Development of a tissue construct with spatially controllable stiffness via one-step 3D bioprinting and dual-crosslinking process

3D bioprinting is a promising technology for manufacturing cellular constructs in which the complex characteristics of real tissues are faithfully represented under in vitro culturing conditions. Many efforts have been...


Scheme of the alginate methacrylation reaction
. Schematic steps of alginate methacrylation by grafting methacrylate groups into sodium alginate chain.

Detailed interpretation of FTIR spectra
As observed from Figure 1(d and e), both spectra display wide bands in the region ranging from 3600 cm -1 to 3000 cm -1 and from 2980 cm -1 to 2850 cm -1 , ascribable to the stretching of -OH and -CH groups, respectively, typically of the polysaccharides [1].The others bands might be more representative of the alginate chains since the stretching of carboxylate anions -COO -falls around 1595 cm -1 [1][2], the C-OH deformation along with the symmetric stretching of O-C-O of the carboxylate groups [2][3] falls around 1403 cm -1 , while the vibrations of C-O and C-C of the pyranose rings produce the bands at ca. 1083 cm -1 and at ca. 1026 cm -1 , respectively [1].Furthermore, all the bands at low frequency (946 cm -1 , 883 cm -1 and 812 cm -1 ) might be assigned to the C-O stretching of uronic acid [1], to the C1-H deformation of β-mannuronic acid [1], and to the C-H bending vibrations of mannuronic acid residues [4].In addition to these bands, the spectrum related to the AlgMa product exhibits more intense peaks at 2980 cm −1 -2850 cm −1 and the presence of a "shoulder" at 1711 cm −1 (both highlighted with the red arrows in Figure 2e), not observed in the pristine alginate spectrum (Figure 2 d).These marked bands along with the "shoulder" can be respectively assigned to the stretching of the -CH of the alkane and alkene bonds contained in the methacrylate functionalization and to the stretching of the C=O group of the esters.and 120 sec (BB120, red curve) of UV light; (c) BB after dual cross-linking process with different UV irradiation time: 60 sec (BA60Ca, black curve), 90 sec (BA90Ca, green curve), 120 sec (BA120Ca, red curve).

Mass spectrometry data of AlgMa products after hydrolysis
Table S4.Summary of the storage (G') and loss (G") moduli values of the 3D bioprinting scaffolds produced by using bioink A and bioink B (colored in yellow), and the corresponding scaffolds not containing cells (colored in green), after dual crosslinking processes.

Table S1 .
Mass spectrometry data of AlgMa products after hydrolysis, reported as observed m/z

Table S2 .
Isotope cluster area (ICA) of all identified species is reported.Three sets of experiments (1, 2, 3) were performed.The listed ICA values are calculated as media from three consecutive acquisitions to obtain a total of 9 subset data.In black are reported the oligosaccharides chains with no derivatization sites; in red are reported methacrylate species.

Table S3 .
Summary of the stability tests and cell viability results of different AlgMa ink formulations.