(Image courtesy of Delft University of Technology.)
Complete regeneration of functional tissues is the holy grail of tissue engineering and could revolutionise treatment of many diseases. Effective tissue regeneration often calls for multifunctional biomaterials. A lot of research is currently going in that field.
One example is the large research project, led by Maastricht UMC and with TU Delft as one of the participants, in the field of ‘smart’ 3D printed implants for recovery of bone defects. The project started this month; if it’s successful, it will lead to faster recovery of patients and less operations.
But the potential applications of 3D printed bio-implants is much bigger than only bone defects. Dr. Amir Zadpoor is one of the researchers at TU Delft in this field, cooperating closely with hospitals.
“Ideally, biomaterials should be optimised not only in terms of their 3D structure but also in terms of their surface nano-patterns,” said Zadpoor. “3D printing enables us to create very complex 3D structures, but the access to the surface is very limited during the 3D printing process. Nanolithography techniques enable generation of very complex surface nano-patterns but generally only on flat surfaces. There was no way of combining arbitrarily complex 3D structures with arbitrarily complex surface nano-patterns.”
Origami and 3D Printing
Zadpoor looks to the ancient Japanese art of paper folding (origami) to solve this deadlock. In this approach, flat surfaces are first 3D printed in a particular way to teach them how to self-fold. The flat surface is then decorated with complex nano-patterns. Finally, the self-folding mechanism is activated (for instance by a change in temperature) to enable folding of the flat sheet and the formation of complex 3D structures.
“We used different arrangements of bi- and multi-layers of a shape memory polymer (SMP) and hyperelastic polymers to program four basic modes of shape-shifting including self-rolling, self-twisting (self-helixing), combined self-rolling and self-wrinkling, and wave-like strips,” Zadapoor added.
Some of the modes of shape-shifting were then integrated into other two-dimensional constructs to obtain self-twisting DNA-inspired structures, programmed pattern development in cellular solids, self-folding origami, and self-organizing fibers.
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