2.4.1 Chemical structure of carrageenan-based bioink
The Fourier-transform infrared spectroscopy (FT-IR) spectrum of the kc, kc-s, and kc-c was analysed using Fourier-transformed infrared-attenuated total reflectance (Nicolet Avatar 370, USA). Moreover, the printing and non-printing FTIR spectra of kc-s and kc-c were analysed. A background spectrum was collected before acquiring the transmission infrared spectra of the samples. All the spectra were between 4000 and 400 cm−1.