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International Journal of Bioprinting 3D bioprinting of ultrashort peptides for chondrogenesis

1. Introduction conducted layer-by-layer with the nozzle suspended above
the print and carried along a set platform. This approach
Hydrogels are a class of materials composed of hydrophilic allows the extrusion of bioinks with high cell density,
networks of crosslinked polymers, which can be used to which makes them preferred candidates for cellular 3D
[1]
mimic the extracellular matrix (ECM) of the body . These bioprinting. It is also cost-effective and easily customizable.
materials have been used in tissue engineering for various However, its main tradeoff is its limitations in resolution
applications, including chondrogenic engineering. They and speed .
[15]
can create a three-dimensional (3D) structure to support
the growth of cells and can be used to deliver drugs and Another procedure is material jetting, which uses
other therapeutic agents . A variety of natural and an inkjet technique for 3D-bioprinting desired objects.
[2]
synthetic hydrogels, including collagen, polyacrylamide, It involves droplet formation through piezo-electric or
and hyaluronic acid-based hydrogels, have been used in thermally induced bubbles and downstream ejection
chondrogenic engineering. However, one of the main created by a volumetric change upstream of the nozzle [16-20] .
disadvantages of natural hydrogels, such as collagen and Its high printing speeds, cost-effectiveness, and contactless
hyaluronic acid, is their limited mechanical strength, method that reduces contamination risks make it a viable
which can limit their use in specific applications . 3D bioprinting approach. However, the fact that it is more
[3]
Moreover, the synthetic polyacrylamide hydrogel are suitable for highly viscous bioinks makes it less possible
poorly biocompatible, very costly, and difficult to work for cellular 3D bioprinting . Hence, extrusion-based
[15]
with [4,5] . approaches are preferred for the creation of cell-laden
On the other hand, ultrashort peptide hydrogels have bioprinted structures.
gained recognition recently, particularly for biomedical The final technique for 3D bioprinting is vat
applications and tissue engineering . These ultrashort photopolymerization. It includes several approaches, such
[6]
peptide hydrogels possess a range of properties that make as stereolithography (SLA) and digital light processing
them particularly attractive for tissue engineering and (DLP) . The primary approach comprises solidifying
[14]
regenerative medicine applications. For example, they a photo-initiated liquid material using a laser or LCD
are biocompatible, biodegradable, and nontoxic, and light source. A platform upon which the liquid is set, is
have the spontaneous ability to rapidly form a hydrogel continuously raised after the light source hardens each
at concentrations as low as 0.01% under physiological layer, thus creating a high-resolution print structure . In
[21]
conditions . Furthermore, these ultrashort peptide SLA, the laser is directed at specific solidification points to
[6]
hydrogels can be designed to have a range of mechanical form layers. On the other hand, in DLP, the laser is directed
properties, such as stiffness, elasticity, and strength, making at the entire surface, and the use of a mask between it and
them highly suitable for use in various tissue engineering the liquid achieves solidification of the desired regions.
applications . Intuitively, this approach offers very high resolution but
[6]
Chondrogenic engineering is a rapidly growing field of does not allow the incorporation of cells during the 3D
biotechnology that focuses on using stem cells and other bioprinting process, making it challenging to incorporate
[21]
cell types to create new tissues and organs . It is a complex high cell densities into a construct .
[7]
and challenging field of research since it requires the Different 3D bioprinting materials have been used
development of effective and safe methods for delivering to fabricate cartilage constructs. Xue et al. tested the
therapeutic agents to the target tissue, controlling the possibility of culturing cartilage precursor cells with
growth and differentiation of the engineered cells, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) to
ensuring that the engineered cells can integrate into the manufacture tissue-engineered cartilage . Another group
[22]
existing tissue and function properly . Recent studies have reported the creation of cartilage constructs using collagen
[8]
demonstrated that 3D bioprinting may be a promising hydrogels and human mesenchymal stromal cells (MSCs) .
[23]
in situ cartilage regeneration strategy [9-12] . 3D bioprinting However, one of the main disadvantages of PHBV is its
has provided an avenue for the regeneration of functional relatively high cost. Additionally, the production process
cartilage in many applications .
[13]
for PHBV is more complex and energy-intensive than
3D bioprinting techniques are mainly divided into other thermoplastics, further increasing the cost . On
[24]
three main categories: material extrusion, material jetting, the other hand, collagen is a protein that is sensitive to
and vat polymerization . The most widely used technique temperature and pH changes, which can cause it to degrade
[14]
is extrusion-based printing, involving the extrusion over time. This could result in a reduction of the structural
of biomaterials from nozzles using either mechanical integrity of the printed construct, making it difficult to
or pressure-based pumping systems. The extrusion is maintain its shape and form. Additionally, collagen is

Volume 9 Issue 4 (2023) 63 https://doi.org/10.18063/ijb.719