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International Journal of Bioprinting Tunable GelMA-based bioinks for keloid modeling

and surface roughness through interparticle interactions in G5A1M1R1, with a Young’s modulus of 7.9 ± 1.3 kPa
and water intercalation. Its negatively charged surfaces compared to 2.1 ± 0.92 kPa in G4A1M1R1 (Figure 2H–I).
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can form ionic interactions with the positively charged These findings suggest that mechanical reinforcement
amine groups of GelMA, thereby improving network primarily arises from enhanced GelMA crosslinking,
stability and mechanical reinforcement. 29 rather than bulk rheological differences. Since GelMA
To investigate GelMA’s role as a mechanical crosslinker, relies on chemical crosslinking via photopolymerization
we compared bioinks with 4% (G4A1M1R1) and 5% rather than ionic or physical interactions, the resulting
(G5A1M1R1) GelMA content, representing soft and hydrogel remains stable under physiological ionic
stiff hydrogels, respectively (Figure 2A). Despite the conditions, which might otherwise affect electrostatic
25% increase in GelMA concentration, no statistically interactions and compromise structural integrity
significant differences in viscosity or viscoelastic moduli (Figure 2J–K). Furthermore, slower degradation was
were observed between the groups (Figure 2B–G). observed in G5A1M1R1 (Figure S1C), indicative of a
Both exhibited typical non-Newtonian, shear-thinning denser and more stable polymer network. Enhanced
behavior, with viscosity decreasing as shear rate increased mechanical resilience and matrix stability are likely due
(Figure 2B–C). This property supports extrusion-based to the increased density of covalent and non-covalent
bioprinting, where low viscosity under shear facilitates crosslinks formed at higher GelMA concentrations. 24,31
flow and high viscosity post-extrusion maintains structural In summary, increasing GelMA concentration improves
fidelity. Frequency sweep analysis indicated stable the mechanical performance, degradation resistance,
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viscoelastic behavior across both groups (Figure 2D, G), but and printability of the hydrogel, which are essential for
compression testing revealed significantly higher stiffness supporting cellular viability and long-term culture in

Figure 2. Effect of GelMA as a crosslinker on the rheological and mechanical properties of bioink. (A) Crosslinked hydrogel blend consists of GelMA
(4 and 5% w/v), alginate (1% w/v), methylcellulose (MC) (1% w/v), and laponite-RDS (1% w/v). Scale bar: 5 mm. (B) Viscosity and (C–G) rheological
properties of hydrogel blends with varying concentrations of GelMA. (H–I) Higher mechanical properties observed with higher crosslinker concentration.
*p < 0.05, ***p < 0.001. (J–K) Printability and structural shape fidelity of a hydrogel blend. Scale bar: 2.5 mm.

Volume 11 Issue 4 (2025) 451 doi: 10.36922/IJB025160154