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International Journal of Bioprinting 3D bioprinting of tissue with carbon nanomaterials

counterparts, suggesting that electrical cues have major area than its non-printed counterpart containing the
roles in the differentiation of myoblasts. same amount of GelMA/GO. They demonstrated that by
adding a small amount of GO (<0.07% volume fraction)
3.2. CFNs-containing bioink to the gel, the impedance significantly decreased by 35-
Huang et al. developed a graphene-based nanocomposite fold, while the mechanical property increased by 2-fold
hydrogel for neural TE by mixing water-dispersible compared with GelMA alone. In addition, GO increased
graphene (Pluronic stabilized, G-P) and GO with the rheological properties of the GelMA composite,
polyurethane (PU) [104] . NSCs-embedded gel was extruded improving the printability, shape fidelity, and integrity of
using a commercial EBB bioprinter, and the constructs were the 3D-printed construct. The PC-12 pheochromocytoma
then added to the cell culture medium while maintaining cells incorporated with GelMA/GO-printed gel of 0.40
it at 37°C. The addition of graphene nanomaterials (25 and 1.40 mg/mL GO concentrations demonstrated higher
ppm) to NSCs (4 × 10 cells/mL)-embedded composite metabolic activity compared to GelMA and GelMA/
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(PU/G-P 25 ppm or PU/GO 25 ppm) significantly GO with GO concentration of 0.02 mg/mL 7 days post-
increased adenosine triphosphate production and oxygen treatment. These research findings have supported
metabolism in cells by approximately two- to fourfold the use of 3D-printed GelMA/GO composite gels in
compared to PU hydrogel after 24 hours of culture. electrically directed cell behavior in various types of tissue
The NSCs-treated PU/G-P 25 ppm scaffold showed an regeneration [107] .
increased gene expression of the glial fibrillary acidic
protein and β-tubulin after 3 days of culture by factors of 5.5 For biofabrication of cell-supportive cardiac patches,
and 1.5, respectively, as compared to those of PU and PU/ the scaffold must be mechanically elastic, robust, electrically
GO 25 ppm scaffolds. The synthesized hydrogel composite conductive, and biologically active. Cardiac patches should
system containing thermoresponsive PU and graphene imitate the myocardial extracellular matrix with the
met both, the mechanical requirements of bioprinted capacity for rapid integration with the native tissues [115] .
scaffolds and the biological requirements for stimulating Izadifar et al. developed a nanoreinforced methacrylated
the differentiation of NSCs. Ajiteru et al. formulated a collagen–CNT hybrid cardiac patch laden with human
bioink using glycidyl methacrylated silk fibroin (SB) with coronary artery endothelial cells (HCAECs) with excellent
covalently reduced GO and fabricated a tissue construct mechanical, electrical, and cellular responses [108] . Compared
(SGOB) using a customized digital light processing printer to the CNT-free hybrid constructs, the UV-integrated
(PBB type). The fabricated scaffold exhibited enhanced (365 nm, 45 seconds) EBB-printed hybrid constructs
electroconductive, mechanical, and neurogenic properties, have demonstrated much higher electrical conductivity
as compared to SB alone, and the photocurable bioink in the frequency range (approximately 5 Hz) associated
containing Neuro2a neuroblastoma (1 × 10 cells/mL) with the physiological state. The CNTs in HCAECs
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enhanced cell viability and proliferation, thus proving its promoted enhanced cellular behaviors, such as migration,
suitability as a biocomposite for neural TE [105] . proliferation, and lumen-like formation, 10 days post-
incubation. “Electron hopping” or “tunneling” is known to
Additionally, we have fabricated a 3D-printable bioink govern the electrical conductivity of CNTs by affording a
that is combined with phenol-rich gelatin (GHPA), continuous electron path along the CNT interconnects [116] .
GO, and C2C12 myoblasts via a dual enzyme-mediated Janarthanan et al. developed an ABT bioink with the
crosslinking reaction (glucose oxidase and horseradish incorporation of various concentrations (0.098 g, 0.244 g,
peroxidase) for skeletal muscle TE [106] . The 3D-printed and 0.325 g) of CNTs and 0.02 × 10 cells/mL of MC3T3
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construct obtained via EBB retained its shape fidelity osteoblasts or NIH3T3 fibroblasts. The EBB-printed disk-
immediately after printing. As demonstrated in the live/ shaped scaffolds exhibited cell biocompatibility for up to
dead assay, the printing process did not affect the loaded 21 days of the investigation .
[97]
C2C12 myoblasts because most cells exhibited green
fluorescence. The hydrogel (GO/GHPA) conferred a 4. Conclusion and perspectives
suitable cellular microenvironment that facilitated the
myogenic differentiation of myoblasts. The cells spread The primary purpose of fabricating 3D-bioprinted
their filopodia to adhere to the hydrogel structures on days constructs is to aid in TE and tissue regeneration. Although
3 and 5 and formed a mesh-like morphology on day 7, thus 3D bioprinting techniques demand advanced and costly
denoting cell proliferation (Figure 5). infrastructures, including software, robust computer
workrooms, and cell culture laboratory facilities, these
Mendes et al. formed a 3D-printed structure of techniques allow us to fabricate scaffolds with complex
photo-crosslinkable soft hybrid GelMA/GO using EBB. biological arrangements with greater shape fidelity and
The printed structure has a greater electroactive surface patient-specific designs within a short duration. In this

Volume 9 Issue 1 (2023) 192 https://doi.org/10.18063/ijb.v9i1.635