Page 238 - IJB-9-4

International Journal of Bioprinting Agar production residue for 3D printing

Figure 7. Elastic modulus and force values at different strains for 3D-printed products.
a Two means followed by the same letter at the same strain are not significantly different (p > 0.05).

Furthermore, texture profile analysis provides information hydroxyl groups of cellulose, resulting in 3D-printed
on the hardness and cohesiveness of the hydrogels, which products with high swelling capacity with their integrity
are highly relevant for analyzing their workability for 3D preserved under physiological conditions. Additionally,
printing. In this sense, hardness, which is the maximum 3D-printed products showed thermal stability up to
force required to produce the first deformation, showed a 200°C. Furthermore, morphological evaluation showed
value of 1004 ± 43 g for the control hydrogel. The hardness that cellulose was well distributed in the protein matrix,
increased with the addition of agar residue up to 1389 ± since no aggregate was observed by SEM, resulting in
52 g for the SPI8C hydrogel. Regarding cohesiveness, 3D-printed products that maintain their integrity even
which is related to the ability of a gel to maintain its own at a compression strain of 50% and display a shape
structure under compressive stress, the control hydrogel recovery behavior in compression-decompression cycles.
showed a high cohesive value of 0.858 ± 0.014, which Considering the swelling capacity of the 3D-printed
remained nearly constant with residue addition (0.843 ± products at physiological conditions and the mechanical
0.021 for SPI8C), indicating a high ability to maintain performance of the hydrated 3D-printed products, the
3D structural integrity and thus structure after printing, suitability of these products for biomedical applications
as demonstrated by rheological analysis. This mechanical could be assessed.
behavior revealed that 3D-printed products do not break
under compression and maintain mechanical integrity; Acknowledgments
therefore, they are strong enough not to be damaged by None.
handling or replacement.
Funding
4. Conclusion
This work was supported by a grant PID2021-124294OB-C22
Agar production residue was used without further funded by MCI/AEI10.13039/501100011033 and by “ERDF
purification in order to reduce the carbon footprint A way of making Europe.” This work was also supported
associated to the manufacture of products based on by the Basque Government (IT1658-22). J.U. thanks the
valorized polymers. This residue is mainly constituted by University of the Basque Country (ESPDOC21/74) and
cellulose and was used as a filler in soy protein-based inks. T.C. thanks the Basque Government (PRE_2022_2_0005)
The rheological assessment revealed that the hydrogels for their fellowships.
have shear-thinning behavior, which is favorable for 3D
printing, as well as suitable printability values. The use of Conflict of interest
cellulose as a filler in soy protein hydrogels led to hydrogen
bonding between the polar groups of protein and the The authors declare they have no competing interests.

Volume 9 Issue 4 (2023) 230 https://doi.org/10.18063/ijb.731