Fig. 2.

Rheological properties of printing inks. A, C) Viscosity changes in SA and SA@dNC (upper-layer inks) with different pre-crosslinking degrees at 25 °C. B, D) Storage modulus (G′) and loss modulus (G″) changes in SA and SA@dNC with different pre-crosslinking degrees depending on the shear stress; the black dots represent the yield stress value. E) Viscosity changes in Gel–SA and Gel@nHA–SA (lower-layer inks) with different pre-crosslinking degrees at 37 °C. F) G′ and G″ change in Gel–SA and Gel@nHA–SA inks (lower-layer inks) with different pre-crosslinking degrees; black dot represents the yield value. G) Macrophotograph of the upper- and lower-layer inks. H) Dynamic modulus change in Gel–SA and Gel@nHA–SA inks after 5-min UV irradiation.