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

developed it into a 3D scaffold using extrusion-based fabricated scaffolds (3D-PPF, 3D-PPF-ssDNA, 3D-PPF-
3D printing pneumatically for BTE . According to the CNTs, and 3D-PPF-ssDNA@CNTs) expressed osteogenic
[98]
in vitro results, the 3D PIC/MWCNTs scaffolds showed differentiation markers, including alkaline phosphatase,
excellent cytocompatibility with rat bone marrow- osteocalcin, and osteopontin, in conjunction with ES, as
derived MSCs (rBMSCs). In addition, the PIC/MWCNTs compared with the activity of the scaffolds without ES on
scaffolds facilitated osteogenic differentiation of rBMSCs, day 14 of culture.
with increased osteogenesis-related gene upregulation
and mineralized matrix formation compared to PIC 3.1.2. Other CFNs in biomaterial ink
scaffolds. A rat calvarial defect model was used to Apart from graphene and CNTs, other CFNs have also
investigate the bone tissue regeneration potential of the been explored for 3D printing formulations. Serafin et
prepared scaffolds (PIC and PIC/MWCNTs) in vivo. al. reinforced an alginate/gelatin (Alg–Gel) hydrogel
Micro-computer tomography analysis revealed that with commercially available carbon nanofibers (CNFs;
bone regeneration occurred between 2 and 8 weeks 100 nm in diameter and 20–200 µm in length) for
after implantation in both scaffolds. However, the PIC/ applications in cardiac or neuronal TE [102] . The tissue
MWCNTs exceeded the PIC in terms of bone mineral construct fabricated by EBB contained two layers (2 mm
density and bone volume/total volume ratio. Lee et al. per layer) with a height of 4 mm and a width of 9 mm. It
investigated the proliferative capacity and differential was crosslinked in 200 mM CaCl solution over 24 hours.
2
potential of neural stem cells (NSCs) after seeding The researchers investigated the mechanical properties,
on amine-functionalized MWCNTs-incorporated shear-thinning behavior, and electrical conductivity
3D-printed scaffolds of PEG diacrylate (PEGDA) . of the printable Alg–Gel scaffolds by using different
[99]
A stereolithography-based 3D PBB bioprinter was concentrations of CNFs (0.5%, 1%, 2%, and 5% [w/v]).
employed to fabricate neural scaffolds with intricate Incorporating CNFs into the Alg–Gel system increases
microarchitectures and a tunable porous structure. When the viscosity of the scaffold, thus allowing for improved
the scaffolds were subjected to biphasic pulse stimulation ink extrusion. While optimizing the printability of the
with a 500 µA current, they significantly stimulated gels, all the scaffolds, except for Alg–Gel–CNFs-5, were
NSC proliferation, early neuronal differentiation, and printed successfully. Although the shape of Alg–Gel–
neuronal maturity. The research concluded that an CNFs-5 scaffold was not affected, there were multiple
electroconductive MWCNTs-based scaffold combined breakages in the printed lines. The biocompatibility
with electrical stimulation (ES) synergistically enhanced study using NIH-3T3 cells demonstrated that the
neurite outgrowth in nerve tissue regeneration. proliferation of the cells at 96 hours was higher for the
Alg–Gel–CNFs-0 group (110.43 ± 56.5%), followed by
Li et al. fabricated cylindrical large-sized blood vessels
using a hybrid bioink containing gelatin, sodium alginate, Alg–Gel–CNFs-0.5 (82.83 ± 23.9%).
and CNTs through a combination of perpendicular Skeletal muscle contains highly oriented and densely
directional extrusion of the printing nozzle (EBB type) packed myofibrils that are mechanically and electrically
and axial rotary motion of the stepper motor module [100] . active [114] . When injury occurs, the tissue’s self-regeneration
Murine epidermal fibroblasts harvested from the skins capacity may be limited in the case of volumetric loss.
of BALB/c rats were inoculated into the inner wall Although conventional therapeutic approaches have been
(3 mm) and outer wall (0.5 mm) of a hollow tubular developed to enhance the capacity, 3D bioprinting has
scaffold to imitate the vascular construct. The in vitro been found to be effective in recapitulating the native
study demonstrated that the doping of CNTs to the microenvironment of tissues with a parallel-aligned
scaffold reinforced its mechanical strength and electrical structure that induces biophysical signals. In a study, Bilge
conductivity, but the scaffold exhibited poor cell affinity. et al. synthesized carbonaceous materials derived from
Liu et al. prepared water-dispersible negatively charged algae-based biomass via hydrothermal carbonization
single-stranded deoxyribonucleic acid-stabilized CNTs and blended them (2% w/v) within a polycaprolactone
nanocomplex (ssDNA@CNTs) and incorporated (PCL) matrix in dichloromethane (70% w/v). They then
them into a 3D-printed scaffold composed of amine- developed 3D-printed scaffolds with dimensions of
functionalized PPF for bone tissue regeneration [101] . 15 mm × 5 mm × 0.5 mm using an EBB printer for skeletal
The VIPER si2 Stereolithography System based on PBB muscle TE [103] . Murine C2C12 myoblasts were incubated
equipped with a 365 nm UV laser was used to print the on the electroactive scaffolds and electrically stimulated
scaffold. The homogenous dispersion of the nanocomplex during the culture period. The electroactive scaffold
in the scaffold enhanced cell adhesion and proliferation groups promoted enhanced myotube formation following
as well as modulated cell behavior under ES. The various electrical stimulation compared with their non-conductive

Volume 9 Issue 1 (2023) 191 https://doi.org/10.18063/ijb.v9i1.635