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International Journal of Bioprinting 3D-printed nanocomposites: Synthesis & applications

substrate stiffness in some representative tissues has been provide finer control over filler alignment than those with
investigated. Therefore, by controlling the alignment single-material extrusion capability. By extruding multiple
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of AFs, the scaffold exhibits anisotropic mechanical materials at once, each with its own unique properties,
properties, thus regulating cellular behaviors. For instance, scientists may design structures with precisely controlled
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human umbilical vein endothelial cells (HUVECs) are filler orientation. This method is perfect for fabricating
found to align themselves along the direction of fibers. composite tissues and scaffolds with tailored architectural
Additionally, aligning the conductive fillers increases properties. In smart rheological control, the viscosity and
the possibility of filler connections, which help establish shear-thinning behavior of the bioink are adjusted for
conductive network and promote cell growth in scaffolds, optimal performance. By fine-tuning these characteristics,
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such as cardiac tissues. we can improve the bioink’s ability to aid with filler
alignment during printing. Rheological optimization
Filler alignment is a complex problem warranting a keeps the filler oriented while the bioink flows smoothly.
solution by means of novel technical approaches. There
are a number of intriguing approaches for achieving exact Filler alignment can be stabilized through post-printing
filler orientation, including the use of external stimuli like crosslinking techniques. After bioprinting, the structure
magnetic and electric fields, the optimization of nozzle can be treated with UV radiation, chemical crosslinkers,
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design, gradient printing, and multimaterial extrusion. or enzymatic reactions. The fillers can be permanently
Researchers can use external magnetic fields to precisely fixed in their preferred orientation using any one of these
move and align fillers in bioink that contains magnetic treatments to enhance the structure’s durability.
nanomaterials. This method provides interesting new The combination of smart rheological control, real-
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opportunities for the printing of highly shaped tissues time monitoring, and post-printing crosslinking has
by allowing for dynamic control over filler orientation placed us closer to realizing the full potential of bioprinting
both during and after the printing process. Pardo et al. in regenerative medicine and tissue engineering. However,
suggested that magnetically assisted 3D bioprinting and recreating the organization of ECM and the cell patterns
matrix-assisted 3D bioprinting be used together to make of anisotropic tissues in bioengineered constructs is still a
high-resolution hybrid composites that can not only copy major problem in the realm of biofabrication.
the anisotropy of native tissues but also allow for remote
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control of tissue constructs as they mature. For this 6. Applications of 3D-printed polymer
purpose, bioinks made of gelatin-methacryloyl (GelMA), composites for biomedical applications
short magnetically responsive microfibers (sMRFs), and
human adipose-derived stem cells (hASCs) were extruded To demonstrate the applicability of bioprinting in tissue
into fibrillar cellulose nanocrystals (CNCs)-based baths engineering, most studies focused on developing bioink
while low-strength magnetic fields were applied. This materials because cell-friendly environment is one of the
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produced high-resolution constructs with controlled most important factors influencing its feasibility.
anisotropic architectures. Additionally, AF-PNCs are under investigation as the
orientation of the AF has significant influence on the
In the quest for filler alignment, electric fields are cellular behaviors.
another potent instrument. Electrostatic forces can be used
to direct and orient charged fillers within the bioink. 6.1. Skin tissue
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It is feasible to engineer tissues with desired qualities by Skin is the largest organ of human body and composed of
aligning charged fillers to form structures using controlled multilayered structures, including epidermis, dermis, and
electric fields. Moreover, shear forces within the printing hypodermis, and various cell types, such as keratinocytes,
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nozzle can be manipulated to achieve filler alignment. fibroblasts, and melanocytes. Artificial skins can not
With optimized nozzle design, bioprinters may generate only serve as skin grafts for wound healing but also
controlled shear pressures on the bioink during extrusion. experimental platform to investigate its permeability
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Mechanically enforcing filler alignment along the shear and inflammatory response during the transdermal and
direction paves the way for highly anisotropic design. By topical drug formulation development and screening.
adjusting the filler content or bioink properties, gradient The development of techniques has allowed for the highly
printing is a flexible method. Fillers position themselves as accurate and complex 3D bioprinting of multistratified
bioink moves from one area to another, creating structures skin tissue that closely resembles natural skin.
with acceptable orientation gradients. This method is Cubo et al. fabricated a human plasma-derived bi-
applicable to the development of multilayered, complex layered skin. To replicate the structure of natural skin,
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tissues. Bioprinters with dual or multinozzle systems they printed the dermis with fibroblasts-laden fibrin
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Volume 10 Issue 2 (2024) 89 doi: 10.36922/ijb.1637