Page 10 - IJB-9-1

International Journal of Bioprinting Biocompatible materials and Multi Jet Fusion

accessibility is a major limitation. Therefore, cartilage which convert mechanical stimuli into biochemical signals
regeneration or substitute through a tissue-engineered that regulate various cellular pathways . The mechanical
[24]
scaffold is extensively explored. stimulation is further enhanced by shear forces exerted on
Three-dimensional (3D) bioprinting emerges as a cells during 3D bioprinting [7,25] . This phenomenon is known
versatile method to manufacture structurally defined as mechanotransduction and is one of the chondrogenesis
constructs . In short, 3D bioprinting utilizes a carrier stimulators.
[4]
matrix termed bioink to provide a microenvironment for Extrusion-based bioprinting, which is the most
cells suspended within it . The main advantage of 3D popular type of bioprinting, utilizes compressed air or a
[5]
bioprinting is the architectural control over products . mechanical piston to extrude bioink from a cartridge [5,26] .
[6]
A perfectly tailored scaffold can be developed using data It is a relatively affordable technique and is compatible
from various imaging techniques, like magnetic resonance with various materials, including alginate- and gelatine-
imaging (MRI) . The growing interest in this field of based bioinks [27,28] . The applicability of extrusion-based
[7]
research is anticipated . Presently, 3D bioprinting is bioprinting can be expanded by integrating additional
[8]
used to manufacture tissues, organs, or cancer models for modules, such as the microfluidic printhead or the UV
research, including orthopedic applications . module for photo-curable materials [29,30] . Inkjet bioprinting
[9]
is another 3D bioprinting technology that ejects droplets;
Literature presents various bioink compositions
developed for orthopedic 3D bioprinting . An hence, it allows the manufacturing of constructs in a
[5]
. Laser-assisted bioprinting
drop-on-demand fashion
[31,32]
interesting idea is to formulate bioink based solely on the systems, such as laser-induced forward transfer (LIFT) and
decellularized extracellular matrix (ECM) from porcine vat polymerization-based bioprinting, can also be used as
menisci [10,11] . This low immunogenic component exhibits 3D bioprinting techniques for cartilage tissue engineering.
good biocompatibility and stimulates chondrogenesis. LIFT is a nozzle-free and noncontact technique that
However, constructs suffer from poor mechanical stability, is applicable for high-viscosity bioinks with high cell
which is an issue that has to be addressed. Polycaprolactone densities . The laser is pulsed on a ribbon that absorbs
[5]
(PCL) is frequently used as a reinforcement in orthopedic energy and generates a bubble of bioink on the opposite
applications [12,13] . For example, PCL supports alginate- side [5,33] . Vat polymerization is based on the polymerization
based bioinks mixed with porcine inner or outer meniscal of photo-curable inks in vats and is mainly used for 3D
ECM [10,14] . Nevertheless, ECM extraction requires the use printing with inks without cells. Nevertheless, digital light
of surfactants that may elicit cytotoxic effects even at low processing is a vat polymerization technology that has
concentrations . Alternative methods of supercritical been successfully used for bioprinting with bioinks mixed
[15]
carbon dioxide (CO ) extraction require advanced and with cells [34,35] . A bioink composed of alginate, gelatin, and
2
costly equipment. As a result, alginate, collagen derivatives, carboxymethylated cellulose nanocrystal (CCNC) was
chitosan, nanocellulose, and hyaluronic acid are some of formulated and evaluated for meniscal tissue engineering.
the more widely investigated biomaterials .
[5]
The addition of CCNC is a novelty selected for its
The most commonly used bioink component is an carboxymethylated groups that increase its solubility. All
accessible and affordable alginate that crosslinks with materials are natural, biocompatible, accessible, and
divalent cations, usually calcium ions (Ca ). Nonetheless, affordable. Rheological analysis was performed on bioinks
2+
the rapid alginate gelation limits the control over this with varying concentrations of alginate, gelatin, and CCNC.
process during bioprinting . Therefore, it is usually Based on the rheological analysis, a bioink was selected for
[16]
mixed with other materials, like gelatin, to obtain printing accuracy analysis, and the bioink was subsequently
bioinks with dual-stage gelation . The gelation of gelatin enriched with normal human knee articular chondrocytes
[7]
is temperature-dependent; it is fluid above 30°C but (NHAC-kn) for 3D bioprinting. The constructs were
solid at lower temperatures. In addition, gelatin, unlike created with an extrusion-based bioprinter. The viability
alginate, has a positive charge that ensures cell and protein and gene expression of the embedded cells were assessed.
binding . Alginate-gelatin bioink is commonly used as a
[17]
basis for bone and cartilage tissue engineering [18–20] . 2. Materials and methods
In cartilage-related research, the addition of 2.1. Bioink preparation for rheological analysis
nanocellulose enhances the mechanical properties and Table 1 presents the investigated bioink formulations.
shear forces affecting cells and printability [7,21,22] . The cell Firstly, weighted sodium alginate (Sigma-Aldrich),
mobility inside constructs and phenotypic changes are gelatin from porcine skin (Sigma-Aldrich), and CCNC
related to the mechanical properties of bioink . Cells (Cellulose Lab) were sterilized under ultraviolet (UV) light
[23]
detect mechanical stress through mechanoreceptors, for 30 minutes. The components were then dissolved in

Volume 9 Issue 1 (2023) 2 https://doi.org/10.18063/ijb.v9i1.621