Researchers from George Washington University (GWU) have developed a 4D bioprinting technique to create multi-responsive smart structures for nerve regeneration. In a proof-of-concept study published in Advanced Biosystems, the researchers produced a smart nerve guidance conduit capable of “blooming like a flower.”
Blossoming 4D printed biostructures
Regenerative medicine research working towards functional artificial organs has enabled 3D printed complex vascular tissue structures and cell scaffolds for repairing the damage to the human body.
Nevertheless, according to the study, 3D printed biostructures with integrated time-dependent shape changes, i.e. 4D printing, “offers the opportunity to realize more complicated folded structures in biomedical devices or soft robotics, as well as in tissue engineering to mimic dynamic changes of native tissues and organs.”
The GWU researchers propose a stereolithographic 3D printing method applied with the “universal concept of stress‐induced shape transformation” to achieve the 4D dynamic reversible movement reminiscent of a flower in bloom. The following clip from GWU demonstrates the blooming movement.
SLA 4D printing
Using a naturally derived photocrosslinkable monomer – Soybean Oil Epoxidized Acrylate (SOEA) – as an ink, the GWU team were able to create a solidified flat star structure as a result to UV light‐induced graded internal stress.
The SOEA is then washed with ethanol for solvent‐induced relaxation which dynamically transforms the structure into a claw formation. This change is autonomous and reversible. Furthermore, various nanoparticles, such as nanohybrids with graphene, are incorporated into the structures during the printing process for further shape modification. This addition has been used to generate structures resembling flying birds.
Following an in-depth analysis, the researchers concluded that these smart structures can provide “outstanding multifunctional characteristics for nerve regeneration including physical guidance, chemical cues, dynamic self‐entubulation, and seamless integration.”
“By employing this fabrication technique, creating multiresponsive smart architectures, as well as demonstrating application potential, this work paves the way for true initiation of 4D printing in various high‐value research fields.”
The research paper “Stereolithographic 4D Bioprinting of Multiresponsive Architectures for Neural Engineering“ is co-authored by Lijie Grace Zhang, Shida Miao, Haitao Cui, Margaret Nowicki, Lang Xia, Xuan Zhou, Se‐Jun Lee, Wei Zhu, Kausik Sarkar, and Zhiyong Zhang.
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Featured image shows blossoming 4D smart structures forming birds and flowers. Photo via GWU.