4.1 Chemical structure of bioink
As shown in Figure 2 , the main absorption bands were stretching vibrations of C=O at 1652 cm−1 and O-H at 3480 cm−1, which was a broad and redshift due to the formation of H-bond (Figure 2a). After printing, the redshift tendency of kc-sa and kc-SA-C was reduced, indicating that a part of the hydrogen bonds was destroyed during printing (Figure 2b).