Effect of gelatin on dimensional stability of silk fibroin hydrogel structures fabricated by digital light processing 3D printing

Abstract This work describes development of a silk fibroin (SF)-based ink material for digital light processing 3D printing. Riboflavin initiates the crosslinking of SF molecules under irradiation with visible light to form an SF hydrogel through dityrosine bonding. Rapid formation of a β-sheet structure induces shrinkage of SF hydrogels in phosphate-buffered saline solution at 37 °C. Such shrinkage of SF hydrogel is effectively prevented by addition of gelatin to SF ink. As the ratio of gelatin in the composite ink is increased, the density of β-sheet structures is reduced, and structural deformation of the 3D SF/gelatin hydrogel is inhibited. Printability is critical in fabrication of 3D SF/gelatin composite hydrogel structures. For evaluation of printing performance, the actual width of the hydrogel formed by 3D printing is compared with the designed width. The 3D printing of SF is performed by irradiating a series of features with different shapes or sizes in a vertical manner.