We also thank FCT in the framework of Strategic Funding UID/QUI/00686/2013 and UID/QUI/00686/2016, and funding under project PEst-OE/QUI/UI0616/2014. R.F.P.P. acknowledges FCT for a grant (SFRH/BPD/87759/2012).
