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

Figure 4. Tuning the viscoelasticity by increasing MC concentration. (A) Crosslinked hydrogel blend consists of GelMA (5% w/v), alginate (1% w/v),
MC (0.5 and 1% w/v), and laponite-RDS (1% w/v). Scale bar: 5 mm. (B) Viscosity and (C–G) viscoelastic properties of hydrogel blends with varying
concentrations of MC. (H–I) Increased viscoelasticity with a higher concentration of MC content. *p < 0.05. (J–K) Printability and structural shape fidelity
of a hydrogel blend. Scale bar: 2.5 mm.

To evaluate its contribution, we compared formulations RDS. The disc-shaped laponite particles possess a net
29
with (G5A1M1R1) and without (G5A1M1) laponite- negative charge on their faces due to exposed silicate
RDS (Figure 5A). The inclusion of laponite-RDS (SiO₄⁴ ) groups, while their edges carry a slight positive
–
increased viscosity by approximately 75%, contributing charge from divalent cations such as Mg² and monovalent
+
to the formation of a thicker and more cohesive bioink Li . These charge distributions enable reversible ionic
+
(Figure 5B). Both groups exhibited clear shear-thinning interactions with the amphoteric side chains of GelMA,
behavior, but the addition of laponite-RDS enhanced contributing to increased pre-gel viscosity and enhanced
this effect, facilitating improved extrusion performance network stabilization prior to photopolymerization.
during printing. Interestingly, while the impact of laponite-RDS on Gʹ and
Rheological profiling showed increased storage (Gʹ) G˝ was consistent, the differences did not reach statistical
and loss (G˝) moduli in the presence of laponite-RDS, significance (Figure 5G), suggesting that its primary
with 62 and 47% increases, respectively (Figure 5C–G). function may be to fine-tune rather than drastically
Although the enhancement in elastic behavior was alter bulk viscoelasticity. Nevertheless, mechanical
modest, the overall viscoelastic balance shifted toward testing revealed a lower stress response and reduced
greater rigidity. These effects are attributed to electrostatic toughness in the absence of laponite-RDS (Figure 5H,
interactions between the cationic amine groups of GelMA Table S5), indicating compromised structural integrity.
and the negatively charged silicate surfaces of laponite- The degradation rate was also higher in laponite-RDS-free

Volume 11 Issue 4 (2025) 454 doi: 10.36922/IJB025160154