Page 261 - IJB-9-5

International Journal of Bioprinting

DLP 3D printing technology has been widely used in tissue such as PEGDA, polyurethane, and poly (glycerol
engineering due to its high precision and fast molding sebacate methacrylate) [5,52] . Thus, ASF-MA hydrogels
speed. However, the functional biological materials were have potential application prospects in 3D printing cell
limited because the printing ink still needs to meet the delivery system.
characteristics of the photopolymerization reaction. BSF
has been explored for biomedical applications since the last Another important factor to consider in printing
century because it is easily accessible, and it has promoted 3D tissue structures is the mechanical properties, which
[48]
[53]
the development of silk fibroin with RGD sequences. The also influence the functioning of cells and tissues .
researchers added crosslinking agents to BSF to create Collagen and hyaluronic acid are both components of
porous scaffolds materials, such as glutaraldehyde , the extracellular matrix and have great biocompatibility.
[49]
EDC, and NHS . For example, Park et al. used GMA- However, the compressive strength was generally at
[50]
modified silk fibroin for DLP 3D printing. It showed great 10–100 kPa and had inferior tensile performance. As for
printability and could be mixed with chondrocytes to PEGDA and BSF-GMA, they showed superior compressive
produce artificial tracheal scaffolds for in vivo use . The modulus of about 1 MPa, but the difficulty of cell adhesion
[6]
result from Park et al. prompted us to try to modify the on the hydrogels affected the normal function of cells
functional groups of regenerated ASF. In the current study, and tissues to some extents. In our study, the mechanical
methacrylic anhydride was reacted with free amino groups properties of hydrogels under different conditions were
to introduce photopolymerizable methacryloyl groups explored. We observed that 30% ASF-MA PBS hydrogel
10%
into the molecular chain of ASF, which produced the had the highest compressive modulus of 0.269 MPa (at
modified molecular with photopolymerization properties. 35% deformation), and it was better than BSF-GMA and
However, significant difference existed between ASF’s GelMA hydrogels of the same concentration. In addition,
primary amino acid composition and BSF composed the mechanical properties of the 75% ethanol-soaked ASF-
mainly of glycine-alanine-glycine-serine-glycine-alanine MA hydrogels were all improved due to the change of the
(GAGSGA) repeats . At the same time, the hydrophobic secondary structure and hydrophobic network structure.
[51]
amino acids alanine (43.07%) and glycine (27.27%) in ASF At the 20% deformation, 30% ASF-MA 2.5% EtOH hydrogels
were higher and contained more repetitive sequences of could be compressed with a modulus of 0.561 MPa. At
alanine. The MA was also hydrophobic. Therefore, when the 13% deformation, 30% ASF-MA EtOH hydrogels
5%
the reaction between MA and the amino group exceeded possessed a maximum tensile modulus of about 0.830
a certain level, the ASF would become hydrophobic and MPa. Based on the approximate elastic modulus of human
[53]
unstable in an aqueous solution leading to precipitation. tissues , the different ASF-MA hydrogels fabricated in
Based on the H-NMR and FTIR spectra, the content of our study exhibited varying mechanical properties which
1
the secondary structure β-fold of ASF decreased slightly could potentially be applied in constructing tissues and
with the increase of the degree of methacryloylation. organs, such as skin, liver, and kidney.
It might be one of the reasons causing the instability. In
the present study, a high methacrylate-substitution level Biodegradability is also an significant characteristic
of 45.98% (ASF-MA 10% ) was achieved by repeating the of tissue engineering materials. Under ideal condition,
preparation process. the bionic structure should degrade slowly while the new
tissue gradually grows. At the same time, the degraded
[54]
As the accuracy of printing is a significant factor for products should not cause side effects to the organism .
the personalized 3D-printed products and the precise Gelatin, collagen, elastin, and silk fibroin are natural
medical treatment, a DLP 3D printer with high printing protein materials, and most of the degradation products
accuracy was used in our study. The physicochemical were non-toxic, such as amino acids and short peptides,
properties of the printing ink, such as like photoreaction which are favorably biocompatible . According to our
[6]
rate and light transmission, also affected the accuracy of study, the ASF-MA 10% PBS hydrogel degraded rapidly in
the printed structures. The ASF-MA 10% bioinks obtained the presence of protease XIV. However, the ASF-MA EtOH
formed hydrogel after exposure to 405 nm UV light with hydrogel degraded more slowly in the protease-containing
80 mW/cm intensity for 5 s. It could print complex 3D environment due to the increased crystallinity. The in vivo
2
hollow structures with printability after adding 0.1% experiments showed that ASF-MA 10% hydrogel degraded
lemon yellow to reduce other light interferences. On the by about 30% in 3 months after implantation into mice,
other hand, the bioink prepared with mixing ASF-MA 10% with a rate slightly higher than that of GelMA and BSF-
with cells enabled the printing of specific structures. The GMA hydrogels, and did not manifest swelling. Therefore,
viability of cells within the ASF-MA hydrogel remained our study provided a selection of ASF-MA hydrogels with
at a good level, compared with some synthetic materials, different degradation rates for 3D printing, and it could

Volume 9 Issue 5 (2023) 253 https://doi.org/10.18063/ijb.760