Page 240 - IJB-9-1

International Journal of Bioprinting 3D printing of smart constructs for precise medicine

Figure 1. Illustration of 3D-printed or -bioprinted smart constructs with various intelligent functions in response to external or internal stimuli and their
biomedical applications for tissue regeneration, drug delivery, and diagnosis or monitoring.

materials selected as the basal matrix. Even microcarriers
of cells (e.g., micro-spheroids and -cylinders) and cell
aggregates (composed of only cells) qualify as bioinks.
However, to support cell viability and performance, bioinks
should provide a friendly environment that optimally
mimics the native microenvironment of the human body.
Therefore, bioactive hydrogels that resemble the structure
and composition of the natural extracellular matrix (ECM)
are commonly used in bioinks (Figure 2). Based on their
source, hydrogel bioinks can be divided into two categories,
natural (e.g., collagen, gelatin, alginate, chitosan, cellulose,
fibrin, and their derivatives) and synthetic bioinks (e.g.,
polyethylene glycol (PEG) and Pluronic F127), which have
been comprehensively reviewed .
[19]
In addition, the fabrication techniques designed for each
biomaterial and bioink should be classified accordingly.
Since cells are vulnerable to harsh manufacturing
conditions, such as heat, moisture, pH, osmotic pressure,
and irradiation, 3D printing techniques used for building
structures using biomaterials might not be applicable Figure 2. A schematic for categorizing prevalent 3D printing and
for bioinks. 3D bioprinting, which is based on several bioprinting techniques and distinguishing bioinks from biomaterial inks.
conventional 3D printing techniques, has been developed
to utilize bioinks to fabricate living constructs. or polymerization) in a layer-by-layer manner to rapidly
construct 3D objects by following complex designs that
2.2. General overview of conventional 3D printing are difficult to produce using traditional manufacturing
techniques approaches, such as milling, cutting, drilling, and

3D printing, also known as additive manufacturing (AM) lathing . Since its invention in the 1980s, 3D printing
[20]
or rapid prototyping, is a versatile fabrication technique techniques have been applied to a broad range of domains,
that can assemble a wide range of materials using such as engineering, medicine, military, food industry, and
various principles (e.g., deposition, binding, sintering, education. Its distinctive advantages and vast demands in

Volume 9 Issue 1 (2023) 232 https://doi.org/10.18063/ijb.v9i1.638