3dbioink.com

A definition with cells in it

In 2019 Biofabrication published a fifteen-author consensus definition: a bioink is “a formulation of cells suitable for processing by an automated biofabrication technology that may also contain biologically active components and biomaterials”.1 Cells are mandatory; a printable material without cells is a biomaterial ink, seeded after printing or used for scaffolds and implants.1 The word is older: a 2013 review in Advanced Materials noted that the cell-laden hydrogels of biofabrication “are termed ‘bioinks’”.2

The bioink families

Bioinks are commonly hydrogels: water-rich networks that hold cells in a supportive 3D environment and are crosslinked after leaving the nozzle.2 The main families each set differently:

• Alginate. Ionic crosslinking with calcium. Blended with nanofibrillated cellulose, it printed ear- and meniscus-shaped cartilage with 73% and 86% chondrocyte viability after 1 and 7 days.3
• Gelatin methacryloyl (GelMA). Crosslinks under light and keeps gelatin’s cell-attachment motifs; used for bone, cartilage, cardiac and vascular tissue.4
• Collagen. The main extracellular-matrix protein. Printed with pH-driven gelation in a support bath at 20 µm resolution into heart valves and ventricles that contracted in sync.5
• Fibrin and plasma. Set enzymatically by thrombin. A plasma bioink with fibroblasts and keratinocytes printed 100 cm² of bilayered skin in under 35 minutes.6
• Decellularised extracellular matrix (dECM). Tissue-specific bioinks from adipose, cartilage and heart tissue.7
• Silk fibroin. Methacrylated for digital light processing; printed into heart, vessel, brain, trachea and ear shapes.8
• Synthetic polymers. Poly(ethylene glycol) diacrylate, cured by projection stereolithography into hydrogels with working vascular networks.9

Printability: what the rheology has to do

A 2017 proposal in Biofabrication tests an extrusion bioink in two steps: does it form a fibre and stack into a 3D construct, and what are its yield point, shear thinning and recovery. Printable inks needed a high yield stress.10 Longer gelation times gave poorer printability in gelatin/alginate bioinks.11 Very soft inks can be printed inside a bath of gelatin microparticles that yields under the nozzle and melts away at 37 °C; this FRESH method handles alginate, collagen and fibrin below 500 kPa.12

Cells have to survive the nozzle

Extrusion pushes cells through a micro-scale nozzle under pressure; the flow model above predicts high shear and long residence times at the needle wall.10 Embryonic stem cell viability fell exponentially with the shear stress induced during printing.11 Once printed, cells more than 100 to 200 µm from a nutrient source sit beyond the diffusion limit, which is why a 2016 human-scale system built microchannels into its constructs.13

Bioinks for 3D bioprinting: one material, several printers

Ink and printer are matched. Extrusion, which the ASTM guide calls “currently the most well-understood modality” for tissue-engineered products, lays down filaments.14 Light-based printers cure photoresponsive bioinks layer by layer,89 or all at once: volumetric bioprinting forms anatomically shaped constructs in seconds with viability above 85%.15

Standards and regulators

ASTM F3659-24, Standard Guide for Bioinks Used in Bioprinting, was approved on 16 April 2024 under Subcommittee F04.42. It covers extrusion bioprinting with bioinks and biomaterial inks, calls both bioinks, and includes sterility and cytocompatibility tests and post-printing viability measures.14 In December 2025 the FDA’s Center for Biologics Evaluation and Research (CBER) gave it complete recognition for regenerative medicine therapies.16 The shared vocabulary of additive manufacturing is ISO/ASTM 52900:2021.17

Regulation follows what is in the ink. The FDA’s 2017 guidance on additive manufactured devices does not address products with cells or tissues and points them to CBER.18 The FDA Modernization Act 2.0 of December 2022 lists bioprinting among the “nonclinical tests” a drug sponsor may use.19 The EU Medical Device Regulation does not apply to products containing viable biological material.20 Which framework applies depends on the product; nothing here is legal or medical advice.

3D bioink, bioink, biomaterial ink

Journals write “bioink” next to “3D bioprinting”.38 The ASTM guide folds biomaterial inks into the same word.14 In speech and in search the phrase is 3D bioink, the singular form 3DBioink.com holds; the plural, 3dbioinks.com, is a separate name from the same owner. Whatever a buyer prints, the material comes first.

1. Groll J et al. A definition of bioinks and their distinction from biomaterial inks.Biofabrication, 2019
2. Malda J et al. 25th anniversary article: Engineering hydrogels for biofabrication.Advanced Materials, 2013
3. Markstedt K et al. 3D bioprinting human chondrocytes with nanocellulose-alginate bioink for cartilage tissue engineering applications.Biomacromolecules, 2015
4. Yue K et al. Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels.Biomaterials, 2015
5. Lee A et al. 3D bioprinting of collagen to rebuild components of the human heart.Science, 2019
6. Cubo N et al. 3D bioprinting of functional human skin: production and in vivo analysis.Biofabrication, 2016
7. Pati F et al. Printing three-dimensional tissue analogues with decellularized extracellular matrix bioink.Nature Communications, 2014
8. Kim SH et al. Precisely printable and biocompatible silk fibroin bioink for digital light processing 3D printing.Nature Communications, 2018
9. Grigoryan B et al. Multivascular networks and functional intravascular topologies within biocompatible hydrogels.Science, 2019
10. Paxton N et al. Proposal to assess printability of bioinks for extrusion-based bioprinting and evaluation of rheological properties governing bioprintability.Biofabrication, 2017
11. Ouyang L et al. Effect of bioink properties on printability and cell viability for 3D bioplotting of embryonic stem cells.Biofabrication, 2016
12. Hinton TJ et al. Three-dimensional printing of complex biological structures by freeform reversible embedding of suspended hydrogels.Science Advances, 2015
13. Kang HW et al. A 3D bioprinting system to produce human-scale tissue constructs with structural integrity.Nature Biotechnology, 2016
14. ASTM F3659-24, Standard Guide for Bioinks Used in Bioprinting.ASTM International, approved 16 April 2024
15. Bernal PN et al. Volumetric bioprinting of complex living-tissue constructs within seconds.Advanced Materials, 2019
16. Standards Recognition Summary, Recognition Number 049: ASTM F3659 (2024).FDA CBER, December 2025
17. ISO/ASTM 52900:2021, Additive manufacturing. General principles. Fundamentals and vocabulary.ISO, edition 2, 2021
18. Technical Considerations for Additive Manufactured Medical Devices: Guidance for Industry and FDA Staff.FDA, 5 December 2017
19. Consolidated Appropriations Act, 2023, Public Law 117-328, Section 3209: the FDA Modernization Act 2.0.Approved 29 December 2022
20. Regulation (EU) 2017/745 on medical devices, Article 1(6)(h).European Parliament and Council, 2017