Bioink

A bioink is a material that is made to produce artificial live tissues through 3D-printing. Bioinks can be made from many different types of materials as bases along with living cells. There are bioinks made from collagen, hyaluronic acid and more. Additionally, they might be used with other materials to envelope the cells in the bioink. Bioinks allow for a very high reproducibility in a controlled environment like a lab where they are typically used making them one of the most advanced tools in biomedical engineering and biotech.

Bioinks are engineered for specific body parts such as vascular tissue, which are blood vessels. This tissue type has a couple requirements, such as resembling native blood vessels and maintaining geometric precision. The similarity to native blood cells arises from how the body treats foreign substances as invaders and destroys them. Because of this, the new artificial blood vessels need to be similar to native ones to bypass the immune system. The geometric precision comes from the nature of the tissue, a blood vessel transports blood to and from the heart to the rest of the body and needs to be able to transport blood efficiently. Along with all of these and many more physiological requirements, there are a couple things that must be supported by bioinks. Endothelialization, which is the formation of an inner lining must be accounted for, smooth muscle alignment, so that the new tissue is flexible and can contract and stretch, and extracellular membrane deposition for long term structural integrity.

Additionally, the base material of a bioink can also affect how it works and what restrictions and requirements it has. Collagen, one of the most abundant extracellular membrane proteins, is difficult to print due to its low viscosity, slow gelation and poor material strength. Despite all of this, collagen manages to be highly biocompatible, and these restrictions are bypassed through blending with other polymers or fillers. Some of these polymers include alginate, hyaluronic acid and GelMA. Alternatively, chemical modifications can be made like methacrylation which enables UV/photo-cross linking and dramatically improves printing fidelity.

References:

Gungor-Ozkerim, P Selcan, et al. “Bioinks for 3D Bioprinting: An Overview.” Biomaterials Science, U.S. National Library of Medicine, 1 May 2018, pmc.ncbi.nlm.nih.gov/articles/PMC6439477. 

Synofzik, Judith, et al. “Ink-Structing the Future of Vascular Tissue Engineering: A Review of the Physiological Bioink Design - Bio-Design and Manufacturing.” SpringerLink, Springer Nature Singapore, 7 Mar. 2024, link.springer.com/article/10.1007/s42242-024-00270-w. 

Debnath, Souvik, et al. “Collagen as a Bio-Ink for 3D Printing: A Critical Review.” Journal of Materials Chemistry B, The Royal Society of Chemistry, 8 Jan. 2025, pubs.rsc.org/en/content/articlelanding/2025/tb/d4tb01060d. 

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