Figure 5.

A. Schematic illustration of 3D printing of silk fibroin-gelatin composite inks for repairing cartilage injury in vivo and in vitro. Reproduced with permission.^[211] Copyright 2017, John Wiley and Sons. B. The 3D prints in the shape of the Eiffel tower and Trachea by photocurable silk-MA. From left to right, CAD design, and the real prints. Reproduced with permission. ^[121]Copyright 2018, Springer Nature. C. SEM images of all-silk-based 3D prints by femtosecond laser-induced polymerization. (i) A microbowl; (ii) Another microbowl; (iii) A overhanging microwire; (iv) A truncated pyramid. Reproduced with permission.^[122] Copyright 2015, Springer Nature. D. Schematic illustration and images (square lattice and circular web) of 3D direct ink writing of silk fibroin in a methanol bath. Reproduced with permission.^[120] Copyright 2017, John Wiley and Sons. E. Schematic illustration of 3D printing with silk fibroin-Konjac gum composite ink with architectural control over multiple levels of hierarchy from macroscale to nanoscale. Latex nanoparticles, PCL, and wax particles are used as sacrificial templates, which can be removed by dissolution and ultrasonication and lead to open porous structures. Reproduced with permission.^[213] Copyright 2007, American Chemical Society. F. 3D printing of monolithic silk fibroin using biomimetic and rationally designed aqueous salt bath. A printed two-layer overhanging orb-web composed of one arithmetic spiral and four radial straight lines in the width of ca. 100 μm. A water droplet sits across two filaments. Reproduced with permission.^[119] Copyright 2019, John Wiley and Sons. G. A printed vase (≈0.0033 g) with high-aspect-ratio wall (Ca. 26) and inward inclination (63°). Three vases in a total of ca. 0.01 g can support a six-order heavier load (1050 g) without breaking or delamination, suggesting the desired mechanical stability. Reproduced with permission.^[119] Copyright 2019, John Wiley and Sons.