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International Journal of Bioprinting 3D printing innovations against infection

possesses remarkable level of control and precision, this method is relatively slow and limited by droplet
empowering researchers to tailor complex cellular size and accuracy. On the other hand, extrusion-based
structures that faithfully mimic the microenvironment bioprinting technology relies on continuous dispensing of
found within living organisms. 29,30 bioink or biomaterials to print 3D structures containing
antimicrobial material through a nozzle controlled by
FDM stands out as the most widely employed method
in 3D printing, where a thermally melted plastic filament— a computerized robotic arm (Figure 1E). However, this
typically composed of acrylonitrile butadiene styrene (ABS) method presents some challenges in terms of maintaining
Laser-
cell viability and improving printing accuracy.
43,44
or polylactic acid (PLA)—is extruded through a tiny nozzle. based bioprinting methods employ laser beams to precisely
This process involves the deposition and stacking of material focus biomaterials, solidifying or crosslinking them at the
layer-by-layer on a build platform, ultimately yielding a intended location and gradually building a 3D structure
3D object with precision and detail, often enhanced with (Figure 1F). The focused laser pulse will generate a bubble
specific functionalities such as antimicrobial properties. In and shock waves forcing biomaterials to transfer toward the
addition, 3D prints fabricated using novel FDM technology collector substrate. Although allowing for high resolution
with thermally melted filaments were able to maintain and precise positioning, this method may pose challenges
relatively high cell viability of 70%–90% when interacting for highly viscous or concentrated biomaterials. Selective
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with cells. 31-33 This finding provides strong support for the laser sintering (SLS) and selective laser melting (SLM)
use of FDM in biomedical applications. The entire printing stand out as prominent laser-based 3D printing techniques
process is governed by a digital model generated through extensively employed in crafting materials ranging from
CAD software. Its advantages lie in its simplicity, ease of use, metals to plastics. Selective laser sintering, a 3D printing
and relatively low cost, making it suitable for prototyping, method, constructs objects layer by layer, predominantly
rapid manufacturing, and personalized production. 34,35 utilizing powdered materials like plastics or metals. Its
However, the limitations of FDM are heat and pressure, distinctive feature lies in its ability to handle intricate
which constrain its application in bioprinting to some geometries without necessitating a support structure,
degree 36,37 (Figure 1A). Stereolithography represents an thanks to the unsintered or unmelted powder serving as
advanced micro- and nano-fabrication technology primarily built-in support. This quality makes SLS particularly adept
used to create micro-sized, high-precision 3D structures, at producing functional parts and prototypes. Selective
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and as a common technique for 3D printing, uses an laser melting mirrors the principles of SLS but is tailored
ultraviolet (UV) light laser, instead of heat, to cure a liquid for laser-melting metal powders on a build platform, as
antimicrobial ink of photopolymer mixed with antibiotics opposed to polymer powders used in SLS for creating 3D
and create a 3D structure layer by layer. Stereolithography objects. Typically applied in fabricating intricate structural
is instrumental in crafting micro biochips, microfluidic components from robust, high-temperature materials,
devices, and bionic structures, fostering the development SLM finds applications in industries like aerospace and
of biomedical research and medical devices associated with medicine. Notably, SLM boasts higher material density
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infection (Figure 1B). Digital light processing printing and superior mechanical properties compared to SLS.
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technology is a more recent alternative method that uses a
digital UV light projector for curing liquid photopolymers 3. Mechanism of biofilm formation on the
with higher printing speed and resolution (Figure 1C). In
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the DLP printing process, the photopolymer is poured into surface of 3D-printed materials
a container, and the UV light is projected through a mask Biofilm formation is the process by which microorganisms,
or a set of mirrors that are used to control the pattern of such as bacteria, attach to a surface and produce a slimy,
light to reach the photopolymer. Nevertheless, DLP printing slippery mass surrounded by a matrix of cells. This matrix
is restricted to antibiotics (other than quinolones) and is called a biofilm and consists of extracellular polymeric
biomaterials that can be photocured and do not biodegrade substances (EPS) secreted by microorganisms. Biofilms
under UV light. Inkjet-based bioprinting methods use can form on a variety of surfaces, including medical
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minute quantities of biological droplets to precisely place devices, natural environments, and industrial equipment.
biomaterials at specific locations through jetting or drip Biofilm formation may have important implications as
irrigation (Figure 1D). This technique is applicable to a wide these microbial populations are often more resistant to
range of materials, including bioinks, conductive materials, antibiotics and the immune system, leading to persistent
and ceramics, offering flexibility and versatility. 41,42 Therefore, infections and other problems in different environments.
it can be utilized for printing a 3D object with antimicrobial When an implant is placed in the host, it triggers the host’s
agents by heating or piezoelectric to form droplets of bioink. own fibrous tissue to create a barrier that wraps around the
Despite possessing high precision in handling biomaterials, implant in all directions. This is not only a natural response

Volume 10 Issue 4 (2024) 126 doi: 10.36922/ijb.2338