Bioprinting 101: Glossary

Exploring Key Terminologies in Bioprinting

Welcome to the Bioprinting Glossary, a guide to help you with all the complex terminologies in this field! Whether you are a student starting up in bioprinting or a researcher diving into the field, this guide is built to help you. It aims to help you understand the complex and ever-changing terminologies in this field!

1. 3D Bioprinting – 3D bioprinting is an advanced additive manufacturing technology that involves precise layer-by-layer deposition of cells, biomaterials, and bioactive molecules to create 3D tissues or organ constructs. It combines the principles of additive manufacturing, cell biology, and tissue engineering to fabricate complex biological structures.

2. Bed leveling – Bed levelling refers to the process of aligning the print bed to make a horizontal surface for bioprinting. This process ensures the accuracy of the bioprinted constructs.

3. Biocompatibility – Biocompatibility is the ability of biomaterials and bioinks to interact with living cells and tissues without causing adverse reactions or triggering immune responses.

4. Bioink – Bioink is a specialised material containing biomaterials, cells and bioactive factors like growth factors used in bioprinting to create 3D tissue constructs by depositing layers in a controlled manner. Bioinks typically consist of a biocompatible matrix, such as hydrogels or polymers. Embedded with living cells, growth factors, and other bioactive components necessary for tissue formation and regeneration.

5. Biomaterials – Biomaterials refer to biocompatible materials that are compatible with living tissues and are used to fabricate scaffolds for biomedical applications. Engineers specifically design these materials to interact with biological systems in ways that promote desired cellular responses, such as proliferation, differentiation, and tissue regeneration. Biomaterials are broadly classified as natural and synthetic biomaterials.

- Natural biomaterials are derived from natural tissues and living organisms.For example, alginate, a natural biomaterial, comes from seaweed. Additionally, specialists derive decellularized extracellular matrix-based biomaterials from human tissues. Decellularized ECM includes the natural proteins and other molecules left behind after removing cellular components from a tissue or organ. By decellularizing tissues, researchers can obtain ECM scaffolds that retain the intricate architecture and bioactive components of the native tissue. This makes them suitable for a wide range of biomedical applications.
- Synthetic biomaterials are artificially processed materials that are engineered to mimic the functions of natural tissues and organs, offering advantages such as tunable properties, controlled degradation, and tailored functionality. Commonly used synthetic biomaterials include Polycaprolactone (PCL), Polyurethane (PU), Poly(lactic-co-glycolic) acid (PLGA) and so on

6. Bioprinter – A bioprinter is a specialized 3D printer that is capable of bioprinting 3D structures composed of living cells, biomaterials, and bioactive molecules. It precisely deposits layers of bioink to create tissue-like constructs or organoids. In turn, enabling the development of biological tissues for applications in regenerative medicine, drug discovery, and tissue engineering.

7. Bioreactor – A bioreactor system used to provide a controlled environment for the cultivation and maturation of bioprinted tissue constructs. Bioreactors maintain optimal conditions such as temperature, pH, and oxygenation, by diffusing nutrients and facilitating cell growth, organization, and tissue development.

8. Build volume – Build volume refers to the maximum size of the object that a Bioprinter can print to.

9. CAD model – Computer-aided design (CAD) model is a digital representation containing information on the dimensions of biological structure or tissue construct created using CAD software. Commonly used CAD software for bioprinting includes Autodesk Fusion 360, SolidWorks, Rhino3D, Blender and so on.

10. Cells – Cells refer to the fundamental building blocks of living tissues that are used as the biological component in fabricating 3D tissue constructs. Researchers derive these cells from various sources, including human or animal cells, stem cells, and tissue-specific cells, and typically culture and prepare them before incorporating them into the bioink or biomaterial used for bioprinting.

- Stem cells are undifferentiated cells that can develop into specialised cells or tissues. These cells can originate from adult tissues or cells ( “adult stem cells”) or embryos generated during embryological development. Despite their origin, stem cells share three common characteristics. They can proliferate extensively; they are unspecialised; and, can be driven to develop into a tissue- or organ-specific cell phenotype. Commonly used stem cells include mesenchymal stem cells (MSC), induced pluripotent stem cells (IPSC), embryonic stem cells and so on
- Primary cells are tissue-specific cells that are derived from native tissues. Unlike stem cells, primary cells have low proliferative capabilities and undergo differentiation to form ECM. Some commonly used primary cells for 3D bioprinting involve fibroblasts, endothelial cells, chondrocytes, osteoblasts, etc

11. Compressor – An air compressor is a device that draws in air from the environment and releases it at an elevated pressure

12. Crosslinking – Crosslinking is a mechanism to improve gelation in bioinks for better structural, mechanical and physicochemical characteristics. Commonly used crosslinking mechanisms are defined below

Chemical crosslinking involves utilising covalent bonding between polymeric chains to create chemically crosslinked bioinks through various chemical reactions, including Schiff base coupling, hydrazide–aldehyde coupling, Diels–Alder linkage and azide–alkyne cycloaddition. These reactions are usually triggered by light or heat.

- Ionic crosslinking is a type of physical crosslinking that utilises ions of an opposite charge to water-soluble and charged polymers to crosslink hydrogels. Researchers commonly use multivalent cations, including Calcium, Barium, Zinc, and Strontium, for crosslinking bioinks.
- Photocrosslinking is a crosslinking that involves using photo-radiation to crosslink hydrogels. Common photocrosslinking mechanisms include UV, visible light etc. Photocrosslinkers are often attached to extruder heads/print heads for crosslinking hydrogels during the bioprinting process. This crosslinking strategy involves the formation of irreversible bonds between two polymer chains.
- Thermal crosslinking is a classification of physical crosslinking, thermal crosslinking is a mechanism that involves the application of heating or cooling to crosslink hydrogels. The thermal crosslinking system is often integrated with extruder heads/print heads and/or print beds in 3D bioprinters.

13. Dual-mode extruder head – Extruder or print heads that have the capability of heating and cooling, both, are known as dual-mode extruder head

14. Extracellular matrix (ECM) – ECM refers to the network of proteins and molecules that provide structural and biochemical support to cells within tissues. Incorporating ECM components into bioink formulations helps mimic the natural microenvironment of native tissues. This promotes cell adhesion, proliferation, and differentiation in 3D bioprinted constructs.

15. Extruder head/print head – The Extruder head/print head is a device that houses several components such as a syringe containing the bioink, nozzle, crosslinker, and so on. The extruder head extrudes bioinks and biomaterials onto the print bed.

16. Extrusion – Extrusion is a process of pushing the biomaterial through nozzles to produce 3D structures.

17. Feed rate – Feed rate refers to the speed at which bioink or biomaterial is extruded or deposited by the 3D bioprinter onto the print bed. It is a crucial parameter that influences the resolution, quality, and structural features of the bioprinted constructs.

18. G-code – G-code, or Geometric programming language, is a programming language used in 3D bioprinting. It is a set of instructions that tells a 3D bioprinter how to move, position, and operate during the bioprinting process. They serve as a standardized format for communicating instructions to the bioprinter’s control system. The G-code file typically contains a series of commands, each beginning with a letter followed by a numerical value.

19. Germicidal UV – A germicidal UV lamp refers to an accessory integrated into the bioprinting system for sterilization purposes. This UV lamp emits ultraviolet light at germicidal wavelengths (typically UVC) to disinfect the bioprinter’s internal components. The germicidal UV lamp can be activated before, during, or after printing sessions to sterilize the bioprinter.

20. Growth factors – Growth factors are signaling molecules that play an essential role in regulating cellular processes, including cell proliferation, differentiation, and migration. They are typically proteins or peptides that bind to specific receptors on the surface of target cells. They trigger an intracellular signaling pathways, and thus eliciting specific cellular responses. Commonly used growth factors include Epidermal growth factor (EGF), Fibroblast growth factor (FGF), Platelet-derived growth factor (PDGF), and Transforming growth factor-beta (TGF-β).

21. HEPA filter – A HEPA (High-Efficiency Particulate Air) filter is a type of air filtration device designed to capture and remove airborne particles and pollutants from the air. HEPA filters are highly efficient at trapping particles as small as 0.3 mm in size, with an efficiency of 99.97%. By incorporating HEPA filters into 3D bioprinters, the air within the printing chamber is continuously filtered, reducing the risk of contamination during the printing process. This helps to maintain aseptic conditions and ensure the viability of the bioprinted constructs.

22. Hydrogels – Hydrogels are hydrophilic polymer chains capable of absorbing and retaining large amounts of water. Hydrogels serve as a foundational bioink or scaffold material in 3D bioprinting due to their biocompatibility, tunable properties, and ability to support cell growth and tissue regeneration. Hydrogels can also be natural or synthetic by nature. Commonly used natural hydrogels include Collagen, Hyaluronic acid, Alginate etc. Synthetic hydrogels include Polyethylene oxide (PEO), Polyethylene glycol (PEG), Polyvinyl alcohol (PVA) and so on.

23. In vitro, in vivo and ex vivo – In vitro refers to experiments or processes conducted outside of a living organism, typically in a laboratory setting.
In vivo refers to experiments or processes conducted within a living organism, typically within an animal model or human subjects.
Ex vivo refers to experiments or processes conducted on tissues or cells removed from the organism and studied in an artificial environment outside of the body.

24. Inkjet bioprinting – Inkjet-based bioprinting is a non-contact bioprinting technique in which droplets of low-viscous bioink are dispensed. Inkjet technology is driven by thermal, piezoelectric, or microvalve processes. The conventional inkjet process used by desktop inkjet printers, which patterns a substrate using individual droplets, forms the basis for this technology.

Inkjet bioprinting

25. Laser-based bioprinting – Laser bioprinting uses laser energy to precisely position and immobilize cells and biomaterials onto a substrate or scaffold. This technique allows for high-resolution printing and control over cell positioning. It is suitable for applications requiring spatial control to create intricate tissue architectures.

26. Luer Lock Syringes – A Luer lock syringe is a syringe containing a threaded tip or connector known as a Luer lock. This threaded tip allows for a secure and leak-proof connection between the syringe and the needle.

27. Microfluidics– Microfluidics is a technology to control fluids at the microscale to perform cellular and molecular assays with accuracy and efficiency. Microfluidic devices incorporating this technology effectively etch tiny labs into a single chip, featuring microscopic chambers, tubes, and valves.

28. Needle gauge – A needle gauge refers to the lumen (opening) size. The higher the gauge, the smaller the diameter. For example, a 30 gauge needle has a narrower lumen than a 25 gauge needle.

29. Nozzle – The nozzle of a 3D bioprinter is part of the extruder through which the biomaterial or bioink is fed onto the print bed. The quality, material, and diameter of the nozzle determine the resolution of bioprinted models

30. Organoids – Organoids are 3D structures composed of self-organized cells that mimic the structure and function of miniature organs. Bioprinted organoids serve as models for studying organ development, disease mechanisms, drug screening, and personalized medicine, offering a platform to replicate and investigate biological processes in vitro.

31. Organ-on-a-Chip: An organ-on-a-chip is a microfluidic device engineered to replicate the structure and function of specific organs or tissues in vitro. Organ-on-a-chip devices incorporate bioprinted tissues or organoids within microfluidic channels to mimic organ-level physiology. Helping study complex interactions between cells, tissues, and fluids in a controlled environment.

32. Pellet extrusion – Pellet extrusion is a method used in additive manufacturing to create 3D objects layer-by-layer by extruding melted material through a nozzle. In pellet extrusion, the raw material is often synthetic polymers that are supplied in the form of pellets

33. Petri plate/Petri dish – A Petri dish or Petri plate is a shallow, cylindrical, lidded dish typically made of clear plastic or glass. They can vary from 35 mm to over 150 mm in diameter. It is commonly used in laboratory settings to culture cells, tissues, and microorganisms for various experimental purposes, including bioprinting.

34. Plunger – A component placed inside the syringe that aids in extruding bioink from the nozzle

35. Pneumatic – Operated by air pressure

36. Pressure gauge – A pressure gauge is a device to indicate air pressure

37. Print bed – A print bed refers to the surface on which a 3D object is bioprinted. The print bed serves as the foundation for the bioprinting process and plays a crucial role in ensuring the adhesion of the printed object to the build surface.

38. Print control software – Print control software is used to control and manage the operation of 3D Bioprinter. It acts as an intermediary between the user and the 3D Bioprinter. The software provides a user-friendly interface to interact with the bioprinter and initiate bioprinting tasks. Generally, print control software provides controls for starting, pausing, and stopping print jobs. It also allows for adjusting printer settings such as temperature and print speed. Furthermore, users can also manually control the movement of the printer’s axes for calibration or troubleshooting purposes. Commonly used print control softwares include Pronterface, OctoPrint, Repetier-Host, Ultimaker Cura, Simplify3D etc

39. Print optimisation – Print optimisation refers to the process of adjusting various bioprinting parameters and settings such as print speed, temperature, print feed etc to improve the quality, and efficiency, of the bioprinting process. The goal of print optimisation is to achieve optimal results in terms of print quality, speed, and material usage. At the same time, minimizing errors, defects, and print failures.

40. Print resolution – Printing resolution defines the quality, or level of detail, of the bioprinted material in the XYZ axes

41. Print speed – The speed at which the extruder head moves to deposit bioinks is called print speed. It is referred to in mm/s units.

42. Rheology – Rheology refers to the study of the flow and deformation of fluids and soft solids under stress. In 3D bioprinting, rheology helps characterize and understand the behavior of bioinks, hydrogels, and other biomaterials. These materials are used in the bioprinting process. The rheological properties of these materials play a critical role in determining their printability and extrudability.

43. Scaffold – A scaffold refers to a 3D structure or framework that serves as a temporary support system for cells to adhere, proliferate, and differentiate. Designers create scaffolds to mimic the ECM of native tissues and organs, providing a conducive microenvironment for tissue regeneration and growth.

44. Servo motor – A servomotor is a rotary or linear actuator. It allows for precise control of angular or linear position, velocity, and acceleration in a mechanical system.

45. Shear stress – In 3D bioprinting, shear stress refers to the mechanical force applied to the bioink or biomaterial as it flows through the printing nozzle during the printing process. Shear stress occurs during deformation in adjacent layers of the material that are moving at different velocities. It is a critical parameter in 3D bioprinting as it directly influences the flow behaviour of bioinks. In turn, maintaining cell viability, and preserving the structural integrity of the bioprinted scaffold.

46. Shear-thinning or thixotropy – Thixotropy or shear-thinning behaviour is the property of bioinks to become less viscous over time when subjected to constant stress. This is beneficial in bioprinting by allowing the bioink to flow more easily during extrusion. But it regains its original viscosity once deposited, helping to maintain structural integrity.

47. Slicing software – Slicing software, also known as slicing engines or slicers, converts a digital 3D model (typically in STL or OBJ file format) into a series of 2D layers to make a G-code. The 3D bioprinter reads this to fabricate the desired object layer-by-layer, forming a 3D object. Examples of popular slicing software include Ultimaker Cura, PrusaSlicer, Simplify3D, Slic3r, and others.

48. Spheroids – Spheroids are typically simple aggregates of cells at high densities that form spherical structures through self-assembly. Spheroids differ from organoids by lacking complex tissue or organ-specific architecture. Researchers commonly use spheroids as simple models for studying cellular behavior, drug responses, toxicity testing, and basic research applications.

49. Stereolithography-based bioprinting – Stereolithography bioprinting involves using a laser or other light source to selectively polymerize photosensitive biomaterials layer by layer to create 3D structures. Stereolithography offers high resolution and rapid printing speed. Making it suitable for fabricating microscale tissue constructs with precise control over feature size and geometry. However, it may be limited in the types of biomaterials that can be used.

50. Tissue engineering – Tissue engineering is a multidisciplinary field that combines principles of engineering, biology, and medicine to develop biological substitutes that restore, maintain, or improve the function of damaged or diseased tissues and organs in the body. It involves the design, and fabrication of biomimetic scaffolds using biomaterials, cells, and signalling molecules such as growth factors to create functional tissue constructs for biomedical applications.

51. Vascularisation – Vascularisation is the process of forming blood vessels within tissues or organs, enabling the transport of oxygen, nutrients, and waste products to and from cells. Vascularisation is essential for supporting the viability, functionality, and integration of engineered tissues and organs.

52. Viscosity – Viscosity is a parameter studied in rheology which refers to the resistance of a fluid to flow. Hence, high-viscous materials flow less readily than low-viscosity materials. Understanding the viscosity of bioinks and hydrogels is crucial for controlling their flow behaviour during extrusion and deposition in bioprinting.

53. Well plate – A well plate, also known as a microplate or multiwell plate, is a flat, rectangular or round laboratory device consisting of an array of individual wells arranged in rows and columns. Each well serves as a separate container for holding samples, reagents, or experimental conditions. Well plates are commonly made of clear sterile plastic or glass. Commonly used well plates for transwell bioprinting involve 6, 12, 24, 48, 96, and 384 wells.

Sign up for our newsletter

Stay up-to-date with the current developments in bioprinting by subscribing to our email newsletter.

CONTACT US

Send us a message by filling in the contact form here.

Address: Next Big Innovation Labs®,
Jyothy Institute of Technology
Kanakapura Main Road Thataguni,
Bengaluru, Karnataka 560082, India

GET STARTED

RESOURCES

JOIN
NEXT BIG INNOVATION LABS®

Next Big Innovation Labs® is a Deep Tech Lifesciences platform, focused on developing Bioprinting Technology and Products for R&D, Industrial and Clinical Applications.