A new way of 3D printing soft biomaterials

Significance 

A new way of 3D printing soft materials such as gels and collagens offers a major step forward in the manufacture of artificial medical implants.

Developed by researchers at the University of Birmingham, the technique could be used to print soft biomaterials that could be used to repair defects in the body.

Printing soft materials using additive manufacturing has been a big challenge for scientists because if they are not supported, they sag and lose their shape. The new technique, called Suspended Layer Additive Manufacturing (SLAM), uses a polymer-based hydrogel in which the particles have been manipulated to create a self-healing gel. Liquids or gels can be injected directly into this medium and built up in layers to create a 3D shape.

The method offers an alternative to existing techniques which use gels that have been minced to form a slurry bath into which the printed material is injected. Called Freeform Reversible Embedding of Suspended Hydrogels (FRESH), these offer many advantages, but frictions within the gel medium can distort the printing.

In a study published in Advanced Functional Materials, a team led by Professor Liam Grover, in the School of Chemical Engineering, show how particles in the gel they have developed can be sheared, or twisted so they separate, but still retain some connection between them. This interaction creates the self-healing effect, enabling the gel to support the printed material so objects can be built with precise detail, without leaking or sagging.

SLAM can also be used to create objects made from two or more different materials so could be used to make even more complex soft tissue types, or drug delivery devices, where different rates of release are required.

About the author

Prof Alan Smith is a Professor of Biopolymer Science. He graduated from Salford University (Biochemical Science) in 1997 before gaining his PhD from Cranfield University developing polysaccharide substitutes for gelatin in the production of pharmaceutical capsules under the supervision of Prof. Ed Morris. Following his PhD he worked for 2 years as a formulation scientist within the pharmaceutical industry before taking up a position as a polysaccharide chemist at Industrial Research Limited, Wellington, New Zealand. On his return to the UK he has worked as a research fellow at the University of Birmingham (School of Dentistry) and Aston University (School of Pharmacy) developing 3D cell scaffolds and polysaccharide based drug delivery systems.

In 2008 he joined the tissue regeneration and interface laboratory within Chemical Engineering at the University of Birmingham where he continued to develop his research on biopolymers for tissue engineering and drug delivery applications before being appointed as a Senior Lecturer in Pharmaceutics at the University of Huddersfield in March 2011, promoted to Reader in 2016 and to Professor in 2018.

Reference

Senior, J.J. et al. (2019) Fabrication of Complex Hydrogel Structures Using Suspended Layer Additive Manufacturing (SLAM). Advanced Functional Materials. doi.org/10.1002/adfm.201904845.

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