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Materials Science in Additive Manufacturing 3D-printed nozzle for 3D bioprinting

eco-friendly coral restoration [5-7] . One of the main branches low-viscosity bioinks to reduce shear force in the nozzle
of 3D printing technology is 3D bioprinting, which fabricates and eliminate post-printing crosslinking procedures. For
cell-based tissue constructs for tissue engineering and instance, several low-viscosity bioinks for 3D bioprinting
regenerative medicine . 3D bioprinting is revolutionizing and cell culture have been developed [19,20] . Incorporating
[8]
tissue engineering with its ability to create cell-integrated the mixing of multiple solutions before extrusion offers the
structures with complex geometries, which were previously potential for creating structures with various properties.
unattainable with traditional manufacturing methods. Multi-material bioinks consisting of solutions such as
Nevertheless, 3D bioprinting technology is still confined proteins, hydrogels, and cells can create a more realistic
by certain constraints. One significant constraint is 3D-bioprinted structure that could be advantageous for
related to the 3D printing of structures similar to the tissue engineering applications.
complex hierarchical structure of natural tissues . Various
[9]
3D printing technologies are used today in 3D bioprinting, In multiple studies, extrusion-based 3D bioprinting and
such as extrusion-based and vat polymerization. customized 3D-printed parts have been combined to create
tissue scaffolds with desired characteristics. For instance,
Vat polymerization is one of the 3D printing Khan et al. combined vat polymerization and extrusion-
[21]
technologies used in fabricating tissue engineering based 3D bioprinting to create a complex human-like ear
scaffolds, relying on a light source, and polymerization structure. Likewise, Abdelrahman et al. implemented a
reaction to cure a photocurable bio-based resin . The hybrid 3D bioprinting and vat polymerization approach
[10]
materials utilized in vat polymerization for 3D bioprinting for the modeling of Parkinson’s disease using dopaminergic
are usually photocurable resins and photocrosslinkable neurons . Furthermore, Scott et al. have 3D-printed
[22]
[23]
hydrogels. Using photocrosslinkable hydrogel in vat a nozzle to enable multi-material 3D bioprinting using
polymerization can enable cell encapsulation and replicate an extrusion-based system. This allows the nozzle to mix
the extracellular matrix found in native tissue . Elomaa multiple solutions and create a multi-material structure.
[11]
et al. developed a bioactive photocrosslinkable resin Through further research, researchers have looked into
[12]
derived from a decellularized small intestine submucosa the advantages of merging various 3D printing techniques
for vat polymerization-based 3D bioprinting. The for utilization in different applications [6,24] . It has been
developed bioactive resin offers a printable material that demonstrated that the convergence of 3D printing
acts as a suitable medium for fabricating a complex 3D techniques can upgrade 3D bioprinters and exploit material
tissue model. However, vat polymerization application in characteristics for enhanced printability and resolution.
fabricating cell-based scaffolds is limited due to the high
ultraviolet (UV) exposure intensity and the cytotoxicity Herein, we propose a design and fabrication process
effect of polymerization reaction . Consequently, this for disposable nozzle connectors (DNC) to accelerate the
[13]
technique is limited to fabricating acellular scaffolds that nozzle-making process for low-viscosity bioinks. It was
can only be seeded with cells post-printing. Therefore, curated to allow instantaneous mixing of three solutions for
other 3D printing technologies can provide the necessary the formulation of a continuous bioink thread embedded
freedom in fabricating and mimicking 3D tissue models. with cells. The connectors were designed to easily fit into
standard Luer lock needle tips, making them versatile and
Extrusion-based 3D printing is a technique that is
widely used in fabricating cell-based scaffolds in the 3D compatible with a wide range of mixing requirements and
bioink viscosities. Our design parameters were set for the
bioprinting process [14,15] . More recently, there has been
an interest to integrate smart and intelligent biomaterials material characteristics of peptide bioinks, and several
with 3D printing technology . A pressure-based or tests were performed to assess workability and printability.
[16]
mechanical feeder is used to extrude material through a With a thorough evaluation, the developed DNC proved
nozzle . While this layer-by-layer approach facilitates to be cost-effective, reproducible, and highly practical for
[17]
fabrication, it has limitations with low-viscosity materials standardization.
when creating complex structures due to resolution 2. Methods
constraints and instantaneous gelation properties of soft
matter bioinks, such as peptide hydrogels. On the other With the assistance of vat polymerization technology,
hand, high-viscosity biomaterials produce a high shear several DNCs were designed to suit peptide bioink
force, resulting in a high degree of cell destruction during requirements and 3D-printed with varied final diameters
extrusion. Often, cross-linking methods are used to reduce and mixing regions. An ideal design was selected based
the viscosity of biomaterials and improve cell viability . on ease of flow and effective gelation. The 3D-printed
[18]
However, alternative solutions could be developed by DNCs were assembled with Luer lock needle tips to
maximizing the instantaneous gelation property of create fully functional nozzles with multiple inlets and a

Volume 2 Issue 1 (2023) 2 https://doi.org/10.36922/msam.52