3D printing, otherwise known as additive manufacturing, has become a key technology in the 21st century, engine of progress in several industries. A pre-proof that will appear in the newspaper Bioprinting investigated the development of 3D printed biodegradable polyester for tissue engineering and biomedical applications.
Study: Biodegradable polyester platform for extrusion bioprinting. Image Credit: Katunes pcnok/Shutterstock.com
3D bioprinting
3D bioprinting is an emerging tissue engineering technology that can produce products with complex architectures that mimic biological structures. Functional 3D products that display bioactivity and well-defined scaffold frameworks can be produced using the simultaneous delivery of two or more biopolymer materials.
There are four main fabrication techniques for bioprinting 3D and 4D functional biomimetic structures: stereolithographic, laser-assisted, inkjet, and extrusion additive manufacturing methods. Among these, extrusion-based methods have been widely explored due to their cost-effectiveness, compatibility with different cell types and biomaterials, and ability to fabricate both viscous hydrogels and thermoplastic polymers.
In extrusion bio-printing, bio-ink is constantly extruded from a nozzle according to a predefined digital design and deposited layer by layer onto a substrate material. Mechanical or pneumatic micro-extrusion is used to achieve the consistent distribution of viscous materials through the system nozzle.
Modern extrusion-based 3D printers use two or more printheads that can extrude multiple biomaterials and with the ability for multi-material and/or coaxial bioprinting, artificial tissues can be printed with many advanced mechanical properties .
Printing materials responsive to smart stimuli
Recent studies in the field of bioprinting have demonstrated that it is possible to create a composite matrix with intelligent stimulus-response behavior, expanding printed architecture beyond simple mechanical support. Aliphatic (co)polyesters have been widely explored for this purpose in tissue engineering due to their biocompatibility and biodegradability.
Bioinks are formulations of biomaterials that contain living cells, signaling molecules, and other biologically important molecules and structures. They are viscous solutions that can be easily printed by methods based on extrusion and other 3D printing techniques. Bio inks are normally converted from their liquid form into a stable hydrogel to help fix biological structures when printed. This can be achieved using thermally, photo or chemically induced crosslinking.
Due to their properties, hydrogels are commonly used to fabricate 3D and 4D bioprinted structures. They create hydrophilic networks that strongly resemble the organic extracellular networks of soft tissues and some hydrogels are inherently bioactive. Conversely, synthetic thermoplastic polymers are mainly used as mechanical supports.
Currently, many polymers that can be printed using additive manufacturing as bio inks are of organic or synthetic origin. Among the library of biocompatible polyesters available, PLA, PGLA and PCL are precursors due to their attractive biocompatibility, mechanical properties, ease of printing and formation of non-toxic products due to their sensitivity. to hydrolytic degradation.
Learn more about AZoM: Which raw materials can be 3D printed?
When choosing suitable biopolymers for bioprinting and tissue engineering, the materials should be biocompatible, biodegradable, non-toxic, and possess similar mechanical properties to the application of the bioprinted structure. This is crucial to meet the demands of tissue engineering and to maintain the viability of the grafted cells. Additionally, smart biopolymer capabilities such as shape morphing, size change, and functional responses to stimuli such as temperature, pH, and ionic strength facilitate 4D processing.
The study
Currently in pre-evidence, the study explored research in the field of 3D bioprinting and tissue engineering. In the research, the authors explored the most important synthetic biopolymers for extrusion 3D printing of functional tissue architectures.
One hundred and twenty-two studies were included in a comprehensive review of the current literature. Due to the extensive literature coverage, the authors did not discuss state-of-the-art 3D bioprinting applications for bone, cartilage, nerve, and liver tissue in detail.
PCL-based 3D bioprinting was discussed, with several applications highlighted in the study, including the use of PCL-based tubular structures for the bioengineering of nerve grafts, due to their properties adequate traction. Another application of this synthetic biopolymer that has been investigated recently is the use of 3D PCL scaffolds to support decellularized extracellular matrix.
PCL has also been widely explored for 4D processing due to capabilities such as shape memory effects exhibited by chemically cross-linked PCL networks. Recent studies have also explored the functionalization of PCL with magnetic nanoparticles to obtain responses to magnetic fields.
The study also investigated 3D PLGA bioprinting. One aspect of the current study highlighted is the use of PLGA to ensure bioactivity and biomechanical function due to scaffolds not possessing optimal mechanical properties that would otherwise make the material suitable for load-bearing applications. 3D and 4D PLA bioprinting was discussed by the authors, along with cryogenic 3D printing, a new 3D bioprinting technique that can fabricate porous, hierarchical, and biomimetic structures that possess gradient mechanical properties.
Based on their extensive review of the current literature and perspectives of 3D bioprinting with synthetic (co)polyesters, the authors concluded that there is vast application potential for this technology in the biomedical sciences. There are potentials to deliver bioactive molecules on the spot for applications such as tissue engineering and drug delivery. The possibility of custom-made biomimicry structures is exciting for the field of medical sciences.
Although the field of 3D bioprinting is still nascent, the authors predicted that it will revolutionize the field of biomedical science in the same way that 3D printing revolutionized engineering and manufacturing.
Further reading
Hermanova, S & Pumera, M (2022) Biodegradable polyester platform for extrusion bioprinting [pre-proof] Bioprinting e00198 | sciencedirect.com. Available at: https://www.sciencedirect.com/science/article/pii/S2405886622000082