Page 192 - IJB-9-1

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

single component or heterogeneous components combined 2. CFNs in biomedical applications
with additives, such as copolymers, nanoparticles, and CFNs, composed of carbon elements, represent various
crosslinking agents [39,40] . There is less toxicity in hydrogel spatial arrangements, such as zero-dimensional carbon
composites with the use of naturally available polymers, quantum dots, nanodiamonds, fullerenes, one-dimensional
including gelatin, chitosan, alginate, and pectin. Synthetic CNTs, nanofibers, nanowires, two-dimensional (2D)
polymers including pluronic, methacrylic acid, poly(vinyl graphene nanosheets, and 3D networks or their bulk
alcohol) (PVA), and poly(ethylene glycol) (PEG) have counterparts [59-63] . Their carbon atoms are organized in a
been blended with natural polymers to increase the cubic or hexagonal lattice following sp or sp hybridization
2
3
stability, biodegradation time, and mechanical strength in conventional allotropes, including diamond and
of the produced hydrogel composites . Gelatin graphite [64,65] . Since the discovery of fullerenes (1985), CNTs
[41]
methacrylate (GelMA) is a commonly employed (1991), and graphene (2004), CFNs have been extensively
polymeric component of printable gels in microextrusion researched on in recent decades [66-68] . CNTs are widely
and laser-based bioprinters because it exhibits used in various fields, including energy production and
photocurable properties by UV radiation [42,43] . Pluronic storage, material science, environmental sciences, as well
F127 (poloxamer 407) hydrogel is thermoresponsive, and as biomedical sciences, owing to their unique properties
it is often used as a sacrificial material, mold, and track (small size, large surface area, and ultrathin thickness) [69-75] .
patterning in TE . When functionalized with the cell- When the colloidal stability of CFNs in aqueous suspensions
[44]
adhesive peptide arginyl-glycyl-aspartic acid (RGD), is poor, the surface of the material is modified using
photoactive PVA hydrogels augment cell attachment and covalent and non-covalent functionalization techniques,
enhance fibroblast spreading . The choice of polymer such as oxidation, dehydrogenation, plasma treatments,
[45]
affects the crosslinking reactions and mechanisms and ozonolysis [76,77] . Oxidized carbon nanomaterials
involved in printable gel. Photopolymerization is a may have 5% to 50% oxygen content depending on the
prominent crosslink reaction in printable bioinks, as synthetic procedures, thus making them water-dispersible
it enables control in space and during gelation . Free when used in several biological applications, including TE
[39]
radical polymerization of acrylate derivatives is often and tissue regeneration , as shown in Figure 2. Carbon
[78]
used to fabricate photoresponsive bioinks; however, nanomaterials like GO and CNTs have been reported to
many researchers have employed photoinitiated thiol-ene exhibit superior optical absorption and near-infrared (NIR)
crosslinking as an alternative to the former method to form conversion properties . The supramolecular π–π stacking
[79]
homogeneous hydrogel networks [46,47] . Thermosensitive in the structure enables them to adsorb a large amount of
polymers, which form supramolecular hydrogels through drug, while their tunable surface chemistry enables them
hydrophobic interactions within a certain temperature to control drug release [80-82] . Yin et al. formulated a multi-
range, have been used in bioprinting formulations [48,49] . functionalized monolayer GO composite to deliver small
Small molecule-mediated cross-linkages, such as calcium interfering RNAs to target pancreatic cancer cells MIA
chloride, glycerylphytate, and curcumin, have also PaCa-2. The tumor volume was reduced by more than
supported the fabrication of printable gels with highly fine 80% with the synergistic combination of gene silencing
printability and customizable mechanical properties [50-52] . and NIR light thermotherapy of the composite . Various
[83]
In order to improve viscosity and printability as well as electrochemical sensors and label-free CFNs-based
enhance cellular activities, researchers are now creating biosensors have also been developed in consideration
complex 3D printable structures that incorporate of their remarkable electronic properties . In a study,
[84]
nanomaterials into bioinks, which leads to the fabrication a composite of antibodies-grafted CNTs was used as an
of functional tissues. Carbonaceous nanomaterials, immunosensor for detecting adiponectin, an obesity
hydroxyapatite, silica-based bioceramics, nanosilicates, biomarker. Cyclic voltammetry was used to monitor
bioactive glasses, strontium carbonate, and their doped the reaction of secondary antibodies conjugated with
nanocomposites [53-56] have been used as additives in horseradish peroxidase-streptavidin with adiponectin and
printable inks for the fabrication of varying scaffolds to quantify them, thus enabling fast detection .
[85]
for TE. In view of their biocompatibility, electrical
conductivity, and mechanical strength, carbon-based The introduction of CFNs into soft materials, such
nanomaterials are frequently used in printable inks [57,58] . as hydrogels, enhances the functional properties of the
In this review, we discuss the contribution of carbon- resulting 3D multicomponent systems; the features of
family nanomaterials (CFNs), such as graphene, graphene CFNs-containing hydrogels meet the requirements of
oxide (GO), and carbon nanotubes (CNTs), in bioink the promising strategies, which makes them advanced
formulation and their biomedical applications for tissue biomaterials in biomedical research [78,86] . Hossein et al.
regeneration. have reported that CNT-loaded nanocomposite hydrogels

Volume 9 Issue 1 (2023) 184 https://doi.org/10.18063/ijb.v9i1.635