Silk fibroin(SF)can be used to construct various stiff material interfaces to support bone formation.An essential preparatory step is to partially transform SF molecules from random coils toβ-sheets to render the mat...Silk fibroin(SF)can be used to construct various stiff material interfaces to support bone formation.An essential preparatory step is to partially transform SF molecules from random coils toβ-sheets to render the material water insoluble.However,the influence of the SF conformation on osteogenic cell behavior at the material interface remains unknown.Herein,three stiff SF substrates were prepared by varying theβ-sheet content(high,medium,and low).The substrates had a comparable chemical composition,surface topography,and wettability.When adsorbed fibronectin was used as a model cellular adhesive protein,the stability of the adsorbed protein-material interface,in terms of the surface stability of the SF substrates and the accompanying fibronectin detachment resistance,increased with the increasingβ-sheet content of the SF substrates.Furthermore,(i)larger areas of cytoskeleton-associated focal adhesions,(ii)higher orders of cytoskeletal organization and(iii)more elongated cell spreading were observed for bone marrow-derived mesenchymal stromal cells(BMSCs)cultured on SF substrates with high vs.lowβ-sheet contents,along with enhanced nuclear translocation and activation of YAP/TAZ and RUNX2.Consequently,osteogenic differentiation of BMSCs was stimulated on highβ-sheet substrates.These results indicated that theβ-sheet content influences osteogenic differentiation of BMSCs on SF materials in vitro by modulating the stability of the adsorbed protein-material interface,which proceeds via protein-focal adhesion-cytoskeleton links and subsequent intracellular mechanotransduction.Our findings emphasize the role of the stability of the adsorbed protein-material interface in cellular mechanotransduction and the perception of stiff SF substrates with differentβ-sheet contents,which should not be overlooked when engineering stiff biomaterials.展开更多
The therapeutic precision and clinical applicability of drug-eluting coatings can be substantially improved by facilitating tunable drug delivery.However,the design of coatings which allows for precise control over dr...The therapeutic precision and clinical applicability of drug-eluting coatings can be substantially improved by facilitating tunable drug delivery.However,the design of coatings which allows for precise control over drug release kinetics is still a major challenge.Here,a double-layered silk fibroin(SF)coating system was constructed by sequential electrophoretic deposition.A mixture of dissolved Bombyx mori SF(bmSF)molecules and pre-made bmSF nanospheres at different ratios was deposited as under-layer.Subsequently,this underlayer was covered by a top-layer comprising Antheraea pernyi SF(apSF)molecules(rich in arginylglycylaspartic acid,RGD)to improve the cellular response of the resulting double-layered coatings.Additionally,model drug doxycycline was either pre-mixed with dissolved bmSF molecules or pre-loaded into pre-made bmSF nanospheres at the same amount before their mixing and deposition.The thickness and nanosphere content of the under-layer architecture were proportional to the deposition time and nanosphere concentration in precursor mixtures,respectively.The surface topography,wettability,degradation rate and adhesion strength were comparable within the double-layered coating system.As expected,RGD-rich apSF top-layer improved cell adhesion,spreading and proliferation compared with bmSF top-layer.Furthermore,the amount and duration of drug release increased linearly with increasing nanosphere concentration at fixed deposition time,whereas drug release amount increased linearly with increasing deposition time.These results indicate that the dosage and kinetics of loaded drugs can be quantitatively tailored by altering nanosphere concentration and deposition time as main processing parameters.Overall,this study illustrates the strong potential of pre-defining coating architecture to facilitate control over drug delivery.展开更多
基金supported by the National Key R&D Program of China(2017YFC1104301,to L.C.)the National Natural Science Foundation of China for Distinguished Young Scholars(31725011,to L.C.)the China Scholarship Council(201606160095,to X.C.)。
文摘Silk fibroin(SF)can be used to construct various stiff material interfaces to support bone formation.An essential preparatory step is to partially transform SF molecules from random coils toβ-sheets to render the material water insoluble.However,the influence of the SF conformation on osteogenic cell behavior at the material interface remains unknown.Herein,three stiff SF substrates were prepared by varying theβ-sheet content(high,medium,and low).The substrates had a comparable chemical composition,surface topography,and wettability.When adsorbed fibronectin was used as a model cellular adhesive protein,the stability of the adsorbed protein-material interface,in terms of the surface stability of the SF substrates and the accompanying fibronectin detachment resistance,increased with the increasingβ-sheet content of the SF substrates.Furthermore,(i)larger areas of cytoskeleton-associated focal adhesions,(ii)higher orders of cytoskeletal organization and(iii)more elongated cell spreading were observed for bone marrow-derived mesenchymal stromal cells(BMSCs)cultured on SF substrates with high vs.lowβ-sheet contents,along with enhanced nuclear translocation and activation of YAP/TAZ and RUNX2.Consequently,osteogenic differentiation of BMSCs was stimulated on highβ-sheet substrates.These results indicated that theβ-sheet content influences osteogenic differentiation of BMSCs on SF materials in vitro by modulating the stability of the adsorbed protein-material interface,which proceeds via protein-focal adhesion-cytoskeleton links and subsequent intracellular mechanotransduction.Our findings emphasize the role of the stability of the adsorbed protein-material interface in cellular mechanotransduction and the perception of stiff SF substrates with differentβ-sheet contents,which should not be overlooked when engineering stiff biomaterials.
基金X.C.is funded by China Scholarship Council(Project No.201606160095)。
文摘The therapeutic precision and clinical applicability of drug-eluting coatings can be substantially improved by facilitating tunable drug delivery.However,the design of coatings which allows for precise control over drug release kinetics is still a major challenge.Here,a double-layered silk fibroin(SF)coating system was constructed by sequential electrophoretic deposition.A mixture of dissolved Bombyx mori SF(bmSF)molecules and pre-made bmSF nanospheres at different ratios was deposited as under-layer.Subsequently,this underlayer was covered by a top-layer comprising Antheraea pernyi SF(apSF)molecules(rich in arginylglycylaspartic acid,RGD)to improve the cellular response of the resulting double-layered coatings.Additionally,model drug doxycycline was either pre-mixed with dissolved bmSF molecules or pre-loaded into pre-made bmSF nanospheres at the same amount before their mixing and deposition.The thickness and nanosphere content of the under-layer architecture were proportional to the deposition time and nanosphere concentration in precursor mixtures,respectively.The surface topography,wettability,degradation rate and adhesion strength were comparable within the double-layered coating system.As expected,RGD-rich apSF top-layer improved cell adhesion,spreading and proliferation compared with bmSF top-layer.Furthermore,the amount and duration of drug release increased linearly with increasing nanosphere concentration at fixed deposition time,whereas drug release amount increased linearly with increasing deposition time.These results indicate that the dosage and kinetics of loaded drugs can be quantitatively tailored by altering nanosphere concentration and deposition time as main processing parameters.Overall,this study illustrates the strong potential of pre-defining coating architecture to facilitate control over drug delivery.
