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International Journal of Bioprinting Fine collagen scaffold for osteogenesis

3. Results Lissajous curves for ink B compared to ink A, indicating
more linear viscoelastic behavior (Figure 6A). Additionally,
3.1. FTIR analysis ink B showed A higher strain-hardening ratio (Figure 6B),
Following the oxidation of cellulose by sodium peroxide,
the hydroxyl groups (–OH) were converted to aldehyde suggesting better structural recovery and printability.
groups. In the FTIR spectra, ink A showed a characteristic The greater linear rheological characteristic of ink B may
–OH peak at 1075 cm , which was markedly reduced contribute to its improved shape fidelity during printing.
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in ink B, indicating successful oxidation. In addition, the 3.3. Morphological study
characteristic amide peak of collagen I at 1542 cm was Cryogenic 3D printing (Figure 7) was attempted using ink
−1
prominent in ink A but nearly absent in ink B (Figure 3), A and B. An optimum combination of pressure and speed
suggesting its consumption via Schiff-base reactions. 32 parameters was evaluated for each ink until rod breakage

3.2. Rheological study occurred. Printing with ink A was more challenging due
At the printing temperature of –1 °C, ink A exhibited to its weaker gelation strength, which limited resolution
higher viscosity than ink B. This was consistent with its improvements at higher printing speeds and led to frequent
lower tan δ value and steeper stress–strain curve slope, rod breakage (Figure 7B). In contrast, ink B enabled
indicating greater stiffness (Figures 4 and 5). Both inks smoother printing, likely due to Schiff-base-induced
demonstrated shear-thinning behavior, as viscosity structural reinforcement (Figure 7C). As a result, samples
decreased monotonically with increasing shear rate 1–3 scaffolds were printed using ink B, while sample 4 was
(Figure 4B). LAOS analysis revealed more flattened printed using a gelatin-based hydrogel ink.

Figure 3. FTIR spectra for ink A (cellulose/collagen I/alginate hydrogel) and B (oxidized cellulose/collagen I/alginate hydrogel). Abbreviation: FTIR:
Fourier transform infrared spectroscopy.

Volume 11 Issue 4 (2025) 229 doi: 10.36922/IJB025140116