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International Journal of Bioprinting Bioprinted liver dECM/GelMA tumor model

to below 50 ng/mg, meeting safety standards for other As depicted in Figure 2E, as the temperature continuously
tissue-derived materials. 46 decreased, the G’ value initially exceeded the G’’ value,
The proton nuclear magnetic resonance, FTIR, and the indicating a more dominant elastic behavior. However, a
thermogravimetric curves results of gelatin and GelMA reversal occurred as the temperature approached a certain
are shown in Figure S1, Supporting Information. Protein point. Specifically, the G’’ value of GM/G/d-5 started to
content significantly decreased after decellularization, increase and eventually surpassed the G’ value around
while substantial amounts of GAGs and collagen 24.5°C, indicating a gradual transition from a solid to a
remained, indicating the favorable biological properties of liquid state. Among the bioink formulations, GM exhibited
the dECM (collagen I and III staining are shown in Figure the lowest solid–liquid transition temperature, occurring
S2, Supporting Information). Our previous study reported at approximately 15°C. The addition of gelatin increased
the proteomic analysis of liver-derived dECM, identifying the solid–liquid transition temperature of the mixture,
“catalytic activity” and “cellular process” as the top-ranked leading to variations in the transition behavior. The
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molecular function and biological process, respectively. diversity observed among the composite dECM groups
Furthermore, cell viability assays and live/dead staining could be attributed to differences in dECM content, where
were performed to assess the impact of decellularization a higher proportion of dECM resulted in a higher solid
on the cell compatibility of native liver tissue. As shown in content within the mixture, leading to a more pronounced
Figure S3, Supporting Information, the extract from native G’ value and a delayed transition from solid to liquid state.
liver tissue exhibited significant cytotoxicity, inhibiting cell 3.3. Printing and characterization of gelatin
proliferation, and inducing extensive cell death. In contrast, methacrylate/decellularized extracellular matrix
the DLM group demonstrated normal cell proliferation, bioink three-dimensional scaffold
nearly matching that of the blank group. For the fabrication of printed constructs, the bioinks were

3.2. Hydrogel preparation and characterization extruded from the printer nozzle and stacked to achieve
Scanning electron microscopy was applied to inspect the desired shape. Subsequently, ultraviolet irradiation
the internal morphology of five hydrogels. As shown in was applied to induce photo-crosslinking and ensure
Figure 2A, all groups exhibited a macroporous structure the curing of the hydrogels (Figure S6). To assess the
(pore size > 50 nm), with average pore sizes of 72.40, 62.74, accuracy of the printed shapes, hydrogels were printed
43.34, 36.51, and 30.02 μm (Figure 2B). The average pore in single-layer grids, featuring square voids between the
sizes were 72.40 μm for GM and 62.74 μm for GM/G filaments. The perimeter and area of these void spaces
without dECM. Upon the addition of dECM, the pore were calculated to determine a printability parameter,
size decreased to below 50 μm, with smaller pore sizes Pr. A Pr value of 1 corresponds to a perfect square shape,
corresponding to higher dECM content. These findings while values <1 indicate a more circular shape, and values
suggest that the incorporation of dECM reduces pore size >1 suggest the presence of jagged edges. In our study, all
and effectively enhances the compactness of the structure. three bioink blends demonstrated Pr values close to 1:
In addition, dECM particles were visible in the SEM images GM/G/d-5 = 0.914 ± 0.007, GM/G/d-3 = 0.879 ± 0.04, and
of dECM-containing groups, appearing as dense and GM/G/d-1 = 0.857 ± 0.020, all of which were higher than
irregular inclusions within the hydrogel network, further that of GM/G (0.803 ± 0.022). Notably, pure GelMA could
confirming their successful integration into the scaffold. not be successfully printed under these specific printing
conditions, highlighting the ideal printability achieved
Rheological properties play a crucial role in studying with the developed bioink formulations (Figure 3A).
the structure and characteristics of hydrogels, providing Furthermore, SEM images revealed a more distinct grid
valuable guidance for parameter settings in 3D printing. structure, indicating superior printability for the GM/G/d-5
Figure 2C displays the shear viscosity measurements bioink compared to other blends, as shown in Figure 3B.
of the printing bioinks at room temperature. It was To more robustly verify printability beyond simple lattice
observed that as the shear rate increased, the viscosity of patterns, complex geometries were also printed using GM/
the bioinks gradually decreased, demonstrating shear- G/d-5, including stylized “HQU” letters, a six-pointed star,
thinning behavior, which is desirable for extrusion-based and a biomimetic flower-like mesh. As shown in Figure S7,
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3D printing applications. Furthermore, the viscosity
increased with rising dECM content, primarily attributed to Supporting Information, these shapes maintained sharp
edges and fine lattice features, demonstrating the bioink’s
the higher solid content in the mixture. This viscosity trend fidelity under challenging design conditions.
also held true for temperature-dependent measurements,
as shown in Figure 2D. G’ and G’’ were utilized to describe Figure 3C illustrates the swelling properties of the five
the elastic and viscous responses of hydrogels, respectively. scaffolds after being immersed in PBS for 12 h. The GM

Volume 11 Issue 4 (2025) 398 doi: 10.36922/IJB025160142