Scheme 1.

Schematic illustration of nanoridge formation on SF films by ice-templating to induce the osteogenic differentiation without additional osteogenic inducers and form ectopic bone in a rat subcutaneous model. SF was regenerated from cocoons and dissolved in hexafluoro-2-propanol (HFIP) for casting a film. The film was soaked in methanol to become hydrophobic and then in H₂O, followed by freezing and lyophilization to form nanoridges (Figure S1, Supporting Information). Nanoridges induce the osteogenic differentiation of MSCs cultured on the film without any additional chemical inducers. The nanoridged SF film can induce the formation of an osteoid matrix in a rat subcutaneous model with or without MSCs seeded.